Abstract:

This essay uses topographic map evidence to interpret landform origins in the Clear Creek-Bear Creek drainage divide area in the Colorado Front Range. Clear Creek is a north and east oriented stream originating in the Colorado Front Range and joining the north, southeast, and northeast oriented South Platte River on the Colorado Piedmont slightly north of Denver. Bear Creek originates east of the north oriented Clear Creek headwaters and flows in an east-northeast and east direction to join the South Platte River slightly south of Denver. Through valleys or mountain passes link the Clear Creek and Bear Creek valleys and with the valley of an east and northeast oriented Clear Creek tributary. The through valleys are found in high mountain areas where the streams originate and also where the streams emerge from the Front Range to flow onto Colorado Piedmont before reaching the north oriented South Platte River. Valley orientations and the through valleys are interpreted in the context of massive melt water floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada to and across Colorado at a time when the Colorado Front Range was just beginning to emerge. East oriented valleys eroded headward in sequence from south to north from south oriented flood flow channels on the Colorado Piedmont to capture south oriented flood flow moving across the emerging Front Range. Headward erosion of the Bear Creek valley captured south and southeast oriented flood flow prior to headward erosion of the east oriented Clear Creek valley. Headward erosion of the Clear Creek valley beheaded and reversed flood flow channels to the newly eroded Bear Creek valley and then beheaded and reversed south oriented flood flow channels west of the Bear Creek valley head to create north oriented Clear Creek headwaters drainage routes. Headward erosion of the deep southwest oriented Colorado River valley north of the Clear Creek headwaters beheaded and reversed south oriented flood flow channels to the Clear Creek headwaters area. At about the same time headward erosion of the deep southeast and northeast oriented South Platte River valley from western Nebraska beheaded south oriented flood flow channels on the Colorado Piedmont. Floodwaters on north ends of beheaded flood flow channels reversed flow direction to create north oriented South Platte River and tributary drainage routes. Ice sheet related crustal warping raised the Front Range and Colorado as floodwaters flowed across the region and probably contributed significantly to flood flow reversals. After flood flow across the region had ended and after the Front Range had become a high mountain range mountains in the Clear Creek and Bear Creek headwaters area were glaciated and valley glaciers deepened and otherwise altered some of the flood eroded valleys.

Preface

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.

Introduction

The purpose of this essay is to use topographic map interpretation methods to explore the Clear Creek-Bear Creek drainage divide area landform origins in the Colorado Front Range. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big-picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain Clear Creek-Bear Creek drainage divide area landform evidence in the Colorado Front Range will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Clear Creek-Bear Creek drainage divide area location map

Figure 1: Clear Creek-Bear Creek drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a location map for the Clear Creek-Bear Creek drainage divide area in the Colorado Front Range and illustrates a region in central Colorado. The South Platte River flows in a north-northeast and north direction from the south center edge of figure 1 to the north edge of figure 1 (east half). North of figure 1 the South Platte River turns to flow in a southeast and then northeast direction to join the North Platte River in western Nebraska and to form the Nebraska Platte River with water eventually reaching the Gulf of Mexico. The Colorado Front Range is located west of the north-northeast and north oriented South Platte River, which is located on the Colorado Piedmont. South Platte River headwaters originate in the Front Range and flow in a southeast direction near the towns of Alma, Fairplay, and Hartsel before reaching the south edge of figure 1 and then turning to flow in a north-northeast direction. North oriented streams near the east edge of figure 1 are tributaries to the southeast oriented South Platte River segment north of figure 1. The green colored area straddling the north edge of figure 1 is the south end of Rocky Mountain National Park. The Colorado River flows in a south direction to Lake Granby at the southwest corner of Rocky Mountain National Park, where it turns to flow in a west-southwest and southwest direction to the west edge of figure 1 (north half) with water eventually reaching the Pacific Ocean. Clear Creek and Bear Creek are shown in figure 1, but are not labeled. Clear Creek is difficult to see and flows in an east direction through Idaho Springs and Golden to join the South Platte River just north of Denver. Bear Creek is easier to see and originates near Mount Evans before flowing in an east-northeast direction to Evergreen and then in an east direction to join the South Platte River near Englewood. The Clear Creek-Bear Creek drainage divide area investigated in this essay is located south of Clear Creek and north of Bear Creek and extends from the Bear Creek headwaters to the South Platte River.

Colorado drainage routes developed during immense melt water floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada to and across Colorado at a time when Colorado mountain ranges were beginning to emerge. The mountain ranges emerged as floodwaters flowed across them, as ice sheet related crustal warping raised the mountain masses and the entire state of Colorado, and as deep valleys eroded headward into Colorado from the Gulf of Mexico and from the Pacific Ocean to capture the massive south oriented melt water flood flow. Present day north oriented South Platte River and tributary drainage routes on the Colorado Piedmont originated as south oriented flood flow channels east of the emerging Front Range. East oriented valleys, such as the Bear Creek and Clear Creek valleys eroded headward from those south oriented flood flow channels in sequence from south to north to capture south and southeast oriented flood flow in the Front Range region. The south oriented flood flow channels on the Colorado Piedmont were captured by headward erosion of the southeast oriented Arkansas River south of figure 1 (south oriented Arkansas River headwaters can be seen near the southwest corner of figure 1). Subsequently headward erosion of the deep southeast and northeast oriented South Platte River valley from western Nebraska (north of figure 1) beheaded the south oriented flood flow channels on the Colorado Piedmont. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow in a north direction to the deeper southeast and northeast oriented South Platte River valley and to create the north oriented South Platte River drainage route and tributary drainage routes seen today. The reversed flood flow captured southeast oriented flood flow still moving across the emerging Front Range. Headward erosion of the deep southwest oriented Colorado River valley then beheaded the south and southeast oriented flood flow channels to the south and southeast oriented Arkansas River and South Platte River headwaters. Floodwaters on north and northwest ends of beheaded flood flow channels reversed flow direction to create north-northwest and northwest oriented Colorado River tributaries. These flood flow captures and reversals took place as ice sheet related crustal warping was raising the entire region and large mountain masses within the region.

Detailed location map for Clear Creek-Bear Creek drainage divide area

Figure 2: Detailed location map of Clear Creek-Bear Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a detailed location map for the Clear Creek-Bear Creek drainage divide area in the Colorado Front Range. Green colored areas are National Forest lands, which in Colorado are usually located in mountain regions. The Denver metropolitan area is located in the east half of figure 2 and the Colorado Front Range is located west of the metropolitan area. The South Platte River flows in a north-northeast direction from the south edge of figure 2 (east half) to the northeast corner of figure 2. South of figure 2 the South Platte River flows in a southeast and then north-northeast direction through Platte Canyon to reach the town of South Platte near the south edge of figure 2. North of figure 2 the South Platte River flows in a north-northeast and north direction before turning in a southeast and northeast direction to flow to western Nebraska. Berthoud Pass is located near the northwest corner of figure 2. The West Fork Clear Creek flows in an east direction from the west edge of figure 2 (just south of Berthoud Pass) to the town of Empire and then to join north and east oriented Clear Creek. South Clear Creek originates near Mount Wilcox (near west edge of figure 2-south of center) and flows in a north direction to Georgetown where it joins east oriented Clear Creek, which turns to flow in a north direction to be joined by its east oriented West Fork before turning to flow in an east direction to flow to Idaho Springs and then to Golden before flowing to join the South Platte River near the northeast corner of figure 2. East of the north oriented Clear Creek headwaters is north-northeast oriented West Chicago Creek, which joins north and northeast oriented Chicago Creek, which then joins east oriented Clear Creek near Idaho Springs. North oriented Chicago Creek headwaters originate just north of Mount Evans. Beaver Brook is the unlabeled east-northeast oriented Clear Creek tributary joining Clear Creek west of Golden. Bear Creek originates just east of Mount Evans and flows in an east-northeast direction to Brookvale, Rosedale, and Evergreen before flowing into the Denver metropolitan area where it joins the South Platte River near Englewood. Corral Creek is the unlabeled south and southeast oriented tributary joining Bear Creek near Brookvale and Vance Creek is the unlabeled east-northeast and east-southeast oriented tributary joining Corral Creek west of Brookvale.

Clear Creek-Vance Creek drainage divide area

Figure 3: Clear Creek-Vance Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of Clear Creek-Vance Creek drainage divide area. The map contour interval for figure 3 is 50 meters. South Clear Creek flows in a north direction from the south edge of figure 3 (near southwest corner) to Georgetown where it joins east oriented Clear Creek, which turns to flow in a north direction before gradually turning to flow in an east and east-southeast direction to Idaho Springs before flowing in an east direction to the east edge of figure 3. East of figure 3 Clear Creek flows in an east direction to join the north oriented South Platte River. West Fork Clear Creek flows in an east direction from the west edge of figure 3 (near northwest corner) through Empire to join east oriented Clear Creek. Empire Pass is located south of Empire and links the east-oriented West Fork valley with the north-oriented Clear Creek headwaters valley. Empire Pass is defined by five contour lines on the northeast side suggesting the pass is at least 200 meters deep. Empire Pass was eroded by south oriented flood flow moving to a south oriented flood flow channel on the present day north oriented South Clear Creek headwaters alignment. The south oriented flood flow channel was beheaded and reversed by headward erosion of the east oriented Clear Creek and West Fork Clear Creek valley. Goliath Peak is located just north of the south center edge of figure 3 and Idaho Springs Reservoir is west of Goliath Peak. Chicago Creek flows in a north and northeast direction from Idaho Springs Reservoir to join east oriented Clear Creek at Idaho Springs. Vance Creek originates east of Goliath Peak and flows in a northeast and east-southeast direction to join south and southeast oriented Corral Creek near the southeast corner of figure 3. South and east of figure 3 Corral Creek joins east oriented Bear Creek, which then flows to the north-oriented South Platte River. Corral Creek originates on the south side of Squaw Pass. North of Squaw Pass are headwaters of northwest oriented Little Bear Creek, which flows to Soda Creek, which then flows to Clear Creek, although the north side of Squaw Pass is drained by an east-northeast tributary to east-northeast oriented Beaver Brook (east of figure 3), which flows to Clear Creek. Squaw Pass was eroded by southeast and south oriented flood flow prior to headward erosion of the east-northeast oriented Beaver Brook and tributary valley, which captured the south oriented flood flow. Headward erosion of the east oriented Clear Creek valley then beheaded and reversed the southeast and south oriented flood flow channel to create the northwest oriented Little Bear Creek drainage route. North of Goliath Peak a west-to-east oriented through valley links the north oriented Chicago Creek valley with an east oriented Vance Creek tributary valley. The through valley floor elevation is between 3250 and 3300 meters. Elevations on Goliath Peak reach 3721 meters and the Clear Creek-Vance Creek drainage divide to the east rises to more than 3500 meters suggesting the through is at least 200 meters deep. The through valley was eroded by south and east oriented flood flow moving on the present day north oriented Chicago Creek alignment to the east oriented Vance Creek and Bear Creek valleys prior to headward erosion of the deep east oriented Clear Creek valley and its northeast oriented Chicago Creek tributary valley. Headward erosion of the northeast oriented Chicago Creek valley segment beheaded and reversed the south oriented flood flow channel to create the north and northeast oriented Chicago Creek drainage route seen today.

Detailed map of Chicago Creek-Vance Creek drainage divide area

Figure 4: Detailed map of Chicago Creek-Vance Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed topographic map of the Chicago Creek-Vance Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 4 is 40 feet. South Chicago Creek can be seen flowing in a northeast direction across the northwest corner of figure 4 and joins Chicago Creek north of figure 4. Chicago Creek flows in a north direction from near the southwest corner of figure 4 to the north edge of figure 4 (near northwest corner). North of figure 4 Chicago Creek turns in a northeast direction to join east oriented Clear Creek. Vance Creek flows in a northeast and east direction from the south center edge of figure 4 to the east center edge of figure 4. East of figure 4 Vance Creek joins Corral Creek, which then flows to east oriented Bear Creek. Beaverdam Creek is an east oriented tributary flowing from section 32 to join Vance Creek in section 34. Echo Lake in section 31 is located in a west-to-east oriented through valley linking the north oriented Chicago Creek valley with the east oriented Beaverdam and Vance Creek valleys. The through valley floor elevation is 10,650 feet. Goliath Peak to the south rises to 12,216 feet and Warrior Mountain to the northeast rises to 11,273 feet suggesting the through valley is approximately 620 feet deep. The through valley is a water-eroded valley and was eroded by south and east oriented flood flow moving from the present day north oriented Chicago Creek alignment to the east oriented Beaverdam Creek-Vance Creek alignment. The south oriented flood flow on the Chicago Creek alignment was beheaded and reversed by headward erosion of the east oriented Clear Creek valley and its northeast oriented Chicago Creek tributary valley (north of figure 4). The Chicago Creek flood flow reversal was probably greatly aided by crustal warping that was raising the Chicago Creek headwaters area. Echo Lake is in a closed depression bounded on the west by a linear ridge that probably is a lateral moraine. If so, the glaciation responsible for the lateral moraine occurred after all flood flow in the region had ended and after crustal warping had uplifted the region and mountains to create the high mountains seen today. The lateral moraine valley would have been formed by a glacier extending northward in the Chicago Creek valley from the higher Chicago Creek headwaters area to the south of figure 4 (to at least the Echo Lake location). A valley glacier in the Chicago Creek valley probably would have deepened the Chicago Creek valley, but would not have eroded new valleys such as the west-to-east oriented through valley.

Clear Creek-Corral Creek drainage divide area

Figure 5: Clear Creek-Corral Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Clear Creek-Corral Creek drainage divide area east of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 50 meters. Clear Creek flows in an east-southeast direction to Idaho Springs from the northwest corner of figure 5 and then in an east direction to the east edge of figure 5 (near northeast corner). East of figure 5 Clear Creek flows to the north oriented South Platte River. Squaw Mountain is south of Idaho Springs and Squaw Pass is located east of Squaw Mountain. The northwest oriented stream north of Squaw Mountain is Little Bear Creek, which flows to north-northeast oriented Soda Creek, which joins Clear Creek at Idaho Springs. The east and east-northeast oriented stream originating east of Little Bear Creek and flowing to join Clear Creek near the northeast corner of figure 5 is Beaver Brook. Beaver Brook headwaters are located north of Squaw Pass. Bear Creek flows in a northeast and east-northeast direction from the south edge of figure 5 (west of center) and then makes a southeast jog to Evergreen Lake before turning in a northeast direction to flow to the east edge of figure 5 (south of center). East of figure 5 Bear Creek flows in an east direction to join the north oriented South Platte River. Corral Creek is a south and southeast oriented tributary flowing from near Squaw Pass to join Bear Creek near Brookvale. Vance Creek flows in a northeast and southeast direction from the west edge of figure 5 (near southwest corner) to join southeast oriented Corral Creek. East of Squaw Pass is Mount Judge. The southeast oriented Bear Creek tributary east of Mount Judge is Witter Gulch. A northwest-to-southeast oriented through valley or pass located east of Mount Judge links a northwest oriented valley draining to east-northeast oriented Beaver Brook with the southeast oriented Witter Gulch valley. Squaw Pass has an elevation of between 2950 and 3000 meters. Mount Judge to east rises to 3140 meters suggesting Squaw Pass is at least 140 meters deep. The Beaver Brook-Witter Gulch through valley or pass has a floor elevation of between 2750 and 2800 meters. Snyder Mountain to the east rises to at least 3000 meters suggesting the through valley or pass is approximately 200 meters deep. Squaw Pass and the Beaver Brook-Witter Gulch through valley (or pass) provide evidence of what were probably diverging and converging south or southeast oriented flood flow channels flowing to the actively eroding Bear Creek valley at a time when the Beaver Brook and Clear Creek valleys to the north did not exist. The southeast oriented flood flow moved on the alignment of present day northwest oriented Little Bear Creek. Headward erosion of the east-northeast oriented Beaver Brook valley captured the southeast and south oriented flood flow and beheaded flood flow channels to the southeast oriented Witter Gulch and to the south and southeast oriented Corral Creek valleys. A 300-meter deep through valley links the northwest oriented Little Bear Creek headwaters valley with the southeast oriented Beaver Brook headwaters valley. The through valley was eroded by southeast oriented flood flow captured by headward erosion of the east-northeast oriented Beaver Brook valley. Headward erosion of the east oriented Clear Creek valley and its north-northeast oriented Soda Creek tributary valley subsequently beheaded and reversed the southeast oriented flood flow channel to Beaver Brook to create the northwest oriented Little Bear Creek drainage route.

Detailed map of Beaver Brook-Corral Creek drainage divide area

Figure 6: Detailed map of Beaver Brook-Corral Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed topographic map of the Beaver Brook-Corral Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet. Beaver Brook flows in a southeast direction in section 17 and then turns to flow in an east and east-northeast direction to the northeast corner of figure 6. North and east of figure 6 Beaver Brook flows to east oriented Clear Creek. Deadman Gulch is the north-northeast and east-northeast oriented Beaver Brook tributary in section 20. The north-northeast oriented stream flowing across the northwest corner of figure 6 is the headwaters of northwest oriented Little Bear Creek, which flows to north-northeast oriented Soda Creek, which in turn flows to east oriented Clear Creek. Squaw Pass is located in the southwest corner of section 20 and has an elevation of 9798 feet and links the north-northeast and east-northeast oriented Deadman Gulch valley with the south oriented Corral Creek valley. South of figure 6 Corral Creek turns in a southeast direction to join east oriented Bear Creek. Squaw Mountain to the west rises 11,486 feet and Mount Judge to the east rises to 10,301 feet suggesting Squaw Pass is approximately 500 feet deep. A northwest-to-southeast oriented through valley or pass is located near the east edge of section 28 and links a northwest and north oriented Beaver Brook tributary valley with the southeast oriented Witter Gulch valley. South of figure 6 Witter Gulch drains to east oriented Bear Creek. The through valley or pass elevation is 9185 feet. Snyder Mountain to the east rises to 9876 feet suggesting the through valley or pass is almost 700 feet deep. Further east between Snyder Mountain and Mount Pence another through valley or pass links the northwest and north oriented Lewis Gulch valley with a south oriented Witter Gulch tributary valley. This third through valley or pass has an elevation of between 9520 and 9560 feet. Mount Pence reaches an elevation of 9800 feet suggesting this third through valley or pass is at least 240 feet deep. While difficult to imagine based on present day topography these three through valleys or passes were eroded by diverging and converging flood flow channels at a time when the Beaver Brook valley did not exist.  Floodwaters were probably flowing to what at that time was the actively eroding east-oriented Bear Creek valley. Headward erosion of the deep east and east-northeast oriented Beaver Brook valley captured the southeast and south oriented flood flow and eroded the 1100-foot deep through valley in the northwest corner of figure 6 linking the northwest oriented Little Bear Creek valley with the southeast, east, and east-northeast oriented Beaver Brook valley. Headward erosion of the east oriented Clear Creek valley and its north-northeast oriented Soda Creek valley (north and west of figure 6) beheaded and reversed the southeast oriented flood flow channel (to the Beaver Brook valley) to create the northwest oriented Little Bear Creek drainage route.

Detailed map of Clear Creek-Beaver Brook drainage divide area

Figure 7: Detailed map of Clear Creek-Beaver Brook drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 provides a detailed topographic map of the Clear Creek-Beaver Brook drainage divide area seen in less detail in figure 5 (east of Saddle Back Mountain) and is located north and east of figure 6. The map contour interval for figure 7 is 40 feet. Clear Creek meanders in an east direction from near the northwest corner of figure 7 to the east edge of figure 7 (north half). Beaver Brook flows in a northeast and east direction from the south center edge of figure 7 (near Golden City Reservoir) to the east edge of figure 7 (south half). East of figure 7 Beaver Brook flows in an east-northeast direction to join east oriented Clear Creek. Saddleback Mountain is located in section 10 (southwest quadrant of figure 7). Beaver Brook Canyon drains in a south-southeast direction on the west side of Saddleback Mountain to east oriented North Beaver Brook, which flows on the south side of Saddleback Mountain and which then joins northeast and east oriented Beaver Brook. A northwest-to-southeast oriented through valley in the south half of section 2 links a northwest oriented Clear Creek tributary valley with a southeast oriented Beaver Brook tributary valley. The through valley is used by the highway to cross the Clear Creek-Beaver Brook drainage divide. The through valley floor elevation at the drainage divide is between 7920 and 7960 feet. Elevations in section 2 to the north and east of the through valley rise to 8695 feet and Saddleback Mountain to the southwest rises to 9568 feet suggesting the through valley is almost 750 feet deep. The through valley is a water eroded valley and was eroded by a southeast oriented flood flow channel, which was beheaded and reversed by headward erosion of the deeper east oriented Clear Creek valley to create the northwest oriented (and barbed) Clear Creek tributary drainage route. This drainage history implies diverging and converging flood flow channels crossed the region because the only way the east oriented Clear Creek valley could capture the southeast oriented flood flow channel would be if floodwaters were flowing on both alignments simultaneously.

Beaver Brook-Bear Creek drainage divide area

Figure 8: Beaver Brook-Bear Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the Beaver Brook-Bear Creek drainage divide area east of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 8 is 50 meters. The east flank of the Colorado Front Range can be seen near the east edge of figure 8. East of the Front Range is the Colorado Piedmont. Clear Creek flows in an east and northeast direction from the west edge of figure 8 (near northwest corner) to the north edge of figure 8 (near northeast corner). North and east of figure 8 Clear Creek flows to the north oriented South Platte River. Beaver Brook flows in an east and northeast direction from the west center edge of figure 8 to join east oriented Clear Creek in the north center area of figure 8. Bear Creek flows in an east-northeast direction from the southwest corner of figure 8 before turning in a southeast direction to Evergreen Lake (near south edge of figure 8). Bear Creek flows in a northeast, east-southeast, and east direction from Evergreen Lake to the east edge of figure 8 (south half). In the center of figure 8 multiple southeast and south-southeast oriented tributaries flow to the northeast oriented Bear Creek segment. These tributaries include Troublesome Creek, Kerr Gulch, Swede Gulch, and Cold Spring Gulch. Headwaters of these southeast and south-southeast oriented Bear Creek tributaries are linked by shallow northwest-to-southeast oriented through valleys with the northeast oriented Beaver Brook valley and its northeast oriented Soda Creek tributary valley. The through valleys are defined by only one or two contour lines on a side suggesting they are may be less than 50 meters deep. However these northwest-to-southeast oriented through valleys suggests diverging and converging southeast oriented flood flow channels crossed the region prior to headward erosion of the northeast oriented Beaver Brook valley and its northeast oriented Soda Creek tributary valley. Headward erosion of the Beaver Brook valley and its tributary Soda Creek valley then captured the southeast oriented flood flow, which was subsequently captured by headward erosion of the deeper east oriented Clear Creek valley.

Lakewood Gulch-Bear Creek drainage divide area

Figure 9: Lakewood Gulch-Bear Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Lakewood Gulch-Bear Creek drainage divide area east and slightly north of figure 8 and there is an overlap area with figure 8. The map contour interval for figure 9 is 50 meters. The Colorado Front Range eastern flank is near the west edge of figure 9 and the Colorado Piedmont is east of the Front Range. The South Platte River flows in a north and northeast direction from the south edge of figure 9 (near southeast corner) to the northeast corner of figure 9. North of figure 9 the South Platte River flows in a north-northeast, and north direction before turning in a southeast and then northeast direction to flow into western Nebraska. Clear Creek flows in an east-northeast direction from the west edge of figure 9 through Golden to the north edge of figure 9 (east of center). North of figure 9 Clear Creek joins the South Platte River. Bear Creek flows in an east direction from the west edge of figure 9 (near southwest corner) to join the north oriented South Platte River near the south edge of figure 9. A north-to-south oriented hogback ridge in the southwest quadrant of figure 9 is labeled “Hogback” and is located along the Front Range eastern flank. Bear Creek has eroded a 200-meter deep or deeper water gap through that hogback ridge and a north-to-south oriented through valley is located west of the hogback ridge. The through valley orientation is determined by the geologic structure, but the through valley is a water-eroded valley and was eroded by south oriented flood flow. East of the north end of the hogback ridge is Green Mountain and a north-to-south oriented through valley is located between the hogback ridge and Green Mountain. These north-to-south oriented through valleys were eroded by diverging and converging south oriented flood flow channels as deeper east oriented valleys eroded headward across the emerging hogback ridge and into the emerging Front Range. The east oriented valleys eroded headward from south oriented flood flow channels on the present day north oriented South Platte River alignment to capture south oriented floodwaters further to the west. Headward erosion of the east oriented Bear Creek valley began at a time when valleys the hogback ridge had not yet been eroded. Headward erosion of the southeast and northeast oriented South Platte River valley (north of figure 9) beheaded the south oriented flood flow channels on the Colorado Piedmont. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to create the north oriented South Platte River drainage route.

Detailed map of Lena Gulch-Rooney Gulch drainage divide area

Figure 10: Detailed map of Lena Gulch-Rooney Gulch drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a detailed topographic map of the Lena Gulch-Rooney Gulch drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 40 feet. The Front Range eastern flank is located in the west half of figure 10. Green Mountain is located in the east half of figure 10 and Dinosaur Mountain is the north-to-south oriented hogback ridge between Green Mountain and the Front Range. Mount Vernon Creek flows in an east direction from the west edge of figure 10 (south half) through Mount Vernon Canyon to Dinosaur Mountain and then turns in a south direction to flow to the south edge of figure 10 (west of center). South of figure 10 Mount Vernon Creek joins east oriented Bear Creek, which then flows through a water gap across the Dinosaur Mountain hogback ridge to reach the South Platte River. Rooney Gulch is the south oriented drainage route immediately east of Dinosaur Mountain and west of Green Mountain. Rooney Gulch drains to the south center edge of figure 10. South of figure 10 Rooney Gulch drains to Bear Creek. Lena Gulch originates on the west side of Dinosaur Mountain just north of the highway interchange (and north of the south oriented Mount Vernon Creek segment) and drains in a north direction to the hogback ridge north end where it turns in an east-northeast direction to the north edge of figure 10 (east half). North of figure 10 Lena Gulch drains to Clear Creek. A north-to-south oriented through valley on the east side of Dinosaur Mountain links the Lena Gulch valley with the south oriented Rooney Gulch valley while a north-to-south oriented through valley on the west side of Dinosaur Mountain links the north oriented Lena Gulch headwaters valley with the south oriented Mount Vernon Creek valley. The eastern through valley has a floor elevation of approximately 6200 feet while the western through valley floor elevation is approximately 6400 feet. The word approximately is used because both through valleys have been altered by highway construction. Elevations on Green Mountain rise to 6855 feet, elevations on Dinosaur Mountain rise to more than 6800 feet, and elevations in the Front Range rise much higher. These elevations suggest the eastern through valley could be as much as 655 feet deep while the western through valley could be as much as 455 feet deep. These two north-to-south oriented through valleys are water-eroded valleys and were eroded by diverging and converging south oriented flood flow channels as Green Mountain, Dinosaur Mountain, and the Colorado Front Range emerged. Emergence of Green Mountain and Dinosaur Mountain can probably be explained in the context of deep erosion by the south oriented flood flow channels. Emergence of the Front Range probably was related to crustal warping and mountain range uplifts, which were occurring as floodwaters flowed across the region. Uplift of the Front Range probably was responsible for the folding that created the Dinosaur Mountain hogback ridge.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories, which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.

