Abstract:

This essay uses topographic map evidence to interpret landform origins in the region between Beaver Creek and the Sweetwater River from the Wind River Range southeast end to Crooks Mountain area, Wyoming and also includes the Sweetwater River-East Alkali Creek drainage divide area in the Crooks Mountain area. Beaver Creek originates at the Wind River Range southeast end and flows in an east-southeast and east direction before turning in north direction to flow into the Wind River Basin with water flowing to the north oriented Wind-Bighorn River and eventually the northeast oriented Yellowstone River. The Sweetwater River originates in the Wind River Range west of the Beaver Creek headwaters and flows in a south-southeast direction before turning to flows in an east-northeast direction south of the Wind River Basin with water eventually reaching the North Platte River. Beaver Divide is northwest-facing escarpment along the Beaver Creek-Sweetwater River drainage divide and separates the deeper Wind River Basin to the north and east from the higher elevation Sweetwater River drainage basin to the south and west. Crooks Mountain is a west to east oriented upland located south of the Sweetwater River and east of the north oriented Beaver Creek alignment. West-northwest oriented East Alkali Creek drains the Crooks Mountain south side to north oriented Alkali Creek, which is a Sweetwater Creek tributary flowing on approximately the same alignment as the north oriented Beaver Creek alignment further to the north. North to south oriented through valleys including through valleys hanging above the deep Wind River Basin link the Beaver Creek and Sweetwater River drainage basin and north oriented Alkali Creek valley.  The through valleys are interpreted in the context of a major south oriented flood flow channel located between what at one time were the emerging Wind River Range to the west and the emerging Crooks Mountain to the east. North to south oriented through valley also cross the Crooks Mountain upland and are also interpreted as former flood flow channels. Floodwaters were derived from the western margin of a thick North American ice sheet and were flowing from western Canada to and across Wyoming as Wyoming and other regional mountains emerged. Mountains emerged as floodwaters deeply eroded surrounding regions and as ice sheet related crustal warping raised the mountain ranges in relation to adjacent areas. South oriented flood flow across the emerging Crooks Mountain was beheaded and reversed by headward erosion of the much deeper east oriented Sweetwater River valley to the north. South oriented flood flow on the Alkali Creek alignment was probably beheaded and reversed by headward erosion of the deeper east-northeast oriented Sweetwater River valley. South oriented flood flow on the Beaver Creek alignment was beheaded and reversed when headward erosion of the deep northeast oriented Yellowstone River valley in Montana beheaded a south oriented flood flow channel on the present day north oriented Wind River-Bighorn River alignment. The northeast oriented Yellowstone River valley was eroding headward from space at the south end of the deep “hole” the ice sheet had occupied that was being opened up by ice sheet melting. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Wind-Bighorn River and the north oriented Beaver Creek drainage routes. Headward erosion of the deeper north oriented Beaver Creek valley then captured south oriented flood flow moving west of the reversed flood flow channel and this captured flood flow helped erode the deeper Wind River Basin and the Beaver Divide escarpment.

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 Beaver Creek-Sweetwater River drainage divide area landform origins between the Wind River Range southeast end and Crooks Mountain, Wyoming, USA. 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 Beaver Creek-Sweetwater River drainage divide area landform evidence between the Wind River southeast end and Crooks Mountain will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Beaver Creek-Sweetwater River drainage divide area location map

