Abstract:

This essay uses topographic map evidence to interpret landform origins in the region between Deer Creek and Sweetwater River tributaries at the Beaver Divide eastern end in central Wyoming. The Beaver Divide is a north-facing escarpment and the drainage divide between north-oriented drainage routes to the Wind River and south oriented drainage routes to the east oriented Sweetwater River and can be considered the Wind River Basin southern boundary. The Beaver Divide eastern end is located near the Rattlesnake Mountains northwest end and is drained on the north side by north and northwest Deer Creek and its tributaries and on the south side by south and southeast oriented Dry Creek and south and southwest Sage Hen Creek, both of which flow to the Sweetwater River, which follows an east oriented route through the Granite Mountains. Drainage routes in the study region evolved during immense south-oriented melt water floods, which were subsequently reversed to flow in a north direction into the Wind River Basin and to the north oriented Wind and Bighorn Rivers. Floodwaters flowed in south directions from the western margin of a thick North American ice sheet in western Canada to central Wyoming and for a considerable period of time flowed across Wyoming and into Colorado. At least initially Wyoming mountain ranges had not emerged and at first floodwaters could freely flow across what are today major mountain barriers. Mountain ranges emerged as floodwaters flowed across them and deeply eroded surrounding regions and as ice sheet related crustal warping raised the mountain ranges. Present day through valleys, water gaps, wind gaps, barbed tributaries, and other evidence seen on topographic maps are interpreted here in the context of the immense south oriented melt water floods and the subsequent reversal of those floods. The reversal of flood flow occurred when the deep northeast oriented Yellowstone River valley eroded headward across Montana from space at the southern end of the deep “hole” the ice sheet had occupied and that was being opened by ice sheet melting. Headward erosion of the Yellowstone River valley captured the south oriented flood routes to Wyoming in sequence from east to west and diverted floodwaters to the deep “hole”. Floodwaters on north ends of beheaded flood flow routes reversed flow direction to create north oriented drainage routes such as the north oriented Wind and Bighorn Rivers. Reversed flood flow in the Wind River Basin captured large volumes of flood flow from further west and also large volumes of  flood flow that had become trapped south of the Wind Basin as mountain ranges emerged and as ice sheet related crustal warping raised southwest Wyoming. North oriented flood flow into the Wind River eroded the Beaver Divide escarpment until headward erosion of the east oriented Sweetwater River valley captured the north oriented flood flow and diverted the floodwaters to north, northeast, east, and southeast oriented North 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 Deer Creek-Sweetwater River drainage divide area landform origins at the Beaver Divide eastern end, 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 Deer Creek-Sweetwater River drainage divide area landform evidence at the Beaver Divide eastern end will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Deer Creek-Sweetwater River drainage divide area location map

Figure 1: Deer 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 Deer Creek-Sweetwater River drainage divide area at the Beaver Divide eastern end and illustrates a region in west-central Wyoming. Grand Teton National Park is located near the northwest corner of figure 1 and the Wyoming-Idaho state line is located a short distance west of the west edge of figure 1. The Wind River originates near Togwotee Pass (east of Grand Teton National Park) and flows in a southeast direction between the Owl Creek Mountains and Wind River Range to Riverton in the Wind River Basin where the Wind River turns to flow in a northeast and north direction to Boysen Reservoir. From Boysen Reservoir the Wind River flows through Wind River Canyon at the east end of the Owl Creek Mountains to enter the Bighorn Basin near Thermopolis. Once in the Bighorn Basin the river name changes to become the Bighorn River and the Bighorn River flows to the north edge of figure 1 (east of center) and north of figure 1 flows into Montana and then joins the northeast oriented Yellowstone River. Poison Creek originates near the northwest end of the Rattlesnake Hills and flows in a north-northeast direction to near Hiland where it turns to flow in a west-northwest direction to join the north oriented Wind River at Boysen Reservoir. Muskrat Creek is a north and northwest oriented Wind River tributary located south of Poison Creek. Deer Creek is not shown in figure 1, but is a north and northwest oriented Poison Creek tributary located east of Muskrat Creek. The North Platte River flows in a north direction from the south edge of figure 1 (east half) to Seminoe Reservoir, Pathfinder Reservoir, and Alcova Reservoir and then turns to flow in a northeast direction to Casper (located near east center edge of figure 1 and at northwest end of Laramie Mountains. At Casper the North Platte River turns to flow in an east and southeast direction along the Laramie Mountains north and northeast flanks and then into Nebraska to the east oriented Platte River. The Sweetwater River originates near the south end of the Wind River Range and flows in a south and southeast direction along the southwest margin of the Wind River Range to near South Pass before turning to flow in an east-northeast and east direction to turn in a south direction at Pathfinder Reservoir to join the north oriented North Platte River as a barbed tributary. The Deer Creek-Sweetwater River drainage divide area investigated in this essay is located south of Poison Creek, north of the Sweetwater River, west and south of the Rattlesnake Hills, and east of Muskrat Creek headwaters and includes areas in the Granite Mountains.