BSG_Workshop2013

Abstract:

This essay uses topographic map evidence to interpret landform origins in the South St Vrain Creek-Boulder Creek drainage divide area in the Colorado Front Range. South St Vrain Creek originates near the east-west continental divide and flows in an east-northeast and northeast direction to join southeast and northeast oriented St Vrain Creek, which east of the Front Range flows to the north, northeast, southeast, and northeast oriented South Platte River. North Boulder Creek is located south of South St Vrain Creek, originates near the continental divide, and flows in a southeast and east-northeast direction to join Middle Boulder Creek and to form east oriented Boulder Creek, which east of the Front Range turns in a northeast direction to join northeast oriented St Vrain Creek. Fourmile Creek is an east, northeast, and southeast oriented Boulder Creek tributary located north of North Boulder Creek. Left Hand Creek originates near the continental divide and flows in an east-northeast, northeast, east, north, southeast, and northeast direction to St Vrain Creek and is located north of Fourmile Creek and south of South St Vrain Creek. James Creek is an east-northeast and east-southeast oriented Left Hand Creek tributary located north of Left Hand Creek. Headwaters of these east oriented streams are surrounded by mountain peaks rising to elevations of almost 4000 meters. East of the high mountains crests of Front Range drainage divides between the east-oriented valleys are less than 2800 meters and suggest the valleys were eroded into a former erosion surface. East of the Front Range on the Colorado Piedmont elevations are generally less than 1700 meters. Shallow north-to-south oriented through valleys cross drainage divides between the east oriented stream valleys and provide evidence of diverging and converging south oriented flood flow channels that were captured as the east oriented valleys eroded headward (in sequence from south to north) toward the present day continental divide. The shallow north-to-south oriented through valleys are present both in the Colorado Front Range and on the Colorado Piedmont east of the Front Range. Floodwaters were derived from the western margin of a thick North American ice sheet and flowed from western Canada to and across Colorado at a time when Colorado mountain ranges were beginning to emerge. The mountain ranges emerged as floodwaters flowed across them, as ice sheet related crustal warping raised the mountain masses and the entire region, and as deep valleys eroded headward into the region (from both the east and the west). The east-west continental divide marks the boundary between south oriented flood flow channels captured by headward erosion of the southwest oriented Colorado River valley and by headward erosion of the southeast and northeast oriented South Platte River valley. The north oriented South Platte River drainage route on the Colorado Piedmont was created by a reversal of south oriented flood flow, which also created northeast oriented Boulder Creek and St Vrain Creek and tributary drainage routes on the Colorado Piedmont as floodwaters reversed their flow direction to flow to deeper southeast and northeast oriented South Platte River valley.

Preface

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.

Introduction

The purpose of this essay is to use topographic map interpretation methods to explore the South St Vrain Creek-Boulder Creek drainage divide area landform origins in the Colorado Front Range. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big-picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain South St Vrain Creek-Boulder Creek drainage divide area landform evidence in the Colorado Front Range will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

South St Vrain Creek-Boulder Creek drainage divide area location map

Figure 1: South St Vrain Creek-Boulder Creek drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a location map for the South St Vrain Creek-Boulder Creek drainage divide area in the Colorado Front Range and illustrates a region in north central Colorado. The Colorado Front Range is located just west of the cities of Fort Collins, Boulder, and Golden and the Colorado Piedmont is immediately east of the Front Range. The South Platte River flows in a north-northeast and north direction from the south edge of figure 1 (east half) to Denver and then to Milliken where it turns in a northeast and then southeast direction to flow to the east edge of figure 1 (north half). East of figure 1 the South Platte River turns to flow in a northeast direction to reach the Platte River in western Nebraska. Rocky Mountain National Park is located in the mountains near the center of figure 1. The Big Thompson River originates in Rocky Mountain National Park and flows in a southeast, northeast, and east-southeast direction to join the South Platte River near Milliken. The Colorado River originates in the northwest quadrant of Rocky Mountain National Park and then flows in a south direction to Lake Granby before turning in a southwest direction to eventually reach the Pacific Ocean. The east-west continental divide is located east of the south oriented Colorado River in Rocky Mountain National Park and then extends in roughly a south direction to Berthoud Pass and Loveland Pass and then to the south edge of figure 1. The unlabeled stream located south of the Big Thompson River and flowing in a southeast direction from Lyons to Longmont before turning in a northeast direction to join the South Platte River is St Vrain Creek. St Vrain Creek headwaters include North St Vrain Creek, Middle St Vrain Creek, South St Vrain Creek, and Boulder Creek with Boulder Creek being the east and northeast oriented St Vrain Creek tributary flowing near the city of Boulder. These major St Vrain Creek headwaters streams all originate near the east-west continental divide. South St Vrain Creek originates near the east west continental divide just south of Rocky Mountain National Park and flows in an east-northeast and northeast direction to join North St Vrain Creek near Lyons with Middle St Vrain Creek being a tributary to South St Vrain Creek. The tributary located between South St Vrain Creek and Boulder Creek and joining St Vrain Creek near Longmont is Left Hand Creek. The South St Vrain Creek-Boulder Creek drainage divide area investigated in this essay is located east of the continental divide, north and west of Boulder Creek, and south and east of South St Vrain Creek. The Colorado River-North St Vrain Creek drainage divide area essay illustrates and discusses regions along the continental divide.

Drainage routes in the Colorado Front Range and on the Colorado Piedmont developed during immense melt water floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada to and across Colorado at a time when the Front Range was beginning to emerge. The Front Range emerged as south oriented floodwaters flowed across it, as ice sheet related crustal warping raised the mountain mass and the entire region, and as deep valleys eroded headward into Colorado from the Gulf of Mexico in the east and from the Pacific Ocean in the west. Initially floodwaters moved in south directions, but flood flow directions were changed as crustal warping raised the mountains and as headward erosion of deep valleys captured and beheaded diverging and converging flood flow channels. The present day north oriented South Platte River drainage route and its north oriented tributaries on the Colorado Piedmont originated as south oriented flood flow channels, with floodwaters flowing to the southeast oriented Arkansas River valley south of figure 1. East oriented valleys eroded headward in sequence from south to north from these south oriented flood flow channels to capture south oriented flood flow in the emerging Colorado Front Range. At the same time the deep southwest oriented Colorado River valley eroded headward into the emerging mountains to also capture the south oriented flood flow. The east-west continental divide between Berthoud Pass and the Big Thompson River headwaters marks the boundary between south oriented flood flow channels captured by headward erosion of east oriented valleys from the present day Colorado Piedmont and the south oriented flood flow channels captured by headward erosion of the southwest oriented Colorado River valley. As the east oriented valleys were eroding headward into the emerging Front Range headward erosion of the deep southeast and northeast oriented South Platte River valley from western Nebraska beheaded the south oriented flood flow channels on the Colorado Piedmont. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow to the much deeper southeast and northeast oriented South Platte River valley. Because flood flow channels were beheaded in sequence from east to west and because the flood flow channels were anastomosing the newly reversed flood flow channels could capture yet to be beheaded flood flow in flood flow channels further to the west. Such captures of yet to be beheaded flood flow helped create significant north oriented South Platte River tributary drainage routes. The reversal of flood flow on the north-northeast and north oriented South Platte River drainage route captured significant south oriented flood flow still flowing in the emerging Front Range and that captured flood flow once on the Colorado Piedmont turned to flow in northeast and north directions to join the newly reversed flood flow route.

Detailed location map for South St Vrain Creek-Boulder Creek drainage divide area

Figure 2: Detailed location map of South St Vrain Creek-Boulder Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a detailed location map for the South St Vrain Creek-Boulder Creek drainage divide area in the Colorado Front Range. County lines are shown and Gilpin and Boulder Counties are labeled. The east-west continental divide follows the west boundary of Boulder and Gilpin Counties from the north edge of figure 2 (west half) and then continues in a south and southwest direction to Berthoud Pass near the southwest corner of figure 2. The red-brown region near the northwest corner of figure 2 is located in Rocky Mountain National Park. Green colored are National Forest lands located in the mountain regions. North St Vrain Creek originates just east of the continental divide in the southeast corner of Rocky Mountain National Park and flows in an east and northeast direction to the north center edge of figure 2 and north of figure 2 turns to flow in a southeast direction. Middle St Vrain Creek originates near the continental divide and just south of Rocky Mountain National Park and flows in a southeast and east direction to Peaceful Valley and then in a northeast direction to Raymond before turning in an east direction to join northeast oriented South St Vrain Creek. South St Vrain Creek also originates near the continental divide and flows in an east and northeast direction to join southeast oriented North St Vrain Creek at the north edge of figure 2 (east of center) and to form St Vrain Creek, which then flows in a southeast direction to Longmont before turning in an east and northeast direction to flow to northeast corner of figure 2. North and east of figure 2 St Vrain Creek flows to the north, northeast, southeast, and northeast oriented South Platte River. Left Hand Creek originates near the continental divide (north of Kiowa Creek and south of the South St Vrain Creek headwaters) and flows in an east-northeast direction to Jamestown before turning in a southeast, northeast, southeast, and northeast direction to join St Vrain Creek near Longmont. Boulder Creek has several tributaries converging near the city of Boulder and then flows in an east-northeast and northeast direction to join St Vrain Creek east of Longmont. The northernmost Boulder Creek tributary is east and southeast oriented Fourmile Creek. North Boulder Creek originates near the continental divide (south of Kiowa Peak) and flows in an east, southeast, and east-northeast direction to where it converges with other tributaries to form east oriented Boulder Creek. Middle Boulder Creek flows in an east and east-northeast direction through the towns of Eldora and Nederland before joining North Boulder Creek to form Boulder Creek. South Boulder Creek originates in the far west region of Gilpin County and flows in a northeast direction to East Portal and then in an east direction to Eldorado Springs before turning in a north direction to join Boulder Creek east of Boulder. The north oriented “River” west of the continental divide is the Fraser River, which is flowing on the alignment of a south oriented flood flow channel, which was beheaded and reversed by headward erosion of the much deep southwest oriented Colorado River valley.

South St Vrain Creek-North Boulder Creek drainage divide area

Figure 3: South St Vrain Creek-North Boulder Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of South St Vrain Creek-North Boulder Creek drainage divide area near the continental divide. The map contour interval for figure 3 is 50 meters. The east-west continental divide follows the crest of the high mountains near the west edge of the northwest quadrant of figure 3. South St Vrain Creek originates near the continental divide (south of Shoshoni Peak) and flows in an east-northeast and northeast direction to the north center edge of figure 3. North of figure 3 South St Vrain Creek flows in a northeast direction to join southeast oriented North St Vrain Creek and to form southeast and northeast oriented St Vrain Creek. Duck Lake is located south of the north center edge of figure 3. James Creek originates at Duck Lake and flows in an east-northeast direction to the north edge of figure 3 (east half). North of figure 3 James Creek turns in an east-southeast direction to join Left Hand Creek. Left Hand Creek originates at Left Hand Park Reservoir (in northwest quadrant of figure 3) and flows in an east-northeast, southeast, and east-northeast direction to the east edge of figure 3 (north half). East of figure 3 Left Creek flows in a northeast, north, southeast, and northeast direction to join St Vrain Creek. Fourmile Creek originates in the west center region of figure 3 and flows in a southeast, northeast, east, and northeast direction to the east edge of figure 3 (north of center). East of figure 3 Fourmile Creek turns in a southeast direction to join east and northeast oriented Boulder Creek. North Boulder Creek originates near the continental divide and flows in a southeast and east-northeast direction before turning in a southeast direction near Comforter Mountain to join northeast oriented Middle Boulder Creek and to form east oriented Boulder Creek, which flows to the east edge of figure 3. East of figure 3 Boulder Creek turns to flow in a northeast direction to join northeast oriented St Vrain Creek, which then joins the South Platte River. Middle St Vrain Creek flows in a northeast direction from the south center edge of figure 3 to join North Boulder Creek near Comforter Mountain. The North Fork Middle Boulder Creek flows in a southeast and south direction across the southwest corner of figure 3. A highway extends from the north center edge of figure 3 to the south center edge of figure 3. Elevations along the continental divide and the adjacent high ridges west of the highway exceed 3500 meters and in places exceed 4000 meters. East of the highway elevations along the drainage divides are much lower and are generally in the 2600-2800 meter range. The consistency of elevations along the drainage divides suggests the east oriented valleys eroded headward into a former erosion surface. A close look at that former erosion surface reveals evidence for shallow north-to-south oriented flood flow channels that were captured in sequence (from south to north) by headward erosion of the deeper east oriented valleys. An example of evidence for such a north-to-south oriented flood flow channel is found between Bald Mountain and Sugarloaf Mountain on the Fourmile Creek-North Boulder Creek drainage divide. Figure 4 provides a detailed topographic map of that region to better illustrate the evidence.

Detailed map of Fourmile Creek-North Boulder Creek drainage divide area

Figure 4: Detailed map of Fourmile Creek-North Boulder Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed topographic map of the Fourmile Creek-North Boulder Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 4 is 40 feet. Fourmile Creek flows in an east direction from the northwest corner of figure 4 to the northeast corner of figure 4. East of figure 4 Fourmile Creek turns in a southeast direction to join Boulder Creek. North Boulder Creek flows in a northeast and east direction across the southeast corner of figure 4. East of figure 4 North Boulder Creek turns in a southeast direction (with some significant twists and turns) to join northeast oriented Middle Boulder Creek and to form east oriented Boulder Creek. Gordon Gulch is the southeast, east, southeast, and south oriented North Boulder Creek tributary draining from section 29 along the west edge of figure 4. Bald Mountain is a high point in northeast corner of section 28 and reaches an elevation of 9147 feet. Sugarloaf Mountain is a high point in section 26 and reaches an elevation of 8917 feet. Farewell Gulch is a south oriented Gordon Gulch tributary originating in section 27 and is linked by a through valley or pass with the valley of a northeast oriented Fourmile Creek tributary. The through valley floor elevation is between 8440 and 8480 feet, which is at least 400 feet lower than the top of Sugarloaf Mountain. East of the through valley two more north-to-south oriented through valleys link the Fourmile Creek valley with valleys of south oriented North Boulder Creek tributaries. These three north-to-south oriented through valleys or passes were eroded by diverging and converging south oriented flood flow channels prior to headward erosion of the east oriented Fourmile Creek valley. Floodwaters were first captured by headward erosion of the North Boulder Creek valley and its tributary Gordon Gulch valley. Headward erosion of the east oriented Fouurmile Creek valley then beheaded the south oriented flood flow channels in sequence from east to west and ended flood flow to the North Boulder Creek valley and its tributary valleys. In the northwest quadrant of section 28 west of Bald Mountain a through valley links the north oriented Bear Gulch valley with a southeast oriented Gordon Gulch tributary valley. The through valley floor elevation is between 8600 and 8640 feet. Approximately four sections (miles) to the west elevations exceed the Bald Mountain elevation suggesting there is a broad north-to-south oriented through valley linking the Fourmile Creek valley with the North Boulder Creek valley. The broad through valley at its deepest points is at least 500 feet deep. These through valleys are evidence the east oriented valleys and their tributary valleys eroded headward across diverging and converging south oriented flood flow channels, which were eroding the present day high-level erosion surface seen in the Colorado Front Range.

South St Vrain Creek-Left Hand Creek drainage divide area

Figure 5: South St Vrain Creek-Left Hand Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the South St Vrain Creek-Left Hand Creek drainage divide area north and east of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 50 meters. The Colorado Front Range eastern flank can be seen along the east margin of figure 5. Niwot Mountain in the southwest corner of figure 5 has an elevation of 3496 meters and is an eastern extension of the high continental divide ridge west of figure 5 (and seen in figure 3). Elevations greater than 3000 meters are also found in the northwest corner region of figure 5. Elevations on the Colorado Piedmont east of figure 5 are generally less than 1700 meters. In between the continental divide high ridge elevations and the Front Range eastern flank elevations along Front Range drainage divides are generally in the 2500 to 2700 meters range again suggesting the east oriented valleys eroded headward into what is today an uplifted erosion surface. Left Hand Park Reservoir is located along the west edge of the southwest quadrant of figure 5. Left Hand Creek flows in an east-northeast and southeast direction from Left Hand Park Reservoir before turning in an east-northeast, northeast, and east direction to flow to the east margin of the Colorado Front Range where Left Hand Creek turns in a north direction before flowing an east direction to the east edge of figure 5 (north half). East of figure 5 Left Hand Creek flows in a southeast and northeast direction to join northeast oriented St Vrain Creek. South St Vrain Creek flows from the west edge of figure 5 (north of Left Hand Park Reservoir) in a northeast, east, north, and northeast direction to the north edge of figure 5 (east half). North and east of figure 5 South St Vrain Creek joins southeast oriented North St Vrain Creek to form southeast and northeast oriented St Vrain Creek. Duck Lake is located in the southwest quadrant of figure 5 between South St Vrain Creek and Left Hand Creek. James Creek originates at Duck Lake and flows in a east-northeast and east-southeast direction to join northeast and east oriented Left Hand Creek (in east center area of figure 5). Little James Creek is a southeast oriented tributary joining James Creek at its elbow of capture (where James Creek turns in an east-southeast direction). The highway in the west half of figure 5 extending from the north edge of figure 5 to the south edge of figure 5 is located in north-to-south oriented through valleys crossing drainage divides. Figure 6 provides a detailed topographic map of the region where the highway crosses South St Vrain Creek-James Creek drainage to better illustrate the through valley crossing that drainage divide.

Detailed map of South St Vrain Creek-James Creek drainage divide area

Figure 6: Detailed map of South St Vrain Creek-James Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed topographic map of the South St Vrain Creek-James Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet. South St Vrain Creek flows in an east-northeast and north-northeast direction from the southwest corner of figure 6 to the north edge of figure 6 and north of figure 6 turns to flow in an east-southeast direction across the northeast corner of figure 6. East and north of figure 6 South St Vrain Creek turns again to flow in a north and northeast direction to join southeast and northeast oriented St Vrain Creek. James Creek flows in an east-northeast and east direction from the south edge of figure 6 (in section 31) to the east edge of figure 6 (in section 33). East of figure 6 James Creek flows in an east-northeast and east-southeast direction to join Left Hand Creek, which then flows in a north, southeast, and northeast direction to join northeast oriented St Vrain Creek. A through valley in the north center area of section 32 links the north-northeast oriented South St Vrain Creek valley with the east oriented James Creek valley. The through valley floor elevation is between 8880 and 8920 feet (probably closer to 8880 feet). Elevations in the northwest quadrant of section 28 rise to 9096 feet with much higher elevations located west of the through valley. These elevations suggest the through valley is approximately 200 feet deep. The through valley was eroded by south oriented flood flow, which was flowing on the present day north-northeast oriented South St Vrain Creek alignment. The south oriented floodwaters were first captured by headward erosion of the east oriented James Creek valley. At that time the east-southeast oriented South St Vrain Creek valley in the northeast corner of figure 6 did not exist. Headward erosion of that east-southeast oriented valley (from a reversed flood flow channel on a north oriented South St Vrain Creek valley segment which had been beheaded and reversed by headward erosion of the northeast oriented South St Vrain Creek valley north and east of figure 6-see figure 5) next beheaded and reversed the south oriented flood flow in figure 6 to create the north-northeast oriented South St Vain Creek drainage route.

Left Hand Creek-Boulder Creek drainage divide area

Figure 7: Left Hand Creek-Boulder Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Left Hand Creek-Boulder Creek drainage divide area south of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 50 meters. The city of Boulder is located along the eastern flank of the Colorado Front Range with the Colorado Piedmont to the east of figure 7. Middle Boulder Creek flows in a northeast direction from the south edge of figure 7 (west half) to near Comforter Mountain where it is joined by east-northeast and southeast oriented North Boulder Creek to form east oriented Boulder Creek, which then flows to the city of Boulder and the east edge of figure 7. East of figure 7 Boulder Creek turns to flow in a northeast direction to join northeast oriented St Vrain Creek, which then flows to the South Platte River. Fourmile Creek flows in an east direction from the west edge of figure 7 (slightly south of center) to Wallstreet and then in a northeast direction to Salina. From Salina Fourmile Creek turns to flow in a southeast direction to join Boulder Creek near Orodell. Left Hand Creek flows in a southeast direction from the west edge of figure 7 (north half) and then turns to flow in an east-northeast, northeast, east, and north direction to the north edge of figure 7 (east half). North of figure 7 Left Hand Creek turns to flow in a southeast and northeast direction to join St Vrain Creek. Elevations on the Colorado Piedmont east of the Front Range are generally less than 1700 meters while elevations on drainage divides seen in figure 7 range from 2400 to 2800 meters. The lack of really high mountains suggests the Front Range area seen in figure 7 is an uplifted erosion surface into which the east oriented valleys eroded. Study of drainage divides between the east oriented streams reveals additional evidence for shallow north-to-south oriented through valleys suggesting the east oriented valleys eroded headward in sequence (from south to north) across diverging and converging south oriented flood flow channels. The south oriented flood flow was probably responsible for creating the erosion surface, which was probably being uplifted as floodwaters flowed across it. Figure 8 provides a detailed topographic map of the Left Hand Creek-Fourmile Creek drainage divide area near Gold Hill to better illustrate evidence for former flood flow channels in that region.

Detailed map of Left Hand Creek-Fourmile Creek drainage divide area

Figure 8: Detailed map of Left Hand Creek-Fourmile Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 provides a detailed topographic map of the Left Hand Creek-Fourmile Creek drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 40 feet. Fourmile Creek flows in an east, northeast, and southeast direction from near the southwest corner of figure 8 to near the southeast corner of figure 8. East of figure 8 Fourmile Creek flows in a southeast direction to join east and northeast oriented Boulder Creek, which joins northeast oriented St Vrain Creek. Left Hand Creek flows in an east-northeast direction from the west edge of figure 8 (north half) to the north center edge of figure 8. North and east of figure 8 Left Hand Creek flows in an east-northeast, northeast, north, southeast, and northeast direction to join northeast oriented St Vraiin Creek. The town of Gold Hill is located on the Left Hand Creek-Fourmile Creek drainage divide (in sections 11 and 12 in the west half of figure 8). Gold Run is a south, northeast, east-southeast, and southeast oriented Fourmile Creek tributary originating near Gold Hill. The south oriented Gold Run headwaters valley is linked by a through valley with the north-northwest oriented Lick Skillet Gulch valley, which drains to Left Hand Creek. The through valley floor has an elevation of between 8200 and 8240 feet. Elevations on Bighorn Mountain to the east rise to more than 8520 feet and elevations in section 11 to west rise to more than 8760 feet suggesting the Gold Hill through valley is almost 300 feet deep. Another interesting north-to-south oriented through valley is Sunshine Saddle located in the southeast corner of section 5 (near northeast corner of figure 8). Fourmile Canyon Creek flows in a southeast direction through the town of Sunshine in section 8 and then turns to flow in an east direction to the east edge of figure 8. East of figure 8 Fourmile Canyon Creek flows in an east and southeast direction to join Boulder Creek. Sunshine Saddle has a floor elevation of between 7480 and 7520 feet. Lee Hill to the east rises to more than 7880 feet and Butzel Hill to the west rises to more than 8200 feet suggesting Sunshine Saddle is at least 360 feet deep. Other much shallower north-to-south oriented through valleys or notches can be seen crossing the Left Hand Creek-Fourmile Creek and in the Gold Run-Fourmile Creek drainage divides in figure 8. These north-to-south oriented through valleys or notches are evidence of diverging and converging south oriented flood flow channels that existed prior to headward erosion of the deep east-northeast oriented Left Hand Creek valley. Headward erosion of the deep east-northeast oriented Left Hand Creek valley beheaded the south oriented flood flow channels in sequence from east to west and ended flood flow across the present day Left Hand Creek-Fourmile Creek drainage divide. The entire Front Range region seen in figure 8 was probably being uplifted relative to the Colorado Piedmont as the deep east oriented valleys eroded headward into the region.

Left Hand Creek-South Boulder Creek drainage divide area

Figure 9: Left Hand Creek-South Boulder Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Left Hand Creek-South Boulder Creek drainage divide area east and slightly north of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 50 meters. The east flank of the Colorado Front Range can be seen along the west edge of figure 9. East of the Front Range is the Colorado Piedmont. The city of Boulder is located in southwest corner of figure 9. The grid of roads east of Dominion along the north edge of figure 9 is the south edge of the city of Longmont. Boulder Creek flows in an east, east-northeast, and northeast direction from near the southwest corner of figure 9 to the east edge of figure 9 (north half). East and north of figure 9 Boulder Creek joins northeast oriented St Vrain Creek, which then flows to the north, northeast, southeast, and northeast oriented South Platte River. Fourmile Canyon Creek flows in an east, southeast, and east direction from the west edge of figure 9 along the north edge of the city of Boulder to join Boulder Creek near Valemont. South Boulder Creek flows in a north direction from the south edge of figure 9 (west half) to join Boulder Creek near Valemont (east of Boulder). Left Hand Creek flows in a north, southeast, and northeast direction from the west edge of figure 9 (north half) to the north edge of figure 9 (east half-just east of Longmont) and north of figure 9 joins east and northeast oriented St Vrain Creek. Boulder Reservoir is located in the west center region of figure 9 between the southeast-northeast Left Hand Creek elbow of capture and the north oriented South Boulder Creek valley (south of Valemont). A close look at figure 9 shows Boulder Reservoir is located in a north-to-south oriented through valley between Gun Barrel Hill to the east and the Colorado Front Range to the west. The 50-meter contour interval hides much of the through valley detail. Figure 10 provides a detailed topographic map to better illustrate the through valley features. The through valley was eroded by south oriented flood flow flowing to the present day north oriented South Boulder Creek alignment. The flood flow was moving in a south direction along the east flank of what at that time was the emerging Front Range and was probably derived from east oriented valleys eroding headward into the emerging Front Range to capture south oriented flood flow. East of figure 9 south oriented flood flow was also moving on the present day north oriented South Platte River alignment. Headward erosion of the southeast and northeast oriented South Platte River valley from Nebraska (north of figure 9) beheaded and reversed flood flow on the South Platte River alignment and northeast oriented valleys then eroded headward from that reversed flood flow to capture south oriented flood flow channels west of the South Platte River alignment. Headward erosion of the northeast oriented Boulder Creek valley captured the south oriented flood flow moving in the Boulder Reservoir through valley. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented South Boulder Creek drainage route. Next headward erosion of the northeast oriented Left Hand Creek valley captured the south oriented flood flow and ended flood flow in the Boulder Reservoir through valley.

Detailed map of Left Hand Creek-Boulder Creek drainage divide area

Figure 10: Detailed map of Left Hand Creek-Boulder Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a detailed topographic map of the Left Hand Creek-Boulder Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 10 feet except near the west edge where the contour interval is 40 feet. Boulder Creek flows in an east direction near the southeast corner of figure 10. East of figure 10 Boulder Creek turns to flow in a northeast direction to join northeast oriented St Vrain Creek, which then joins the north, northeast, southeast, and northeast oriented South Platte River. Left Hand Crek can be seen flowing in a southeast and then northeast direction near the north center edge of figure 10. North of figure 10 Left Hand Creek joins east and northeast oriented St Vrain Creek. Dry Creek is a northeast oriented stream flowing from Boulder Reservoir to the northeast corner of figure 10. North and east of figure 10 Dry Creek joins St Vrain Creek. Gun Barrel Hill can be seen along the east edge of figure 10 and rises to 5420 feet. Elevations greater than 5420 feet are seen along the west edge of figure 10 and west of figure 10 elevations rise much higher. The Dry Creek-Boulder Creek drainage divide east of the Boulder Reservoir dams has an elevation of less than 5150 feet suggesting the Dry Creek-Boulder Creek through valley is at least 370 feet deep. South of the Dry Creek-Boulder Creek through valley and south of figure 10 is the north oriented South Boulder Creek valley. The Dry Creek-Boulder Creek through valley was eroded by south oriented flood flow moving to the present day north oriented South Boulder Creek alignment. Left Hand Creek appears to have been flowing on the surface of a southeast oriented pediment or alluvial fan and was probably initially captured by headward erosion of a southwest oriented valley on the present day northeast oriented Dry Creek alignment. Flood flow on the Dry Creek alignment was then reversed by the reversal of flood flow on the present day north oriented South Platte River alignment (east of figure 10). The reversed flood flow changed the alluvial fan or pediment orientation near the northeast corner of figure 10 to a northeast oriented slope and in the process created the southeast-northeast oriented Left Hand Creek elbow of capture and ended south oriented flood flow in the Dry Creek-Boulder Creek through valley.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories, which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.

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Abstract:

This essay uses topographic map evidence to interpret landform origins in the Little Thompson River-St Vrain Creek drainage divide area in the Colorado Front Range. The Little Thompson River originates east of Rocky Mountain National Park and flows in a southeast, east-northeast, and southeast direction to the Colorado Piedmont and then in an east-northeast direction to join the Big Thompson River, which flows to the South Platte River. St Vrain Creek is located south of the Little Thompson River and is formed at the confluence of east, northeast, and southeast North St Vrain Creek and east and northeast oriented South St Vrain Creek and then flows in a southeast direction onto the Colorado Piedmont before turning in northeast direction to join the north, northeast, southeast, and northeast oriented South Platte River. Middle St Vrain Creek is a southeast, east, northeast, and east-southeast oriented South St Vrain Creek tributary. North-to-south oriented through valleys link the Little Thompson River valley with the St Vrain Creek and North St Vrain Creek valleys and also link the various St Vrain Creek tributary valleys. These north-to-south oriented through valleys are found both on the Colorado Piedmont and in the Colorado Front Range to the west. The north-to-south oriented through valleys are interpreted to have been eroded as south oriented flood flow channels prior to headward erosion of the east oriented St Vrain Creek valley and its tributary valleys, which was prior to headward erosion of the east oriented Little Thompson River valley. The east oriented valleys in the Colorado Front Range are interpreted to have eroded headward from south oriented flood flow channels on the Colorado Piedmont into an emerging Colorado Front Range across massive south oriented flood flow. Floodwaters are interpreted to have been derived from the western margin of a thick North American ice sheet and flowed from western Canada to and across the present day South Platte River drainage basin at a time when the Colorado Front Range and other regional mountain ranges were just beginning to emerge. The mountain ranges emerged as floodwaters flowed across them, as deep valleys eroded headward into the region to capture the immense south oriented flood flow, and as ice sheet related crustal warping raised the mountain masses and the entire study region. South oriented flood flow on the Colorado Piedmont was captured by headward erosion of the deep southeast and northeast oriented South Platte River valley from western Nebraska. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow in north directions to the deeper southeast and northeast oriented South Platte River valley and to create the present north oriented South Platte River and tributary drainage routes.

Preface

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.

Introduction

The purpose of this essay is to use topographic map interpretation methods to explore the Little Thompson River-St Vrain Creek drainage divide area landform origins in the Colorado Front Range. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big-picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain Little Thompson River-St Vrain Creek drainage divide area landform evidence in the Colorado Front Range will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Little Thompson River-St Vrain Creek drainage divide area location map

Figure 1: Little Thompson River-St Vrain Creek drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a location map for the Little Thompson River-St Vrain Creek drainage divide area in the Colorado Front Range and illustrates a region in north central Colorado. The west to east oriented Wyoming-Colorado border is located along the north edge of figure 1. The Colorado Front Range is the mountain area west of the cities of Fort Collins, Longmont, Boulder, and Denver. Rocky Mountain National Park is located near the west center edge of figure 1. The South Platte River flows in a north direction from south of Denver to near Greeley where it turns to flow in a northeast and then southeast direction (with a northeast jog) to Fort Morgan and then turns to flow in a northeast direction to the east edge of figure 1. East and north of figure 1 the South Platte River flows into western Nebraska. The Big Thompson River originates in Rocky Mountain National Park and flows in a southeast, northeast, east-southeast, and southeast direction to enter the South Platte River valley near Milliken and then turns in an east-northeast direction to join the northeast oriented South Platte River. The Little Thompson River is shown, but not labeled in figure 1 (and the headwaters are incorrectly drawn), but is the southeast and east-northeast oriented drainage route originating south of Estes Park and joining the Big Thompson River near Milliken. St Vrain Creek is south of the Little Thompson River and is also shown, but not labeled in figure 1. The St Vrain Creek headwaters of interest in this essay originate near the south margin of Rocky Mountain National Park and flow in east directions through the mountains to Longmont. From Longmont St Vrain Creek flows in an east and northeast direction to join the north, northeast, southeast, and northeast oriented South Platte River. North St Vrain Creek is the northernmost headwaters stream, Middle St Vrain Creek is to the south and South St Vrain Creek is further to the south. The St Vrain Creek tributary flowing through Boulder is Boulder Creek, which is not addressed in this essay. The Little Thompson River-St Vrain Creek drainage divide area investigated in this essay is located east of Rocky Mountain National Park, south of the Little Thompson River, north of Middle St Vrain Creek, and west of the South Platte River.

Drainage routes in Colorado and adjacent states developed during immense south oriented melt water floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada to and across Colorado at a time when Colorado mountain ranges were beginning to emerge. Colorado mountain ranges emerged as floodwaters flowed across them, as ice sheet related crustal warping raised mountain masses and the entire region, and as deep valleys eroded headward into Colorado to capture the massive melt water floods. Initially floodwaters flowed in south directions across the Colorado Front Range and Colorado Piedmont (east of the mountains), but directions of flood flow changed and even reversed in some case cases as crustal warping raised the region and mountains within the region and as deep valleys eroded headward into the region. The present day north oriented South Platte River drainage route (south of Greeley) and north oriented South Platte River tributary drainage routes in the southeast quadrant of figure 1 are located on alignments of what at one time were south oriented flood flow channels. Prior to headward erosion of the southeast and northeast oriented South Platte River valley from western Nebraska the south oriented flood flow east of the emerging Colorado Front Range was flowing to the southeast oriented Arkansas River valley (south of figure 1). East oriented valleys eroded headward from these south oriented flood flow channels on the present day Colorado Piedmont to capture south oriented flood flow moving across the emerging Colorado Front Range. Headward erosion of these valleys occurred in sequence from south to north with headward erosion of each new valley beheading flood flow routes to the newly eroded valley immediately to the south. Sometimes the east oriented valleys eroded in northeast directions across southeast oriented flood flow and at other times the east oriented valleys eroded headward along southeast oriented flood flow channels. North and northwest oriented valley segments and tributary routes were created by reversals of flood flow on north and northwest ends of beheaded south and southeast oriented flood flow channels. Headward erosion of the deep southeast and northeast oriented South Platte River valley from western Nebraska captured the south oriented flood flow channels on the present day Colorado Piedmont. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow to the deeper South Platte River valley and create north oriented South Platte River tributary drainage routes and the north oriented South Platte River drainage route. Because flood flow channels were beheaded in sequence from east to west and because flood flow channels were diverging and converging newly reversed flood flow channels could capture floodwaters from yet to be beheaded flood flow channels further to the west. Such captures of flood flow helped create significant north oriented drainage routes, including the present day north oriented South Platte River drainage route.

Detailed location map for Little Thompson River-St Vrain Creek drainage divide area

Figure 2: Detailed location map Little Thompson River-St Vrain Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a detailed location map for the Little Thompson River-St Vrain Creek drainage divide area in the Colorado Front Range. The red-brown region along the western margin of figure 2 is Rocky Mountain National Park. Green colored area in the west half of figure 2 are National Forest lands located in the Colorado Front Range. The Colorado Piedmont is located in the east half of figure 2. The black dashed line extending from the west center edge of figure 2 to the south edge of figure 2 (near southwest corner) is the east-west continental divide. East of the continental divide drainage eventually reaches the Gulf of Mexico and west of the continental water flows to the Colorado River and eventually reaches the Pacific Ocean. The South Platte River flows in a north and northeast direction from the south edge of figure 2 (near southeast corner) to the east center edge of figure 2. East of figure 2 the South Platte River turns to flow in a southeast direction before turning to flow in a northeast direction to reach western Nebraska. The Big Thompson River flows in a southeast, east, and northeast direction from the west edge of figure 2 (north of center) to Estes Park and then in a northeast direction to Drake. From Drake the Big Thompson River flows in an east-southeast direction to the south edge of Loveland and then in an east and southeast direction to near Milliken where it turns in an east-northeast direction to join the South Platte River near the east center edge of figure 2. The Little Thompson River originates a short distance south and east of Estes Park and flows in a southeast direction almost to Pinewood Springs before turning to flow in an east-northeast, southeast, and east-northeast direction to join the Big Thompson River near Milliken. North St Vrain Creek originates along the continental divide just north of the southern boundary of Rocky Mountain National Park and flows in an east, east-northeast, and southeast direction to Lyons, where it joins northeast oriented South St Vrain Creek to form St Vrain Creek. St Vrain Creek then flows in a southeast direction to Longmont where it turns to flow in an east and then northeast direction to join the South Platte River near the east center edge of figure 2. Middle St Vrain Creek originates near the continental divide just south of the Rocky Mountain National Park southern boundary and flows in a southeast, east, and northeast direction to Raymond and then in a northeast and east direction to join northeast oriented South St Vrain Creek. South St Vrain Creek flows in an east and northeast direction to join North St Vrain Creek at Lyons and to form southeast, east, and northeast oriented St Vrain Creek. Highway number 7, which extends south from Estes Park just east of Rocky Mountain National Park,follows an unlabeled north oriented Big Thompson River tributary (Fish Creek) and then an unlabeled south oriented North St Vrain Creek tributary (Tahosa Creek). Note the large number of southeast oriented drainage routes or drainage route segments flowing from the Colorado Front Range onto the Colorado Piedmont to join the north oriented South Platte River.

Little Thompson River-St Vrain Creek drainage divide area

Figure 3: Little Thompson River-St Vrain Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of Little Thompson River-St Vrain Creek drainage divide area on the Colorado Piedmont. The map contour interval for figure 3 is 50 meters except near the east edge where the contour interval is 10 meters. The Little Thompson River flows in an east and east-northeast direction from the west edge of figure 3 (north of Rabbit Mountain) to the north center edge of figure 3. North and east of figure 3 the Little Thompson River flows in an east-northeast direction to join the east-northeast oriented Big Thompson River, which flows to the northeast, southeast and northeast oriented South Platte River. St Vrain Creek flows in a southeast direction from the west edge of figure 3 (south of Rabbit Mountain) to near the south center edge of figure 3 and then turns to flow in an east-northeast direction to the east edge of figure 3. East of figure 3 St Vrain Creek turns to flow in a northeast direction to join the South Platte River. Rabbit Mountain is located along the east flank of the Colorado Front Range and the region east of Rabbit Mountain is the Colorado Piedmont. West of figure 3 the Little Thompson River flows in a southeast direction to reach the Colorado Piedmont (see figure 5) and St Vrain Creek flows in a southeast direction as it emerges onto the Colorado Piedmont. The southeast orientations of the Little Thompson River and St Vrain Creek valleys as they emerge onto the Colorado Piedmont are evidence the valleys eroded headward from south oriented flood flow channels on the Colorado Piedmont and drainage on the Colorado Piedmont has since been reversed to flow in a north direction. The Little Thompson River and St Vrain Creek drainage routes on the Colorado Piedmont eroded headward from reversed flood flow on the present day South Platte River alignment and captured the southeast oriented flood flow emerging from the what at that time was the emerging Colorado Front Range west of figure 3. The 50-meter contour interval does not show most landforms on the low relief Colorado Piedmont surface. Figure 4 provides a more detailed topographic map of the region north of Longmont to illustrate topographic map evidence for former north-to-south oriented flood flow channels on the Colorado Piedmont.

Detailed map of Little Thompson River-St Vrain Creek drainage divide area

Figure 4: Detailed map of Little Thompson River-St Vrain Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed topographic map of the Little Thompson River-St Vrain Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 10 feet except near the northwest corner where the contour interval is 40 feet (with some dotted lines at 20 feet intervals). Longmont is the city straddling the south edge of figure 4. Lakes seen in figure 4 appear to be reservoirs used in the regional irrigation systems. Table Top Mountain in the west center area of figure 4 is an erosional residual east of Rabbit Mountain (seen in figures 3 and 5) and provides evidence 200 or more feet of surrounding bedrock material has been stripped from the Colorado Piedmont surface. The Little Thompson River flows in an east and east-northeast direction from the west edge of figure 4 (near northwest corner) to the north edge of figure 4 (west half). North of figure 4 the Little Thompson River flows in an east-northeast direction to join the east-northeast oriented Big Thompson River, which then joins the northeast, southeast, and northeast oriented South Platte River. St Vrain Creek can just barely be seen flowing in a southeast direction across the southwest corner of figure 4. South and east of figure 4 St Vrain Creek flows in a southeast direction before turning in an east-northeast and then northeast direction to join the north oriented South Platte River. Terry Lake is located in sections 9 and 16 north of Longmont and is located in what was once a north-to-south oriented flood flow channel used by southeast oriented flood flow emerging from the southeast oriented Little Thompson River valley west of figure 4 (see figure 5) and flowing in a south direction to the St Vrain Creek valley. The hill in section 4 near the north edge of figure 4 reaches an elevation of 5235 feet while elevations on the Little Thompson River-St Vrain Creek drainage divide west of Highland No. 2 Reservoir in section 6 are between 5160 and 5180 feet. These elevations suggest there is 55-foot deep or deeper north-to-south oriented through valley. Divide Reservoir and Ish Reservoir are located in an even deeper north-to-south oriented through valley east of Terry Lake. This deeper through valley has a floor elevation of between 5130 and 5140 feet. The hill on the county line between sections 12 and 7 to the east rises to more than 5220 feet suggesting this through valley is at least 80 feet deep. These north-to-south oriented through valleys were eroded by south oriented flood flow prior to the flood flow reversal on the Colorado Piedmont. When the flood flow reversal took place northeast oriented valleys eroded headward into the region to capture the south oriented flood flow. The north and northeast oriented drainage route east of Ish Reservoir is located in one of those northeast oriented valleys that captured the south oriented flood flow. The north oriented headwaters drainage route east of Divide Reservoir was created by a reversal of flood flow on the north end of the beheaded flood flow channel.

North St Vrain Creek-South St Vrain Creek drainage divide area

Figure 5: North St Vrain Creek-South St Vrain Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the North St Vrain Creek-South St Vrain Creek drainage divide area west of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 50 meters. Rabbit Mountain is located near the east center edge of figure 5. North-to-south oriented ridges in the east half of figure 5 are hogback ridges along the east flank of the Colorado Front Range, which is seen to the west. The Little Thompson River flows in a southeast direction from the north edge of figure 5 (west half-next to highway) almost to the town of Pinewood Springs and then turns to meander in an east-northeast, southeast, and east direction to the east edge of figure 5 (north half). The West Fork Little Thompson River flows in an east-northeast and northeast direction from the west edge of figure 5 (north of center) to join the southeast oriented Little Thompson River near Moose Mountain. North St Vrain Creek flows in an east direction from the west edge of figure 5 (south of center) to Button Rock Reservoir and then in a northeast direction before turning in a south and southeast direction to Lyons and then to flow as St Vrain Creek to the east edge of figure 5 (near southeast corner). South St Vrain Creek flows in a northeast direction from the south edge of figure 5 (west half) to join southeast oriented North St Vrain Creek at Lyons. Middle St Vrain Creek flows in a northeast and east-southeast direction from near the southwest corner of figure 5 to join South St Vrain Creek east of Riverside. Numerous north-to-south oriented through valleys link the various east oriented drainage routes. Some of these north-to-south oriented through valleys are strike valleys between the steeply dipping hogback ridges and valley orientations are determined by underlying geologic structures. However, each through valley is a water-eroded valley and was eroded by south oriented flood flow in what was probably a huge south oriented anastomosing channel complex. At that time the Colorado Front Range was emerging and floodwaters were eroding deeper and deeper valleys into the emerging mountain mass. Headward erosion of the east oriented valleys captured the south oriented flood flow in sequence from south to north and from east to west and diverted floodwaters to what were initially south oriented flood flow channels on the Colorado Piedmont to the east of figure 5, although the flood flow reversal on the Colorado Piedmont probably occurred while south oriented flood flow was still moving into and across the emerging Colorado Front Range. Figure 6 illustrates a detailed map of through valleys in the West Fork Little Thompson River-North St Vrain Creek drainage divide area.

Detailed map of West Fork Little Thompson River-North St Vrain Creek drainage divide area

Figure 6: Detailed map of West Fork Little Thompson River-North St Vrain Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed topographic map of the West Fork Little Thompson River-North St Vrain Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet. The West Fork Little Thompson River flows in an east-northeast direction (with some incised meanders) from the west edge of figure 6 (north of center) to the north center edge of figure 6 and north of figure 6 joins the south-southeast, east-northeast, and southeast oriented Little Thompson River, which once on the Colorado Piedmont turns in an east-northeast direction. North St Vrain Creek flows in an east direction from near the southwest corner of figure 6 to the west side of Cook Mountain where it turns to flow in a south and northeast direction around the south end of Cook Mountain to Button Rock Reservoir. North St Vrain Creek flows from Button Rock Reservoir in a northeast direction to the east edge of figure 6. East of figure 6 North St Vrain Creek flows in a northeast, south, and southeast direction to join South St Vrain Creek and to form southeast oriented St Vrain Creek, which once on the Colorado Piedmont turns to flow in an east-northeast and northeast direction. Two deep north-to-south oriented through valleys (in the center of figure 6) link the West Fork Little Thompson River valley with the east oriented North St Vrain Creek valley. Rattlesnake Gulch drains the eastern through valley south end and Coulson Gulch drains the western through valley south end. The eastern through valley floor elevation at the drainage divide in the northeast quadrant of section 1 is between 7600 and 7640 feet. The western through valley floor elevation on the border between sections 1 and 2 is between 7640 and 7680 feet. Button Rock Mountain to the east rises to 8450 feet and elevations in the northeast corner of section 10 to the west rise to 8572 feet suggesting the through valleys are more than 750 feet deep. Today these through valley link south oriented North St Vrain Creek tributary valleys with north oriented West Fork Little Thompson River tributary valleys. The through valleys are water-eroded valleys and were eroded by diverging south oriented flood flow channels prior to headward erosion of the east-northeast oriented West Fork Little Thompson River valley. The south oriented floodwaters were captured by headward erosion of the east oriented North St Vrain Creek valley and the deep south oriented Rattlesnake Gulch and Coulson Gulch valleys eroded headward along the south oriented flood flow channels. Headward erosion of the deeper east-northeast oriented West Fork Little Thompson River valley next beheaded the south oriented flood flow channels. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow to the deeper West Fork Little Thompson River valley and to create north oriented West Fork Little Thompson River tributary drainage routes.

Fish Creek-Tahosa Creek drainage divide area

Figure 7: Fish Creek-Tahosa Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Fish Creek-Tahosa Creek drainage divide area west and north of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 50 meters. Estes Park and Lake Estes are near the north center edge of figure 7. The Big Thompson River flows in an east direction from the west edge of figure 7 (north half) through Moraine Park and then in a northeast direction to Lake Estes before flowing in a northeast direction to the north edge of figure 7 (east of center). North of figure 7 the Big Thompson River turns to flow in an east-southeast direction to reach the Colorado Piedmont. Muggins Gulch is located adjacent to the highway extending in a southeast direction from Estes Park. Muggins Gulch is a southeast oriented headwaters drainage route for the Little Thompson River, which turns to flow to the east edge of figure 7 (north of Pinewood Springs). East of figure 7 the Little Thompson River flows in an east-northeast and southeast direction to reach the Colorado Piedmont. The southeast oriented highway is located in a northwest-to-southeast oriented through valley linking southeast oriented Big Thompson River tributary valleys (north of the Big Thompson River) with the southeast oriented Muggins Gulch (or Little Thompson River) valley. The through valley is approximately 250 meters deep and was eroded by southeast oriented flood flow moving to the southeast oriented Muggins Gulch valley prior to headward erosion of the northeast oriented Big Thompson River valley. Further west another highway extends south from Estes Park to the south edge of figure 7 (west of center) and crosses the Big Thompson River-North St Vrain Creek drainage divide at Wind River Pass. North of Wind River Pass the highway makes use of the north oriented Fish Creek valley while south of Wind River Pass the highway makes use of the south-southeast oriented Tahosa Creek valley. Wind River Pass has an elevation of between 2750 and 2800 meters. Twin Sisters Peaks to the east rises to 3483 meters and elevations near the southwest corner of figure 7 rise to more than 4300 meters. These elevations suggest Wind River Pass is at least 700 meters deep. Wind River Pass was eroded by south oriented flood flow prior to headward erosion of the northeast oriented Big Thompson River valley. Headward erosion of the northeast oriented Big Thompson River valley beheaded the south oriented flood flow and floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Fish Creek drainage route. The reversal of flood flow was probably aided by crustal warping that was raising the Wind River Pass region as floodwaters flowed across it.

Detailed map of Fish Creek-Tahosa Creek drainage divide area

Figure 8: Detailed map of Fish Creek-Tahosa Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 provides a detailed topographic map of the Fish Creek-Tahosa Creek drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 40 feet. Lily Lake is located in section 14 in the northeast quadrant of figure 8. Fish Creek originates at Lily Lake and flows in a north-northeast direction to the north edge of figure 8 (east half). North of figure 8 Fish Creek flows to the northeast and east-southeast oriented Big Thompson River. The north-northwest oriented stream just west of Lily Lake in the east half of section 15 and flowing to the north center edge of figure 8 is Aspen Brook. North of figure 8 Aspen Brook also flows to the Big Thompson River. South of the Aspen Brook headwaters is Wind River Pass (located on the line between sections 22 and 23). Just south of Wind River Pass are headwaters of south and south-southeast oriented Tahosa Creek, which flows to the south edge of figure 8. South of figure 8 Tahosa Creek joins a southeast oriented tributary to east, northeast, and southeast oriented North St Vrain Creek. Wind River Pass has an elevation of 9130 feet. Twin Sisters Peaks to the east reach an elevation of 11,413 feet while Mount Lady Washington near the southwest corner of figure 8 reaches an elevation of 13,281 feet. Based on these elevations Wind River Pass is almost 2300 feet deep. Wind River Pass is a water-eroded feature, which means at one time large volumes of water flowed through it. The deep valley suggests large volumes of water eroded the valley deeper and deeper as the mountain ridge was uplifted around it. The water was flowing in a south direction prior to headward erosion of the Big Thompson River valley to the north of figure 8. The south oriented flow was first captured by headward erosion of the deep east, northeast, and southeast North St Vrain Creek valley (south of figure 8) and was subsequently beheaded by headward erosion of the deep northeast and east-southeast oriented Big Thompson River valley. Erosion of these deep valleys into a rising mountain mass could only be accomplished by immense volumes of floodwaters, which were flowing across the region as the mountains were being uplifted. The north-northeast and north-northwest oriented Fish Creek and Aspen Brook valleys north of Wind River Pass were eroded by south-southwest and south-southeast oriented flood flow channels that converged to flow through the deep Wind River Pass valley. These converging flood flow channels provide evidence of an anastomosing channel complex, which further supports the massive flood flow interpretation.

North St Vrain Creek-Middle St Vrain Creek drainage divide area

Figure 9: North St Vrain Creek-Middle St Vrain Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the North St Vrain Creek-Middle St Vrain Creek drainage divide area south and slightly east of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 50 meters. North St Vrain Creek flows in a southeast, east-northeast, and east direction from the west center edge of figure 9 to Button Rock Reservoir and then in a northeast direction to the east edge of figure 9 (north half). East of figure 9 North St Vrain Creek flows in a northeast and southeast direction to join South St Vrain Creek and to form southeast oriented St Vrain Creek, which then flows onto the Colorado Piedmont before turning to flow in a northeast direction. Tahosa Creek flows in a south-southeast direction from the north edge of figure 9 (west half) to join southeast oriented Cabin Creek, which then flows to join east oriented North St Vrain Creek. South St Vrain Creek flows in a north and northeast direction from the south center edge of figure 9 to the east center edge of figure 9 and east of figure 9 joins southeast oriented North St Vrain Creek to form southeast oriented St. Vrain Creek. Middle St Vrain Creek flows in a southeast and east direction from the west edge of figure 9 (near southwest corner) to Peaceful Valley and then turns in a northeast direction to flow to Riverside before turning in an east-southeast direction to join northeast oriented South St Vrain Creek. Multiple north-to-south oriented through valleys cross the drainage divide between North St Vrain Creek and Middle St Vrain Creek and between North St Vrain Creek and South St Vrain Creek. Some of the deepest through valleys are located north of Riverside where northeast oriented Dry St Vrain Creek is located between North St Vrain Creek and Middle St Vrain Creek. The Dry St Vrain Creek-Middle St Vrain Creek drainage divide at its lowest point has an elevation of between 2300 and 2350 meters. The high point in section 36 immediately to the east is 2557 meters and elevations west of Riverside rise to more than 3000 meters suggesting the through valley is at least 200 meters deep. Further east a north-to-south oriented through valley can be seen immediately west of Coffintop Mountain and links the Button Rock Reservoir area with the northeast oriented South St Vrain Creek valley. This through valley has an elevation of between 2200 and 2250 meters. Coffintop Mountain rises to 2453 meters suggesting the through valley is also at least 200 meters. These and other north-to-south oriented through valleys seen in figure 9 are evidence of south oriented flood flow channels that crossed the region prior to headward erosion of the deep North St Vrain Creek valley and its northeast oriented Dry St Vrain Creek tributary valley.

Detailed map of North St Vrain Creek-Middle St Vrain Creek drainage divide area

Figure 10: Detailed map of North St Vrain Creek-Middle St Vrain Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a detailed topographic map of the North St Vrain Creek-Middle St Vrain Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 40 feet. North St Vrain Creek flows in an east direction (with multiple northeast and southeast turns) from the west edge of figure 10 (near northwest corner) to Button Rock Reservoir near the northeast corner of figure 10. East and north of figure 10 North St Vrain Creek flows in a northeast and southeast direction. South St Vrain Creek flows in an east-northeast direction across the southeast corner of figure 10 and east of figure 10 flows in a northeast direction to join southeast oriented North St Vrain Creek and to form southeast oriented St Vrain Creek. Middle St Vrain Creek flows in a northeast direction from the south edge of figure 10 (west of center) to Riverside and then in an east-southeast direction to join east-northeast oriented South St Vrain Creek near the south edge of figure 10. Dry St Vrain Creek originates near the southwest corner of figure 10 and flows in a northeast direction to join North St Vrain Creek near the east edge of section 23. Numerous north-to-south oriented through valleys link the various east oriented St Vrain Creek tributary valleys. For example in the south half of section 22 a north-to-south oriented through valley on the west side of South Sheep Mountain links the North St Vrain Creek valley with a southeast oriented tributary to northeast oriented Dry St Vrain Creek. The through valley floor elevation is between 7720 and 7760 feet. South Sheep Mountain rises to 8171 feet and Big John Mountain to the west rises to more than 9080 feet suggesting the through valley is at least 400 feet deep. The through valley was eroded by south oriented flood flow, which initially had flowed to the Middle St Vrain Creek valley, but which was captured by headward erosion of the northeast oriented Dry St Vrain Creek valley, which had eroded headward from what at that time was the actively eroding North St Vrain Creek valley. Headward erosion of the much deeper North St Vrain Creek valley then captured the south oriented flood flow channel and ended flood flow in the through valley. The gap between Big John Mountain and Taylor Mountain to the west of the through valley was eroded by south oriented flood flow moving at a much higher elevation, which suggests floodwaters initially flowed on an erosion surface now largely removed.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories, which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.

Abstract:

This essay uses topographic map evidence to interpret landform origins in the Cache la Poudre River-Big Thompson River drainage divide area in the Colorado Mummy Range. The Mummy Range is located in northeast Rocky Mountain National Park and the region immediately to the north. The Cache la Poudre River originates south and west of the Mummy Range and flows in a north and east direction around the north end of the Mummy Range before turning in a southeast direction to flow to the South Platte River. The South Fork Cache la Poudre River originates in the Mummy Range and flows in a northeast direction to join the east oriented Cache la Poudre River. South of the north oriented Cache la Poudre River headwaters is the south oriented Colorado River headwaters valley and southeast oriented headwaters of the Big Thompson River and its tributaries. The Big Thompson River then flows in a southeast, east, northeast, east, and southeast direction to join the South Platte River. Deep passes link the north oriented Cache la Poudre River headwaters valleys with the south oriented Colorado River headwaters valley and with the southeast oriented Big Thompson River headwaters valleys. Further mountain passes link northwest and west oriented Cache la Poudre River tributary valleys with the northeast oriented South Fork Cache la Poudre River valley or with southeast oriented South Fork tributary valleys. Valley orientations and through valleys (defined by the passes) are interpreted to have been eroded as anastomosing south oriented flood flow channels at a time when the Mummy Range and surrounding mountains were beginning to emerge. Floodwaters are interpreted to have been derived from the western margin of a thick North American ice sheet and were flowing from western Canada to and across emerging mountain ranges. The Mummy Range and surrounding mountain ranges emerged as floodwaters flowed across them and as deep valleys eroded headward into them to capture immense south oriented floods. After flood flow across the region had ended the mountain ranges had emerged flood eroded valleys in the newly uplifted mountains were filled with valley glaciers, which further modified the valleys, but which did not erode new valleys or significantly change valley orientations.

Preface

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.

Introduction

The purpose of this essay is to use topographic map interpretation methods to explore the Cache la Poudre River-Big Thompson River drainage divide area landform origins in the Colorado Mummy Range. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big-picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain Cache la Poudre River-Big Thompson River drainage divide area landform evidence in the Colorado Mummy Range will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Cache la Poudre River-Big Thompson River drainage divide area location map

Figure 1: Cache la Poudre River-Big Thompson River drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a location map for the Cache la Poudre River-Big Thompson River drainage divide area in the Colorado Mummy Range and illustrates a region in north central Colorado. Rocky Mountain National Park is shown and labeled. The South Platte River flows in a north-northeast direction from the south edge of figure 1 (east of center) through Denver to Brighton and then in a north and northeast direction to near Greeley where it turns to flow in a southeast direction to the east edge of figure 1. East of figure 1 the South Platte River turns to flow in a northeast direction into western Nebraska with water eventually reaching the Gulf of Mexico. The Cache la Poudre River originates in the northwest corner of Rocky Mountain National Park and flows in a north direction before turning to flow in an east, southeast, and east direction to join the South Platte River near Greeley (at the point where the South Platte River turns to flow in a southeast direction). The Big Thompson River originates a short distance south of the Cache la Poudre River headwaters and flows in a southeast and northeast direction to Estes Park and then in a northeast, east, and southeast direction to join the South Platte River near Milliken (after entering the South Platte River valley the Big Thompson River flows in a northeast direction before joining the northeast oriented South Platte River). The North Fork Big Thompson River (shown, but labeled in figure 1) originates in the northeast corner of Rocky Mountain National Park and flows in a southeast direction to join the Big Thompson River east of Rocky Mountain National Park. The Colorado River headwaters are not shown in figure 1, but originate near the Cache la Poudre and Big Thompson River headwaters and flow in a south direction near the west edge of Rocky Mountain National Park. At the southwest corner of Rocky Mountain National Park  the Colorado River turns to flow in a southwest, west, and southwest direction to Bond (near west edge in southwest quadrant of figure 1) where it makes a turn to flow in a northwest direction to the west edge of figure 1 with water eventually reaching the Pacific Ocean. The Mummy Range (not labeled in figure 1) straddles the Rocky Mountain National Park northern boundary and is primarily located between the east oriented Cache la Poudre River and the Big Thompson River headwaters. The Cache la Poudre River-Big Thompson River drainage divide area in the Mummy Range investigated in this essay is located in northern Rocky Mountain National Park and the region immediately to the north.

Today the Mummy Range and adjacent mountains are high mountains, yet drainage routes in the present day South Platte River drainage basin, including in the Rocky Mountain National Park area, developed during immense south oriented melt water floods from the western margin of a thick North American ice sheet. The gigantic melt water floods flowed from western Canada to and across the present day South Platte River drainage basin at a time when Colorado mountain ranges were beginning to emerge. Colorado mountain ranges, including the Mummy Range, emerged as floodwaters flowed across them, as ice sheet related crustal warping raised the mountain masses and the entire region, and as floodwaters deeply eroded surrounding regions. The present day north oriented South Platte River drainage route south of Greeley and north oriented South Platte River tributary drainage routes east of Denver (e.g. Kiowa Creek) originated as south oriented flood flow channels east of the emerging Colorado Front Range. East oriented valleys eroded headward from these south oriented flood flow channels into the emerging Colorado Front Range to capture south oriented floodwaters flowing into, along, and across the emerging mountain masses further to the west. Headward erosion of these deep east oriented valleys was in sequence from south to north. For example, headward erosion of the Big Thompson River valley occurred in advance of headward erosion of the Cache la Poudre River valley, which then captured south and southeast oriented flood flow moving to the newly eroded Big Thompson River valley and tributary valleys. The north oriented Cache la Poudre River headwaters drainage route was created by a reversal of flood flow on the north end of flood flow channels to the deep south and southwest oriented Colorado River valley, which had also eroded headward into the region to capture the massive south oriented flood flow. Floodwaters on the north ends of the beheaded flood flow channels reversed flow direction to flow to the deeper east oriented Cache la Poudre River valley. Northeast oriented valley segments were formed by eroding headward across southeast oriented flood flow. Headward erosion of the southeast and northeast oriented South Platte River valley from western Nebraska in time captured flood flow moving on the Cache la Poudre River drainage route and beheaded the south oriented flood flow channels on the present day Colorado Piedmont. Floodwaters on north ends of the beheaded flood flow routes reversed flow direction to create north oriented South Platte River tributary drainage routes and the north oriented South Platte River drainage route. These flood flow reversals were probably greatly aided by ice sheet related crustal warping that was raising the entire region.

Detailed location map for Cache la Poudre River-Big Thompson River drainage divide area

Figure 2: Detailed location map Cache la Poudre River-Big Thompson River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a detailed location map for the Cache la Poudre River-Big Thompson River drainage divide area in the Colorado Mummy Range. The red-brown region is Rocky Mountain National Park and green colored areas are National Forest lands in surrounding mountain regions. The cities of Fort Collins and Loveland near the east edge of figure 2 are located on the Colorado Piedmont, which is located along the eastern margin of the Colorado Front Range. The Mummy Range location is labeled and straddles the Rocky Mountain National Park northern border. The east-west continental divide is shown and extends in a north-northeast direction from the west edge of figure 2 along the crest of the Never Summer Range before turning in a south-southeast direction to the south edge of figure 2 (west half). The area enclosed by the continental divide in the southwest quadrant of figure 2 is drained by the Colorado River, which flows in a south direction in the Kawuneeche Valley to the south edge of figure 2. South of figure 2 the Colorado River turns in a southwest direction and eventually reaches the Pacific Ocean. The Cache la Poudre River headwaters are located on the north and northeast side of the continental divide and flow in a northwest, northwest, north, and northeast direction to Kinikinik near the north edge of the northwest quadrant of figure 2. From Kinikinik the Cache la Poudre River flows in an east direction to the east edge of the green colored area and then in a southeast direction to the east edge of figure 2 (east of Fort Collins). East of figure 2 the Cache la Poudre River turns to flow in an east direction to join the southeast and northeast oriented South Platte River. The South Fork Cache la Poudre River originates in the Mummy Range near the north margin of Rocky Mountain National Park and flows in a northeast direction to join the east oriented Cache la Poudre River near the north center edge of figure 2. The Big Thompson River originates near the Cache la Poudre headwaters at Milner Pass and flows in a southeast, east, and northeast direction to Estes Park. From Estes Park the Big Thompson River flows in a northeast direction to Drake and then in an east-southeast direction to the east edge of figure 2 (near Loveland). East of figure the Big Thompson River turns to flow in a southeast direction to enter the northeast oriented South Platte River valley near where the South Platte River turns from flowing in a north direction to flowing in a northeast direction. Fall River is a southeast oriented Big Thompson River tributary originating south of the north oriented Cache la Poudre River segment in Rocky Mountain National Park. The North Fork Big Thompson River originates in the northeast quadrant of Rocky Mountain National Park (south of the South Fork Cache la Poudre River headwaters) and flows in a northeast, east-southeast, and southeast direction to join the Big Thompson River near Drake. Headward erosion of the northeast oriented South Fork Cache la Poudre River valley captured south and southeast oriented flood flow moving to the North Fork Big Thompson River valley and its tributary valleys. Headward erosion of the east oriented Cache la Poudre River valley beheaded south oriented flood flow channels to the newly eroded Big Thompson River and Fall River valleys and to the actively eroding south oriented Colorado River valley. Headward erosion of these valleys and flood flow captures occurred as floodwaters were flowing across emerging mountains, which contributed the erosion of deep valleys.

Cache la Poudre River-South Fork Cache la Poudre River drainage divide area

Figure 3: Cache la Poudre River-South Fork Cache la Poudre River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of Cache la Poudre River-South Fork Cache la Poudre River drainage divide area. The map contour interval for figure 3 is 50 meters. The Cache la Poudre River flows from the south edge of figure 3 (near southwest corner) in a north direction and then turns flows in a northeast direction across the northwest corner of figure 3. After a short jog north of figure 3 the Cache la Poudre River flows in an east direction near the north edge of figure 3 to the northeast corner. East of figure 3 the Cache la Poudre River flows in an east, southeast, and east direction to join the southeast and northeast oriented South Platte River. The South Fork Cache la Poudre River flows in a northeast direction across the southeast corner of figure 3. East of figure 3 the South Fork flows in a northeast direction to join the east oriented Cache la Poudre River. The north end of the Mummy Range is located between the north and northeast oriented Cache la Poudre River near the west edge of figure 3 and the northeast oriented South Fork Cache la Poudre River seen near the east edge of figure 3. Tributaries from the Mummy Range to the north and northeast oriented Cache la Poudre River segments are oriented in northwest directions while tributaries from the Mummy Range to the northeast oriented South Fork Cache la Poudre River are oriented in southeast and east-southeast directions. For example Sheep Creek is a north-northwest oriented tributary with East and West Forks and flows to the northeast oriented Cache la Poudre River segment. Beaver Creek originates in the Mummy Range and flows in an east-southeast direction to join the South Fork Cache la Poudre River near the south edge of figure 3. The northwest oriented West Fork Sheep Creek valley is linked by a pass with the east-southeast oriented Beaver Creek valley. The pass elevation is between 3350 and 3400 meters. Elevations north and east of the pass rise to 3547 meters and elevations south and west of the pass rise to 3615 meters suggesting the pass is 150 meters deep or deeper. The pass is really a drainage divide on what was once a through valley, which had been eroded by southeast oriented flood flow moving to the east-southeast oriented Beaver Creek valley. At that time the Cache la Poudre River valley to the northwest did not exist and elevations west and north of the pass were at least as high as the pass elevation. The deep northeast oriented South Fork Cache la Poudre River valley had eroded headward from the actively eroding east oriented Cache la Poudre River valley to capture southeast oriented flood flow moving across the emerging Mummy Range. Headward erosion of the Cache la Poudre River valley then beheaded the southeast oriented flood flow routes to the actively eroding Beaver Creek valley and floodwaters on northwest ends of the beheaded flood flow routes reversed flow direction to flow to the deeper Cache la Poudre River valley and to create the northwest oriented Sheep Creek drainage route. Next headward erosion of the northeast and east oriented Cache la Poudre River valley beheaded a south oriented flood flow channel on the west side of the emerging Mummy Range. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Cache la Poudre River drainage route seen along the west edge of figure 3.

Detailed map of Sheep Creek-Beaver Creek drainage divide area

Figure 4: Detailed map of Sheep Creek-Beaver Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed topographic map of the Sheep Creek-Beaver Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 4 is 40 feet. Beaver Creek originates in section 8 and flows in a northeast direction before turning to flow in an east-southeast direction to Comanche Lake and the east edge of figure 4 (near southeast corner). East of figure 4 Beaver Creek flows to the northeast oriented South Fork Cache la Poudre River. A Beaver Creek tributary originates in the northeast corner of section 4 and flows in a southeast direction to Browns Lake and then in a southeast, east, and south direction to join Beaver Creek. The East Fork Sheep Creek originates north of Browns Lake and south of Crown Point and flows in a southwest direction before turning in a northwest direction to flow to the north edge of figure 4 (west half). West Fork Sheep Creek flows in a north-northeast and north-northwest direction in section 5 and then flows in a north-northwest direction to the north edge of figure 4 (near northwest corner). North of figure 4 the East and West Forks join to form north-northwest oriented Sheep Creek, which then flows to the northeast and east oriented Cache la Poudre River. A pass in the southeast quadrant of section 5 links the north-northwest oriented West Fork Sheep Creek valley with the east-southeast oriented Beaver Creek valley. The pass floor elevation is between 11,000 and 11,040 feet. A second pass just north of the northeast corner of section 4 links the northwest oriented East Fork Sheep Creek valley with the southeast oriented Beaver Creek tributary valley. The second pass floor elevation is between 11,160 and 11,200 feet. Elevations just north of section 2 rise to 11,631 feet while elevations in section 17 near the south edge of figure 4 rise to 11,859 feet. These elevations suggest the section 5 pass is approximately 600 feet deep and the second pass is more than 400 feet deep. These parallel and adjacent passes were eroded by diverging and converging southeast oriented flood flow channels at a time when elevations west and north of the passes were at least as high as the pass elevations (which means the deep Cache la Poudre River valley had not eroded headward into the region north and west of figure 4). Headward erosion of the deep Cache la Poudre River valley beheaded the southeast oriented flood flow channels and floodwaters on the northwest ends of the beheaded flood flow channels reversed flow direction to flow to the much deeper Cache la Poudre River valley and to create the northwest oriented Sheep Creek drainage route.

Cache la Poudre River-North Fork Big Thompson River drainage divide area

Figure 5: Cache la Poudre River-North Fork Big Thompson River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Cache la Poudre River-North Fork Big Thompson River drainage divide area south and slightly east of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 50 meters. The Cache la Poudre River flows in a north, northwest, and north direction from the south edge of figure 5 (west half) to the north edge of figure 5 (near northwest corner). North of figure 5 the Cache la Poudre River turns to flow in a northeast and then east direction and eventually turns to flow in a southeast direction before joining the South Platte River. Comanche Peak is located near the center of figure 5 and Mummy Pass is located south of Comanche Peak. The South Fork Cache la Poudre River originates south of Mummy Pass and flows in a north direction to near Mummy Pass and then in a northeast direction to the northeast corner of figure 5. North and east of figure 5 the South Fork flows to the east and southeast oriented Cache la Poudre River. Rowe Peak is located south of Mummy Pass and Hagues Peak is south of Rowe Peak. The North Fork Big Thompson River originates between Rowe Peak and Hagues Peak and flows in a northeast, east, and east-southeast direction to the east edge of figure 5 (south half). East of figure 5 the North Fork Big Thompson River turns to flow in a southeast direction to join the Big Thompson River. Icefield Pass is located east and slightly south from Mummy Pass. While many other passes are visible in figure 5 this essay will focus on the history of Mummy Pass and Icefield Pass. Today Mummy Pass links the northeast oriented South Fork Cache la Poudre valley with the west oriented Mummy Pass Creek valley, which drains to the west oriented Hague Creek valley, which in turn drains to the northwest and north oriented Cache la Poudre River valley. Mummy Pass has an elevation of between 3400 and 3450 meters. Comanche Peak to the north rises to 3872 meters and Hagues Peak to the south rises to 4133 meters. These elevations suggest Mummy Pass is at least 420 meters deep. While the region has been glaciated and the glaciers probably have deepened and otherwise altered some of the valleys the glaciers did not erode new valleys, which means the Mummy Pass valley is a water eroded valley. The Mummy Pass valley was eroded by east oriented flood flow diverging from a south oriented flood flow channel on the present day north oriented Cache la Poudre River alignment and moving floodwaters to what at that time was the actively eroding northeast oriented South Fork Cache la Poudre River valley. Icefield Pass provides evidence of an earlier stage when the east oriented flood flow moved to the actively eroding east and southeast North Fork Big Thompson River valley. Headward erosion of the much deeper northeast oriented South Fork Cache la Poudre River valley captured the east oriented flood flow that had been moving to the North Fork Big Thompson River valley.

Detailed map of Mummy Pass Creek-North Fork Big Thompson River drainage divide area

Figure 6: Detailed map of Mummy Pass Creek-North Fork Big Thompson River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed topographic map of the Mummy Pass Creek-North Fork Big Thompson River drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet. Hagues Peak is located near the south center edge of figure 6 and Rowe Peak is located north of Hagues Peak. Rowe Glacier is located between Rowe Peak and Hagues Peak and the North Fork Big Thompson River originates at Rowe Glacier and then flows in a northeast and east-southeast direction to the east edge of figure 6 (south of center). East of figure 6 the North Fork Big Thompson River turns to flow in a southeast direction to join the Big Thompson River. Icefield Pass is located west of the elbow of capture where the northeast oriented North Fork Big Thompson River turns to flow in an east-southeast direction. Mummy Pass is located west of Icefield Pass and is slightly north and west of the center of figure 6. The north oriented drainage route flowing just east of Mummy Pass and then flowing in a northeast and north direction to the north edge of figure 6 (near northeast corner) is the South Fork Cache la Poudre River. North and east of figure 6 the South Fork Cache la Poudre River flows in a northeast direction to join the east and southeast oriented Cache la Poudre River. Mummy Pass Creek flows in a west direction from Mummy Pass and then turns in a south-southwest direction to enter the much deeper north-northwest and west oriented Hague Creek valley. West of figure 6 Hague Creek flows to the north, northwest, north, northeast, and east oriented Cache la Poudre River. Mummy Pass has an elevation of between 11,240 and 11,280 feet. Fall Mountain to the north rises to 12,258 feet and Comanche Peak (north of figure 6) rises to 12,702 feet. Hague Peak to the south rises to 13,500 feet. These elevations suggest Mummy Pass is approximately 1400 feet deep. While the region in figure 6 has been glaciated with valley glaciers deepening and otherwise altering many of the valleys the glaciers filled existing valleys and did not erode new valleys. In other words, while Mummy Pass has probably been altered by glacial activity the Mummy Pass through valley was present before the Mummy Range was glaciated. The same can be said for Icefield Pass and Flint Pass (south of Mummy Pass) and probably for most other passes seen in figure 6. Perhaps the most intriguing pass is the pass between Rowe Peak and Hagues Peak at the top of Rowe Glacier. Compared to Mummy Pass the Rowe Glacier Pass is shallow (perhaps 200 feet deep) and what looks like a deep cirque is located on the west side, yet that pass links the northeast oriented North Fork Big Thompson River headwaters valley with the northwest and oriented Hague Creek valley. An argument could be made the Rowe Glacier pass was formed by glacial erosion, but an argument could also be made the Rowe Glacier pass originated as a water-eroded valley at a time when floodwaters were flowing on an erosion surface that has since been almost completely removed as floodwaters deeply eroded the surrounding region and as crustal warping raised the Mummy Range. In either case Mummy Range glaciation did not occur until after flood flow across the region had ended and until after the Mummy Range had been uplifted to become the high mountain range it is today.

Cache la Poudre River-Fall River drainage divide area

Figure 7: Cache la Poudre River-Fall River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Cache la Poudre River-Fall River drainage divide area south and west of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 50 meters. The Larimer-Grand County line near extends in an east and south direction from near the west edge of figure 7 (north half) to the south edge of figure 7 (west half) and is located along the east-west continental divide. The south oriented drainage route in Grand County, which originates on the south side of La Poudre Pass (in northwest quadrant of figure 7) and which flows to the southwest corner of figure 7, is the Colorado River. South and west of figure 7 the Colorado River turns in a southwest direction and eventually reaches the Pacific Ocean. The Cache la Poudre River originates near Milner Pass (in the southwest quadrant of figure 7 where highway crosses the continental divide) and flows in a northeast and north direction to the north edge of figure 7 (slightly west of center). The northeast oriented stream on the north side of La Poudre Pass is La Poudre Pass Creek, which joins the north oriented Cache la Poudre River just north of the north edge of figure 7 (west of center). La Poudre Pass and Milner Pass are deep through valleys eroded across the continental divide and link the north oriented Cache la Poudre River headwaters with the south oriented Colorado River headwaters. The passes were eroded by diverging flood flow channels on the present day north oriented Cache la Poudre River headwaters alignment, which converged again in the south oriented Colorado River valley south and west of Milner Pass. Headward erosion of the east oriented Cache la Poudre River valley north of figure 7 beheaded the south oriented flood flow channels and floodwaters on north ends of the diverging flood flow channels reversed flow direction to flow to the deeper east oriented Cache la Poudre River valley. Chapin Creek is a north oriented Cache la Poudre River tributary near the center of figure 7 and originates just north of Chapin Pass. The east-southeast oriented drainage route south of Chapin Pass is the Fall River, which originates near Fall River Pass (west of Chapin Pass) and which flows to the east edge of figure 7. East of figure 7 the Fall River flows to the Big Thompson River. Chapin Pass has an elevation of between 3350 and 3400 meters. Mount Chapin to the east rises to 3796 meters and an unnamed mountain west of Chapin Pass rises to more than 3750 meters. These elevations suggest Chapin Pass is at least 350 meters deep. Chapin Pass was eroded by south oriented flood flow moving from the present day north oriented Cache la Poudre River alignment to the east-southeast oriented Fall River valley. Forest Canyon is a deep southeast oriented valley draining to the south center edge of figure 7 and is drained by the southeast oriented Big Thompson River headwaters. The Big Thompson River originates near Forest Canyon Pass, which is located a short distance north and east of Milner Pass. Forest Canyon Pass is another deep pass linking the north oriented Cache la Poudre River headwaters valley with a southeast oriented drainage route, although Forest Canyon Pass history is more complex than the drainage histories of Chapin, Milner, and La Poudre Passes.

Detailed map of Chapin Creek-Fall River drainage divide area

Figure 8: Detailed map of Chapin Creek-Fall River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 provides a detailed topographic map of the Chapin Creek-Fall River drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 40 feet. The east-west continental divide is the dashed line extending from the north edge of figure 8 (west half) to the south edge of the figure 8 west half). The Cache la Poudre River originates at Poudre Lake (north and east of continental divide in the southwest quadrant of figure 8) and then flows in a northeast direction to the north edge of figure 8 (east of center). North of figure 8 the Cache la Poudre River turns to flow in a north, northwest, north, northeast, east, southeast, and east direction to join the southeast and northeast oriented South Platte River with water eventually reaching the Gulf of Mexico. Forest Canyon Pass is a short distance north and east of the Cache la Poudre River headwaters. The Big Thompson River originates near Forest Canyon Pass and flows in a southeast direction to the south edge of figure 8 (east of center). South and east of figure 8 the Big Thompson River flows in east, northeast, east, and southeast directions to reach the northeast, southeast, and northeast oriented South Platte River. Fall River Pass is located north and east of the center of figure 8 and Fall River originates on the southeast side of Fall River Pass. Fall River flows in an east-southeast, southeast, and east direction to the east edge of figure 8 (south of center) and east of figure 8 joins the northeast, east, and southeast oriented Big Thompson River. Chapin Pass is east of Fall River Pass and north and northwest oriented Chapin Creek originates north of Chapin Pass and flows to the north edge of figure 8 (east half). North of figure 8 Chapin Creek joins the north oriented Cache la Poudre River. Chapin Pass has an elevation of between 11,120 and 11,160 feet, Fall River Pass has an elevation of 11,796 feet, and Forest Canyon Pass has an elevation of between 11,280 and 11,320 feet. Milner Pass (at the southwest end of Poudre Lake and west of figure 8) has an elevation of 10,758 feet and links the northeast oriented Cache la Poudre River headwaters with south-southwest oriented Beaver Creek, which south and west of figure 8 flows to the south and southwest oriented Colorado River. Using elevations located south of figure 8 Milner Pass is approximately 2000 feet deep and is approximately 400 feet deeper than Chapin Pass and more than 500 feet deeper than Forest Canyon Pass, which is almost 500 feet deeper than Fall River Pass. Forest Canyon Pass and Fall River Pass link the northeast oriented Cache la Poudre River valley with southeast oriented valleys and were probably eroded by southeast oriented flood flow channels prior to headward erosion of a deeper southwest oriented flood flow channel on the present day northeast oriented Cache la Poudre River alignment, which beheaded the southeast oriented flood flow channels and diverted floodwaters in a southwest direction to the actively eroding Colorado River valley. The region was being uplifted as floodwaters flowed across it and floodwaters eroded deeper and deeper valleys into the rising mountain masses until headward erosion of deeper valleys beheaded the flood flow channels and in the case of the Cache la Poudre River and Chapin Creek caused flood flow reversals to create north oriented drainage routes.

Fall River-Big Thompson River drainage divide area

Figure 9: Fall River-Big Thompson River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Fall River-Big Thompson River drainage divide area south and east of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 50 meters. Chapin Creek originates near Chapin Pass and flows in a north direction near the northwest corner of figure 9. North of figure 9 Chapin Creek flows to the north, east, and southeast oriented Cache la Poudre River, which flows to the southeast and northeast oriented South Platte River. The Big Thompson River flows in a southeast direction from the west center edge of figure 9 through Forest Canyon before turning to flow in an east and northeast direction to Estes Park and the east center edge of figure 9. East of figure 9 the Big Thompson River flows in a northeast, east-southeast, east, and southeast direction to join the northeast, southeast, and northeast oriented South Platte River. The Fall River flows from the west edge of figure 9 (west of Chapin Pass) in an east-southeast direction to join the Big Thompson River near Estes Park. Fish Creek is the north-northeast oriented stream flowing from the south edge of figure 9 (east half) to join the Big Thompson River at Estes Lake. In the southwest quadrant of figure 9 there are many erosional residuals surrounded by present day drainage routes and/or through valleys which link the present day drainage routes. Several of these erosional residuals are named and include Deer Mountain, Eagle Cliff Mountain, Prospect Mountain, Castle Mountain, and many others. Some of these erosional residuals rise more than 300 meters above the surrounding valley floors. The maze of valleys between these erosional residuals was eroded by a former anastomosing complex of flood flow channels that eroded headward into the region as the Big Thompson River valley and its tributary valleys beheaded south and southeast oriented flood flow channels flowing across the region. The landscape is complicated because it was probably eroded by an east oriented anastomosing channel complex that was capturing a south oriented anastomosing channel complex and was subsequently further altered by valley glaciers in the mountain valleys. The South Lateral Moraine and Moraine Park on the south side of the Big Thompson River (north of the south center edge of figure 9) provide evidence the valley glaciers extended eastward in the Big Thompson River valley to at least that location. The valley glaciers did fill and modify pre-existing valleys, but the valleys had been eroded by flood flow prior to the glaciation. Glaciation occurred after all flood flow across the region had ended and after the mountains had been uplifted to create the high mountains seen today.

Detailed map of Fall River-Big Thompson River drainage divide area

Figure 10: Detailed map of Fall River-Big Thompson River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a detailed topographic map of the Fall River-Big Thompson River drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 40 feet. The Big Thompson River flows in an east direction from the west edge of figure 10 (near southwest corner) through Moraine Park and south of Eagle Cliff Mountain turns to flow in a northeast direction to the east edge of figure 10 (slightly south of center). East of figure 10 the Big Thompson River flows in a northeast, east-southeast, east, and southeast direction to join the northeast, southeast, and northeast oriented South Platte River. The Fall River flows in a southeast and east direction from the north edge of figure 10 (west half) through Horseshoe Park to the north center edge of figure 10 (north of Deer Mountain) and then turns to flow in a southeast direction to the east edge of figure 10 (slightly north of center) and joins the Big Thompson River east of figure 10. Large erosional residuals seen in figure 10 include Deer Mountain, Eagle Cliff Mountain, Castle Mountain, and Oldman Mountain and are bounded by present day drainage routes and/or through valleys linking present day drainage routes. For example a north to south oriented through valley west of Deer Mountain links the Fall River valley with east-southeast oriented Beaver Brook, which flows to the northeast oriented Big Thompson River. A through valley west of Eagle Cliff Mountain links the Beaver Brook valley with the east oriented Big Thompson River valley. The through valley west of Deer Mountain crosses Deer Ridge and has an elevation of between 8960 and 9000 feet at the drainage divide. Deer Mountain to the east rises to 10,000 feet and the mountains to the west rise even higher suggesting the Fall River-Beaver Creek through valley is at least 1000 feet deep. Horseshoe Park to the north of Deer Ridge has an elevation of between 8480 and 8520 feet, which suggests the Fall River valley floor was lowered by approximately 500 feet since the time south oriented flood flow moved across Deer Ridge or that Deer Ridge is a depositional feature (e.g. lateral moraine) formed after the through valley had been eroded. Lateral moraines are definitely present on both sides of the Big Thompson River valley in Moraine Park to the south. South Lateral Moraine is located along the south edge of figure 10 and the north lateral moraine is located between Beaver Brook and Moraine Park and extends across the north to south oriented through valley west of Eagle Cliff Mountain. Elevations in Beaver Meadows to the north of the north lateral moraine are between 8200 and 8400 feet while elevations in Moraine Park are slightly greater than 8000 feet. Eagle Cliff Mountain rises to 8906 feet suggesting the north to south oriented through valley is between 500 and 700 feet deep depending on where and how it is measured. The north to south oriented through valley west of Eagle Cliff Mountain and of Deer Mountain was eroded by south oriented flood flow prior to headward erosion of the Big Thompson River valley, which was prior to headward erosion of the Beaver Brook valley, which was prior to headward erosion of the Fall River valley. The region seen in figure 10 was deeply eroded as deep valleys eroded headward to capture immense south oriented floods moving across the emerging mountain mass. Valley glaciers did not fill the valleys until after all flood flow across the region had ended and all valleys had been eroded and until after the high mountains had fully emerged.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories, which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.

Forecast surface map valid 6am CST Monday

This is a classic Puget Sound windstorm scenario. And a scenario where meteorology and geomorphology come into play in shaping a weather event. As the strong surface low makes landfall onto southern Vancouver Island, the pressure field is oriented perpendicular to the north-south Puget Sound basin. A strong pressure difference develops between the north end and south end of the basin, creating a strong, southerly pressure-driven wind between the Olympic and Cascade Mountains. Strong windstorms have been known to produce gusts of 65-75mph in the Seattle Area with other intense gusts throughout Greater Puget Sound. There are other types of windstorm scenarios such as small scale intense lee-mountain lows in the Olympic Mountains leading to enhanced localized winds speeds, Willamette Valley windstorms (similar scenario to Puget Sound events, but involving the Oregon Coast Range and the Cascades) and widespread wind events produced by re-curving low-pressure systems which move up and parallel to the shoreline and impact areas from San Francisco to Vancouver, BC.

I grew up with windstorms. They are probably the one of the most significant winter severe weather threats for the western Pacific Northwest (the other being river flooding). The last big one for Seattle that I can remember (unless I missed one after moving) was December 2006, almost exactly 6yrs ago, which produced a gust to 69mph at Seattle’s airport and knocked out tons of trees in my home neighborhood because of watery soils and rotting tree roots. Hopefully, no significant damage from tomorrow’s storm, which (for reference for those of you in hurricane country) will be the equivalent to a landfalling tropical storm.

Abstract:

This essay uses topographic map evidence to interpret landform origins in the Crow Creek-South Platte River drainage divide area in Weld and Morgan Counties, Colorado. Before entering Weld County the South Platte River flows in a north direction east of the Colorado Front Range and once in Weld County the South Platte River turns flows in a northeast, southeast, northeast, southeast, and northeast direction into Morgan County and then continues to flow in a northeast and east direction to western Nebraska where it joins the southeast oriented North Platte River to form the Nebraska Platte River. Crow Creek flows in an east direction in southeast Wyoming before turning in a southeast, south, west, and southwest direction to join the South Platte River near the western point where the northeast oriented South Platte River turns to flow in a southeast direction. East of the eastern South Platte River northeast-southeast jog South Platte River tributaries from the north are oriented in southeast directions with southeast oriented Wildcat Creek being the westernmost of these southeast oriented tributaries. Between Crow Creek and Wildcat Creek South Platte River tributaries are oriented in south directions and Crow Creek has short northwest oriented tributaries. Valley orientations, barbed tributaries, streamlined erosional residuals, through valleys crossing drainage divides, and upland erosion surfaces in the Crow Creek-Wildcat Creek drainage divide area are interpreted to have developed during immense melt water floods from the western margin of a thick North American ice sheet. Initially floodwaters flowed in south directions, although directions of flood flow changed and were even reversed in some cases as ice sheet related crustal warping raised mountain ranges and plateaus and as deep valleys eroded headward into the region to capture the immense melt water floods. The northeast oriented South Platte River valley (east of the northeast-southeast jogs) eroded headward from western Nebraska across southeast oriented flood flow moving to what at that time was the actively eroding Republican River valley. The south and southwest oriented Crow Creek valley eroded headward from southwest and south oriented flood flow channels on the present day north and northeast oriented South Platte River and north oriented South Platte River tributary alignments and beheaded southeast oriented flood flow routes to the actively eroding South Platte River valley. The South Platte River northeast-southeast jogs were created when the South Platte River valley eroded headward along southeast oriented flood flow channels for short distances before turning to erode across southeast oriented flood flow. Headward erosion of the South Platte River valley captured south oriented flood flow on the Crow Creek alignment and diverted floodwaters into Nebraska. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow to the deeper South Platte River valley and created the north and northeast oriented South Platte River drainage route and north oriented South Platte River tributary drainage routes.

Preface

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.

Introduction

The purpose of this essay is to use topographic map interpretation methods to explore the Crow Creek-South Platte River drainage divide area landform origins in Weld and Morgan Counties, Colorado. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big-picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain Crow Creek-South Platte River drainage divide area landform evidence in Weld and Morgan Counties, Colorado will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Crow Creek-South Platte River drainage divide area location map

Figure 1: Crow Creek-South Platte River drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a location map for the Crow Creek-South Platte River drainage divide area in Weld and Morgan Counties, Colorado and illustrates a region in northern Colorado in the south with the southeast corner of Wyoming in the northwest corner and southwest corner of the Nebraska panhandle in the northeast corner. The Colorado Front Range, which merges into the Wyoming Laramie Mountains, can be seen near the west edge of figure 1. The South Platte River originates in the Colorado Front Range (south of figure 1 and flows in a southeast direction before turning to flow in a north and north-northeast direction along the east margin of the Colorado Front Range to Denver (near south edge of figure 1). From Denver the South Platte River flows in a north and northeast direction to Greeley and then in a southeast-northeast, and southeast direction to Fort Morgan. From Fort Morgan the South Platte River flows in a northeast direction to the east edge of figure 1 (near Colorado-Nebraska state line) and east of figure 1 flows into western Nebraska to join the southeast oriented North Platte River and to form the Nebraska Platte River. Note the northeast-southeast jog the South Platte River makes just west of Fort Morgan. East of that jog South Platte River tributaries from the north are oriented in southeast directions while west of that jog South Platte River tributaries are oriented in south and even south-southwest directions. South Platte River tributaries from the south between the Fort Morgan area and Greeley are generally oriented in north directions and include Kiowa Creek, Bijou Creek, and Beaver Creek. Further to the east there are no South Platte River tributaries from the southeast shown in figure 1, suggesting the South Platte River has an asymmetric drainage divide with the southeast and east oriented streams flowing towards the east edge of figure 1. Crow Creek originates in the Wyoming Laramie Mountains (near northwest corner of figure 1) and flows in an east and southeast direction to Cheyenne, Wyoming and then in an east, southeast, south, and south-southwest direction to join the east-southeast oriented South Platte River a short distance east of Greeley. The Crow Creek-South Platte River drainage divide area investigated in this essay focuses on the drainage divide between Crow Creek and streams flowing to the South Platte River in the vicinity of the South Platte River’s northeast-southeast jog just west of Fort Morgan.

The South Platte River and tributary drainage routes developed during immense melt water floods from the western margin of a thick North American ice sheet at a time when Wyoming and Colorado mountain ranges were beginning to emerge. Floodwaters flowed from western Canada to and across the present day South Platte River drainage basin initially in south oriented complexes of diverging and converging flood flow channels. However, as ice sheet related crustal warping raised mountain and plateau areas and as deep east oriented valleys eroded headward into the region from the developing Missouri River drainage basin floodwaters were diverted in other directions and even reversed to flow in north directions. Present day drainage patterns generally reflect directions of flood flow at the time floodwaters finally drained from a region and varies from region to region. In the case of the South Platte River drainage basin the northeast oriented South Platte River valley downstream from the northeast-southeast jog (just west of Fort Morgan) eroded headward across southeast oriented flood flow, which was moving to the newly eroded Republican River valley (the Arikaree River in the southeast corner of figure 1 is a Republican River tributary). The southeast oriented South Platte River valley west of the northeast-southeast jog eroded headward across south oriented flood flow channels, which were probably flowing to the southeast oriented Arkansas River valley in southern Colorado, however prior to Arkansas River valley headward erosion floodwaters flowed to southeast and south oriented valleys further to the south. Headward erosion of the south oriented flood flow channels west of the South Platte River northeast-southeast jog was at that time in the process of capturing southeast and east oriented flood flow moving to the actively eroding Republican River valley and subsequently to the actively eroding South Platte River valley. Headward erosion of the much deeper South Platte River valley then eroded headward across the south oriented flood flow channels (changing the South Platte River valley direction of headward erosion as it encountered flood flow moving in different directions). Floodwaters on north ends of beheaded flood flow channels reversed flow direction to create north oriented South Platte River tributary drainage routes. Flood flow channels were beheaded in sequence from east to west and because flood flow channels diverged and converged so a newly beheaded and reversed flood flow channel could capture floodwaters from adjacent and yet to beheaded flood flow channels further to the west. In addition to north oriented South Platte River tributary drainage routes the north and north-northeast oriented South Platte River drainage route along the Colorado Front Range east flank was created by a flood flow reversal and captured significant south and southeast oriented flood flow from flood flow channels in the emerging Colorado Front Range further to the west. Today the Colorado Front Range is a high mountain range, but at the time the Front Range was still emerging and south and southeast oriented flood flow from the north and northwest could reach what are today southeast oriented South Platte River headwaters (south of figure 1).

Detailed location map for Crow Creek-South Platte River drainage divide area

Figure 2: Detailed location map Crow Creek-South Platte River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a detailed location map for the Crow Creek-South Platte River drainage divide area in Weld and Morgan Counties, Colorado. County boundaries are shown and Weld and Morgan Counties are labeled. Greeley is located near the southwest corner of figure 2. Fort Morgan is located just south of figure 2 (south of the “R” in the word “MORGAN”). The South Platte River flows in a northeast direction from the southwest corner of figure 2 along the southeast side of Greeley and then turns to flow in a southeast direction to near Masters (near the south center edge of figure 2). From Masters the South Platte River flows in a northeast direction to Goodrich and then turns to flow in a southeast direction and just north of Fort Morgan turns again to flow in a northeast direction to the east edge of figure 2. Tributaries joining the South Platte River east of Weldon (a town on the South Platte River in western Morgan County) are generally oriented in southeast directions. Wildcat Creek is a labeled southeast oriented tributary in Morgan County. East and southeast oriented streams in the northeast quadrant of figure 2 all flow in southeast directions east of figure 2 to join the northeast oriented South Platte River. Crow Creek flows from the north center edge of figure 2 (near the town of Grover) in a south direction and makes a jog to the west just north of Seven Cross Hill before flowing in a south, southwest, and south direction to join the southeast oriented South Platte River east of Greeley. Crow Creek tributaries from the west are numerous and are generally oriented in south-southeast directions while Crow Creek has almost no tributaries from the east. This asymmetric drainage divide suggests the Crow Creek valley eroded headward across multiple south-southeast oriented flood flow channels and diverted floodwaters in a southwest direction to southwest and south oriented flood flow channels on alignments of what are today the north and northeast oriented South Platte River and north oriented South Platte River tributary drainage routes. The southeast oriented South Platte River segment west of Fort Morgan was created by headward erosion of the South Platte River valley along a southeast oriented flood flow channel. The northeast oriented South Platte River segment between Masters and Goodrich was created by headward erosion of the South Platte River valley across southeast oriented flood flow. The southeast oriented South Platte River segment between Greeley and Masters was created by headward erosion of the South Platte River valley across southwest oriented flood flow. Just north of Seven Cross Hill Crow Creek turns in a southeast direction before turning to flow in a west direction. The southeast oriented turn is where the south oriented Crow Creek valley captured a southeast oriented flood flow channel and eroded headward along that flood flow channel for a sort distance before headward across southeast oriented flood flow.

Wildcat Creek-South Platte River drainage divide area

Figure 3: Wildcat Creek-South Platte River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of Wildcat Creek-South Platte River drainage divide area. The map contour interval for figure 3 is 10 meters. Fort Morgan is the town straddling the south center edge of figure 3. The South Platte River flows in a southeast direction from the west center edge of figure 3 to Fort Morgan and then turns to flow in a northeast direction to the east edge of figure 2 (south half). Elevations in the South Platte River valley near Fort Morgan are about 1300 meters. Wildcat Creek flows in a southeast direction from the north center edge of figure 3 to join the northeast oriented South Platte River near the east edge of figure 3. Box Canyon and Porter Canyon are two north and northeast oriented Wildcat Creek tributaries near the north center edge of figure 3. Elevations on Fry Hill (just west of Porter Canyon and near north edge of figure 3) exceed 1460 meters and are approximately 160 meters higher than the South Platte River valley floor at Fort Morgan. Aker Draw and Lamborn Draw are south and south-southwest oriented South Platte River tributaries near the west edge of figure 3. Unnamed southeast oriented South Platte River tributaries flow across the northeast corner of figure 3. While subtle there is a difference in the orientations of South Platte River tributaries in the east half of figure 3 and the orientations in the west half of figure 3. The north and northeast oriented Box Canyon and Porter Canyon valleys were eroded by reversals of flood flow as the deep southeast oriented Wildcat Creek valley eroded headward across south and south-southwest oriented flood flow. At that time the deep southeast oriented South Platte River valley in the west half of figure 3 was being eroded and south and south-southwest oriented flood flow was moving to the actively eroding South Platte River valley head. Headward erosion of the deep southeast oriented Wildcat Creek valley beheaded and reversed flood flow on the Box Canyon alignment first. The reversed flood flow captured south oriented flood flow still moving on the yet to be beheaded and reversed Porter Canyon alignment and the captured flood flow helped erode the deep northeast and north oriented Box Canyon valley. Headward erosion of the deep Wildcat Creek valley next beheaded and reversed flood flow on the Porter Canyon alignment and the process was repeated.

Detailed map of the Porter Canyon-Aker Draw drainage divide area

Figure 4: Detailed map of Porter Canyon-Aker Draw drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed topographic map of the Porter Canyon-Aker Draw drainage divide area south and east of figure 3 and seen in less detail in figure 3. The map contour interval for figure 4 is 10 feet. Wildcat Creek flows in a southeast direction across the northeast corner of figure 4. East and south of figure 4 Wildcat Creek flows in a southeast direction to join the northeast oriented South Platte River. Box Canyon originates in the east half of section 27 and drains in a southeast, northeast, and north-northeast direction to enter the southeast oriented Wildcat Creek valley as a barbed tributary. Porter Canyon originates near the north edge of section 27 and drains in a north, northeast, and north-northeast direction to also enter the southeast oriented Wildcat Creek valley as a barbed tributary. Aker Draw originates near the northeast corner of section 19 and drains in a south-southwest direction to the southwest corner of figure 4. South and west of figure 4 Aker Draw drains to the southeast oriented South Platte River. Fry Hill is located near the northwest corner of section 21. A south-southwest and west oriented Aker Draw tributary originates near Fry Hill and joins Aker Draw in section 31 near the southwest corner of figure 4. Fry Hill is located on an upland erosion surface, which today is the Wildcat Creek-Aker Draw drainage divide (and Wildcat Creek-South Platte River drainage divide in the southeast quadrant of figure 4). The upland erosion surface was eroded by headward erosion of the deep southeast oriented Wildcat Creek valley and its tributary valleys and also by the deep south-southwest oriented Aker Draw and tributary valleys (and south oriented South Platte River tributary valleys in the southeast quadrant of figure 4), but remnants of the earlier erosion surface still survive along the drainage divide. A high point in the west half of section is labeled “Newton” has an elevation of 4774 feet. The Fry Hill elevation is at least 4810 feet. Between these two high points drainage divide elevations decreases to between 4700 and 4710 feet suggesting the presence of a northeast to southeast oriented through valley or former flood flow channel that once crossed the upland surface (prior to headward erosion of the deep southeast oriented Wildcat Creek valley). A shallower through valley in the north half of section 27 links the north oriented Porter Canyon headwaters valley with the southeast oriented Box Canyon headwaters valley. Prior to the reversal of flood flow on the Porter Canyon alignment floodwaters flowed in a southeast direction into the newly beheaded and reversed Box Canyon drainage route. Floodwaters that eroded the north and northeast oriented Porter Canyon valley apparently flowed in a southeast and east direction around the south side of Fry Hill and were subsequently captured by headward erosion of the deep south-southwest and southwest oriented Aker Draw tributary valley.

Wildcat Creek-Cottonwood Draw drainage divide area

Figure 5: Wildcat Creek-Cottonwood Draw drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Wildcat Creek-Cottonwood Draw drainage divide area north and west of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 10 meters. Fry Hill is located near the southeast corner of figure 5. Jackson Reservoir in the southwest quadrant of figure 5 is located north of the eastern South Platte River jog where the northeast oriented river segment turns to flow in a southeast direction. Wildcat Creek flows in a southeast direction from the north center edge of figure 5 to the east edge of figure 5 (south half) and east and south of figure 5 joins the northeast oriented South Platte River. Jackson Hills is the upland erosion surface extending in a southeast direction from the north edge of figure 5 to the Fry Hill area near the southeast corner of figure 5. The upland erosion surface is also present in the northeast corner of figure 5 on the northeast side of the southeast oriented Wildcat Creek valley. A southwest-facing escarpment extending from the north edge of figure 5 (west half) to the southeast corner of figure 5 is drained by south and south-southwest oriented tributaries headed towards the southeast oriented South Platte River (south of figure 5). Many of these south oriented streams end as surface drainage routes before they reach the South Platte River. Two Cottonwood Draws can be seen in figure 5. The first Cottonwood Draw drains in a south direction from the southwest-facing escarpment slope to the south edge of figure 5 (east of Jackson Reservoir). The second Cottonwood Draw drains in a south-southeast direction from the west edge of figure 5 toward Jackson Reservoir, but ends as a surface drainage route. The southwest-facing escarpment probably was eroded as the northeast wall of a southeast oriented flood flow channel, which was subsequently captured by a southwest oriented flood flow channel on the present day northeast oriented South Platte River alignment (in the northeast-southeast jog). The southwest oriented flood flow channel was then beheaded and reversed by headward erosion of the deeper southeast oriented South Platte River valley (again in the northeast-southeast jog) to create the northeast-southeast jog in the South Platte River west of Fort Morgan. Southeast oriented flood flow in the southeast oriented flood flow channel was beheaded at about that time by headward erosion of the south-southwest oriented Crow Creek valley (see figure 7).

Detailed map of Wildcat Creek-Cottonwood Draw drainage divide area

Figure 6: Detailed map of Wildcat Creek-Cottonwood Draw drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed topographic map of the Wildcat Creek-Cottonwood Draw drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 10 feet. Wildcat Creek flows in a southeast direction from the north edge of figure 6 (east of center) to the east edge of figure 6 (north of center). East and south of figure 6 Wildcat Creek flows to the northeast oriented South Platte River. South oriented streams draining to the south edge of figure 6 are headwaters of south oriented Cottonwood Draw, which south of figure 6 drains to the South Platte River at northern point in the eastern South Platte River northeast-southeast jog. The low relief upland surface between the southeast oriented Wildcat Creek valley and the south oriented Cottonwood Draw headwaters valleys is the Jackson Hills seen in figure 5. While no deep valleys cross the Jackson Hills upland there are shallow through valleys and what may be streamlined erosional residuals. In addition there are shallow depressions usually defined by a single 10-foot contour line. The depressions may be wind eroded deflation basins and it possible some of the small streamlined hills are wind deposited sand dunes. However, the relatively smooth upland surface was eroded by south, south-southeast, and/or southeast oriented flood flow, which was being captured by headward erosion of the deep southeast oriented Wildcat Creek valley which was eroding headward from the northeast oriented South Platte River valley and by headward erosion of south oriented valleys from what initially was probably a southwest oriented flood flow channel on the present day northeast oriented South Platte River alignment (in the eastern South Platte River northeast-southeast jog), although which was later beheaded and reversed to become the northeast oriented South Platte River segment in the eastern South Platte River northeast-southeast jog. Flood flow across the Jackson Hills upland surface was beheaded by headward erosion of the deeper southwest oriented Crow Creek valley west of figure 6 (see figures 7 and 8).

Crow Creek-Sanborn Draw drainage divide area

Figure 7: Crow Creek-Sanborn Draw drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 uses a reduced size topographic map to illustrate the Crow Creek-Sanborn Draw drainage divide area west and north of figure 5 and includes an overlap area with figure 6. The map contour interval for figure 7 is 10 meters. Crow Creek flows in a south and southwest direction from the north edge of figure 7 (west half) to the west edge of figure 7 (south half). West and south of figure 7 Crow Creek joins the South Platte River. Sanborn Draw originates slightly north and west of the center of figure 7 and drains in a south direction to the south edge of figure 7 (slightly west of center). South of figure 7 Sanborn Draw drains to Riverside Reservoir, which is located north of an east oriented South Platte River segment. The upland in the northeast quadrant of figure 7 is a continuation of the Jackson Hills upland seen in figure 5 and north of figure 7 merges into Seven Cross Hill with Crow Creek flowing in a west and south direction around the northwest end of Seven Cross Hill. Greasewood Flats is located at the base of the northwest end of the southwest-facing escarpment seen in figure 5 (on southwest side of Jackson Hills) and is actually a shallow southeast oriented through valley defined by three 10-meter contour lines. Perhaps easier to visualize is the northwest to southeast oriented through valley crossing the Crow Creek-Sanborn Draw drainage divide. Point of Rocks is a labeled high point in the southwest quadrant of figure 7 and reaches an elevation of more than 1520 meters. Elevations along the Crow Creek-Sanborn Draw drainage divide north of Point of Rocks drop to less than 1500 meters and then rise to more than 1520 meters on Seven Cross Hill near the north edge of figure 7. These elevations suggest a 20 meter deep or deeper southeast oriented flood flow channel eroded the drainage divide. Initially floodwaters flowed in a southeast direction toward the southeast corner of figure 7, but were captured by headward erosion of south oriented valleys. For example, headward erosion of south oriented Sanborn Draw captured the southeast oriented flood flow and diverted floodwaters in a south direction. Headward erosion of the southwest oriented Crow Creek valley next captured the southeast oriented flood flow and diverted floodwaters in a southwest direction. Floodwaters on northwest ends of beheaded flood flow routes reversed flow direction to create northwest oriented tributary drainage routes to southwest oriented Crow Creek. Coal Creek is the south-southeast oriented stream flowing from the northwest corner of figure 7 to join Crow Creek near Cornish and provides further evidence that headward erosion of the southwest oriented Crow Creek valley captured south-southeast oriented flood flow.

Detailed map of Crow Creek-Sanborn Draw drainage divide area

Figure 8: Detailed map of Crow Creek-Sanborn Draw drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 provides a detailed topographic map of the Crow Creek-Sanborn Draw drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 10 feet. Crow Creek can just barely be seen flowing in a southwest direction across the northwest corner of figure 8. West and south of figure 8 Crow Creek flows to the South Platte River. Northwest oriented streams in the west half of figure 8 flow to Crow Creek as barbed tributaries. South and southeast oriented streams in the east half of figure 8 are tributaries to south oriented Sanborn Draw. South of figure 8 Sanborn Draw drains to Riverside Reservoir, which is located just north of an east oriented South Platte River segment. Point of Rocks is a labeled high point in section 17 near the south edge of figure 8 (west half) and reaches an elevation of 4975 feet. North of section 17 the Crow Creek-Sanborn Draw drainage divide elevation decreases to between 4910 and 4920 feet in section 32. Elevations along the drainage divide remain below 4950 feet to the north edge of figure 8, but north of figure 8 rise to more than 5040 feet on Seven Cross Hill. These elevations suggest there is a broad northwest to southeast oriented through valley between Point of Rocks and Seven Cross Hill, which at its deepest points is at least 55 feet deep. Multiple shallower northwest-to-southeast oriented through valleys are eroded into the floor of that broader through valley. The shallower through valleys are defined by two or more contour lines on a side and suggest floodwaters flowed in diverging and converging flood flow channels. At the time floodwaters flowed in a southeast direction across figure 8 the southwest oriented Crow Creek valley did not exist. Headward erosion of the southwest oriented Crow Creek valley captured the southeast oriented flood flow. Floodwaters on northwest ends of beheaded flood flow channels reversed flow direction to flow in northwest directions to the deeper southwest oriented Crow Creek valley and to create northwest oriented Crow Creek tributary drainage routes.

Crow Creek-South Platte River drainage divide area

Figure 9: Crow Creek-South Platte River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Crow Creek-South Platte River drainage divide area south and west of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 10 meters. The South Platte River flows in a southeast direction across the southwest corner of figure 9. Crow Creek flows in a southwest and south direction from the north edge of figure 9 (west of center) to join the South Platte River north of the town of Kuner. Sanborn Draw drains in a south direction from near the northeast corner of figure 9 to the east center edge of figure 9. East and south of figure 9 Sanborn Draw drains to Riverside Reservoir, which is located north of an east oriented South Platte River segment, just west of the eastern South Platte River northeast-southeast jog. Point of Rocks is the labeled high point in the northeast quadrant of figure 9. Shallow northwest-to-southeast oriented through valleys can be seen crossing the drainage divide south and west of Point of Rocks. Generally these through valleys are defined by one 10-meter contour line on each side. The through valleys combined with evidence for the deeper through valleys seen north and east of Point of Rocks provide evidence of southeast oriented flood flow moving across the region in figure 9 prior to headward erosion of the southwest oriented Crow Creek valley. While not seen in figure 9 the southwest oriented Crow Creek valley (before it turns in a south direction) is headed towards the present day northeast oriented South Platte River valley segment west of Greeley (see figure 10). Headward erosion of the southwest oriented Crow Creek valley probably was from a southwest and south oriented flood flow channel on the present day north and northeast oriented South Platte River alignment south of Greeley (see figure 1). Headward erosion of the deep southeast oriented South Platte River valley captured the flood flow on the newly eroded southwest oriented Crow Creek flood flow route and beheaded the southwest and south oriented flood flow channel on the present day north and northeast oriented South Platte River alignment. Floodwaters on the northeast and north ends of the beheaded flood flow channel reversed flow direction to create the north, northeast, and southeast oriented South Platte River drainage route near Greeley.

Lone Tree Creek-Crow Creek drainage divide area

Figure 10: Lone Tree Creek-Crow Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a topographic map of the Lone Tree Creek-Crow Creek drainage divide west and slightly south of figure 9 and includes an overlap area with figure 9. The map contour interval for figure 10 is 10 meters. Greeley is the city near the west center margin of figure 10. The South Platte River flows in a northeast direction from near the southwest corner of figure 10 to Scout Island (near center of figure 10) and then turns to flow in a southeast direction to the east edge of figure 10 (near southeast corner).  The Cache la Poudre River flows from the west edge of figure 10 (north of Greeley) along the north edge of Greeley in an east-southeast direction to join the South Platte River near Scout Island. Crow Creek flows in a west direction from near the northeast corner of figure 10 and west of Barnesville turns to flow in a south direction to join the southeast oriented South Platte River just north of the town of Kuner. Lone Tree Creek flows in a south direction from the north center edge of figure 10 to join the South Platte River at its elbow of capture (where it turns from flowing in a northeast direction to flowing in a southeast direction). Sand Creek is a south oriented stream flowing from the north edge of figure 10 (west half) to join the east oriented Cache la Poudre River near the County Municipal Airport (just west of Scout Island). The northeast oriented “Creek” and South Platte River tributary south of Kuner is Box Elder Creek, which south of figure 10 flows in a north direction. The South Platte River elbow of capture seen in figure 10 is where headward erosion of the deep southeast oriented South Platte River valley captured south flood flow channels that had been flowing in a south direction along the alignments of the present day north and northeast oriented South Platte River and its north oriented tributary drainage routes. The Cache la Poudre River originates in the high mountains west of figure 10 and prior to being captured by headward erosion of the deeper southeast oriented South Platte River valley probably turned in a southeast direction west of Greeley on an alignment now used by a southeast oriented Big Thompson River segment, which joins the north and northeast oriented South Platte River as a barbed tributary (south of Greeley) near the point where the north oriented South Platte River turns to flow in a northeast direction, although a different essay illustrates and discusses the Cache la Poudre River-Big Thompson River drainage divide area.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories, which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.

Abstract:

This essay uses topographic map evidence to interpret landform origins in the Pawnee Creek-South Platte River drainage divide area in Weld, Morgan, and Logan Counties, Colorado. Pawnee Creek is an east and southeast oriented tributary to the northeast oriented South Platte River in northeast Colorado. Topographic map evidence shows drainage divides between Pawnee Creek tributary and headwaters valleys are crossed by shallow northwest to southeast oriented through valleys while the east oriented tributaries have short southeast tributaries from the north and north, northwest, or north-northwest tributaries from the south. The barbed tributaries, valley orientations, and shallow through valleys are interpreted to have originated as the Pawnee Creek valley and its tributary valleys eroded headward across southeast oriented flood flow with Pawnee Creek tributary and headwaters valleys being eroded in sequence from the southeast to the northwest. Floodwaters are interpreted to have been derived from the western margin of a thick North American ice sheet and were flowing from western Canada to and across northeast Colorado at a time when the much larger Missouri River drainage system was also developing as deep east oriented tributary valleys eroded headward in sequence from the southeast to the northwest. The north oriented South Platte River drainage route south and west of the Pawnee Creek drainage basin was created by a reversal of flood flow on the north ends of south oriented flood flow channels, which were beheaded by headward erosion of the much deeper northeast oriented South Platte River valley.

Preface

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.

Introduction

The purpose of this essay is to use topographic map interpretation methods to explore the Pawnee Creek-South Platte River drainage divide area landform origins in Weld, Morgan, and Logan Counties, Colorado. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big-picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain Pawnee Creek-South Platte River drainage divide area landform evidence in Weld, Morgan, and Logan Counties, Colorado will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Pawnee Creek-South Platte River drainage divide area location map

Figure 1: Pawnee Creek-South Platte River drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a location map for the Pawnee Creek-South Platte River drainage divide area in Weld, Morgan, and Logan Counties Colorado and illustrates the northeast corner of Colorado with the southeast corner of Wyoming and southwest corner of the Nebraska panhandle to the north. The east edge of the Colorado Front Rant, which merges with the Wyoming Laramie Mountains, can be seen along the west edge of figure 1. The South Platte River flows in a north direction to Denver (near southwest corner of figure 1) and then in a north-northeast direction to Greeley. Near Greeley the South Platte River flows in an east-southeast direction with a northeast jog to near Fort Morgan and then in a northeast direction to the east edge of figure 1 (near the Nebraska-Colorado border). East of figure 1 the South Platte River flows in an east direction to join the southeast oriented North Platte River and to form the Nebraska Platte River. East of Denver there are several north oriented South Platte River tributaries including Kiowa Creek, Bijou Creek, and Beaver Creek. Several south oriented tributaries, including Crow Creek, join the South Platte River near Greeley. Crow Creek originates in the Wyoming Laramie Mountains and flows in an east and southeast direction to Cheyenne. From Cheyenne Crow Creek flows in an east, south-southeast, south, and south-southwest direction to join the South Platte River east of Greeley. Pawnee Creek is a southeast oriented South Platte River tributary located east of the south oriented Crow Creek segment. Pawnee Creek originates near Pawnee Buttes and joins the South Platte River near Atwood. Note the difference in the orientations of South Platte River tributaries from the north on either side of South Platte River northeast-southeast jog near Weldona. East of the jog South Platte River tributaries from the north are oriented in southeast directions. West of the jog tributaries from the north are oriented in south and even south-southwest directions. This essay investigates the region between Pawnee Creek and the South Platte River, which is located just east of the South Platte River jog. My next essay will address the region west of the South Platte River jog. The Lodgepole Creek-South Platte River drainage divide area near the Wyoming-Nebraska-Colorado corner essay addresses the region immediately to the north of the region addressed in this essay and the Crow Creek-South Platte River drainage divide area along the Wyoming-Colorado border addresses the region to the northwest of the region described in this essay.

The South Platte River drainage route, like all other Missouri River drainage routes, developed during immense melt water floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada to and across the present day South Platte River drainage basin at a time when Wyoming and Colorado mountain ranges were just beginning to emerge. Floodwaters initially flowed in large complexes of anastomosing flood flow channels in south directions, but were subsequently diverted to flow in other directions as ice sheet related crustal warping raised mountain ranges and plateau areas and as deep valleys eroded headward to capture the massive flood flow. Present day drainage routes generally reflect flood flow directions at the time the final floodwaters drained from a region. The northeast oriented South Platte River valley downstream from the northeast-southeast jog (or Fort Morgan area) eroded headward across southeast and east-southeast oriented flood flow moving to the what was at that time the actively eroding Republican River valley east of figure 1 (the Arikaree River in the southeast corner of figure 1 is a Republican River tributary). The east-southeast oriented South Platte River valley west of the Fort Morgan area eroded headward across south oriented flood flow channels moving floodwaters along the east margin of what was at that time the emerging Colorado Front Range. Floodwaters at that time were probably flowing to the southeast oriented Arkansas River valley in southern Colorado (although prior to headward erosion of the Arkansas River valley floodwaters flowed to southeast and south oriented valleys further to the south). Headward erosion of the east-southeast oriented South Platte River valley segment beheaded south oriented flood flow channels in sequence from east to west. Floodwaters on north ends of beheaded flood flow channels reversed flow direction to flow in a north direction to the deeper South Platte River valley. Because flood flow channels were beheaded in sequence from east to west and because flood flow channels were anastomosing (diverging and converging) reversed flood flow on a newly beheaded and reversed flood flow channel could capture floodwaters from yet to be beheaded flood flow channels further to the west. Such captures enabled newly beheaded and flood flow channels to create significant north oriented South Platte River tributary drainage routes. The north oriented South Platte River drainage route south of Greeley was also created by a reversal of flood flow and the southeast oriented South Platte River headwaters (south of figure 1) illustrate how a how a reversed flood flow channel could capture floodwaters from yet to be beheaded flood flow channels further to the west (in the case of the South Platte River headwaters the yet to be beheaded flood flow channels were located in what was at that time the emerging Colorado Front Range, which has since emerged as a high mountain range).

Detailed location map for Pawnee Creek-South Platte River drainage divide area

Figure 2: Detailed location map for Pawnee Creek-South Platte River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a detailed location map for the Pawnee Creek-South Platte River drainage divide area in Weld, Morgan, and Logan Counties, Colorado. The west to east oriented Wyoming-Colorado state line is located near the north edge of figure 2. Cheyenne, Wyoming is the city located near the northwest corner of figure 2 and Greeley, Colorado is located north of the southwest corner of figure 2. Fort Morgan, Colorado is located just north of the south center edge of figure 2 and Sterling, Colorado is located in the east center area of figure 2. County boundaries are shown and Weld, Morgan, and Logan Counties are labeled. The South Platte River flows in a north-northeast and northeast direction from the southwest corner of figure 2 to the south side of Greeley where the South Platte River turns to flow in an east-southeast direction to near the Weld-Morgan County boundary. Near the county line the South Platte River turns in a northeast direction before turning to flow in a southeast direction to Fort Morgan. From Fort Morgan the South Platte River flows in a northeast direction to the east edge of figure 2 (north of center). Crow Creek flows from Cheyenne in an east and southeast direction to near Hereford (just south of the state line) and then in a south and south-southwest direction to join the South Platte River a short distance east of Greeley. North Pawnee Creek originates in the north center area of figure 2 (east of Crow Creek and south of the state line) and flows in a southeast direction to join east-northeast and east oriented South Pawnee Creek and to form southeast oriented Pawnee Creek, which flows to the northeast oriented South Platte River as a barbed tributary near Atwood (south of Sterling). South Pawnee Creek originates west of Raymer, Colorado and flows in an east-northeast and east direction to join North Pawnee Creek. Wild Horse Creek is a south, southeast, and east-southeast oriented South Pawnee Creek tributary and Igo Creek is a southeast and east-southeast oriented North Pawnee Creek tributary. South of the South Pawnee Creek headwaters are headwaters of southeast oriented Wildcat Creek, which joins the South Platte River a short distance downstream from Fort Morgan. South Platte River tributaries (from the north) downstream from Pawnee Creek are oriented in southeast directions suggesting headward erosion of the South Platte River valley captured southeast oriented flood flow. The southeast oriented flood flow to the newly eroded South Platte River valley was subsequently beheaded by headward erosion of northeast and east oriented Lodgepole Creek tributary valleys near the Wyoming-Colorado border. The east oriented Lodgepole Creek valley is located just north of figure 2 and eroded headward from the South Platte River valley located east and north of figure 2. Crow Creek tributaries from the west are generally oriented in south-southeast directions suggesting headward erosion of the south oriented Crow Creek valley captured south-southeast oriented flood flow. The Pawnee Creek-South Platte River drainage divide area, which includes drainage divide between Pawnee Creek tributaries, was crossed by southeast oriented floodwaters as the Pawnee Creek and tributary valleys eroded headward to capture the flood flow.

Raymer Creek-Sand Creek drainage divide area

Figure 3: Raymer Creek-Sand Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of Raymer Creek-Sand Creek drainage divide area. The map contour interval for figure 3 is 10 meters. The South Platte River flows in a northeast direction across the southeast corner of figure 3. Pawnee Creek flows in a southeast direction from the north edge of figure 3 (west of center) to the east edge of figure 3 (south of center) and east of figure 3 joins the northeast oriented South Platte River as a barbed tributary. Raymer Creek flows in a northeast, southeast, east, and north-northeast direction across the northwest corner of figure 3 and north of figure 3 joins southeast oriented Pawnee Creek. Note north and northwest oriented Raymer Creek tributaries and the southeast oriented tributaries near the northwest corner of figure 3. Sand Creek originates in the west center area of figure 3 and flows in a southeast direction to Willard and then in an east and north and northeast direction to join southeast oriented Pawnee Creek as a barbed tributary. Two southeast oriented tributaries join Sand Creek east of Willard. A shallow northwest to southeast oriented through valley in the northwest quadrant of figure 3 links a northwest and north oriented Raymer Creek tributary valley with the southeast oriented Sand Creek headwaters valley. The through valley was eroded by southeast oriented flood flow moving to the actively eroding southeast oriented Sand Creek valley prior to headward erosion of the Raymer Creek valley. Headward erosion of the Raymer Creek valley beheaded the southeast oriented flood flow route ending flood flow to the Sand Creek valley. The northwest and north oriented Raymer Creek tributary drainage route was created by a reversal of flood flow on the northwest end of the beheaded flood flow route. The Sand Creek drainage route was also created by a reversal of flood flow on the north end of a flood flow route beheaded and reversed by headward erosion of the deeper southeast oriented Pawnee Creek valley. Floodwaters on the north end of the beheaded flood flow route reversed flow to flow to the deeper Pawnee Creek valley. The southeast and east oriented Sand Creek valley then eroded headward from the newly formed north oriented Sand Creek drainage route to capture south and southeast oriented flood flow west of the actively eroding Pawnee Creek valley head. The Raymer Creek valley eroded headward from the actively eroding Pawnee Creek valley and subsequently beheaded flood flow routes to the actively eroding Sand Creek valley. The sequence in which valleys were beheaded is important in deciphering drainage route histories.

Detailed map of Raymer Creek-Sand Creek drainage divide area

Figure 4: Detailed map of Raymer Creek-Sand Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed topographic map of the Raymer Creek-Sand Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 10 feet. Sand Creek originates in section 16 (in south center area of figure 4) and flows in a southeast direction near the railroad tracks (now abandoned) to the south edge of figure 4. South and east of figure 4 Sand Creek flows in a southeast, east, north, and northeast direction to join southeast oriented Pawnee Creek, which then joins the northeast oriented South Platte River. The northwest oriented stream in section 31 (near northwest corner of figure 4) flows to Raymer Creek at a point where Raymer Creek turns from flowing in a south direction to flowing in a northeast direction. Further east (and north of figure 4) Raymer Creek flows in a southeast, east, northeast, and east direction to join southeast oriented Pawnee Creek. The north oriented stream originating section 5 is also a tributary to Raymer Creek. Several landforms in figure 4 were streamlined in northwest to southeast directions as south and southeast oriented floodwaters flowed across the region (prior to headward erosion of the Raymer Creek valley). A northwest to southeast oriented hill crosses the southwest quadrant of section 5. Another northwest to southeast oriented hill crosses the southwest corner of section 10 and still other streamlined hills can be found. These streamlined hills suggest diverging and converging flood flow channels crossed the region with floodwaters flowing in a south and southeast direction. Prior to headward erosion of the Sand Creek valley floodwaters continued in a southeast direction toward the South Platte River valley. Headward erosion of the Raymer Creek valley (north of figure 4) captured the south and southeast oriented flood flow and diverted floodwaters to the newly eroded southeast oriented Pawnee Creek valley.

Pawnee Creek-Raymer Creek drainage divide area

Figure 5: Pawnee Creek-Raymer Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates a topographic map of the Pawnee Creek-Raymer Creek drainage divide area north and west of figure 3 and includes an overlap area with figure 3. The map contour interval for figure 5 is 10 meters. North Pawnee Creek flows in a southeast direction from the northwest corner of figure 5 to join northeast and east oriented South Pawnee Creek and to form east oriented Pawnee Creek, which flows almost to the east edge of figure 5 before turning in a south-southeast direction to flow to the east edge of figure 5 (south of center). East and south of figure 5 Pawnee Creek flows in a southeast direction to join the northeast oriented South Platte River. Raymer Creek is the Pawnee Creek tributary located in a the southeast quadrant of figure 5 and in addition to north and northwest oriented tributaries seen in figure 3 Raymer Creek also has south-southeast oriented headwaters and tributaries seen here in figure 5. Pawnee Creek and South Pawnee Creek tributaries from the south are generally oriented in northwest and north-northwest directions and join Pawnee Creek and South Pawnee Creek as barbed tributaries. These northwest and north-northwest oriented and barbed tributaries to an east and southeast oriented stream are evidence the Pawnee Creek valley and South Pawnee Creek valleys eroded headward across multiple southeast and/or south-southeast oriented flood flow routes. The flood flow routes were captured in sequence from east to west and floodwaters on northwest ends of beheaded flood flow routes reversed flow direction to flow to the newly eroded Pawnee Creek or South Pawnee Creek valley. Southeast and south-southeast oriented tributaries from the north also flow to Pawnee Creek. Cottonwood Creek is the southeast oriented Pawnee Creek tributary flowing from the north center edge of figure 5. Spring Creek is the south and south-southeast oriented “Creek” near the northeast corner of figure 5. These southeast and south-southeast oriented tributary drainage routes were created by southeast and south-southeast oriented flood flow moving into the newly eroded Pawnee Creek valley.

Detailed map of South Pawnee Creek-Raymer Creek drainage divide area

Figure 6: Detailed map of South Pawnee Creek-Raymer Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed topographic map of the South Pawnee Creek-Raymer Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 10 feet. Shaded regions in the west half of figure 6 are located in Pawnee National Grasslands. Pawnee Creek flows in an east direction north of figure 6 and then turns to flow in a southeast direction across the northeast corner of figure 6. Raymer Creek originates in section 24 (west half of figure 6) and flows in a south-southeast, northeast, southeast, east, northeast, and east direction to the east center edge of figure 6. East of figure 6 Raymer Creek joins southeast oriented Pawnee Creek, which flows to the northeast oriented South Platte River. Several depressions can be seen on the upland surfaces in figure 6. These depressions may indicate sinkholes formed in some type of soluble bedrock material, although topographic map evidence is not adequate to say for sure. Narrow ridges surround the depressions in section 18, which suggests the possibility of some sort of excavation, although other origins are also possible. Without additional evidence I cannot determine what the ridge are. In addition to the south-southeast oriented Raymer Creek headwaters south-southeast and southeast oriented Raymer Creek tributaries are located in sections 30, 19, 20, and 21 as well as in section 15 and 16. These south-southeast and southeast oriented drainage routes to the Raymer Creek valley and the southeast oriented Raymer Creek headwaters provide evidence the east, northeast, and east oriented Raymer Creek valley eroded headward across southeast oriented flood flow. The southeast oriented Raymer Creek valley segment was eroded as the  valley eroded headward along a southeast oriented flood flow route. The south-southeast and southeast oriented headwaters and tributary drainage routes were created by south-southeast and southeast oriented flood flow moving into the Raymer Creek valley. The north-northeast oriented valley in section 12 (in northwest quadrant of figure 6) eroded headward from what at that time was the actively eroding east oriented Pawnee Creek valley north of figure 6 to capture south-southeast oriented flood flow west of the Pawnee Creek valley head.  The north-northwest oriented tributaries to that valley were created by reversals of flood flow on north-northwest ends of beheaded flood flow routes. Likewise the north oriented drainage route in section 11 (near northwest corner of figure 6) was created by a reversal of flood flow beheaded by headward erosion of the east oriented Pawnee Creek valley. Shallow through valleys can be seen in figure 6 linking the north oriented Pawnee Creek tributary valleys with the south oriented Raymer Creek tributary and headwaters valleys. One or two contour lines on a side define these shallow through valleys and provide further evidence of south-southeast oriented flood flow across the Pawnee Creek-Raymer Creek drainage divide.

Wild Horse Creek-South Pawnee Creek drainage divide area

Figure 7: Wild Horse Creek-South Pawnee Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Wild Horse Creek-South Pawnee Creek drainage divide area west and slightly south of figure 5 and there is an overlap area with figure 5. The map contour interval for figure 7 is 10 meters. Buckingham is the small town located in the southwest quadrant of figure 7 and Raymer is the slightly larger town located in the southeast quadrant of figure 7. South Pawnee Creek originates south of Buckingham and then flows in a northeast direction until it is north of Raymer and then turns to flow in more of an east direction to the east edge of figure 7. Wild Horse Creek flows from the northwest corner of figure 7 in a southeast, east, and east-southeast direction to join South Pawnee Creek north of Raymer. The southeast oriented stream located east of Raymer and flowing to the east edge of figure 7 (near southeast corner) ends south and east of figure 7 in a depression, but is headed towards the northeast oriented South Platte River. Wild Horse Creek and South Pawnee Creek tributaries from the north are oriented in southeast directions suggesting the east oriented South Pawnee Creek and Wild Horse Creek valley segments eroded headward across southeast oriented flood flow. Tributaries from the south are short and are oriented in north and north-northwest directions and were created by reversals of flood flow on north and northwest ends of beheaded flood flow routes. Shallow northwest to southeast oriented through valleys defined by one or two 10-meter contour lines on each side can be seen crossing the Wild Horse Creek-South Pawnee Creek drainage divide. These through valleys can be seen by following the drainage divide in a southwest direction from the Wild Horse Creek-South Pawnee Creek confluence to and beyond Buckingham. These northwest to southeast oriented through valleys provide evidence of multiple shallow southeast oriented flood flow channels that once crossed the drainage divide.

Detailed map of Wild Horse Creek-South Pawnee Creek south drainage divide area

Figure 8: Detailed map of Wild Horse Creek-South Pawnee Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 provides a detailed topographic map of the Wild Horse Creek-South Pawnee Creek drainage divide area seen is less detail in figure 7. The map contour interval for figure 8 is 10 feet. The small town of Buckingham is located in section 33 near the south edge of figure 8. South Pawnee Creek flows in a northeast and east direction near the southeast corner of figure 8. Wild Horse Creek flows in a southeast, east, and southeast direction from the north edge of figure 8 (west of center) to the east edge of figure 8 (north half). East of figure 8 Wild Horse Creek joins South Pawnee Creek, which then joins North Pawnee Creek to form east and southeast oriented Pawnee Creek. A stream flows in an east-southeast direction from the west edge of figure 8 to section 20 and then turns in an east-northeast direction to the south margin of section 16 where it turns to flow in a southeast, northwest and north-northeast direction to join Wild Horse Creek in the northeast corner of section 14. Two northwest to southeast oriented through valleys in section 15 link the southeast oriented Wild Horse Creek valley with the southeast segment of this Wild Horse Creek tributary. The eastern through valley has a floor elevation of between 4810 and 4820 feet while the western through valley floor elevation is between 4820 and 4830 feet. Elevations in the southeast corner of section 15 rise to more than 4850 feet as do elevations near the east margin of section 16. These elevations suggest the eastern through valley is at least 30 feet deep and the western through valley is at least 20 feet deep. To the southeast in sections 24 and 25 a northwest to southeast oriented through valley crosses the drainage divide between the Wild Horse Creek tributary and South Pawnee Creek. The through valley floor elevation is between 4830 and 4840 feet. Elevations in the northwest quadrant of section 24 rise to 4891 feet and elevations in section 26 rise to more than 4900 feet. These elevations suggest the through valley crossing the Wild Horse Creek-South Pawnee Creek drainage divide is at least 51 feet deep. Additional northwest to southeast oriented through valleys cross the drainage divides. These through valleys were eroded by southeast oriented flood flow prior to headward erosion of the southeast and east oriented Wild Horse Creek valley. Headward erosion of the Wild Horse Creek valley captured the southeast oriented flood flow and floodwaters on north and northwest ends of beheaded flood flow routes reversed flow direction to create north and northwest oriented Wild Horse Creek tributary drainage routes.

Igo Creek-South Pawnee Creek drainage divide area

Figure 9: Igo Creek-South Pawnee Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Igo Creek-South Pawnee Creek drainage divide area north and east of figure 7 and there is a large overlap area with figure 7. The map contour interval for figure 9 is 10 meters. South Pawnee Creek flows in a north-northeast, east, northeast, and east direction from the south center edge of figure 9 to the east edge of figure 9 (south half). North Pawnee Creek flows in a south and southeast direction from the north center edge of figure 9 to the east edge of figure 9 (south of center) and east of figure 9 joins South Pawnee Creek to form east and southeast oriented Pawnee Creek, which flows to the northeast oriented South Platte River. Wild Horse Creek flows in an east-southeast direction from the west edge of figure 9 (south half) to join north-northeast oriented South Pawnee Creek just south of the south center edge of figure 9. Igo Creek flows in a south-southeast and east-southeast direction from near the northwest corner of figure 9 to join southeast oriented North Pawnee Creek in the east half of figure 9. Cottonwood Creek is the southeast oriented stream near the northeast corner of figure 9 and east of figure 9 joins Pawnee Creek. Multiple shallow northwest-to-southeast oriented through valleys link the Igo Creek valley with southeast oriented Wild Horse Creek and South Pawnee Creek tributary valleys. One to four contour on each side define the through valleys and the streamlined erosional residuals located between the through valleys. The through valleys and erosional residuals were eroded by diverging and converging southeast oriented flood flow channels prior to headward erosion of the east-southeast oriented Igo Creek valley. Headward erosion of the east-southeast oriented Igo Creek valley captured the southeast oriented flood flow and ended flood flow to the Wild Horse Creek and South Pawneee Creek valleys seen in figure 9. The process seen in figure 9 and in earlier figures illustrates how the Pawnee Creek drainage system developed from the southeast to the northwest as Pawnee Creek tributary valleys captured southeast oriented flood flow and beheaded flood flow routes to newly eroded Pawnee Creek tributary valleys immediately to the southeast.

Detailed map of Igo Creek-South Pawnee Creek drainage divide area

Figure 10: Detailed map of Igo Creek-South Pawnee Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a detailed topographic map of the Igo Creek-South Pawnee Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 10 feet. Igo Creek flows in an east-southeast direction from the north edge of figure 10 (west of center) to the east edge of figure 10 (north half). Southeast oriented streams in the east half of figure 10 flow to east oriented South Pawnee Creek while the south-southeast oriented stream in the west half of figure 10 flows to east-southeast oriented Wild Horse Creek, which then flows to South Pawnee Creek (see figure 9). A north to south oriented through valley along the boundary between sections 13 and 18 (near north center edge of figure 10) links the east-southeast oriented Igo Creek valley with the valley of a southeast oriented South Pawnee Creek tributary. The through valley floor elevation is between 4860 and 4870 feet. Elevations on the northwest to southeast oriented hill in the east half of section 19 to the southeast rise to more than 4930 feet while elevations in the northwest corner of figure 10 rise to more than 5000 feet. These elevations suggest the north to south oriented through valley is at least 60 feet deep. Similar through valleys can be found elsewhere in figure 10 and provide evidence of diverging and converging south oriented flood flow channels that once crossed the present day Igo Creek-South Pawnee Creek drainage divide (prior to headward erosion of the Igo Creek valley). Northwest to southeast oriented erosional residuals seen in figure 10 are located between these former diverging and converged flood flow channels and are further evidence of the southeast oriented flood flow. Headward erosion of the east-southeast oriented Igo Creek valley captured the southeast oriented flood flow and created the present day Igo Creek-South Pawnee Creek drainage divide.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories, which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.

Mount St. Helens before the eruption which destroyed the original landscape and reshaped Spirit Lake. The area was a major destination for tourism and recreation.

After months of earthquakes and magma movement, including the development of a massive bulge on the north face of the mountain, Mount St. Helens, a formerly 9,677ft tall stratovolcano with a history of major eruptions over thousands of years had yet another eruption on May 18, 1980. It first produced the largest landslide in recorded human history as much of the north face of mountain slid down towards Spirit Lake. This exposed the water-rich magma chamber, leading to a catastrophic steam explosion (as pressurized water in the magma flash boiled and dissolved gases were released). This led to an enormous lateral blast, quickly overtaking the landslide and producing a pyroclastic surge blowing down and scorching the forest on the north side of the mountain as well as burying and reshaping the shoreline of Spirit Lake.

Mount St. Helens seconds after the beginning of the eruption sequence. The pyroclastic surge has overtaken the landslide by this point.

Not long after the lateral blast, the eruption lifted upwards into the stratosphere (I believe to 70-80,000ft), with upper-level winds carrying the ash eastward and precipitating it across Eastern Washington, Oregon, Idaho and beyond (including the Nebraska Panhandle). The destruction of extensive glaciers also led to a massive lahar which flooded the Toutle River Valley and flowed mud and dead trees all the way to the Columbia River.

Mount St. Helens spewing its guts out across the Washington State landscape.

I had the opportunity to visit the Mount St. Helens Volcanic Monument in October 2006 as part of my geology class. Granted, while it was nearly impossible to see the actual mountain because it was a rainy October day in the Pacific Northwest, I did see the old, dead trees in the blowdown zone and learned a lot of geology related to the Cascades that day. It’s amazing to see the ecosystem of the area recover, including fish returning to Spirit Lake, new plants and trees in the blowdown zone and animals returning as the plant food returns. Nature creates scars, but always renews itself.

Grand Canyon in Winter (credit: Wikipedia)

Among the best known and certainly the most visited topographic feature on the planet, the Grand Canyon resulted from erosion by the Colorado River keeping pace with uplift of the south-central United States. It is the archetype for what is known as antecedent drainage. Since that uplift is still going on, albeit slowly, the Grand Canyon has been assumed to be a relative young landform. By dating the first appearance of debris from the eastern end of the canyon in sediments at its western limit geomorphologists estimated that incision began around 6 Ma ago. Yet a range of other observations present puzzling contradictions. One means of settling the issue is to somehow to date the uplift radiometrically.

A long-used technique is to determine ‘cooling ages’ of crustal rocks exposed by uplift and erosion, exploiting the way in which rock temperature determines whether or not products of radioactive decay cab be preserved intact. One method uses the tracks of defects produced by electrons or helium nuclei from radioactive decay as they pass through various minerals that incorporate high amounts of elements such as uranium. Above a certain temperature the fission tracks anneal and disappear quickly, while below it they accumulate over time. Quantifying that build-up allows the date of cooling below the threshold temperature to be estimated. Similarly, gases produced by radioactive decay of some radioactive isotopes, such as argon from the decay of ⁴⁰K or helium from uranium and thorium isotopes, can only stay in their host mineral if it remains cooler than a narrow range of temperatures. As rock rises towards the Earth’s surface, it starts out hot at depth but cools by conduction as it get closer to the surface. For the 1.8 km of uplift of the Grand Canyon and the relatively cool nature of the underlying crust, neither the fission-track nor the  ⁴⁰Ar/³⁹Ar cooling-age methods give meaningful results. However, minerals lose helium at temperatures above about 70°C, so a method based on helium accumulation from uranium and thorium isotope decay is a possible means of assessing uplift timing. But there have been plenty of snags to overcome to make this approach reliable. In the case of the Grand Canyon analytical quality and careful sample collection has given a credible result (Flowers, R.M. & Farley, K.A. 2012. Apatite ⁴He/³He and (U-Th)He evidence for an ancient Grand Canyon. Science , doi 10.1126/science.1229390)

Flowers and Farley from the University of Colorado at Boulder and the California Institute of Technology, Pasadena, respectively, produced a result that completely overturns previous conceptions. The western end of the Canyon had been incised to within a few hundred metres of modern depths by 70 Ma ago; more than ten times earlier than previously thought. The eastern end has a more complex history that reveals cooling events in the Neogene as well as an end-Cretaceous initiation of uplift and erosion. Their data are consistent with early incision of the Grand Canyon by a Cretaceous river flowing eastward from the Western Cordillera, with a reversal of flow in the late-Tertiary as uplift of the Colorado Plateau began and western mountains subsided. Whether or not this fits with Cretaceous and later geological history of the SW US, is beyond my ken, but you can bet there will be a storm of comment from US geomorphologists once the paper appears in the print issue of Science.

Abstract:

This essay uses topographic map evidence to interpret landform origins in the South Platte River-Frenchman Creek drainage divide area in the Colorado northeast corner. The South Platte River originates in the Colorado Front Range and flows in a southeast, north-northeast, and east-southeast direction before turning to flow in a northeast direction to the Colorado northeast corner and then in an east direction to join the southeast oriented North Platte River in western Nebraska and to form the Nebraska Platte River. Frenchman Creek headwaters originate along the South Platte River southeast valley rim and flow in northeast, east, and east-southeast directions to eventually converge in east-southeast oriented Frenchman Creek, which flows to the east oriented Republican River, which then flows across southern Nebraska before turning to flow into Kansas to join the east oriented Kansas River. The drainage divide between the South Platte River and Frenchman Creek in the Colorado northeast corner is an asymmetric drainage divide with the South Platte River valley ranging from about 90 to more than 180 meters deep. Short northwest and north-northwest oriented streams drain the South Platte River southeast valley wall and some of those streams reach the South Platte River as barbed tributaries. Shallow through valleys cross the South Platte River southeast valley rim and link the northwest and north-northwest drainage routes with the Frenchman Creek headwaters. The asymmetric drainage divide, barbed tributaries, through valleys, and valley orientations are interpreted to have been formed when the deep northeast oriented South Platte River valley eroded headward across southeast oriented flood flow moving to what at that time was a newly eroded east oriented Republican River valley in southern Nebraska. Floodwaters are interpreted to have been derived from the western margin of a thick North American ice sheet and were flowing from western Canada to the newly eroded Republican River valley at a time when the Missouri River tributary valleys were being eroded headward in sequence from the southeast to the northwest. The short northwest and north oriented South Platte River tributary drainage routes were created when floodwaters on northwest and north ends of beheaded flood flow routes reversed flow direction to flow to the much deeper and newly eroded South Platte River valley.

Preface

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.

Introduction

The purpose of this essay is to use topographic map interpretation methods to explore the South Platte River-Frenchman Creek drainage divide area landform origins in the Colorado northeast corner. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big-picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain South Platte River-Frenchman Creek drainage divide area landform evidence in the Colorado northeast corner will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

South Platte River-Frenchman Creek drainage divide area location map

Figure 1: South Platte River-Frenchman Creek drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a location map for the South Platte River-Frenchman Creek drainage divide area in the Colorado northeast corner with western Nebraska in the north and east. Kansas is located south of Nebraska in the east half of figure 1. The South Platte River flows in a northeast direction from Fort Morgan, Colorado at the west edge of figure 1 (near southwest corner) to the northeast corner of Colorado and then flows in an east direction to join the southeast and east oriented North Platte River near North Platte, Nebraska and to form the Nebraska Platte River, which then flows to the south and east oriented Missouri River. The Republican River flows in an east-northeast and east direction from Haigler, Nebraska (near south center edge of figure 1 and at the corner of Nebraska, Colorado, and Kansas) to the east edge of figure 1. East of figure 1 the Republican River flows in an east direction across southern Nebraska until it turns to flow in a southeast direction into Kansas to join the east oriented Kansas River, which then flows to the Missouri River. Frenchman Creek headwaters are located south and east of the South Platte River in the northeast corner of Colorado and originate east of Sterling, Colorado. South of Frenchman Creek in northeast Colorado are east and east-southeast oriented streams originating near the South Platte River and flowing toward the Republican River, but which disappear as surface streams. Frenchman Creek flows in an east-southeast direction from the northeast corner of Colorado to join the Republican River near Culbertson, Nebraska. Frenchman Creek and the Republican River have several long southeast and east-southeast oriented tributaries from the north.

The South Platte River also has long east-southeast and southeast oriented tributaries from the west and north. Near the southwest corner of figure 1 the South Platte River has north oriented tributaries from the south, but further downstream no South Platte River tributaries from the south are shown in figure 1 and the South Platte River-Frenchman Creek drainage divide is an asymmetric drainage divide. The asymmetric South Platte River-Frenchman Creek drainage divide in northeast Colorado was created when the South Platte River valley eroded headward across southeast oriented flood flow moving to what was at that time the newly eroded east oriented Republican River valley in southwest Nebraska. Floodwaters were derived from the western margin of a thick North American ice sheet and flowed from western Canada to and across western Nebraska and northeast Colorado to reach what was at that time the actively eroding Republican River valley. At that time the southeast oriented North Platte River valley did not exist, although at that time the North Platte River valley and tributary valleys were probably eroding headward and beheading flood flow routes to the newly eroded South Platte River valley and tributary valleys. West of figure 1 the South Platte River valley eroded headward across south oriented flood flow nearer to what was at that time the emerging Colorado Front Range. The mountains were emerging as floodwaters flowed across them and their emergence was probably caused by ice sheet related crustal warping and deep erosion of surrounding regions by the immense volumes floodwaters moving across the region. Floodwaters on north ends of beheaded flood flow routes reversed flow direction to create north oriented South Platte River tributary drainage routes and the north-northeast oriented South Platte River drainage route (south and west of figure 1).

Detailed location map for South Platte River-Frenchman Creek drainage divide area

Figure 2: Detailed location map for South Platte River-Frenchman Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a detailed location map for the South Platte River-Frenchman Creek drainage divide area in the Colorado northeast corner. Logan, Sedgwick, and Phillips are counties in the northeast corner of Colorado. The Nebraska panhandle is located north of Logan and Sedgwick Counties and southern Nebraska is located east of figure 2. The South Platte River flows in a northeast direction from near the southwest corner of figure 2 to near the northeast corner of figure 2. Tributaries from the north are oriented in south-southeast directions and while generally short are present and are shown in figure 2. Two short northwest oriented tributaries are located near the southwest corner of figure 2 and two relatively short north-northwest oriented tributaries are shown in Sedgwick County. Otherwise figure 2 shows no South Platte River tributaries from the south and east. Frenchman Creek headwaters originate south of the railroad and east of Sterling in Logan County and flow in an east direction to near Holyoke in Phillips County and then turn to flow in an east-southeast direction to the east edge of figure 2. East of figure 2 Frenchman Creek flows in an east-southeast direction to join the east oriented Republican River. Wildhorse Creek originates just north of the Frenchman Creek headwaters and flows in an east-northeast and east-southeast direction to the east edge of figure 2 and east of figure 2 joins east-southeast oriented Frenchman Creek. Sand Creek (south) originates south of the Frenchman Creek headwaters in Logan County and flows in an east direction into Phillips County where it disappears as a surface stream in the region south of Holyoke. Sand Creek (north) is located in Sedgwick County and flows in an east-southeast, east, and east-southeast direction to the east edge of figure 2 (north of center). East of figure 2 Sand Creek (north) flows in an east direction to join southeast oriented Spring Creek, which then flows to east-southeast oriented Frenchman Creek. Marks Butte is a labeled high point in the southwest corner of Sedgwick County. The asymmetric drainage divide is apparent in figure 2 and the short northwest oriented South Platte River tributary drainage routes were created by reversals of flood flow on northwest ends of beheaded flood flow routes. The two Sand Creeks in the region suggest an abundance of sand, which could be flood-transported and deposited materials. With the exception of the South Platte River and irrigation canals drainage routes in figure 2 are shown with dashed lines suggesting the streams are intermittent and that the region is dry, which could mean there are wind blown sand deposits in the region.

South Platte River-Sand Draw drainage divide area

Figure 3: South Platte River-Sand Draw drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of South Platte River-Sand Draw drainage divide area. The map contour interval for figure 3 is 10 meters. The South Platte River flows in an east and northeast direction from the west edge of figure 3 (north half) to the north edge of figure 3 (east of center) and north and east of figure 3 flows in a northeast and east direction to join the North Platte River and to form the Nebraska Platte River. Julesburg, Colorado is the town located near the north center edge of figure 3. Ovid is the smaller town in the South Platte River valley west of Julesburg and is located where south oriented Lodgepole Creek joins the east and northeast oriented South Platte River. Southeast oriented streams in the southeast quadrant of figure 3 are headwaters of southeast and east oriented Sand Creek, which east of figure 3 flows to southeast oriented Spring Creek, which then flows to east-southeast oriented Frenchman Creek, which flows to the east oriented Republican River. Sand Draw is an east oriented Sand Creek tributary located near the south center edge of figure 3. The South Platte River valley floor near Julesburg has an elevation of approximately 1060 meters. Elevations on the upland surface directly south of Julesburg and south of the South Platte River valley are approximately 1150 meters. These elevations suggest the South Platte River south valley wall is approximately 90 meters high. Numerous north-northwest oriented South Platte River tributaries drain the South Platte River south valley wall, but none of these tributaries extends headward into the adjacent upland, which is drained by the southeast oriented Republican River tributaries. The 90-meter deep South Platte River valley eroded headward across southeast oriented flood flow moving to what at that time was the actively eroding Republican River valley (south and east of figure 3). As the deep South Platte River valley eroded headward floodwaters on the north ends of beheaded flood flow routes reversed flow direction to flow in northwest and north directions to the newly eroded and deep South Platte River. These reversed floodwaters created the numerous north-northwest oriented South Platte River tributary drainage routes seen in figure 3. Apparently floodwaters were flowing as sheets of flood flow and were not concentrated in deep channels, which accounts for the lack of longer northwest or north oriented South Platte River tributary drainage routes.

Detailed map of South Platte River-Sand Creek drainage divide area

Figure 4: Detailed map of South Platte River-Sand Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed topographic map of the South Platte River-Sand Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 10 feet with dotted contour lines at 5 foot intervals on the upland surface in the southeast half of figure 4. Julesburg, Colorado is the town located in the northwest corner of figure 4. The South Platte River flows in a northeast direction across the northwest corner of figure 4 and crosses the 3450-foot contour line near Julesburg. The Radio Tower base near the northwest corner of section 23 on the upland south of Julesburg has an elevation of more than 3790 feet suggesting the South Platte River southeast valley wall at Julesburg is approximately 340 feet deep. The radio tower in section 23 is located at one of the higher elevations on the South Platte River southeast valley wall rim with some lower rim elevations being less than 3720 feet. A northwest to southeast oriented through valley in sections 16 and 17  (in the southeast quadrant of figure 4) links a northwest oriented South Platte River tributary valley with a southeast oriented valley draining to southeast and east oriented Sand Creek and has an elevation of less than 3720 feet. A high point on the South Platte River valley rim in the southeast quadrant of section 5 exceeds 3740 feet suggesting the through valley is more than 20 feet deep. The through valley was probably eroded as a shallow southeast oriented flood flow channel. The South Platte River southeast valley wall is drained by numerous northwest and north-northwest oriented South Platte River tributaries. These tributaries flow to the northeast oriented South Platte River as barbed tributaries, which provides more evidence headward erosion of the 340-foot deep South Platte River valley beheaded southeast oriented flood flow. Flood flow on northwest ends of beheaded flood flow routes reversed flow direction to flow in northwest directions into the newly eroded and deep northeast oriented South Platte River valley. Apparently the amount of reversed flood flow was not great as the northwest oriented South Platte River tributary valleys do not extend far into the upland surface to the southeast. The upland surface in the southeast half of figure 4 slopes gradually in a southeast direction with drainage routes flowing to southeast and east oriented Sand Creek, which flows to southeast oriented Spring Creek, which then flows to east-southeast oriented Frenchman Creek, which flows to the east oriented Republican River. Elevations near the southeast corner of figure 4 are less than 3690 feet, which is 30 to 100 feet lower than elevations along the present day South Platte River-Sand Creek drainage divide.

South Platte River-Wildhorse Creek drainage divide area

Figure 5: South Platte River-Wildhorse Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates a topographic map of the South Platte River-Wildhorse Creek drainage divide area south and west of figure 3 and includes an overlap area with figure 3. The map contour interval for figure 5 is 10 meters. The South Platte River can just barely be seen in the northwest corner of figure 5 and is flowing in a northeast direction. The South Platte River valley floor elevation in the northwest corner of figure 5 is less than 1120 meters. Elevations on the valley rim at the west edge of figure 5 exceed 1250 meters suggesting the South Platte River valley is approximately 130 meters deep. The South Platte River southeast valley wall is again drained by short north-northwest and north oriented tributaries while the upland surface to the south and east is drained in an east and east-southeast direction with water eventually reaching east-southeast oriented Frenchman Creek and the east oriented Republican River. Wildhorese Creek is the east-northeast and east-southeast oriented stream flowing from the west edge of figure 5 (near southwest corner) to the south edge of figure 5 (east of center). South and east of figure 5 Wildhorse Creek water eventually reaches Frenchman Creek. East-southeast and east oriented streams flowing to the east edge of figure 5 flow towards southeast oriented Spring Creek, but end as surface streams in sand covered regions. Marks Butte is the labeled high point north of the center of figure 5 and reaches an elevation of 1241 meters, which is only 30 to 50 meters higher than the surrounding upland surface, which slopes in an east and/or east-southeast direction. The north-northwest and north oriented South Platte River tributary drainage routes were again created by reversals of flood flow on the north ends of beheaded flood flow routes with water flowing in north-northwest and north directions into the much deeper and newly eroded South Platte River valley. The gentle east and/or east-southeast oriented upland surface slope probably prevented large volumes of floodwaters from reversing flow direction and creating more significant north and northwest oriented tributary drainage routes.

Detailed map of South Platte River-Marks Butte drainage divide area

Figure 6: Detailed map of South Platte River-Marks Butte drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed topographic map of the South Platte River-Marks Butte drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 10 feet. The north-northwest oriented slope in the northwest quadrant of figure 6 is located along the rim of the northeast oriented South Platte River southeast valley wall. A high point along the rim is located near the west center edge of figure 6 and reaches an elevation 4093 feet. Marks Butte is located in section 29 (in southeast quadrant of figure 6) and reaches an elevation of 4072 feet. It is difficult to tell from topographic map evidence how these high points were formed, but for purposes of this discussion the assumption is made the high points are erosional residuals. If this assumption is incorrect then interpretations made in this discussion may be incorrect. Assuming the high points are erosional residuals there is a northwest to southeast oriented through valley on the west side of Marks Butte with a valley floor elevation of less than 4000 feet. Based on the Marks Butte elevation this through valley is at least 72 feet deep and was probably eroded by southeast oriented flood flow moving across the region prior to headward erosion of the deep northeast oriented South Platte River valley. Small north-northwest to south-southeast hills can be seen in figure 6. It is possible some or all of these streamlined hills are wind deposited features, although it is possible some or all of these streamlined hills are erosional residuals. Assuming some or all of these streamlined hills are erosional residuals the streamlined hills provide further evidence of south-southeast oriented flood flow across the region. The north-northwest valleys on the South Platte River valley wall in the northwest quadrant of figure 6 were eroded by reversals of flood flow at the time the deep northeast oriented South Platte River valley eroded headward across the southeast oriented flood flow. Floodwaters reversed flow direction to flow into the much deeper and newly eroded South Platte River valley.

South Platte River-North Fork Frenchman Creek drainage divide area

Figure 7: South Platte River-North Fork Frenchman Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the South Platte River-North Fork Frenchman Creek drainage divide area south and west of figure 5 and there is no overlap area with figure 5. The map contour interval for figure 7 is 10 meters. The South Platte River flows in a northeast and north-northeast direction from the west center edge of figure 7 to the north edge of figure 7 (west half). Elevations on the South Platte River valley floor near the west edge of figure 7 are slightly above 1190 meters and decrease to about 1170 meters near the north edge of figure 7. The rim of the South Platte River southeast valley wall extends in a northeast direction from the south edge of figure 7 (west of center) to the east edge of figure 7 (north half). The North Reiradon Hill elevation on the southeast valley rim (near the south edge of figure 7) is 1375 meters while elevations along the valley rim near the east edge of figure 7 are slightly above 1310 meters. These elevations suggest the South Platte River valley is between 140 and 185 meters deep. The northeast oriented stream labeled “North” in the southeast quadrant of figure 7 is the North Fork Frenchman Creek. East of figure 7 the North Fork Frenchman Creek flows in an east direction and eventually turns in an east-southeast direction to join the South Fork and to form east-southeast oriented Frenchman Creek, which eventually joins the east oriented Republican River. The northeast and east oriented drainage routes south and east of the South Platte River valley rim and north and east of the North Fork Frenchman Creek headwaters are headwaters of Wildhorse Creek with water eventually ending up in Frenchman Creek. In other words the upland surface south and east of the South Platte River valley rim drains to Frenchman Creek and the Republican River and not to the adjacent South Platte River. The South Platte River southeast valley wall is drained by multiple north and northwest oriented streams, which originate and end on the valley wall slope. These north and northwest oriented South Platte River tributary drainage routes were created by reversals of flood flow when the South Platte River valley eroded headward across southeast oriented flood flow. Shallow northwest to southeast oriented through valleys can be seen along the South Platte River valley rim, although these through valleys are defined by only one 10-meter contour line on a side. The northeast oriented Wildhorse and North Fork Frenchman Creek headwaters drainage routes were probably created as shallow northeast oriented valleys eroded headward to capture the southeast oriented flood flow prior to headward erosion of the much deeper South Platte River valley.

Detailed map of South Platte River-Wildhorse Creek south drainage divide area

Figure 8: Detailed map of South Platte River-Wildhorse Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 provides a detailed topographic map of the South Platte River-Wildhorse Creek drainage divide area seen is less detail in figure 7. The map contour interval for figure 8 is 10 feet with dotted contour lines at 5-foot intervals. Fleming, Colorado is the town near the east edge of figure 8. The rim of the South Platte River southeast valley wall extends from near the southwest corner of figure 8 to near the northeast corner of figure 8 and north and northwest oriented valleys north of the valley wall rim drain to the northeast oriented South Platte River. Wildhorse Creek originates in section 11 (in west half of figure 8) and flows in a southeast direction to the northeast corner of section 13 and then turns in an east direction to flow to the northwest corner of section 16 where it turns in a north and east direction to flow to the east edge of figure 8 (on south side of Fleming). East of figure 8 Wildhorse Creek flows in an east, east-northeast, and east-southeast direction with water eventually reaching east-southeast oriented Frenchman Creek, which flows to the east oriented Republican River. Figure 8 illustrates shallow northwest-to-southeast oriented through valleys linking north-northwest oriented South Platte River tributary valleys with southeast oriented Wildhorse Creek headwaters valleys. One through valley is located in the southeast quadrant of section 10 and links the southeast oriented Wildhorse Creek headwaters valley with a north-northwest and north oriented South Platte River tributary valley. The through valley floor elevation is between 4330 and 4340 feet. Elevations north of the through valley rise to more than 4380 feet while elevations south of the through valley and seen in figure 8 rise to more than 4370 feet (and just south of figure 8 to more than 4380 feet). These elevations suggest the through valley is at least 40 feet deep. This 40-foot deep through valley was eroded by southeast oriented flood flow moving to the Wildhorse Creek valley prior to headward erosion of the much deeper South Platte River valley. The railroad in section 1 is located in a through valley linking northwest oriented headwaters of a north-northwest oriented South Platte River tributary with east oriented headwaters of an adjacent north-northwest oriented South Platte River tributary. This section 1 through valley is approximately 50 feet deep and illustrates have the much deeper northeast oriented South Platte River eroded headward across southeast oriented flood flow. Headward erosion of the South Platte River valley beheaded southeast oriented flood flow routes in sequence from east to west. Floodwaters on northwest ends of beheaded flood flow channels reversed flow direction to create northwest, north-northwest, or north oriented South Platte River tributary drainage routes. Because flood flow routes diverged and converged floodwaters on a newly beheaded and reversed flood flow channel could capture floodwaters from an adjacent yet to be beheaded flood flow channel. The section 1 through valley (now used by the railroad) was eroded by such captured floodwaters moving in an east direction from a yet to be beheaded flood flow channel in section 34 to a newly beheaded and reversed flood flow channel eroding the north-northwest oriented South Platte River tributary valley in section 36.

South Platte River-Sandy Creek drainage divide area

Figure 9: South Platte River-Sandy Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the South Platte River-Sandy Creek drainage divide area south and west of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 10 meters. Sterling, Colorado is the town in the northwest corner of figure 9. The South Platte River flows in a north-northeast direction across the northwest corner of figure 9. The rim of the South Platte River east valley wall extends in a north-northeast direction from the south center edge of figure 9 to the north edge of figure 9 (east half). The North Fork Frenchman Creek originates along that east valley rim between North and South Reiradon Hills (in northeast quadrant of figure 9) and flows in an east, northeast, southeast, and northeast direction to the east edge of figure 9 (near northeast corner). East and north of figure 9 the North Fork Frenchman Creek turns to flow in an east direction and eventually joins the South Fork to form east-southeast oriented Frenchman Creek, which flows to the east oriented Republican River. East oriented streams flowing to the east edge of figure 9 (and south of the North Fork Frenchman Creek) flow to east oriented Sandy Creek, which flows towards east-southeast oriented Frenchman Creek, but which disappears as a surface stream before reaching Frenchman Creek. Southeast oriented streams flowing to the south edge of figure 9 (east half) are headwaters of southeast and south-southeast oriented Coyote Creek, which joins east oriented Rock Creek, which then also disappears as a surface stream. Northwest and north oriented streams can be seen draining the South Platte River east valley wall. Many of these streams do not reach the South Platte River and are lost in a region of what appear to be sand dunes on the east side of the South Platte River. Also northwest to southeast oriented erosional residuals and shallow through valleys are located along the east valley wall rim. These erosional residuals and through valleys provide additional evidence the South Platte River valley eroded headward across southeast oriented flood flow. Southeast oriented Coyote Creek headwaters valleys were eroded by southeast oriented flood flow prior to headward erosion of the South Platte River valley while the northeast oriented North Fork Frenchman Creek valley and the east oriented Sandy Creek headwaters valley probably eroded headward across the southeast oriented flood flow.

Detailed map of South Platte River-Coyote Creek drainage divide area

Figure 10: Detailed map of South Platte River-Coyote Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a detailed topographic map of the South Platte River-Coyote Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 10 feet. The rim of the South Platte River east valley wall extends in a northeast direction from Eagle Point Hill (near southwest corner of figure 10) to the north edge of figure 10 (east of center). North-northwest and northwest oriented streams flowing to the north edge of figure 10 flow towards the South Platte River, but disappear in what are probably sand dunes before reaching the river. Coyote Creek flows in a south-southeast direction across section 2 to the south edge of figure 10 in section 12 (near southeast corner of figure 10). South and east of figure 10 Coyote Creek flows in a southeast and south-southeast direction to join east oriented Rock Creek, which then disappears as a surface stream. The east oriented stream in sections 9 and 10 near the south edge of figure 10 is a Coyote Creek tributary. A northwest to southeast oriented erosional residual is located on the line between sections 34 and 35 and is also on the South Platte River east valley rim. Elevations on that erosional residual reach 4639 feet. Eagle Point Hill near the southwest corner of figure 10 reaches 4608 feet. Between the erosional residual and Eagle Point Hill elevations along the South Platte River east valley rim are lower with lowest elevations being between 4560 and 4570 feet. These elevations suggest there is a 30-40 foot deep northwest to southeast oriented through valley crossing the valley rim between the erosional residual and Eagle Point Hill and linking north and northwest oriented South Platte River tributary valleys with the south-southeast and southeast oriented Coyote Creek valley. This through valley was eroded by southeast oriented flood flow prior to headward erosion of the much deeper north-northeast oriented South Platte River valley.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories, which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.

Intro: Well, here goes a very last minute decision, to travel to Brazil. With <2 weeks to go I decided to join up with my sister (who is a video blogger and recorded out trip, you can check it out at http://www.heynadine.com) and her two friends (for the 1^st part) and go travel for 3 weeks in Brazil. Now, Brazil is a huge country (mind you, not as big as Canada…) but that mean lots of flying is required. We got an air pass with departures to: Sao Paulo – Iguazu Falls – Manaus (Amazon) – Salvador – Rio.

Map of Brazil with our route in Red.

The renowned natural beauty, exotic ecosystems and diverse culture of Brazil makes it a challenging but rewarding destination. We started off in Sao Paulo with only a day and a bit to explore some of the historical centre, the central park, and a cool graffiti alley called Batman’s Alley. After that we took a late flight out to see one of the new 7 wonders of the world (which I was told was a must-see if visiting Brazil). Therefore I’ll start off this blog with one of this location, and one of the most spectacular sights I’ve ever seen in my life, Iguazu Falls.

Science-Spheel: Rock and Water Floods (Geology, Physical Geography - Geomorphology)

Like many famous waterfalls, the creation of this impressive landscape usually has an equal-as-impressive origin. Turns out Iguazu falls does not disappoint.

Iguazu Falls in Brazil

Hawaii Basalt Lava (pahoehoe lava)

There are over 275 individual falls and these can be attributed to the rocks they’re sitting on! 135 million years ago a massive volcanic eruption flooded the area with basaltic lava (like the fast moving, black lava currently forming Hawaii). This lava covered a former desert that was present in the region, and there were several stages to the lava flow. Thus the interlayered basalt with minor sandstone form the basis of this natural wonder. As well, this region has been subjected to various faults; cracks within the earth’s surface (due to moving tectonic plates, usually causing earthquakes). The actual waterfalls only formed recently (geologically speaking recently, so <20,000 years) from flowing water from the Iguazu River that utilized these natural breaks and weaknesses within the bedrock. And vol-la, the waterfalls were formed.

Rainbow within Iguazu Falls, Brazil

Like Niagara and most waterfalls, Iguazu is retreating due to the erosion of the water on the basalt landscape. The original location of the falls was actually 28km downstream from present day, and these falls will keep on moving farther and farther back as time goes on.

Iguazu Falls, Brazil

Why-You-Might-Recognize-It: South American Gem (Indiana Jones Quatro)

Indiana Jones

Iguazu Falls is far from an unknown destination  but recently it’s been gaining more publicity as one of the New 7 Wonders of the World. In terms of recent popular culture as well, it was a location in the newest Indiana Jones movie, Kingdom of the Crystal Skull. Now, I really love the Indiana Jones franchise  but like most people I do have to agree with this wasn’t my favorite movie of the lot, but it was still very enjoyable and well, it is Indiana Jones after all …

Final Thoughts:

Being a Canadian, I know I should probably have been to our waterfalls, Niagria, at some point. But alast, I have not. Though, sorry Niargia, I don’t think it will compare…

Iguazu Falls Panorama of Devil’s Throat in Argentina, Brazil

Seeing impressive, massive waterfalls is one thing, but to stick it in the middle of a sub-tropical rainforest and have over 275 individual waterfalls is something only Iguazu has. I would definitely recommend making a stop over here if ever in Brazil, and spend 2 days rather than trying to cram both the Brazil and Argentina side in one day like some people did… The falls undeniably earn their place as one of the 7 Wonders of the World and are a sight not soon forgotten. Next stop, the Amazon…

-Stephanie

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Nadine, Ashley, Maggie and Myself at Iguazu Falls

Iguazu Falls, Brazil

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Abstract:

This essay uses topographic map evidence to interpret landform origins in the Laramie River–North Fork Cache la Poudre River drainage divide area along the Wyoming-Colorado border. The Laramie River flows in a north direction between the Medicine Bow Mountains and the Colorado Laramie Mountains and then in a northeast and north direction in the Wyoming Laramie Basin before turning to flow in an east and northeast direction across the Wyoming Laramie Mountains and finally to the southeast oriented North Platte River. The North Fork Cache la Poudre River originates in the Colorado Laramie Mountains and flows in a northeast, east, and southeast direction to join the south and southeast oriented Cache la Poudre River, which then flows to the east-southeast and northeast oriented South Platte River. A northwest to southeast oriented through valley between the Colorado Laramie Mountains and the Wyoming Laramie Mountains links north oriented Laramie River tributaries with southeast and south oriented North Fork Cache la Poudre River tributaries. The through valley , drainage route and drainage divide orientations, and other landforms in the Laramie River-North Fork Cache la Poudre River drainage divide area are interpreted in the context of immense melt water floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada to and across the present day Laramie River-North Fork Cache la Poudre drainage divide at a time when the Laramie Mountains and other regional mountain ranges were just beginning to emerge. At first floodwaters flowed across the emerging mountains, but as the mountains emerged floodwaters were systematically channeled into deeper and deeper south oriented flood flow channels. The Laramie Mountains and other mountain ranges emerged as ice sheet related crustal warping raised the mountain masses and as floodwaters deeply eroded surrounding regions. Headward erosion of the deep east and northeast oriented Laramie River valley across the emerging Wyoming Laramie Mountains from the deep southeast oriented North Platte River valley beheaded south oriented flood flow channels in the Laramie Basin. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow to the deeper east and northeast oriented Laramie River valley and to create north oriented Laramie River and tributary drainage routes and also to create the present day Laramie River-North Fork Cache la Poudre River drainage divide. The newly reversed Laramie River valley probably captured flood flow moving in a south direction west of the Medicine Bow Mountains and the captured floodwaters flowed around the south end of the Medicine Bow Mountains and in a north direction in the Laramie River valley, although that captured flood flow route ended when floodwaters west of the Medicine Bow Mountains were beheaded and reversed. Crustal warping that was raising mountain masses as floodwaters flowed across them probably aided greatly in the Laramie River flow reversal.

Preface

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.

Introduction

The purpose of this essay is to use topographic map interpretation methods to explore the Laramie River-North Fork Cache la Poudre River drainage divide area landform origins along the Wyoming-Colorado border. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big-picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain Laramie River-North Fork Cache la Poudre River drainage divide area landform evidence along the Wyoming-Colorado border will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Laramie River-North Fork Cache la Poudre River drainage divide area location map

Figure 1: Laramie River-North Fork Cache la Poudre River drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a location map for the Laramie River-North Fork Cache la Poudre River drainage divide area along the Wyoming-Colorado border and in the south half illustrates a region in northern Colorado with the southeast corner of Wyoming to the north and western Nebraska in the northeast corner. The South Platte River flows in a north and northeast direction from the south center edge of figure 1 to Greeley, Colorado and then in an east-southeast, east, and northeast direction to the east edge of figure 1 (south half).  The North Platte River flows in a southeast direction across the northeast corner of figure 1 and east of figure 1 joins the South Platte River to form the Nebraska Platte River. The Laramie Mountains are the north to south oriented mountain range immediately east of Laramie, Wyoming and extend in a south direction into Colorado where the Laramie Mountains become the Front Range. The Medicine Bow Mountains extend in a north-northwest to south-southeast direction from the northwest corner of figure 1 to near Rocky Mountain National Park in Colorado. The region in Wyoming between the Medicine Bow Mountains and the Laramie Mountains is known as the Laramie Basin. The Laramie River originates north of Rocky Mountain National Park and flows in a north and northeast direction to Laramie, Wyoming and then in a north direction to the north edge of figure 1. North of figure 1 the Laramie River turns to flow in an east and northeast direction across the Laramie Mountains and then to the southeast oriented North Platte River. The Cache la Poudre River originates in northern Rocky Mountain National Park (near the Laramie River headwaters) and flows in a north, east, and southeast direction to join the South Platte River near Greeley, Colorado. The North Fork Cache la Poudre River is shown, but is not labeled in figure 1 and flows in an east direction just south of the Wyoming-Colorado border to Halligan Reservoir and then in a south direction to join the Cache la Poudre River. The unlabeled south oriented tributary originating in Wyoming and joining the North Fork Cache la Poudre River at Halligan Reservoir is Dale Creek. The unlabeled north oriented stream originating just west of the North Fork Cache la Poudre River headwaters and joining the Laramie River in Wyoming is Sand Creek. The Laramie River-North Fork Cache la Poudre River drainage divide area investigated in this essay is primarily located north of the east oriented North Fork Cache la Poudre River segment, east of Sand Creek, and west of Dale Creek.

The Laramie River, North Fork Cache la Poudre River, and tributary drainage routes developed during immense melt water floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada to and across Wyoming and Colorado at a time when the Laramie Mountains and other regional mountain ranges were just beginning to emerge. The Laramie Mountains and other mountain ranges emerged as floodwaters flowed across them and deeply eroded surrounding regions and as ice sheet related crustal warping raised mountain masses and entire regions of the continent. At first floodwaters flowed in diverging and converging south oriented flood flow channels along and across the emerging Laramie Mountains and other mountain ranges, but were diverted in other directions by headward erosion of deeper valleys. Some floodwaters west of the Laramie Mountains flowed in east directions across the emerging mountain mass to reach deep east oriented valleys eroding headward into Nebraska, although significant flood flow west of the Laramie Mountains moved in south direction to deep south oriented valleys on either side of the emerging Front Range. Floodwaters flowing to the west side of emerging Front Range moved on the present day north oriented Laramie River alignment to the actively eroding southwest oriented Colorado River valley. Floodwaters flowing to the east side of the emerging Front Range flowed to south oriented flood flow channels on the alignment of the present day north oriented South Platte River (south of Greeley) and south oriented Cache la Poudre River and tributary valleys eroded headward from those flood flow channels. The south oriented floodwaters east of the Front Range at one time flowed to the southeast oriented Arkansas River valley, although earlier floodwaters had flowed to actively eroding valley systems further to the south. The south oriented flood flow channels east of the emerging Front Range were first beheaded by headward erosion of the deep east-southeast and northeast oriented South Platte River valley. Floodwaters on north ends of beheaded flood flow channels reversed flow direction to create the present day north oriented South Platte River drainage route and parallel north oriented South Platte River tributary drainage routes. This massive reversal of flood flow was probably greatly aided by crustal warping that was raising large areas of Colorado. A similar reversal of flood flow occurred in the Laramie Basin when headward erosion of deep east and northeast oriented valleys eroded headward across the emerging Laramie Mountains from the deep North Platte River valley and beheaded south oriented flood flow channels in the Laramie Basin. Floodwaters on north ends of beheaded flood flow channels reversed flow direction to create the north oriented Laramie River and tributary drainage routes and to create the Laramie River-North Fork Cache la Poudre River drainage divide. The Laramie Basin flood flow reversal was also aided by crustal warping that was raising the Laramie Mountains as floodwaters flowed across them.

Detailed location map for Laramie River-North Fork Cache la Poudre River drainage divide area

Figure 2: Detailed location map Laramie River-North Fork Cache la Poudre River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a detailed location map for the Laramie River-North Fork Cache la Poudre River drainage divide area along the Wyoming-Colorado border. The Wyoming-Colorado border extends in a west to east direction across figure 2 (south of center). Green colored areas are National Forest lands, which in this region are usually located in mountainous regions. The Laramie River flows in north-northwest direction across the southwest corner of figure 2 and then flows in an east and northeast direction from the west edge of figure 2 (north half) to the city of Laramie. North of Laramie the Laramie River flows in a north direction before turning to flow in an east and northeast direction across the Laramie Mountains and then to the southeast oriented North Platte River.  The north-northwest oriented Laramie River segment is located in the Colorado Laramie Mountains while the northeast oriented Laramie River segment to the north is located in the Laramie Basin. Sand Creek originates in the Laramie Colorado Mountains and flows in a north-northeast direction to join the northeast oriented Laramie River in the Laramie Basin. Other named north oriented Laramie River tributaries seen in figure 2 include Antelope Creek, Lone Tree Creek, Willow Creek, and Hermosa Creek. The North Fork Cache la Poudre River originates in the Colorado Laramie Mountains (near the Sand Creek headwaters) and flows in an east-northeast and east direction to Halligan Reservoir and then a southeast and south direction to the south edge of figure 2 (east of center). South of figure 2 the North Fork Cache la Poudre River joins the south and southeast oriented Cache la Poudre River, which flows to the east-southeast, east, and northeast oriented South Platte River. Named tributaries to the North Fork Cache la Poudre River seen in figure 2 include northeast, east, and southeast oriented Sheep Creek, east-northeast and southeast oriented Trail Creek, southeast oriented Fish Creek, and south oriented Dale Creek. Dale Creek is interesting because it originates in the Wyoming Laramie Mountains. Today the South Platte River drainage basin is a north oriented drainage basin yet many of the northern Colorado streams seen in figure 2 are oriented in south directions. These south oriented drainage routes are relics of south oriented flood flow channels that once crossed the region and which were in the process of capturing east oriented flood flow channels in southeast Wyoming (flowing across what were at that time the emerging Wyoming Laramie Mountains to deep valley eroding headward into western Nebraska). The east oriented flood flow ended because of uplift in the Wyoming Laramie Mountains and/or because of the massive flood flow reversal in the Laramie Basin. South oriented drainage routes east of the Colorado Laramie Mountains and east oriented drainage routes east of the Wyoming Laramie Mountains preserve routes of flood flow channels at the time flood flow across those regions ended. North oriented drainage routes south of the northeast oriented Laramie River segment in the Laramie Basin probably reflect drainage routes established when south oriented flood flow channels in the Laramie Basin were beheaded and reversed.

Willow Creek-Dale Creek drainage divide area

Figure 3: Willow Creek-Dale Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of Willow Creek-Dale Creek drainage divide area. The map contour interval for figure 3 is 20 meters. The Wyoming Laramie Mountains are located in the east half of figure 3. Boulder Ridge is the high area in the southwest corner of figure 3 and the southeast end of the Laramie Basin is located between Boulder Ridge and the Wyoming Laramie Mountains. Willow Creek is the north, northwest, north, and northwest oriented stream flowing from the south edge of figure 3 (west of center) to the northwest corner of figure 3. North of figure 3 Willow Creek joins north oriented Fivemile Creek, which then joins the northeast and north oriented Laramie River. Grant Creek is a northwest oriented Willow Creek tributary on the west side of the highway near Tie Siding (a small town in the south center area of figure 3). Harney Creek is the north-northwest oriented stream on the east side of the highway near Red Buttes (near northwest corner of figure 3) and north of figure 3 flows in a north direction to join the north oriented Laramie River. Dry Creek is a northwest oriented Harney Creek tributary north of Tie Siding. Dale Creek originates a short distance north of figure 3 in the Wyoming Laramie Mountains and flows across the north edge of figure 3 (just west of the highway in the northeast quadrant of figure 3). From the small lake near the north edge of figure 3 Dale Creek flows in a south and southeast direction to the south edge of figure 3 (near southeast corner). South of figure 3 Dale Creek flows in a southeast and south direction into Colorado to join the southeast oriented North Fork Cache la Poudre River at Halligan Reservoir. Remember the North Fork Cache la Poudre River flows to the south and southeast oriented Cache la Poudre River. The southeast oriented stream originating just north of the south edge of figure 3 and east of the highway near Tie Siding flows to the West Fork Dale Creek (south of figure 3), which then flows to Dale Creek. In other words the highway crosses the Laramie River-North Fork Cache la Poudre River drainage divide between Tie Siding and the south edge of figure 3. Elevations where the highway crosses the drainage divide are between 2440 and 2460 meters. Elevations on the same drainage divide near the north edge of figure 3 (west of Dale Creek) exceed 2640 meters and elevations on Boulder Ridge near the south edge of figure 3 also exceed 2640. These elevations suggest there is a 180-meter deep or deeper through valley in the Tie Siding area linking the north oriented Laramie River valley with the south and southeast oriented Cache la Poudre River valley. At least to some extent this large through valley is a water-eroded feature and was eroded by south-southeast oriented flood flow moving from the present day north oriented Laramie River alignment to a south oriented flood flow channel on the present day north oriented South Platte River alignment (south of where the Cache la Poudre River joins the South Platte River near Greeley, Colorado-see figure 1). Flood flow on the present day north oriented South Platte River alignment was beheaded and reversed by headward erosion of the deeper east-southeast, east, and northeast oriented South Platte River valley. Flood flow in the Laramie Basin was beheaded by headward erosion of the deeper east and northeast oriented Laramie River valley across the Laramie Mountains.

Detailed map of Grant Creek-Dale Creek drainage divide area

Figure 4: Detailed map of Grant Creek-Dale Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed topographic map of the Grant Creek-Dale Creek drainage divide area just south of figure 3 and seen in less detail in figures 3 and 5. The map contour interval for figure 4 is 40 feet except near the west margin where the contour interval is 20 feet. Willow Creek flows in a north-northeast and north-northwest direction from the west edge of figure 4 (south half) to the west edge of figure 4 (north of center) and then flows in a north direction just west of figure 4. North of figure 4 Willow Creek flows to north oriented Fivemile Creek, which then flows to the northeast and north oriented Laramie River. A northwest to southeast oriented highway extends from near the northwest corner of figure 4 to the south edge of figure 4 (slightly east of center). Tie Siding is a small town located on that highway. Grant Creek originates in the north half of section 33 (near south center edge of figure 4) and flows in a northwest direction along and across the highway to Tie Siding and then to the west edge of figure 4 (north half) and joins Willow Creek just west of figure 4. The south oriented stream originating in the south half of section 33 is a tributary to southeast oriented Fish Creek, which flows to south oriented Dale Creek, which then flows to the southeast oriented North Fork Cache la Poudre River. The Beacon where the highway crosses the drainage divide in section 33 has an elevation of 8106 feet, but is not located at the lowest point on the drainage divide. Dale Creek flows in a southeast and south-southeast direction from the north edge of figure 4 (east half) to the east center edge of figure 4 and east and south of figure 4 flows in a southeast and south direction to join the southeast oriented North Fork Cache la Poudre River. Johnson Creek is an east oriented Dale Creek tributary originating near the west edge of section 34 and flowing to the east edge of figure 4 (south half). Woodard Creek is an east oriented Dale Creek tributary originating in section 27 and is located north of Johnson Creek. Still further north is an unnamed Dale Creek tributary. West of Tie Siding is a small town of Hermosa located on the railroad. The railroad crosses the Grant Creek-Dale Creek drainage divide near Hermosa at a point where elevations are between 8000 and 8040 feet. While not seen in figure 4 elevations on the Willow Creek-Dale Creek drainage divide rise to more than 9720 feet to the north of figure 4. Also, while not seen in figure 4, elevations on the Willow Creek-Fish Creek drainage south and west of figure 4 exceed 8700 feet. These elevations suggest the large through valley seen in figure 4 is almost 700 feet deep. This broad through valley is at least to some extent a water-eroded valley and was eroded by immense volumes of south-southeast oriented flood flow prior to the massive flood flow reversal in the Laramie Basin to the north.

Willow Creek-Fish Creek drainage divide area

Figure 5: Willow Creek-Fish Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Willow Creek-Fish Creek drainage divide area south and west of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 20 meters. The west to east oriented Wyoming-Colorado state line is located just south of the south edge of figure 5. Dale Creek flows in south and southeast direction from the north edge of figure 5 (near northeast corner) to the east edge of figure 5 (north of center) and east and south of figure 5 flows in a southeast and south direction to join the southeast oriented North Fork Cache la Poudre River. Boulder Ridge is the prominent ridge in the west half of figure 5. Fish Creek originates on Boulder Ridge and flows in an east and southeast direction to the south edge of figure 5 (east half). South of figure 5 Fish Creek flows in a southeast direction to join south oriented Dale Creek, which then flows to the southeast oriented North Fork Cache la Poudre River. Willow Creek originates in the south center area of figure 5, east of Boulder Ridge and north of Fish Creek, and flows in a north-northeast, north, northwest, and north direction to the north edge of figure 5 (west of center). North of figure 5 Willow Creek flows to north oriented Fivemile Creek, which then flows to the northeast and north oriented Laramie River. Lone Tree Creek originates on the west side of Boulder Ridge and flows in a north-northwest and north-northeast direction to the north edge of figure 5 (west half). North of figure 5 Lone Tree Creek flows to north oriented Fivemile Creek, which then flows to the northeast and north oriented Laramie River. The Willow Creek-Fish Creek drainage divide just east of Boulder Ridge is remarkable because it is almost the same elevation (between 2420 and 2440 meters) as the Grant Creek-Dale Creek drainage divide elevation further to the east and because near Boulder Ridge the two streams are flowing almost parallel to each other in shallow valleys. The size of the northwest to southeast oriented through valley located east of Boulder Ridge is remarkable. While Boulder Ridge appears to be an uplifted block the large through valley is at least to some extent a water-eroded valley and was eroded by southeast and south-southeast oriented flood flow moving from the present day Laramie Basin to south oriented flood flow channels on the east side of the Laramie Mountains and Front Range. The large valley west of Boulder Ridge is drained (west of figure 5) by north-northeast oriented Sand Creek (seen in figures 7, 8, 9,  and 10), which flows to the northeast and north oriented Laramie River. The north and northeast oriented Laramie River valley is located west of the north-northeast oriented Sand Creek valley (see figures 1,2, and 9).

Detailed map of Willow Creek-Fish Creek drainage divide area

Figure 6: Detailed map of Willow Creek-Fish Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed topographic map of the Willow Creek-Fish Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 20 feet. Boulder Ridge is the upland located in the west half of figure 6. Fish Creek flows from the west edge of figure 6 (south of center) in an east-southeast, east, and southeast direction to the east edge of figure 6 (near southeast corner). South and east of figure 6 Fish Creek flows to south oriented Dale Creek, which flows to the southeast oriented North Fork Cache la Poudre River, which flows to the south and southeast oriented Cache la Poudre River. Little Fish Creek originates near the west center edge of figure 6 and flows in an east and south-southeast direction to join east oriented Fish Creek in section 10. Willow Creek originates in sections 10 and 3 along the east edge of Boulder Ridge and just north of Fish Creek and  flows in a northeast and north-northeast direction to the north edge of figure 6 (east of center). North of figure 6 Willow Creek flows in a north, northwest, and north direction to join north oriented Fivemile Creek, which flows to the northeast and north oriented Laramie River. Boulder Creek originates on Boulder Ridge just north of the Little Fish Creek headwaters and flows in an east direction to the base of Boulder Ridge and then turns to flow in a north-northeast direction to the north edge of figure 6. North of figure 6 Boulder Creek flows to north oriented Willow Creek. A low point on the Willow Creek-Fish Creek drainage divide in sections 11 has an elevation of 7970 feet. Elevations on the drainage divide near the northeast corner of figure 6 rise to more than 8100 feet suggesting there is a 130-foot deep or deeper north to south oriented through valley in sections 11 and 12 linking the north-northeast oriented Willow Creek valley with the southeast oriented Fish Creek valley. The through valley is a water-eroded feature and was eroded by south oriented flood flow moving to the southeast oriented Fish Creek valley. Flood flow across the drainage divide ended when flood flow in the Laramie Basin was beheaded and reversed to create the north oriented Laramie River and Willow Creek drainage routes. What is intriguing about the Willow Creek-Fish Creek drainage divide is that Willow Creek headwaters originate in section 10 near the point where Little Fish Creek joins Fish Creek. This evidence suggests the north oriented Willow Creek valley was eroded by floodwaters coming from Boulder Ridge. Apparently the flood flow reversal that reversed flood flow on the Willow Creek alignment did not reverse flood flow crossing the much higher Boulder Ridge, which suggests valleys were eroded in sequence from east to west and also that flood flow channels were beheaded and reversed in sequence from east to west. While this concept requires massive quantities of floodwaters and very deep erosion and is contrary to what most geologists have been taught the evidence is difficult to explain in other ways.

Sand Creek-Sheep Creek drainage divide area

Figure 7: Sand Creek-Sheep Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Sand Creek-Sheep Creek drainage divide area south and west of figure 5 and includes an overlap area with figure 5. The Wyoming-Colorado border extends in a west to east direction across the north half of figure 7. The map contour interval for figure 7 is 50 meters in Colorado and 20 meters in Wyoming. Boulder Ridge extends in a northeast direction from the southwest quadrant of figure 7 to the north edge of figure 7 (east half). Fish Creek flows in an east direction from Boulder Ridge to the east edge of figure 7 (near northeast corner). East of figure 7 Fish Creek flows in a southeast direction to join south oriented Dale Creek, which flows to the southeast oriented North Fork Cache la Poudre River. The North Fork Cache la Poudre River flows in a northeast and east direction across the southeast corner of figure 7 and east of figure 7 turns to flow in a southeast direction to join the south and southeast oriented Cache la Poudre River. Green Mountain is a southwest to northeast oriented ridge east of the center of figure 7. Trail Creek flows in a northeast direction from north of Green Mountain before turning in a south-southeast and east direction to the east center edge of figure 7. East of figure 7 Trail Creek flows in a southeast direction to join the east and southeast oriented North Fork Cache la Poudre River. Most Trail Creek tributaries seen in figure 7 are oriented in southeast and south directions. Sheep Creek flows in a north and northeast direction from the south edge of figure 7 (west half) to Eaton Reservoir and then in an east and southeast direction to join the North Fork Cache la Poudre River near the southeast corner of figure 7. Sand Creek flows in a north and north-northeast direction along the northwest side of Boulder Ridge before turning in a northwest direction to near Chimney Rock and then flowing in a north-northeast direction to the north edge of figure 7. North of figure 7 Sand Creek flows to the northeast and north oriented Laramie River. North oriented streams west of Sand Creek are Laramie River tributaries. Sheep Creek and Sand Creek are intriguing because Sheep Creek originates near the north oriented Sand Creek valley (just south of figure 7 and seen in detail in figure 8) and then the two streams flow parallel to each other, although at very different elevations, before Sheep Creek turns to flow to the south oriented Cache la Poudre River drainage basin while Sand Creek continues in a north direction to reach the north oriented Laramie River drainage basin. A northeast oriented Sand Creek tributary flows from near the southwest corner of figure 7 to join north and north-northeast oriented Sand Creek and is located in a deep north-northeast oriented valley, which is seen in detail in figures 9 and 10. The northeast oriented Sheep Creek headwaters and tributaries seen in figure 7 probably are flowing in strike valleys, which were eroded initially by southwest oriented flood flow moving to a deeper south oriented flood flow channel west of figure 7. Headward erosion of the east and southeast oriented Sheep Creek valley beheaded and reversed the southwest oriented flood flow to create the present day northeast oriented Sheep Creek headwaters drainage route and the northeast oriented Sheep Creek tributary drainage routes. The north-northeast oriented Sand Creek tributary valley in the southwest corner of figure 7 was likewise eroded by south-southwest oriented flood flow to a deeper south oriented flood flow channel west of figure 7, but flood flow in that valley was beheaded and reversed by the massive reversal of flood flow in the Laramie Basin that created the present day north oriented Laramie River drainage system.

Detailed map of Sand Creek-Sheep Creek drainage divide area

Figure 8: Detailed map of Sand Creek-Sheep Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 provides a detailed topographic map of the Sand Creek-Sheep Creek drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 40 feet. Sand Creek flows in a north direction from the south edge of figure 8 (west of center) to the north edge of figure 8 (west of center). North of figure 8 Sand Creek flows in a north direction to join the north oriented Laramie River. A north-northeast oriented Sand Creek tributary flows on the floor of a deep north-northeast oriented valley from the west edge of figure 8 (south half) to join Sand Creek near the north edge of figure 8. Sheep Creek originates in section 23 and flows in a north, northeast, and east direction to the east edge of figure 8. East of figure 8 Sheep Creek flows in a northeast, east, and southeast direction to join the east and southeast oriented North Fork Cache la Poudre River, which then flows to the south and southeast oriented Cache la Poudre River. An irrigation ditch in section 23 links the north oriented Sand Creek valley with the northeast oriented Sheep Creek headwaters valley and is located in a through valley linking the two valleys. The through valley is only defined by one or two contour lines on the north side and appears minor compared to the much deeper north-northeast oriented Sand Creek tributary valley just to the west. But the through valley provides evidence of what were probably diverging north oriented drainage routes, with one of the north oriented drainage routes flowing into the deep north-northeast oriented valley and to a north oriented drainage basin while the other diverging drainage route flowed in a northeast direction before turning to flow in a southeast direction to join a south oriented drainage basin. These two drainage routes diverged on what is today the east wall of a deep north-northeast oriented valley. Cow Creek is the northwest and northeast oriented stream seen near the east center edge of figure 8 and east and north of figure 8 flows to northeast, east, and southeast oriented Sheep Creek. Drainage routes in figure 8 probably originated as south-southwest oriented flood flow channels at a time when the Laramie Mountains were emerging. Floodwaters flowed in south-southwest directions to the present day north oriented Laramie River valley and then to actively eroding south oriented valleys in the present day Laramie River headwaters area including the southwest oriented Colorado River valley. Diverging and converging south-southwest oriented flood flow channels on the Laramie Mountain upland region in the east half of figure 8 were beheaded and reversed by headward erosion of the east and southeast oriented Sheep Creek valley (north and east of figure 8-see figure 7), although the east and southeast oriented Sheep Creek valley was not deep enough to behead and reverse south-southwest oriented flow in the present day deep north-northeast oriented valley now draining to Sand Creek. Flood flow in that deeper valley was beheaded and reversed by the reversal of flood flow in the Laramie Basin that created the north oriented Laramie River drainage system. The reversal of flood flow in the deeper valley combined with Laramie Mountains uplift resulted in the capture of the north oriented Sand Creek headwaters.

Sand Creek-Laramie River drainage divide area

Figure 9: Sand Creek-Laramie River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Sand Creek-Laramie River drainage divide area south and west of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 50 meters. The Laramie River flows in a north-northwest direction from the south edge of figure 9 to the northwest corner of figure 9. North of figure 9 the Laramie River turns to flow in a north, northeast, and north direction in the Laramie Basin before turning in an east and northeast direction to flow across the Wyoming Laramie Mountains and then to join the southeast oriented North Platte River. South of figure 9 the north oriented Laramie River valley is linked by through valleys (or passes) with the west and northwest oriented Michigan River, which flows to the north oriented North Platte River headwaters and is also linked with the Cache la Poudre River and Colorado River valleys. The Medicine Bow Mountains are located west of the Laramie River valley in figure 9 and the Colorado Laramie Mountains are located east of the Laramie River valley. Sand Creek flows in a north and north-northeast direction across the Colorado Laramie Mountains from the south edge of figure 9 (east of center) and then in a north and northeast direction to enter the deep north-northeast oriented valley located east of Bull Mountain to the north edge of figure 9 (near northeast corner). North of figure 9 Sand Creek flows in a north direction to join the northeast and north oriented Laramie River. Sand Creek Pass is located near the center of figure 9 and links the deep north-northeast oriented Sand Creek valley with the deeper north-northwest oriented Laramie River valley. Sand Creek Pass has an elevation of 2736 meters. Bull Mountain to the west rises to 3073 meters and Little Bald Mountain to the east rises to 3179 meters suggesting Sand Creek Pass is at least 330 meters deep. Sand Creek is a water-eroded valley and was initially eroded by a southwest oriented flood flow channel that converged south of Bull Mountain with a south-southeast oriented flood flow channel on the present day north-northwest oriented Laramie River alignment. South oriented flood flow on the Sand Creek and Laramie River alignments was subsequently reversed to create the present day north oriented drainage routes. Crustal warping that raised regions to the south and headward erosion of the deep east and northeast oriented Laramie River valley across the emerging Wyoming Laramie Mountains that beheaded and reversed south oriented flood flow channels in the Laramie Basin were responsible for the flood flow reversal. Probably the reversal of flood flow in the Laramie River valley captured flood flow still moving in a south direction on the west side of the Medicine Bow Mountains. The captured floodwaters moved in a southeast and east direction on the present day west and northwest oriented Michigan River alignment to the newly reversed Laramie River valley (and also to the Cache la Poudre River valley) and then in a north direction into the Laramie Basin. Subsequently flood flow west of the Medicine Bow Mountains was beheaded and reversed to create the north oriented North Platte River west and northwest oriented Michigan River drainage routes.

Detailed map of Sand Creek-Laramie River drainage divide area

Figure 10: Detailed map of Sand Creek-Laramie River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a detailed topographic map of the Sand Creek-Laramie River drainage divide area seen is less detail in figure 9. The map contour interval for figure 10 is 40 feet. The Colorado Laramie Mountains are located in southeast quadrant of figure 10. The south end of Bull Mountain is the upland region seen in section 19. The Laramie River flows in a north and northwest direction across the southwest corner of figure 10. West and north of figure 10 the Laramie River flows in a north-northwest, north, northeast, and north direction into and across the Laramie Basin before turning in an east and northeast direction to flow across the Wyoming Laramie Mountains and then to the southeast oriented North Platte River. Sand Creek flows in a northeast direction across the southeast corner of figure 10 and east of figure 10 turns to flow in a north direction to enter the Laramie Basin and to join the northeast and north oriented Laramie River. Sand Creek Pass is located in the north half of section 29 and has an elevation of 8976 feet. Jimmy Creek originates on the southwest side of Sand Creek Pass and flows in southwest direction into section 36 where it turns to flow in an east direction into section 35 where it turns again to flow in a northwest direction to the west edge of figure 10. West of figure 10 Jimmy Creek joins the north-northwest oriented Laramie River. A northeast oriented Sand Creek tributary originates in section 29 south of Sand Creek Pass and flows to the northeast corner of figure 10 and north and east of figure 10 joins north oriented Sand Creek. Bull Mountain achieves an elevation just north of figure 10 of 10,082 feet. Elevations in the Colorado Laramie Mountains in the southeast corner of section 32 exceed 10,240 feet. These elevations suggest Sand Creek Pass is at least 1100 feet deep. Sand Creek Pass is a water-eroded through valley and was eroded by a southwest oriented flood flow channel that converged with a south-southeast oriented flood flow channel on the present day north-northwest oriented Laramie River alignment. The south oriented flood flow was beheaded and reversed by headward erosion of the much deeper east and northeast oriented Laramie River valley across the Wyoming Laramie Mountains, which diverted flood flow to the much deeper southeast oriented North Platte River valley. The reversal of flood flow in the Laramie River valley probably captured flood flow still moving in a south direction on the west side of the Medicine Bow Mountains (west of figure 10) and the captured flood flow moved around the south end of the Medicine Bow Mountains to reach the newly reversed Laramie River drainage route. The Laramie River valley floor elevation near the southwest corner of figure 10 is less than 8020 feet suggesting there was almost 900 feet of erosion in the Laramie River valley after the reversal of flood flow, suggesting significant captured floodwaters flowed in a north direction, although some the elevation difference could be the result of crustal warping.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories, which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.