Figure 1: Beaver Creek-Sweetwater 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 Beaver Creek-Sweetwater River drainage divide area between the Wind River Range southeast end and Crooks Mountain and illustrates a region in west-central Wyoming. Grand Teton National Park is located near the northwest corner of figure 1. Togwotee Pass is located east of Grand Teton National Park. The Wind River flows in a southeast direction from near Togwotee Pass between the Wind River Range and the Owl Creek Mountains to Riverton in the Wind River Basin. At Riverton the Wind River turns to flow in a northeast and north direction across the Owl Creek Mountains eastern end and to enter the Bighorn Basin near Thermopolis. Once in the Bighorn Basin the river changes its name to become the Bighorn River. From Thermopolis the Bighorn River flows in a north direction to the north edge of figure 1 and north of figure 1 in Montana the Bighorn River joins the northeast oriented Yellowstone River. Beaver Creek originates east of Granite Peak near the Wind River Range southeast end and flows in an east and north direction to join the Wind River near Riverton. The Sweetwater River originates near the Wind River Range southeast end west and slightly north of Granite Peak and flows in a south and south-southeast direction to South Pass. At South Pass the Sweetwater River turns to flow in an east-northeast and east direction between the Granite Mountains and Green Mountains to join the North Platte River at Pathfinder Reservoir. West of the Green Mountains and south of the Sweetwater River is Crooks Mountain, which is drained by Sweetwater River tributaries. The North Platte River flows in a north direction from the south edge of figure 1 (east half) to Seminoe, Pathfinder, and Alcova Reservoirs and then turns to flow in a northeast direction to Casper at the Laramie Mountains northwest end. At Casper the North Platte River turns to flow in an east direction to the east center edge of figure 1 and east of figure 1 the North Platte River flows in a southeast direction to reach Nebraska and the east oriented Platte River. The Green River originates west of Gannett Peak near the Wind River Range northwest end and flows in a south direction to the south edge of figure 1 (near the town of Green River). South of figure 1 in Colorado the Green River joins the southwest oriented Colorado River. The Beaver Creek-Sweetwater Creek drainage divide area between the Wind River Range and Crooks Mountain is located south and east of Beaver Creek, east of the Wind River Range, and includes the Sweetwater River tributaries draining the Crooks Mountain area, which is located west of the Green Mountains.

Present day Wyoming drainage routes developed during immense melt water floods that flowed across Wyoming. Floodwaters were derived from the western margin of a thick North American ice sheet and initially flowed from western Canada to and across Wyoming. At that time Wyoming and other regional mountain ranges had not yet emerged and floodwaters could freely flow across what are today high mountain ranges. The mountain ranges emerged as floodwaters deeply eroded surrounding regions and as ice sheet related crustal warping raised the mountain ranges relative to the adjacent areas. Ice sheet related crustal warping combined with deep glacial erosion also created a deep “hole” in which the huge ice sheet was located. At first floodwaters flowed in a south direction across the Wind River Range to the actively eroding Green River valley and tributary valleys, which had eroded headward from the actively eroding Colorado River valley. These south oriented floodwaters eroded the Wind River Range southwest flank. A major south oriented flood flow channel developed just east of the emerging Wind River Range with the floodwaters flowing on the alignment of present day north oriented Beaver Creek and the Wind-Bighorn River.  Just where these south oriented floodwaters went is not determined in this essay, although south of the Wind River Range the floodwaters may have flowed in a southwest direction to South Pass and then along the southwest oriented Pacific Creek alignment to the south oriented Green River valley. Other floodwaters flowed in a south direction into the present day Great Divide Basin and then further south to actively eroding Colorado River tributary valleys. Another major south oriented flood flow channel developed between the Rattlesnake Hills and Laramie Mountains on the alignment of the present north oriented North Platte River. This south oriented flood flow channel between the Rattlesnake Hills and Laramie Mountains was beheaded by headward erosion of a deeper east and southeast oriented flood flow channel that had eroded headward along the emerging Laramie Mountains northeast and north flanks. Floodwaters on the north end of this beheaded flood flow channel reversed flow direction to flow to the much deeper east and southeast oriented flood flow channel and created the present north, east, and southeast oriented North Platte River drainage route. The Sweetwater River valley had begun to erode headward between the Rattlesnake Mountains and the Ferris Mountains prior to the reversal of flood flow on the North Platte River alignment (note how at Pathfinder Reservoir) the Sweetwater River turns in a south direction to join the north oriented North Platte River as a barbed tributary). The Sweetwater River valley continued to erode headward after the North Platte River flood flow reversal occurred and continued to capture south oriented flood flow west of the newly reversed North Platte River valley.

Other major flood flow reversals began to take place when ice sheet melting opened up space at the south end of the deep “hole” the ice sheet had occupied. At first this newly opened up space drained in a south direction across eastern Nebraska, although later other drainage routes opened up. The deep northeast oriented Yellowstone River valley eroded headward from this newly opened up deep “hole” space to capture south oriented melt water floods flowing across Montana to Wyoming. Floodwaters on north ends of the beheaded flood flow routes reversed flow direction to flow to the much deeper northeast oriented Yellowstone River valley and to create north oriented drainage routes. A major flood flow reversal occurred in the present day Bighorn and Wind River Basins when the south oriented flood flow channel located east of the emerging Wind River Range southeast end was beheaded and reversed in Montana. This flood flow reversal created the north oriented Bighorn and Wind River drainage routes and also created the north oriented Beaver Creek drainage route. East, northeast, and southeast oriented valleys then eroded headward from this newly formed north oriented flood flow channel to capture south oriented flood flow west of the newly reversed flood flow channel. As this massive flood flow reversal was taking place the east oriented Sweetwater River valley eroded headward into the region to capture reversed flood flow moving toward the newly reversed Wind-Bighorn River drainage route and also to capture south oriented flood flow routes crossing the Wind River Range southeast end. Headward erosion of the Sweetwater River valley occurred as the reversed flood flow was draining northward into the Wind River Basin and as flood flow across the emerging Wind River Range southeast end was ending. Today evidence of the former flood flow channels is found in the form of water gaps, wind gaps, through valleys, elbows of capture, major escarpments, and orientations of present day drainage routes.

Detailed location map for Beaver Creek-Sweetwater River drainage divide area

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

Figure 2 provides a more detailed location map for the Beaver Creek-Sweetwater River drainage divide area between the Wind River Range southeast end and Crooks Mountain. The green colored area is National Forest land in the Wind River Range. South Pass is located near the southwest corner of figure 2. Pacific Creek is the southwest oriented stream flowing from near South Pass to the southwest corner of figure 2. South and west of figure 2 water in Pacific Creek eventually reaches the south oriented Green River. The Sweetwater River flows in a southeast direction from the west edge of figure 2 to South Pass and then turns in an east-northeast direction to Sweetwater Station. From Sweetwater Station the Sweetwater River flows in an east-northeast, southeast, and east direction to the east edge of figure 2 (south half). East of figure 2 the Sweetwater River flows to the North Platte River with water eventually flowing to Nebraska. Crooks Mountain is located in the southeast quadrant of figure 2 and Green Mountain is east of Crooks Mountain and straddle the east edge of figure 2. Crooks Creek flows in a northwest direction from the southeast corner of figure 2 and then turns to flow in a north direction between Green Mountain and Crooks Mountain before turning to flow in a northeast direction to join the Sweetwater River east of figure 2. East Alkali Creek originates near the east end of Crooks Mountain and flows in a west-northwest direction to join northeast oriented West Alkali Creek and to form Alkali Creek, which flows in a north-northwest direction west of Crooks Mountain. Beaver Creek originates near the Wind River Range east end and flows in an east-southeast direction near the town of Miners Delight and then turns to flow in an east direction before turning to flow in a north direction to the north center edge of figure 2. Note how the north oriented Beaver Creek alignment is approximately the same as the north oriented Alkali Creek alignment. North of figure 2 Beaver Creek joins the northeast oriented Popo Agie River, which then joins the northeast and north oriented Wind River, with the Wind River becoming the north oriented Bighorn River, which in Montana joins the northeast oriented Yellowstone River. Note how Beaver Creek is flowing towards the Sweetwater River before it turns to flow in a north direction. Beaver Divide, which is labeled north of Sweetwater Station, is the Wind River-Sweetwater River drainage divide and is a north- and northwest-facing escarpment marking the southern boundary of the Wind River Basin. Elevations on the Wind River Basin floor are significantly lower than elevations in the Sweetwater River drainage basin to the south. Beaver Divide extends in a southwest direction along the Beaver Creek-Sweetwater River drainage divide to the region north of the Antelope Hills.

Beaver Creek-Alkali Creek drainage divide area

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

Figure 3 provides a topographic map of Beaver Creek-Alkali Creek drainage divide area. The map contour interval for figure 3 is 50 meters in the north half and is 20 meters in the south half of figure 3. The Sweetwater River flows in a northeast and east-northeast direction from the south edge of figure 3 (west of center) to the east center edge of figure 3. East of figure 3 the Sweetwater River flows to the North Platte River with water eventually reaching Nebraska and the Platte River. Note the deep Sweetwater River canyon near the south edge of figure 3. Alkali Creek is the north oriented stream flowing from near the southeast corner of figure 3 to join the Sweetwater River near the east center edge of figure 3. Beaver Creek flows in an east direction from the west edge of figure 3 (slightly north of center) to near the center of figure 3 and then turns to flow in a north direction along the east flank of Schoettlin Mountain before turning to flow in a west and north direction to the north edge of figure 3. North of figure 3 Beaver Creek flows in a north-northeast direction and then turns to flow in a north direction on approximately the same alignment as the Alkali Creek alignment  before turning in a north-northwest direction to join the northeast and north oriented Popo Agie, Wind, and Bighorn Rivers with water eventually reaching Montana and the Yellowstone River. The 50-meter contour line obscures many topographic features including the northwest-facing Beaver Divide escarpment located between the Beaver Creek valley and the Sweetwater River valley and which is better seen in figures 5 and 6. Likewise figure 3 does not do justice to the north to south oriented through valley linking the north oriented Beaver Creek valley with the east-northeast oriented Sweetwater River valley. Elevations along the west edge of the southwest quadrant of figure 3 rise to more than 2300 meters. The Beaver Creek-Sweetwater River drainage divide south of the Beaver Creek elbow of capture has an elevation of between 2100 and 2120 meters. Further to the northeast in figure 3 the drainage divide elevations rise to more than 2160 meters and then fall again to less than 2100 meters. But, much higher elevations are found further to the east where the Sweetwater River is flowing through the Granite Mountains. Higher elevations in the Granite Mountains exceed 2400 meters. In other words figure 3 is showing the west wall of broad north to south oriented through valley linking the north oriented Beaver Creek valley with the east-northeast oriented Sweetwater River valley. North oriented Alkali Creek is flowing on the through valley floor south of the Sweetwater River. The through valley is at least 200 meters deep and was eroded by south oriented flood flow moving into the present day Great Divide Basin south of figure 3 and represents a continuation of the south oriented flood flow channel that originated on the present day north oriented Beaver Creek-Wind River-Bighorn River alignment. Headward erosion of the deep northeast oriented Yellowstone River valley in Montana 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 Yellowstone River valley and create the north oriented Bighorn River, Wind River, and Beaver Creek drainage route. Headward erosion of the  east-northeast oriented Sweetwater River valley captured the reversed flood flow and diverted that flood flow in an east direction.

Detailed map of Beaver Creek-Alkali Creek drainage divide area

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

Figure 4 provides a greatly reduced detailed topographic map of the Beaver Creek-Alkali Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 20 feet. The Sweetwater River flows in an east-northeast direction from the south edge of figure 4 (west of center) to the east edge of figure 4 (south half) and east of figure 4 flows to the North Platte River. Alkali Creek flows in a north direction from the southeast corner of figure 4 to join the Sweetwater River. Beaver Creek flows in a an east, northeast, and north direction from the west center edge of figure 4 to the north edge of figure 4 (east of Schoettlin Mountain). Beaver Divide (or Beaver Rim) is the north- and northwest-facing escarpment on the southeast side of the Beaver Creek valley and is as much as 400 feet high. Beaver Divide marks the southern boundary of the Wind River Basin, although escarpment in figure 4 it is probably marking the southern boundary of the Beaver Creek valley. North of Beaver Divide Beaver Creek has eroded water gaps across hogback ridges (see section 2 for an example) providing evidence the Beaver Creek route was established at a time when the region north of Beaver Divide was at least as high as the region south of Beaver Divide. The Beaver Divide escarpment was eroded as a giant headcut as floodwaters in the Beaver Creek valley eroded the Wind River Basin floor. A through valley crossing the Beaver Creek-Sweetwater River drainage divide can be seen near the corner of sections 7, 12, 13, and 18 just west of the south center area of figure 4. At its deepest point the through valley floor elevation is between 6860 and 6880 feet. East of the through valley in section 7 elevations rise to more than 7120 feet and in section 5 to the northeast elevations rise to 7300. Elevations rise to more than 7300 feet near the southwest corner of figure 4 suggesting the through valley is at least 420 feet deep. As the figure 3 discussion noted, elevations rise to the west in the Wind River Range and to east elevations rise once the Sweetwater River enters the Granite Mountains. Depending on how the through valley is viewed it could be much broader and deeper than the through valley seen in figure 4. The through valley is a water-eroded valley. The narrower through valley near the corner of sections 7, 12, 13, and 18 appears to have been eroded by south oriented flood flow from the Beaver Creek valley moving to the Sweetwater River valley, although prior to erosion of that narrower through valley probably there were much larger flood flow movements in both south and north directions in the broader through valley. Apparently the final flood flow movements were governed by floodwaters entering the Beaver Creek valley west of figure 4 (which is today located in the Wind River Range). Apparently at that time the Wind River Range southeast end did not stand high above regions to the north and west as it does today. Otherwise the south oriented floodwaters would not have been able to reach the Beaver Creek headwaters area located in what is today the Wind River Range.

Beaver Creek- Sweetwater River drainage divide area

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

Figure 5 illustrates the Beaver Creek-Sweetwater River 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. Beaver Creek flows in a north and west direction near the southwest corner of figure 5 and then turns to flow in a north-northeast and north direction to the north edge of figure 5 (west half). North of figure 5 Beaver Creek flows to the Popo Agie River, which flows to the Wind-Bighorn River with water eventually reaching Montana and the Yellowstone River. Beaver Creek tributaries from the east are generally oriented in northwest and north-northwest directions. Beaver Divide is labeled and even with the 50-meter contour interval shows up as an identifiable northwest-facing escarpment. Near Devils Gap (near the center of figure 5) the Beaver Divide escarpment is shown with as many as six contour lines suggesting the escarpment may be as much as 300 meters high (depending on how and where it is measured). North and west of the escarpment is the Wind River Basin southern end. South and east of the escarpment is the higher Sweetwater River drainage basin. The Sweetwater River flows in an east-northeast direction across the southeast corner of figure 5. Government Meadows Draw is a southeast oriented Sweetwater River tributary in the east half of figure 5. Cedar Rim Draw (in northeast corner of figure 5) drains a southwest and south direction to Government Meadows Draw. Cedar Rim near the northeast corner of figure 5 is a southwest-facing escarpment and is better seen in figure 6. Cedar Rim forms the northeast and east wall of broad northwest to southeast and north to south oriented through valley (or hanging valley) crossing the Beaver Divide escarpment. Once across Beaver Divide the through valley turns to become more of a north to south oriented through valley. Dishpan Butte is an erosional remnant standing above the through valley floor. Devils Gap is eroded into another erosional remnant standing above the through valley floor (or perhaps a remnant of the through valley southwest or west wall). The through valley was eroded by south-southeast oriented flood flow moving from the Wind River Basin across the present day east-northeast oriented Sweetwater River to and across the Crooks Mountain region to the south and east of figure 5. At that time there was no Beaver Divide escarpment and the Wind River Basin had not yet been eroded. Floodwaters probably flowed in a south direction on the present day north oriented Alkali Creek alignment  before being captured by headward erosion of the east oriented Sweetwater River valley and its tributary valleys. The massive flood flow reversal in the Wind River Basin including in the Beaver Creek drainage basin ended the south-southeast oriented flood flow and eroded the deep north oriented Beaver Creek drainage basin north and west of Beaver Divide. Immense volumes of north oriented floodwaters were required to erode the deep Beaver Creek drainage basin and most of those floodwaters had to enter the Beaver Creek drainage basin in the Beaver Creek headwaters area, which is today located in the high Wind River Range to the west.

Detailed map of Government Slide Draw-Government Meadows Draw drainage divide area

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

Figure 6 provides a greatly reduced detailed topographic map of the Government Slide Draw-Government Meadows Draw drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 20 feet. Government Slide Draw is the northwest and west oriented stream flowing to the northwest corner of figure 6. Government Slide Draw crosses the 5700-foot contour line near the northwest corner of figure 6. West of figure 6 Government Slide Draw drains to north oriented Beaver Creek with water eventually reaching the Yellowstone River in Montana. Cedar Rim Draw originates near the northeast corner of figure 6 (at an elevation of approximately 7100 feet) and drains in a southwest direction to join south-southwest and south oriented Government Meadows Draw, which drains to the south center edge of figure 6 (at an elevation of approximately 6700 feet). South of figure 6 Government Meadows Draw turns to drain in a southeast direction to join the Sweetwater River with water eventually reaching the Platte River in Nebraska. Beaver Divide is the west- and northwest-facing escarpment extending from near the southwest corner of figure 6 to the north edge of figure 6 (east of center). Beaver Divide is the southeast margin of the Beaver Creek drainage basin, which is the southernmost extension of the Wind River Basin. Cedar Rim in the northeast quadrant of figure 6 is a south-southwest-facing escarpment and was formed as the east wall of a north-to south oriented flood flow channel. Remnants of the west wall can be seen in sections 30 and 32 and adjacent sections along the Beaver Divide rim and also include Dishpan Butte in section 29. At the time south oriented flood flow moved in the what is today a hanging valley the deep Beaver Creek drainage basin to the north and west did not exist and floodwaters were flowing in a south direction on the present day north oriented Beaver Creek alignment. Elevations along the Beaver Divide rim in sections 16 and 17 are slightly less than 6800 feet or almost 1100 feet higher than the Government Slide Draw elevation at the northwest corner of figure 6. Elevations along the Cedar Rim escarpment crest in section 34 reach 7346 feet although the Cedar Rim crest elevation decreases to the south. The Cedar Rim escarpment in sections 2, 3, and 11 exceeds 200 feet in height. Dishpan Butte in section 29 stands more than 200 feet above the surrounding valley floor. And the valley wall remnant west of Dishpan Butte also stands more than 200 feet higher than the floor of the former south oriented flood flow channel to the east. The south oriented flood flow channel (and now hanging valley) was beheaded when south oriented floodwaters on the Beaver Creek alignment were beheaded and reversed. The flood flow reversal created the north oriented Beaver Creek drainage route and the northwest and north-northwest oriented Beaver Creek tributary drainage routes. It is possible there was a reversal of flood flow in the present day hanging through valley. However, if water flowed north in the abandoned flood flow channel that north oriented flood flow was reversed again to flow in a south and southeast direction along the Government Meadows Draw alignment to the east-northeast and east oriented Sweetwater Creek valley. Evidence in figure 6 suggests final flood flow movement in the hanging through valley was in a south and southeast direction.

Alkali Creek-Haypress Creek drainage divide area

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

Figure 7 illustrates the Alkali Creek-Haypress Creek drainage divide area east and slightly south of figure 3 and includes an overlap area with figure 3. The map contour interval for figure 7 is 20 meters. The Sweetwater River flows in an east-northeast direction across the northwest corner of figure 7. North of figure 7 the Sweetwater River turns to flow in an east direction to eventually join the North Platte River. Alkali Creek is formed at the confluence of west-northwest oriented East Alkali Creek and north-northwest oriented West Alkali Creek near the south edge of the southwest quadrant of figure 7 and then flows in a north-northwest and north direction to join the Sweetwater River near the northwest corner of figure 7. Haypress Creek originates near the southeast corner of figure 7 and flows in a north and north-northeast direction to the east edge of figure 7 (north half) and east and north of figure 7 disappears as a surface stream, although it is headed toward the Sweetwater River. Happy Spring Creek originates at Happy Spring near the center of figure 7 and flows in a northeast direction to join northeast oriented Ice Slough, which drains to the northeast corner of figure 7. Crooks Mountain extends in a southeast and east direction across much of the region seen in figure 7 and areas both north and south of Crooks Mountain drain to the Sweetwater River. West of Crooks Mountain is north oriented Alkali Creek and its west-northwest oriented East Alkali Creek tributary, which drains much of the region south of Crooks Mountain. Several well-defined wind gaps or through valleys cross the present day Crooks Mountain drainage divide and provide evidence of former south oriented flood flow channels. One such wind gap or through valley is found south of the Haypress Creek headwaters and is seen again in figures 9 and 10. Another wind gap or through valley used by the road from the Soap Holes valley is found south of the north oriented valley labeled Soap Holes in the east half of figure 7. The through valley floor elevation is between 2220 and 2240 meters. Immediately to the west is a ridge with an elevation of 2329 meters and to the east of the through valley the ridge elevation climbs to 2362 meters. These elevations suggest the through valley is approximately 100 meters deep. Further west the next north to south oriented road crossing Crooks Mountain also makes use of a through valley and intersects with a road from Happy Spring on the through valley floor. The road intersection elevation is between 2220 and 2240 meters. Elevations to the east rise to 2329 meters and to the west elevations rise to more than 2280 meters suggesting the through valley is at least 40 meters deep and is probably deeper. South oriented flood flow channels eroded these and other similar through valleys across Crooks Mountain at a time when the region north of Crooks Mountain was at least as high as the top of Crooks Mountain. At that time the Sweetwater River valley north of figure 7 did not exist and floodwaters were flowing in a south direction on the present day north oriented Alkali Creek alignment. Headward erosion of the east and east-northeast oriented Sweetwater River valley and its northeast oriented tributary valleys captured the south oriented flood flow and diverted the floodwaters in a northeast and east direction to the North Platte River. the present day north oriented Alkali Creek drainage route was created when headward erosion of the much deeper Sweetwater River valley beheaded the south oriented flood flow channel on that alignment. Flood flow routes were captured in sequence from east to west and newly eroded northeast oriented Sweetwater River tributary valleys captured south oriented flood flow from west of the actively eroding Sweetwater River valley head. These captures of flood flow helped erode the Crooks Mountain north flank.

Detailed map of Happy Spring Creek-East Alkali Creek drainage divide area

Figure 8: Detailed map of Happy Spring Creek-East Alkali 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 Happy Spring Creek-East Alkali Creek drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 20 feet. Happy Spring is located in the southeast corner of section 35 (in northwest quadrant of figure 8). Happy Spring Creek flows in a north and northeast direction from Happy Spring to the north center edge of figure 8. North of figure 8 water in Happy Spring Creek eventually reaches the east oriented Sweetwater River. South and east of Happy Spring a north oriented stream flows from section 12 through a deep water gap in the south half of section 1 where it turns to flow in a northeast, north, and northeast direction to the north edge of figure 8 (east half). The north oriented stream crosses the 7000-foot contour line as it flows through the water gap. Elevations on the east side of the water gap rise to 7502 feet and on the west side of the water gap to 7471 feet. These elevations suggest the water gap is almost 500 feet deep. South of the water gap in the southwest corner of section 12 a road intersection is located in a wind gap or through valley linking the north oriented stream valley with a south oriented stream valley in section 13. The through valley is actually much broader than the deeper channel where the road intersection is located. The through valley extends from the northeast corner of section 14 to the northwest corner of section 18. The through valley floor elevation is between 7300 and 7320 feet. Elevations west of the through valley rise to 7500 feet in section 11 and elevations in section 18 to the east rise to 7641 feet. These elevations suggest the through valley is almost 200 feet deep. In addition to being linked to the north, northeast, north, and northeast oriented stream valley in section 1 the through valley is also linked to a northwest oriented valley in section 2. The stream flowing in that northwest oriented valley is flowing toward Happy Spring, but instead of continuing to Happy Spring the stream turns in the northwest corner of section 2 to flow through a 200-foot deep water gap to enter section 36 and then turns in a northeast direction. Other water and wind gaps can also be found. The wind gaps, water gaps, and through valleys were eroded by diverging and converging south oriented flood flow channels crossing what is today Crooks Mountain. A southeast oriented flood flow channel converged with a south oriented flood flow channel to erode the through valley seen along the south margin of section 12. At the time flood flow moved across the region Crooks Mountain had not emerged and elevations to the north were at least as high as the top of Crooks Mountain. Headward erosion of the Sweetwater River valley north of figure 8 beheaded and reversed the south oriented flood flow channels in sequence to create the northeast oriented Sweetwater River tributaries and to erode the Crooks Mountain north flank. Figure 9 and 10 deal with the region further to the east and also with what happened south of Crooks Mountain.

Haypress Creek-Crooks Creek drainage divide area

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

Figure 9 illustrates the Haypress Creek-Crooks Creek drainage divide area east and south of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 20 meters. The Crooks Mountain eastern end is labeled. Near the southeast end of Crooks Mountain is Crooks Peak. East of Crooks Peak is Crooks Gap and east of Crooks Gap is Sheep Mountain. The forested mountain east of Sheep Mountain is Green Mountain. Crooks Creek flows in a north direction from the south edge of figure 9 (east of center) through Crooks Gap and then turns to flow in a northeast direction to the north edge of figure 9 (east half). North of figure 9 Crooks Creek flows to the east oriented Sweetwater River. South and east of figure 9 Crooks Creek headwaters and tributaries originate on the Green Mountain south flank and flow in southwest directions to join northwest oriented Crooks Creek, which then turns to flow in a north direction into figure 9. Crooks Creek crosses the 2040-meter contour line in Crooks Gap. Elevations on Crooks Mountain to west rise to 2464 meters and elevations on Green Mountain to the east rise to 2768 meters suggesting the Crooks Gap depth is at least 400 meters. Shallower north to south oriented through valleys or wind gaps are located between Crooks Peak and Crooks Mountain and between Sheep Mountain and Green Mountain. Further west a north to south oriented through valley links the north oriented Haypress Creek valley with a south-southwest oriented East Alkali Creek tributary valley. Haypress Creek originates east of the west center edge of figure 9 and flows in a north direction to the north edge of figure 9. East Alkali Creek originates near the southwest corner of figure 9 and flows in a southwest and west-southwest direction to the west edge of figure 9 (near southwest corner). West of figure 9 East Alkali Creek flows in a west-northwest direction south of Crooks Mountain to join north oriented Alkali Creek, which then flows to the east oriented Sweetwater River. East of the East Alkali Creek headwaters are headwaters of south oriented Arapahoe Creek, which south of figure 9 turns to flow in a southwest direction into the Great Divide Basin where it joins south oriented Lost Creek, which disappears as a surface stream at Lost Creek Lake. The north to-south oriented wind gaps and the north oriented Cooks Gap water gap originated as south oriented flood flow channels at a time when Crooks Mountain and Green Mountain did not stand high above regions to the north. At that time the Sweetwater River north of figure 9 did not exist. The west-northwest oriented East Alkali Creek valley probably originated as an east-southeast oriented valley that had eroded headward to capture south oriented flood flow moving across the emerging Crooks Mountain. Headward erosion of the deep Sweetwater River valley beheaded and reversed south oriented flood flow on the present day north oriented Crooks Creek alignment to create the north oriented Crooks Creek route through Crooks Gap. Reversed flow flood flow through Crooks Gap may have captured the east-southeast oriented flood flow on the East Alkali Creek alignment (see southeast, east, and northeast oriented West Fork Crooks Creek route). Next headward erosion of the south oriented Arapahoe Creek valley and tributary valleys captured the east oriented flood flow to the newly formed West Fork Crooks Creek drainage route. Continued headward erosion of the Sweetwater River valley then beheaded and reversed flood flow on the Alkali Creek alignment at the Crooks Mountain west end. This flood flow reversal caused a reversal of flood flow on the East Alkali Creek alignment and created the present day west-northwest oriented East Alkali Creek drainage route.

Detailed map Haypress Creek-East Alkali Creek drainage divide area

Figure 10: Detailed map of Haypress Creek-East Alkali 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 Haypress Creek-East Alkali Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 20 feet. Haypress Creek originates in sections 23 and 24 and flows in a north direction to the north center edge of figure 10. North of figure 4 Hatpress Creek disappears as a surface stream, but is definitely headed toward the east oriented Sweetwater River. A southwest oriented stream flows across the northwest corner of section 25 and into section 26 where it crosses the south center edge of figure 10. South of figure 10 that stream flows to west-northwest oriented East Alkali Creek, which at the Crooks Mountain west end joins north oriented Alkali Creek to flow to the east oriented Sweetwater River. A broad north-to-south oriented through valley links the north oriented Haypress Creek valley with the south oriented East Alkali Creek tributary valley. The through valley floor elevation is between 7420 and 7440 feet. The high point west of the through valley is 7750 feet and the high point in section 19 to the east of the through valley is 7981 feet. These elevations suggest the through valley is at least 300 feet deep. The through valley is a water-eroded valley and was eroded at a time when water flowed across what is today Crooks Mountain. The water was south oriented flood flow, which was flowing on a surface north of figure 10 at least as high as the Crooks Mountain crest elevation. Floodwaters initially were flowing in a south direction to the Great Divide Basin and then south into Colorado to actively eroding Colorado River tributary valleys. Headward erosion of an east-southeast oriented valley on the present day west-northwest oriented East Alkali Creek alignment captured the south oriented flood flow, although the floodwaters probably still flowed in a south direction. Headward erosion of the deep east oriented Sweetwater River valley north of figure 10 beheaded and reversed flood flow on the Haypress Creek alignment to create the north oriented Haypress Creek drainage route. Continued headward erosion of the Sweetwater River valley beheaded and reversed south oriented flood flow west of Crooks Mountain to create the north oriented Alkali Creek drainage route. The reversal of flood flow on the Alkali Creek drainage route reversed flood flow on the East Alkali Creek alignment to create the west-northwest oriented East Alkali Creek drainage route.

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.