Wyoming drainage routes evolved during massive south oriented melt water floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada across Montana and then into and across Wyoming. Initially Montana and Wyoming mountain ranges had not emerged and floodwaters could flow across what are today major mountain barriers. 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 ice sheet was located. The Laramie Mountains south and east of Casper emerged as deep south-oriented flood flow channels eroded headward both east and west of the emerging mountain range. The western south oriented flood flow channel roughly followed the present day north oriented North Platte River alignment between the Rattlesnake Hills and the Laramie Mountains and was beheaded by headward erosion of the much deeper flood flow channel that had eroded headward along the northeast and north flanks of the emerging Laramie Mountains. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to flow to the much deeper east and southeast oriented flood flow channel on the present day east and southeast oriented North Platte River alignment downstream from Casper. In addition to the reversal of floodwaters trapped by rising mountain ranges (to the south of figure 1) the reversed flood flow also captured flood flow still moving in a south direction west of the reversed flood flow channel with the east oriented Sweetwater River valley supplying much of that captured flood flow. Headward erosion of the Sweetwater River valley probably began before the North Platte River flood flow reversal took place, which explains why the Sweetwater River valley turns in a south direction at Pathfinder Reservoir to join the present day north oriented North Platte River as a barbed tributary. The North Platte River flood flow reversal probably took place as the Sweetwater River was eroding westward across south oriented flood flow in the Granite Mountains area and the Sweetwater River route west of the Granite Mountains was determined by a completely different and much larger flood flow reversal in the region between the present day Granite Mountains and the Wind River Range. Note locations of the Ferris Mountains and Green Mountains south of the Sweetwater River. While not seen in this essay the emerging Ferris Mountains and Green Mountains helped channel floodwaters that crossed the region investigated in this essay.

Large volumes of south oriented flood flow moved from the present day Bighorn Basin across the emerging Owl Creek Mountains and then in a south direction between the emerging Wind River Range and Rattlesnake Hills to the Great Divide Basin and then south into Colorado and to the Colorado River drainage basin. In addition some of this south oriented flood flow moved in an east direction between the emerging Rattlesnake Hills and the emerging Bighorn Mountains (north of Rattlesnake Hills) to the deep east and southeast oriented North Platte River valley in the Casper area and subsequently to the deep northeast and north-northeast oriented South Fork Powder River valley, which had eroded headward from a reversed flood flow channel on the present day north oriented Powder River alignment (the Powder River flows in a north direction to the northeast corner of figure 1 and north of figure 1 joins the northeast oriented Yellowstone River). Flood flow on the Powder River alignment was beheaded and reversed by headward erosion of the deep northeast oriented Yellowstone River valley from space at the south end of the deep “hole” the melting ice sheet was opening up. Headward erosion of the deep Yellowstone River valley beheaded and reversed flood flow in the Powder River Basin (east of the Bighorn Mountains) while floodwaters were still flowing in south and southeast directions across the emerging Bighorn Mountains and Bighorn Basin further to the west (see southeast oriented North Fork Powder River route in Bighorn Mountains near northeast corner of figure 1 for evidence the Powder River captured southeast oriented flood flow crossing the Bighorn Mountains). Yellowstone River valley headward erosion eventually beheaded and reversed flood flow routes crossing the Bighorn Basin to create the north oriented Bighorn River drainage route, which captured south and southeast oriented flood flow still moving west of the actively eroding Yellowstone River valley head. Southeast oriented headwaters tributaries to the north oriented Wind River and Bighorn River provide evidence of these flood flow captures. The massive flood flow reversal in the Bighorn Basin took place as the Wind River Range was still emerging and before the deep southeast oriented Wind River valley had been eroded and floodwaters were still moving in a south direction across the Wind River Range. South oriented flood flow crossing the southeast end of the emerging Wind River Range was captured by reversed flood flow moving into the Wind River Basin area and moved in a southwest and then east-northeast direction around the Wind River Range to join north oriented reversed flood flow from the Great Divide Basin and to flow in a north direction across the emerging Owl Creek Mountains and eventually to the south of the deep “hole” the melting ice sheet had once occupied. Headward erosion of the deep southeast oriented Wind River valley soon ended the food flow across the emerging Wind River Range, however the north oriented reversed flood flow flowing between the Wind River Range and the Rattlesnake Mountains combined with the southeast oriented flood flow captured by headward erosion of the deep southeast oriented Wind River valley deeply eroded the present day Wind River Basin and Wind River Canyon and contributed to the deep erosion of the Bighorn Basin further to the north.

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

Figure 2: Detailed location map Deer Creek-Sweetwater 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 Deer Creek-Sweetwater River drainage divide area at the Beaver Divide eastern end. Pathfinder Reservoir is located near the southeast corner of figure 2. The North Platte River flows in a north direction from south of figure 2 to Pathfinder Reservoir and then in a northeast direction Alcova Reservoir (just east of figure 2). East of figure 2 the North Platte River flows in a north and northeast direction to the Laramie Mountains northwest end and then turns to flow in an east and southeast direction to eventually reach Nebraska. The Sweetwater River flows in an east-southeast and east direction from the west edge of figure 2 (south half) to Pathfinder Reservoir, where the flooded Sweetwater River valley turns in a south direction to join the north and northeast oriented North Platte River as a barbed tributary. Dry Creek originates near the northwest end of the Rattlesnake Hills and flows in a south, south-southeast, southeast, south, and southeast direction to join the Sweetwater River near Independence Rock (near west end of Pathfinder Reservoir). West of the Dry Creek headwaters are headwaters of south-southwest, south, and southwest oriented Sage Hen Creek, which joins the east oriented Sweetwater River in the Granite Mountains area as a barbed tributary. Labeled Sage Hen Creek tributaries are south-southwest oriented West Sage Hen Creek and south-southwest and south-southeast oriented Diamond Springs Draw. The unlabeled north and northwest oriented stream originating near the Sage Hen Creek headwaters is Deer Creek and north of figure 2 Deer Creek flow to west oriented Poison Creek with water eventually reaching the north oriented Wind and Bighorn Rivers and the northeast oriented Yellowstone River. The north-northwest oriented stream just west of Deer Creek is Canyon Creek and north of figure 2 Canyon Creek joins Deer Creek before Deer Creek joins Poison Creek. The north oriented drainage system west of Canyon Creek is the Muskrat Creek drainage system with Muskrat Creek turning to flow in a northwest direction north of figure 2 to flow directly to the north oriented Wind River. Beaver Divide north and west of the south-southwest oriented Diamond Springs Draw segment and south of the Muskrat Creek headwaters is the drainage divide between north-oriented Wind River tributaries and south oriented Sweetwater River tributaries and is also a northwest-facing escarpment bounding the Wind River Basin to the northwest. Further west the Beaver Divide orientation changes, although those orientation changes and the Beaver Divide history are addressed in the Wind River-Sweetwater River drainage divide area essay and not in this essay. This essay primarily addresses the region between the north oriented Deer Creek and Canyon Creek headwaters and the Sweetwater River and includes the Granite Mountains region between southeast oriented Dry Creek and southwest oriented Sage Hen Creek.

Deer Creek-Dry Creek drainage divide area

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

Figure 3 provides a topographic map of Deer Creek-Dry Creek drainage divide area. The map contour interval for figure 3 is 20 meters. Cyclone Ridge is near the north center edge of figure 3 and the Rattlesnake Hills extend in a southeast direction from Cyclone Ridge to the east edge of figure 3 and continue in a southeast direction east and south of figure 3. Deer Creek is the north-northwest and northwest oriented stream originating in the east center area of figure 3 (west of the Rattlesnake Hills) and flowing to the north edge of figure 3 (west of Cyclone Ridge). North of figure 3 Deer Creek eventually reaches west oriented Poison Creek, which flows to north oriented Wind River with water eventually reaching the northeast oriented Yellowstone River in Montana. Holiday Draw is a north oriented Deer Creek tributary in the east center area of figure 3. The south oriented stream originating in the Rattlesnake Hills and flowing to the south edge of figure 3 (east half) is Dry Creek. South of figure 3 Dry Creek turns to flow in a southeast direction along the Rattlesnake Hills southwest flank and joins the east and south oriented Sweetwater River, which then joins the north oriented North Platte River with water eventually flowing to the east oriented Platte River in Nebraska. The Middle Fork Sage Hen Creek flows from Beaver Divide to the south center edge of figure 3 and south of figure 3 turns to flow in a southwest direction to join the east oriented Sweetwater River. The east end of Beaver Divide is seen in figure 3. Beaver Divide is both the drainage divide between north oriented Wind River tributaries and south oriented Sweetwater River tributaries, but is also a north-facing escarpment forming the Wind River Basin southern boundary. In figure 3 Beaver Divide is a northwest-facing escarpment, although further to the west the Beaver Divide orientation changes. Beaver Divide was eroded when a massive flood flow reversal in the Wind River Basin caused south oriented flood flow from south and west of Wind River Basin to flow in a north direction towards the newly reversed Wind River Canyon outlet. Beaver Divide could be considered a giant abandoned north oriented headcut. However, here in figure 1 we see the eastern margin of that giant flood flow reversal in the form of a through valley linking the northwest oriented Deer Creek valley with the south and southeast oriented Dry Creek valley.  The through valley is located between northeast end of the Beaver Escarpment and the Rattlesnake Hills and has a floor elevation of between 2260 and 2280 meters. Black Mountain to the southwest rises to 2451 meters and elevations in the Rattlesnake Hills to the north rise to 2433 meters. These elevations suggest the through valley could be as much as 150 meters deep if not deeper. The through valley was eroded by southeast oriented flood flow moving to the east and south oriented Sweetwater River valley, which was eroding headward from a south oriented flood flow channel on the present day north oriented North Platte River alignment (south of Pathfinder Reservoir). The reversal of flood flow in the Wind River Basin beheaded the southeast oriented flood flow channel and floodwaters on the northwest end of the beheaded flood flow channel reversed flow direction to create the north and northwest oriented Deer Creek drainage route and west oriented Poison Creek drainage route. Unlike the region further to the west the reversed flood flow did not erode a major north-facing escarpment.

Detailed map of Deer Creek-Dry Creek drainage divide area

Figure 4: Detailed map of Deer Creek-Dry 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 Deer Creek-Dry Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 20 feet. The Rattlesnake Hills extend from the north center edge of figure 4 in southeast direction to the southeast corner of figure 4. Hogbacks along the Rattlesnake Hills northeast flank can be seen in the northeast region of figure 4. Deer Creek originates near the Strawraker Corral in section 22 (near center of figure 4) and flows in a northwest direction to the northwest corner of figure 4. North and west of figure 4 Deer Creek joins west oriented Poison Creek, which flows to the north oriented Wind River with water eventually reaching the northeast oriented Yellowstone River. Dry Creek originates near the west edge of section 23 and flows across the southeast corner of section 22 before gradually turning to flow in south direction to the south center edge of figure 4. South and east of figure 4 Dry Creek flows to the east and south oriented Sweetwater River, which flows to the north oriented North Platte River with water eventually reaching the Platte River in Nebraska. The northwest and southwest oriented stream seen in sections 29 and 30 (near southwest corner of figure 4) is the Middle Fork Sage Hen Creek (labeling is slightly different in figures 3 and 5). South and west of figure 4 Sage Hen Creek flows in a southwest direction to join the east oriented Sweetwater River as a barbed tributary. The Dry Creek Road crosses the Deer Creek-Dry Creek drainage divide in the southwest quadrant of section 21 (near enter of figure 4). The high point on the road is marked as being 7465 feet although slightly lower drainage divide elevations are found to the southwest of that point. The high point in section 29 to the west of the Deer Creek-Dry Creek through valley is shown as 7766 feet and Black Mountain (southwest of figure 4) rises to more than 8000 feet. Elevations greater than 8000 feet are seen in figure 4 in the Rattlesnake Hills to the east of the through valley. Depending on which elevations are selected the through valley could be 300 feet deep or it could be more than 500 feet deep. In either case the through valley is a water eroded valley and was eroded by southeast oriented flood flow moving from the present day Wind River Basin to what at that time was an actively eroding east and south oriented Sweetwater River valley, which was eroding headward from a south oriented flood flow channel on the present day north oriented North Platte River alignment. At that time the deep Wind River Basin to the northwest had not been eroded and floodwaters were flowing in a south direction on the present day north oriented Wind River Canyon alignment.  The reversal of flood flow on the Wind River Canyon alignment triggered the massive flood flow reversal responsible for erosion of Wind River Basin and the reversal of flood flow that created the northwest oriented Deer Creek drainage route.

Canyon Creek-Sage Hen Creek drainage divide area

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

Figure 5 illustrates the Canyon Creek-Sage Hen Creek drainage divide area south and west of figure 4 and there is a large overlap area with figure 4. The map contour interval for figure 5 is 20 meters. Beaver Divide is labeled and extends in a southwest to northeast direction across figure 5. North of Beaver Divide are two large strip mine areas with the Lucky Mac Camp being north of the western strip mine area and the Gas Hills being north of the Lucky Mac Camp. The northwest and north oriented stream originating at an indentation in Beaver Divide and flowing between the two strip mine areas to the north edge of figure 5 is West Canyon Creek. East Canyon Creek flows in a northwest direction from near the Holiday Draw headwaters at Beaver Divide (east of the eastern strip mine area) to the north center of figure 5 (north of the eastern strip mine area). North of figure 5 East and West Canyon Creek join to form north oriented Canyon Creek, which then flows to Deer Creek. Middle Fork Sage Hen Creek (as labeled in figure 5-labeling in figures 4 and 6 is slightly different) originates near the West Canyon Creek headwaters and flows in a south direction to the south center edge of figure 5. South of figure 5 Sage Hen Creek flows in a southwest direction to join the east oriented Sweetwater River as a barbed tributary. A Middle Fork Sage Hen Creek tributary originates on the south side of Beaver Divide near the north oriented Holiday Draw and East Canyon Creek headwaters and north of Black Mountain and flows in a south-southwest direction to join south oriented Sage Hen Creek. Note the northwest and north oriented West Canyon Creek valley north of Beaver Divide is linked by a through valley with the south oriented Middle Fork Sage Hen Creek valley south of Beaver Divide. The through valley floor elevation is between 2200 and 2220 meters. Elevations along Beaver Divide to the west rise to at least 2254 meters and to the east elevations rise to more than 2340 meters. These elevations suggest the through valley is at least 34 meters deep. While massive south oriented floods crossed the region the V-shaped indentation in Beaver Divide suggests the through valley was probably eroded by reversed north oriented flood flow moving from the Middle Fork Sage Hen Creek valley to reversed flood flow on the West Canyon Creek alignment. Shallower through valleys (defined by one and two contour lines on a side) and somewhat less obvious V-shaped indentations in the Beaver Divide escarpment suggest north oriented flood flow also moved along the Middle Fork Sage Creek valley and tributary valley to reach reversed flood flow on the north oriented East Canyon Creek and Holiday Draw alignments.

Detailed map of Canyon Creek-Sage Hen Creek drainage divide area

Figure 6: Detailed map of Canyon Creek-Sage Hen 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 Canyon Creek-Sage Hen Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 20 feet. West Canyon Creek originates in the north center area of section 4 and flows in a north and northwest direction to the north edge of figure 6. North of figure 6 Canyon Creek flows to north oriented Deer Creek, which flows to west oriented Poison Creek with water eventually reaching the north oriented Wind and Bighorn Rivers and then the northeast oriented Yellowstone River. Labeling for the Middle Fork Sage Hen Creek headwaters in figure 6 is slightly different from in figure 5. In figure 6 the Middle Fork Sage Hen Creek flows in a south-southwest direction from the east edge of figure 6 (near northeast corner) to the south edge of figure 6 (slightly east of center). A southeast oriented tributary originates in section 4 (south of the West Canyon Creek headwaters) and joins the Middle Fork Sage Hen Creek in section 10. A through valley in section 4 links the north oriented West Canyon Creek valley with the south oriented Middle Fork Sage Hen Creek valley. The through valley floor elevation is between 7260 and 7280 feet. Beaver Divide elevations in section 6 to the west rise to 7372 feet and west of figure 6 Beaver Divide elevations rise to 7461 feet and further west rise even higher. North of figure 6 Beaver Divide elevations to the northeast of the through valley rise 7653 feet. Based on these elevations a strong case can be made that the through valley is approximately 200 feet deep if not deeper. The north oriented West Canyon Creek headwaters valley eroded into the north-facing Beaver Divide escarpment suggests final flood flow movement in the through valley was in a north direction. The north oriented flood flow probably represented the final stages of a massive flood flow reversal where large sheets of reversed flood flow eroded the north-facing Beaver Divide escarpment headward as the floodwaters moved into the deeper Wind River Basin. Prior to the flood flow reversal floodwaters had been moving in a south direction to and across the Great Basin to the south of the present day Sweetwater River valley to reach the actively eroding Colorado River drainage system. The massive flood flow reversal was triggered by the reversal of flood flow on the present day north oriented Wind River Canyon alignment, but was probably greatly aided by ice sheet related crustal warping that was raising the Ferris and Green Mountains to the south of figure 6.

Dry Creek-Sage Hen Creek drainage divide area

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

Figure 7 illustrates the Dry Creek-Sage Hen Creek drainage divide area south and east of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 20 meters. Dry Creek flows in a south-southeast direction from the north edge of figure 7 (east half) to the east edge of figure 7 (south half) and east and south of figure 7 joins the east and south oriented Sweetwater River. Greasewood Draw is a southeast oriented Dry Creek tributary located in the east center area of figure 7 and Barlow Springs Draw is a southeast and east oriented Greenwood Draw tributary. The Middle Fork Sage Hen Creek flows in a south direction from the north edge of figure 7 (west half) to near the south edge and then turns to flow in a southwest direction to eventually join the east oriented Sweetwater River south and west of figure 7. West Sage Hen Creek flows in a south direction from the north edge of figure 7 (near northwest corner) to the Landing Strip and then turns to flow in a southwest direction to the west edge of figure 7. West and south of figure 7 West Sage Hen Creek joins the Middle Fork Sage Hen Creek to form southwest oriented Sage Hen Creek. West Sage Hen Rocks are located near the southwest corner of figure 7 and are typical of Granite Mountains outcroppings or “peaks”. Between the “peaks” through valleys link the Dry Creek valley with the Sage Hen Creek valley and with the east oriented Sweetwater River valley to the south. Barlow Gap in the southeast quadrant of figure 7 is an example of through valleys found in the region. The Barlow Gap floor elevation is between 2100 and 2120 meters. The “peak” to the south rises to more than 2280 meters and the high point in the north center area of figure 7 is shown being 2390 meters. South of figure 7 at Savage Peak, which is located north of the Sweetwater River, the elevation rises to 2391 meters. Depending on which elevations are chosen Barlow Gap could be considered to be 100 meters deep or more than 270 meters deep. In the latter case Barlow Gap is merely a deeper channel eroded into the floor of what was a much broader northeast to southwest oriented valley. In either case Barlow Gap provides evidence not all south and southeast oriented flood flow crossing the Deer Creek-Dry Creek drainage divide flowed in a southeast direction to the east and south oriented Sweetwater River valley. Some of the flood flow diverged in a southwest oriented direction to flow to the southwest oriented Sage Hen Creek valley, which suggests the possibility of south oriented flood flow channels further to the west. Headward erosion of a deeper southeast oriented Dry Creek valley and the Greasewood Draw and Barlow Springs Draw valleys captured the diverging southeast oriented flood flow and diverted the floodwaters in a southeast direction to the Dry Creek valley and ended all southwest oriented flood flow on the Barlow Gap alignment.

Detailed map of Barlow Springs Draw-Sage Hen Creek drainage divide area

Figure 8: Detailed map of Barlow Springs Draw-Sage Hen 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 Barlow Springs Draw-Sage Hen Creek drainage divide area seen in less detail in figure 7 above. The map contour interval for figure 8 is 20 feet. Greasewood Draw drains in a southeast direction across the northeast corner of figure 8 and joins south-southeast oriented Dry Creek east of figure 8. Barlow Springs Draw drains in a southeast direction from the north center edge of figure 8 and in section 10 turns to drain in an east direction to join Greasewood Draw near the east edge of figure 8. Sage Hen Creek flows in a south direction from the northwest corner of figure 8 to section 26 and then turns to flow in a southwest direction to the west edge of figure 8 (south half). West of figure 8 Sage Hen Creek joins the east oriented Sweetwater River as a barbed tributary. Barlow Gap is located in section 22 between two “peaks” in the Granite Mountains and the Barlow Gap floor elevation at the road intersection is shown as 6923 feet. The Granite Mountain “peak” in section 21 rises to 7366 feet and the “peak” near the north edge of section 27 rises to at least 7500 feet. Higher elevations can be found both north and south of figure 8. Based on elevations seen in figure 8 Barlow Gap appears to be at least 430 feet deep. A southwest oriented flood flow channel diverging from the south-southeast oriented Deer Creek-Dry Creek through valley (or flood flow channel) was responsible for forming Barlow Gap. The diverging flood flow channel probably moved floodwaters to a south oriented flood flow channel west of figure 8 while the Dry Creek valley moved floodwaters to a south oriented flood flow channel on the present day north oriented North Platte River alignment. The Granite Mountains as seen in figures 7, 8, 9, and 10 could be illustrative of how mountain ranges emerged as floodwaters flowed across them. The Granite Mountains “peaks” appear to be buried by flood transported debris (or debris from earlier events) and floodwaters appear to have been eroding the debris as the “peaks” gradually emerged. Why other mountain ranges emerged and now stand high above the surrounding regions and why the Granite Mountains did not emerge is not obvious (at least to me) from the topographic map evidence.

Dry Creek-Sweetwater River drainage divide area

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

Figure 9 illustrates the Dry Creek-Sweetwater River drainage divide area south and east of figure 7 and there is no overlap area with figure 7. The map contour interval for figure 9 is 20 meters. The Ferris Mountains are located south of figure 9 with a present day north oriented water gap crossing the east end of the Ferris Mountains being located south of the southeast corner of figure 9 and a present day north oriented water gaps across the Ferris Mountains western end being located south and west of the southwest corner of figure 9. The Sweetwater River flows in a southeast and east direction from the west edge of figure 9 to Devils Gate (near south edge of figure 9-east of center) and then turns to flow in a northeast direction to the east edge of figure 9 (slightly south of center). East of figure 9 the Sweetwater River flows in an east and south direction to join the north oriented North Platte River as a barbed tributary. Dry Creek flows in a southeast direction from the north center edge of figure 9 to the east edge of figure 9 and joins the east oriented Sweetwater River east of figure 9. Figure 9 illustrates more Granite Mountain “peaks” and an additional southwest oriented flood flow route linking the south-southeast oriented Dry Creek valley north of figure 9 with the present day east oriented Sweetwater River valley west of figure 9. If correctly interpreted at the time the diverging flood flow moved in a southwest direction the Sweetwater River alignment west of figure 9 did not exist and floodwaters were flowing to what are today north oriented water gaps at the west end of the Ferris Mountains. If so the southeast, east, and northeast oriented Sweetwater River valley seen in figure 9  eroded headward across the region in figure 9 to capture south oriented flood flow being blocked by emergence of the Ferris Mountains to the south. The Devils Gate area provides some clues as to how much erosion took place. While contour lines in the Devils Gate area are difficult to read the Sweetwater River elevation at Devils Gate appears to be between 1820 and 1840 meters. Adjacent elevations on either side of Devils Gate rise to more than 1940 meters suggesting Devils Gate is a 100-meter deep water gap.  What is particularly remarkable about Devils Gate is just a short distance away a broad through valley used by the highway is almost as deep as the Sweetwater River valley route. Also to the northwest of Devils Gate there are several southwest to northeast oriented through valleys (although not as deep), which are located between Devils Gate and Savage Peak. The only way the present day Sweetwater River route through Devils Gate can be explained is that the region was eroded by multiple flood flow channels, which initially flowed on a surface 100 meters higher if not higher than the surface the highway now travels on. If so, the northeast oriented Sweetwater River valley segment eroded headward to capture south oriented flood flow channels that were moving floodwaters to what is today the north oriented Sand Creek water gap located at the east end of the Ferris Mountains south of figure 9 and then once west of Devils Gate the Sweetwater River valley captured southwest oriented flood flow channels moving floodwaters to what are today north oriented water gaps at Whiskey Gap and Muddy Gap at the northwest end of the Ferris Mountains. Headward erosion of the southeast oriented Dry Creek valley beheaded the southwest oriented flood flow channels and diverted the flood flow to the east oriented Sweetwater River valley located east of figure 9.

Sage Hen Creek-Sweetwater River drainage divide area

Figure 10: Sage Hen Creek-Sweetwater River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a topographic map of the Sage Hen Creek-Sweetwater River drainage divide area west and slightly north of figure 9 and there is an overlap area with figure 9. The map contour interval for figure 10 is 20 meters. The Green Mountains are located south of figure 10 and Crooks Mountain is located south and west of figure 10. Crooks Gap is today a deep north oriented water gap located between the Green Mountains and Crooks Mountain and is located south and west of the southwest corner of figure 10. Whiskey and Muddy Gaps between the Green Mountains eastern end and the Ferris Mountains western end are located south of the southeast corner of figure 10.  The Sweetwater River flows in a southeast direction across the southwest corner of figure 10 and then turns to flow in more of an east direction near the south edge of figure 10 to the east edge of figure 10. Sage Hen Creek flows in west-southwest and south direction from the north center edge of figure 10 to join the southeast oriented Sweetwater River near the west edge of figure 10. Cottonwood Creek is the northeast oriented stream joining the southeast oriented Sweetwater River near Castle Rock in the southwest corner of figure 10. Cottonwood Creek headwaters are in the western Ferris Mountains located south and west of the southwest corner of figure 10. Lankin Creek is the southwest oriented stream joining the Sweetwater River opposite from the Cottonwood Creek mouth. Note how Lankin Creek and Cottonwood Creek flow in opposite directions along the same alignment and also note how Lankin Gap is a deep water gap eroded across a Granite Mountains upland area. The Lankin Gap floor elevation is less than 2000 meters. