Abstract:

This essay uses topographic map evidence to interpret landform origins in the Horseshoe Creek-North Laramie River drainage divide area of the Wyoming Laramie Mountains. The North Laramie River originates as a southwest and south oriented drainage route on the west side of the Laramie Mountains and turns to flow in an east-northeast and east-southeast direction across the Laramie Mountains to join the east-northeast oriented Laramie River on the east side of the Laramie Mountains. The Laramie River then flows to the southeast oriented North Platte River. Horseshoe Creek flows in a northeast direction from near the North Laramie River headwaters to join the southeast oriented North Platte River. Laramie Peak is a high point located between the Horseshoe Creek headwaters valley and the North Laramie River valley. Cottonwood Creek originates south of Laramie Peak and flows in a south, east, north-northeast, and east direction to join the southeast oriented North Platte River. North to south oriented through valleys link east and northeast oriented valleys and barbed tributaries and elbows of capture are common in the region. The through valleys, barbed tributaries, elbows of capture, and valley orientations 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 across Montana into and across Wyoming at a time when Wyoming mountain ranges were beginning to emerge. The Laramie Mountains emerged as diverging and converging south oriented flood flow channels were eroded into them. Headward erosion of the east oriented Laramie-North Laramie River valley from what was at that time the deep and actively eroding southeast oriented North Platte River head captured the south oriented flood flow and diverted the floodwaters to the North Platte River valley. Headward erosion of the east oriented Cottonwood Creek valley next captured south oriented flood flow channels and floodwaters on the north end of a beheaded flood flow channel reversed flow direction to create the north-northeast oriented Cottonwood Creek drainage route in Cottonwood Park. Headward erosion of the northeast oriented Horseshoe Creek valley next captured the south oriented flood flow channels and diverted the floodwaters to the actively eroding North Platte River valley head. Floodwaters on north ends of beheaded flood flow channels reversed flow direction to flow to the deeper Horseshoe Creek valley and to create north oriented Horseshoe Creek tributary drainage routes. Headward erosion of the deep southeast oriented North Platte River valley then beheaded flood flow channels supplying floodwaters to a south oriented flood flow channel on the south oriented North Laramie River headwaters alignment. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the present day north-northeast oriented La Bonte Creek drainage route.

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 Horseshoe Creek-North Laramie River drainage divide area landform origins in the Wyoming Laramie Mountains. 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 Horseshoe Creek-North Laramie River drainage divide area landform evidence in the Wyoming Laramie Mountains will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Horseshoe Creek-North Laramie River drainage divide area location map

Figure 1: Horseshoe Creek-North Laramie 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 Horseshoe Creek-North Laramie River drainage divide area in the Wyoming Laramie Mountains and illustrates a region in east-central Wyoming. The Laramie Mountains extend from near Casper to the south center edge of figure 1. The North Platte River flows from Seminoe Reservoir(near southwest corner of figure 1) in a north, north-northeast, northeast, east, south, east, and southeast direction around the northwest end of the Laramie Mountains to the east edge of figure 1 (south of center) and east of figure 1 flows into Nebraska. The Laramie River flows in a north, east, northeast, and east-northeast direction from the south center edge of figure 1 to join the southeast oriented North Platte River near the east edge of figure 1. The North Laramie River originates west of Laramie Peak and flows in a south, east-northeast, and east-southeast direction to join the east-northeast oriented Laramie River on the east side of the Laramie Mountains. Horseshoe Creek originates near the North Laramie River headwaters and flows in a northeast direction to join the southeast oriented North Platte River near Glendo. The unlabeled north-northeast stream flowing from near the Horseshoe Creek headwaters to join the south and east North Platte River at the elbow capture south of Douglas is La Bonte Creek. The Medicine Bow River flows in a north direction from the south edge of figure 1 (west half) to near the town of Medicine Bow and then turns to flow in a northwest, west, and northwest direction to join the north oriented North Platte River at Seminoe Reservoir. Sheep Creek is a south and south-southwest stream west of the south oriented North Laramie River headwaters and flows to the unlabeled south and west oriented Little Medicine Bow River, which joins the Medicine Bow River a short distance northwest of the town Medicine Bow. The Horseshoe Creek-North Laramie River drainage divide area investigated in this essay is primarily located in the Laramie Mountains and is located south and east of Horseshoe Creek and east and north of the North Laramie River.

The North Platte River drainage route and drainage routes of all North Platte River tributaries were established during immense melt water floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada across Montana and into Wyoming at a time when Wyoming mountain ranges, including the Laramie Mountains, were beginning to emerge. At first floodwaters could flow across the emerging mountains, but later were channeled into deep valleys and/or were forced to flow around the emerging mountain ranges. The mountain ranges emerged as ice sheet related crustal warping raised the mountain ranges and as floodwaters deeply eroded surrounding regions and valleys. The north oriented North Platte River drainage route west of the Laramie Mountains and most if not all north, northwest, and north-northeast oriented North Platte River tributary drainage routes originated as south oriented flood flow channels, but were beheaded and reversed by the much deeper southeast oriented North Platte River valley as it eroded headward around the northwest end of the emerging Laramie Mountains. Headward erosion of the deep North Platte River valley captured the south oriented flood flow and diverted the captured floodwaters in a southeast and east direction to the evolving Missouri River drainage route. The northeast and east-northeast oriented Laramie River valley and its east oriented North Laramie River valley eroded headward from the actively eroding North Platte River valley head to capture south oriented flood flow in the emerging Laramie Mountains, which at that time was west of the actively eroding North Platte River valley head. The south oriented North Laramie River headwaters drainage route is on the alignment of a captured south oriented flood flow channel. Headward erosion of the northeast oriented Horseshoe Creek valley captured floodwaters flowing to the newly eroded North Laramie River valley and tributary valleys. The north-northeast oriented La Bonte Creek drainage route was formed when floodwaters on north ends of beheaded flood flow channels reversed flow direction to flow to the much deeper southeast oriented North Platte River valley. These evolving east, northeast, and north-northeast oriented valleys across the emerging Laramie Mountains captured southeast oriented flood flow moving along the southwest side of the Laramie Mountains. This captured flood flow then moved in east, northeast, and north-northeast oriented valleys across the emerging Laramie Mountains to reach the much deeper southeast oriented North Platte River valley. Headward erosion of the deep North Platte River valley around the northwest end of the Laramie Mountains beheaded and reversed flood flow channels west of the Laramie Mountains to and in several steps created the north oriented North Platte River drainage route upstream from Casper. The reversal of flood flow on the North Platte River drainage route west of the Laramie Mountains beheaded and reversed southeast and east oriented flood flow along the southwest side of the Laramie Mountains to create west and northwest oriented North Platte River tributary drainage routes such as the northwest, west, and northwest oriented Medicine Bow River drainage route.

Detailed location map for Horseshoe Creek-North Laramie River drainage divide area

Figure 2: Detailed location map Horseshoe Creek-North Laramie 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 Horseshoe Creek-North Laramie River drainage divide area in the Wyoming Laramie Mountains. Green colored areas are National Forest lands and are located in the Laramie Mountains. Toltec is a small community located slightly south and west of the center of figure 2. The North Laramie River originates near Toltec and flows in a southwest and south direction almost to the south edge of figure 2 before turning to flow in a northeast and east-southeast direction to the east edge of figure 2 (south half-near southeast corner). East of figure 2 the North Laramie River joins the east-northeast oriented Laramie River, which then flows to the southeast oriented North Platte River. Labeled North Laramie River tributaries include southwest oriented Bar M Creek and Antelope Creek and southeast oriented Bear Creek and its southwest and south oriented Friend Creek tributary. Horseshoe Creek originates south of Toltec and flows in a northeast direction to the east edge of figure 2 (north half). East of figure 2 Horseshoe Creek flows to the southeast oriented North Platte River. Roaring Fork is a northeast and north oriented Horseshoe Creek tributary located near the center of figure 2. Lost Creek is a north oriented Roaring Fork tributary and originates on the north side of Laramie Peak. Cottonwood Creek originates south of Laramie Peak and flows for a short distance in a southwest direction before turning to flow in an east direction to the community of Fletcher Park. Cottonwood Creek flows from Fletcher Park in a north-northeast, east, and east-southeast direction to the east edge of figure 2 (slightly south of center). East of figure 2 Cottonwood Creek flows to the southeast oriented North Platte River. La Bonte Creek originates north of the south oriented North Laramie River segment and flows in a north, east-northeast, and north-northeast direction to the north edge of figure 2 (east of center). North of figure 2 La Bonte Creek flows to the southeast oriented North Platte River as a barbed tributary. The community of Marshall is located west of Toltec. Sheep Creek flows in a south direction through Marshall and then turns to flow in a southwest, south, and southwest direction to the west edge of figure 2 (near southwest corner). South and west of figure 2 Sheep Creek joins the south and west oriented Little Medicine Bow River, which flows to the northwest, west, and northwest oriented Medicine Bow River, which flows to the north oriented North Platte River, which then flows around the northwest end of the Laramie Mountains before flowing in a southeast direction to the east of figure 2. Other south oriented streams flowing to west edge of figure 2 are tributaries to the south and west oriented Little Medicine Bow River with water eventually reaching the north oriented North Platte River west of the Laramie Mountains. These south oriented drainage routes originated during south oriented floods prior to headward erosion of the deep North Platte River valley around the northwest end of the Laramie Mountains. North oriented streams flowing to the north edge of figure 2 flow to the east, south, east, and southeast oriented North Platte River on the north and east sides of the Laramie Mountains. These north oriented drainage routes originated as south oriented flood flow channels, which were beheaded and reversed by headward erosion of the much deeper North Platte River valley around the Laramie Mountains.

La Bonte Creek-North Laramie River drainage divide area

Figure 3: La Bonte Creek-North Laramie River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of La Bonte Creek-North Laramie River drainage divide area. The map contour interval for figure 3 is 20 meters. Soldier Creek Lake is located near the center of figure 3 and the community of Toltec is located east and north of Soldier Creek Lake. The North Laramie River (not labeled in figure 3) flows from near Toltec in a southwest and south direction to the south center edge of figure 3. South of figure 3 the North Laramie River turns to flow in a northeast and then east-southeast direction to join the east-northeast oriented Laramie River, which flows to the southeast oriented North Platte River. Soldier Creek flows in a northeast and southeast direction to Soldier Creek Lake and then in a south direction to join the North Laramie River. Sheep Creek is the south oriented stream flowing from near the northwest corner of figure 3 to the near the town of Marshall (near west center edge of figure 3) and then flowing in a southwest direction to the west edge of figure 3. West of figure 3 Sheep Creek flows to the south and west oriented Little Medicine Bow River, which flows to the northwest, west, and northwest oriented Medicine Bow River, which then flows to the north oriented North Platte River on the west side of the Laramie Mountains. Fortymile Flat is located north of Soldier Lake and Fortymile Peak is located west of Fortymile Flat. La Bonte Creek originates south of Fortymile Peak and flows in a northeast direction into Fortymile Flat and then in a north direction to the north center edge of figure 3. North of figure 3 La Bonte Creek flows in a north, east-northeast, and north-northeast direction to join the southeast oriented North Platte River as a barbed tributary. Fortymile Flat is a deep north to south oriented through valley linking the north oriented La Bonte Creek headwaters valley with the south oriented North Laramie River headwaters valley. The through valley floor elevation is between 2320 and 2340 meters. Fortymile Peak to the west rises to 2673 meters. Flattop Mountain to the east rises to more than 2640 meters. These elevations suggest the Fortymile Flat through valley could be as much 300 meters deep. The Fortymile Flat through valley was eroded as a south oriented flood flow channel prior to headward erosion of the deep southeast oriented North Platte River valley to the north and east of figure 3. Headward erosion of the northeast oriented North Laramie River valley segment south of figure 3 first captured the south oriented flood flow. Later headward erosion of the deep southeast oriented North Platte River valley beheaded and reversed the flood flow channel to create the north oriented La Bonte Creek drainage route. Several through valleys link the north to south oriented Fortymile Flat through valley with the south oriented Sheep Creek valley and/or with west and southwest oriented Sheep Creek tributary valleys. These through valleys were eroded as anastomosing flood flow channels first as south oriented floodwaters flowed across the region and later as reversed flood flow moved to the much deeper North Platte River valley on the east side of the Laramie Mountains.

Detailed map of La Bonte Creek-Soldier Creek drainage divide area

Figure 4: Detailed map of La Bonte Creek-Soldier 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 La Bonte Creek-Soldier Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 20 feet. Toltec is located near the east center edge of figure 4. The North Laramie River flows in a southwest direction from near Toltec to the south center edge of figure 4. South of figure 4 the North Laramie River flows in a south direction before turning to flow in a northeast and east-southeast direction to join the east-northeast oriented Laramie River, which then flows to the southeast oriented North Platte River. Soldier Lake is located in the south center region of figure 4. Soldier Creek flows in a northeast and southeast direction to Soldier Creek Lake and then in a south direction to join the North Laramie River near the south center edge of figure 4. Fortymile Flat is located north of Soldier Creek Lake and Fortymile Peak is located west of Fortymile Flat. La Bonte Creek originates south of Fortymile Peak and flows in a northeast direction into Fortymile Flat and then in a north direction to the north center edge of figure 4. North of figure 4 La Bonte Creek flows in a north, east-northeast, and north-northeast direction to reach the southeast oriented North Platte River as a barbed tributary. Fortymile Flat is a deep north to south oriented through valley linking the north oriented La Bonte Creek valley with the south oriented North Laramie River valley. The through valley floor elevation is shown as 7681 feet. Fortymile Peak to the west rises to 8769 feet while Flattop Mountain to the east rises to more than 8720 feet. These elevations suggest the Fortymile Flat through valley is as much as 1000 feet deep. This deep north to south oriented through valley was eroded as a south oriented flood flow channel as the Laramie Mountains were emerging. Headward erosion of the deep southeast oriented North Platte River valley located east and north of figure 4 beheaded the south oriented flood flow channel. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to flow to the much deeper southeast oriented North Platte River valley. Floodwaters from west of the reversed flood flow channel probably were captured by the north oriented flood flow and it is possible such captured floodwaters flowed in a north direction in the Fortymile Flat through valley, although evidence from a larger area is probably needed to say for sure.

North Laramie River-Bear Creek drainage divide area

Figure 5: North Laramie River-Bear Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the North Laramie River-Bear Creek drainage divide area east and slightly south of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 20 meters. The south end of Fortymile Flat can be seen near the northwest corner of figure 5. Soldier Creek Lake is south of Fortymile Flat and Soldier Creek flows in a south direction to join the south oriented North Laramie River (not labeled in figure 5), which then flows to the south edge of figure 5 (near southwest corner). South of figure 5 the North Laramie River turns to flow in a northeast and east-southeast direction to join the east-northeast oriented Laramie River. Poor Mans Peak is located near the center of figure 5. Bear Creek flows in a north direction on the west side of Poor Mans Perak before making a U-turn to flow in a south direction on the east side of Poor Mans Peak and through a deep water gap between Eagle Mountain to the east and Crest Mountain to the west. Once through the water gap Bear Creek turns in an east and southeast direction to flow to the south edge of figure 5 (near southeast corner) and joins the northeast oriented North Laramie River just south of the southeast corner of figure 5. North of Poor Mans Peak Bear Creek is joined by southeast oriented Grouse Creek. East of Grouse Creek is north oriented Windy Creek, which flows to northeast oriented Stratton Creek, which then flows to join south-southeast oriented North Horseshoe Creek (near north center edge of figure 5) and to form northeast oriented Horseshoe Creek, which then flows to the southeast oriented North Platte River. Laramie Peak is located near the east edge of figure 5 (north of center). Friend Creek originates on the west side of Laramie Perak and flows in a southwest and south direction between Eagle Mountain to the west and South Mountain to the east to join east and southeast oriented Bear Creek. Several deep north to south oriented through valleys link north oriented Horseshoe Creek tributary valleys with south oriented Bear Creek tributary valleys. In addition northeast to southwest oriented through valleys link northeast oriented Bear Creek and Horseshoe Creek tributary valleys with valleys of southwest and west oriented tributaries draining to the south oriented North Laramie River segment along the west edge of figure 5. These through valleys were eroded by south and southwest oriented diverging and converging flood flow, although it is possible after south oriented flood flow channels had been beheaded and reversed that north and northeast oriented flood flow moved in some of the through valleys to reach the much deeper southeast oriented North Platte River valley.

Detailed map of Horseshoe Creek-Bear Creek drainage divide area

Figure 6: Detailed map of Horseshoe Creek-Bear 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 Horseshoe Creek-Bear Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet. Poor Mans Peak is located near the south center edge of figure 6. Bear Creek flows in a northeast, east, and south direction from the south edge of figure 6 (west of center) around the north side of Poor Mans Peak to the south edge of figure 6 (east half). South of figure 6 Bear Creek flows in a south direction through a 1000-foot deep water gap before turning to flow in an east and southeast direction to join the northeast and east-southeast oriented North Laramie River. Grouse Creek originates in the south half of section 28 and flows in an east and south-southeast direction to join Bear Creek north of Poor Mans Peak. Stratton Creek flows in a northeast direction from the west edge of figure 6 (north of center) to the north edge of figure 6 (west of center). North of figure 6 Stratton Creek flows to northeast oriented Horseshoe Creek, which then flows to the southeast oriented North Platte River. Thirtytwo Creek originates in section 32 and then flows in a north-northeast and north-northwest direction to join Stratton Creek (near the northwest corner of section 21).  A through valley links the north-northwest oriented Thirtytwo Creek valley with the south-southeast oriented Grouse Creek valley. The through valley floor elevation is between 7960 and 8000 feet. Slick Mountain to the west rises to 8730 feet. The ridge immediately to the east of the through valley rises to 8495 feet suggesting the through valley is at least 495 feet deep. However, Windy Peak a bit further to the east rises to more than 8800 feet and suggests the through valley could be as much as 730 feet deep. Between the through valley and Windy Peak is the north oriented Windy Creek valley, which is linked by a through valley near the southeast corner of section 27 with a southwest oriented Grouse Creek tributary valley. This second through valley has a floor elevation of 7919 feet and is deeper than the Thirtytwo Creek-Grouse Creek through valley. Diverging and converging south oriented flood flow channels eroded these two through valleys into the emerging Laramie Mountains. Headward erosion of the deeper northeast oriented Horseshoe Creek and Stratton Creek valley beheaded the two south oriented flood flow channels and floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow to the deeper Stratton Creek valley. Numerous similar through valleys are seen in the region and provide evidence of what was once a large-scale south oriented anastomosing channel complex that evolved into an east and northeast oriented anastomosing channel complex as the much deeper southeast oriented North Platte River valley eroded headward across the region east and north of figure 6. Floodwaters for the east and northeast oriented anastomosing channel came from west of the emerging Laramie Mountains. Ice sheet related crustal warping assisted in the flood flow reversal process and in the development of the present day drainage divides.

Cottonwood Creek-North Laramie River drainage divide area

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

Figure 7 illustrates the Cottonwood Creek-North Laramie River drainage divide area east and slightly south of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 20 meters. The North Laramie River flows in a northeast and east direction from the southwest corner of figure 7 before turning in south direction between Indian Head Rocks and Chimney Rock (near south edge of figure 7-east of center) and then turning to flow in an east direction to the east edge of figure 7 (near southeast corner). East of figure 7 the North Laramie River flows in an east-southeast direction to join the east-northeast oriented Laramie River, which then joins the southeast oriented North Platte River. Bear Creek flows in a south-southeast direction from the west edge of figure 7(south half) to join the North Laramie River near the southwest corner of figure 7. Laramie Peak is located near the northwest corner of figure 7. Bear Head Mountain is located south of Laramie Peak. Cottonwood Park is a north-northeast oriented valley or basin located east of Bear Head Mountain and Laramie Peak and west of Elk Park and Albany Peak. Cottonwood Creek originates on the south side of Laramie Peak and flows in a southwest direction before turning to flow in an east direction into Cottonwood Park where Cottonwood Creek turns to flow in a north-northeast direction to flow to the north edge of figure 7 (west of center). North of figure 7 Cottonwood Creek turns to flow in an east direction to join the southeast oriented North Platte River. A north to south oriented through valley links the north-northeast oriented Cottonwood Creek valley with a south oriented North Laramie River tributary valley. The through valley floor elevation is 2013 meters. Elevations at the Lookout east of the through valley exceed 2200 meters and the Albany Peak elevation reaches 2363 meters. Bear Head Mountain to the west of the through valley rises to more than 2500 meters. Depending on which elevations are used the through valley depth could be as little as 200 meters or more than 350 meters. The east oriented Cottonwood Creek valley segment south of Laramie Peak is linked by a 200-meter plus deep through valley (seen in figures 5 and 9) with the southwest and south oriented Friend Creek valley and with north and northeast oriented Horseshoe Creek tributary valleys west of Laramie Peak. These through valleys are all water eroded valleys and were probably eroded by south oriented flood flow channels moving floodwaters to what was at that time a newly eroded North Laramie-Laramie River valley, which eroded headward across the emerging Laramie Mountains from the actively eroding southeast oriented North Platte River valley. Headward erosion of the deep east oriented Cottonwood Creek valley (north of figure 7) from the actively eroding southeast oriented North Platte River valley next beheaded and reversed the south-southwest oriented flood flow channel moving floodwaters through Cottonwood Park. The reversal of flood flow captured south oriented flood flow west of Laramie Peak, which then flowed in an east direction between Laramie Peak and Bear Head Mountain to flow into the newly reversed Cottonwood Park valley. Headward erosion of the northeast oriented Horseshoe Creek valley next beheaded and reversed floodwaters west of Laramie Peak to create north and northeast oriented tributary drainage routes while headward erosion of the south oriented Friend Creek captured the east oriented flood flow to the Cottonwood Creek valley.

Detailed map of Cottonwood Creek-North Laramie River drainage divide area

Figure 8: Detailed map of Cottonwood Creek-North Laramie 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 Cottonwood Creek-North Laramie River drainage divide seen in less detail in figure 7. The map contour interval for figure 8 is 40 feet. The North Laramie River flows in an east-northeast direction from the south edge of figure 8 (near southwest corner) to the road north of the south center edge of figure 8 and then makes a jog to the south before flowing in an east and east-northeast direction to the east edge of figure 8 (near southeast corner). East of figure 8 the North Laramie River turns to flow in an east-southeast direction to join the east-northeast oriented Laramie River, which then flows to the southeast oriented North Platte River. Cottonwood Park is the deep non forested valley or basin straddling the north center edge of figure 8 and is drained (north of figure 8) by north-northeast and east oriented Cottonwood Creek, which flows to the southeast oriented North Platte River. A north to south oriented through valley in section 18 links the north-northeast oriented Cottonwood Creek valley with the valley of a south oriented North Laramie River tributary. The through valley floor elevation at its lowest point is between 6560 and 6600 feet. Bear Head Mountain to the west rises to 8359 feet. Elevations just east of figure 8 rise to 7128 feet and Albany Peak (east and north of figure 8) rises to more than 7720 feet. These elevations suggest the through valley could be as little as 528 feet deep or as much as 1120 feet deep. In either case the through valley was eroded by south oriented flood flow, which was captured by headward erosion of the east oriented North Laramie-Laramie River valley, which eroded headward from the southeast oriented North Platte River valley. Headward erosion of the deep east oriented Cottonwood Creek valley next beheaded the south oriented flood flow channel in the Cottonwood Park-North Laramie River through valley. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to flow to the deeper east oriented Cottonwood Creek valley (north of figure 8) and to create the north-northeast oriented Cottonwood Creek drainage route north of figure 8.

Horseshoe Creek-Cottonwood Creek drainage divide area

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

Figure 9 illustrates the Horseshoe Creek-Cottonwood Creek drainage divide area north and west of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 20 meters. Cottonwood Park straddles the south center edge of figure 9. Cottonwood Creek flows in a north-northeast direction from Cottonwood Park to the east center area of figure 9 and then turns to flow in an east oriented valley between Harmon Heights and Elliott Point and then to the east edge of figure 9. East of figure 9 Cottonwood Creek flows to the southeast oriented North Platte River. The Cottonwood Creek valley between Harmon Heights and Elliott Point is more than 200 meters deep even though there are other routes Cottonwood Creek could have taken. For example there is a north to south oriented through valley between Harmon Heights and Black Mountain linking Harris Park with the north-northeast oriented Cottonwood Creek valley. The through valley floor elevation is between 1880 and 1900 meters. Elevations on Harmon Heights exceed 2000 meters meaning the through valley is more than 100 meters deep. The through valley was eroded by south oriented flood flow moving to a south oriented flood flow channel on the present day north-northeast oriented Cottonwood Creek alignment. Horseshoe Creek flows in a northeast direction from the west edge of figure 9 (north half) to the north edge of figure 9 (east of center) and north and east of figure 9 joins the southeast oriented North Platte River. Saltlick Creek is a north oriented stream flowing across the center of figure 9 to join Horseshoe Creek west of Rock Mountain. The Saltlick Creek headwaters are located between Haystack Peaks to the east and Laramie Peak to the west. South of the Saltlick Creek headwaters are south oriented headwaters of south and east oriented North Cottonwood Creek, which flows to north-northeast oriented Cottonwood Creek. A north to south oriented through valley links the north oriented Saltlick Creek valley with the south oriented North Cottonwood Creek headwaters valley. The through valley floor elevation is between 2140 and 2160 meters. Haystack Peaks rise to more than 2300 meters and Laramie Peak rises much higher. These elevations suggest the through valley is at least 140 meters deep. This second through valley was eroded by a south oriented flood flow channel that converged in Cottonwood Park with the south-southwest oriented flood flow channel on the present day north-northeast oriented Cottonwood Creek alignment. Evidence for similar converging and diverging flood flow channels can be found throughout the Laramie Mountains. The south oriented flood flow channel flowing through Cottonwood Park was first (in the context of valleys seen in this essay) captured by headward erosion of the deep east oriented North Laramie River valley. Next headward erosion of the deep east oriented Cottonwood Creek valley beheaded and reversed the south oriented flood flow channel to create the north-northeast oriented Cottonwood Creek drainage route segment. Headward erosion of the deep northeast oriented Horseshoe Creek valley next beheaded and reversed flood flow on the present day north oriented Saltlick Creek alignment. For a time south oriented floodwaters west of Laramie Peak flowed in a through valley between Eagle Peak and Laramie Peak (near southwest corner of figure 9) to the east oriented Cottonwood Creek valley south of Laramie Peak and continued to erode the Cottonwood Creek valley. Headward erosion of the Horseshoe Creek valley next beheaded and reversed the south oriented flood flow channel west of Laramie Peak and ended flood flow to the Cottonwood Creek valley. Throughout this time period floodwaters were eroding deep valleys into the emerging the Laramie Mountains, which were probably being uplifted as the described flood flow captures and reversals were taking place.

Detailed map Saltlick Creek-North Cottonwood Creek drainage divide area

Figure 10: Detailed map of Saltlick Creek-North Cottonwood 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 Saltlick Creek-North Cottonwood Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 40 feet. Cottonwood Creek flows in a north-northeast direction from the south center edge of figure 10 almost to the north edge of figure 10 (east of center) and then turns to flow in a southeast and east direction to the east edge of figure 10 (north half). East of figure 10 Cottonwood Creek flows in an east direction to join the southeast oriented North Platte River. North Cottonwood Creek originates in the east half of section 30 (just west of Haystack Peaks) and flows in a south direction into section 31 where it turns to flow in an east and northeast direction to join north-northeast oriented Cottonwood Creek near the southeast corner of section 28. Saltlick Creek originates in the northeast corner of section 30 and flows in a north direction to the north edge of figure 10. North of figure 10 Saltlick Creek flows to northeast oriented Horseshoe Creek, which then flows to the southeast oriented North Platte River. A north to south oriented through valley in section 30 links the north oriented Saltlick Creek valley with the south oriented North Cottonwood Creek headwaters valley. The through valley floor elevation is between 7080 and 7120 feet. Haystack Peaks to the east rises to more than 7640 feet. Elevations to the west of the through valley rise much higher suggesting the through valley is at least 500 feet deep. The through valley was eroded by south oriented flood flow prior to headward erosion of the deeper northeast oriented Horseshoe Creek valley to the north of figure 10. The south oriented flood flow converged with south-southwest oriented flood flow near the south center edge of figure 10 and then flowed to the east oriented North Laramie River valley, which had previously captured the south oriented flood flow channels. Prior to headward erosion of the deep North Laramie River valley the south oriented floodwaters had continued in a south direction to reach other deep valleys eroding headward from the actively eroding southeast oriented North Platte River valley. Headward erosion of the deep east oriented Cottonwood Creek valley eroded a 800-foot deep water gap near the northeast corner of figure 10 and beheaded and reversed the south-southwest oriented flood flow channel on the present day north-northeast oriented Cottonwood Creek alignment. The depth of that water gap suggests 800 feet of erosion may occurred since flood flow in the Cottonwood Park valley was beheaded and reversed.

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.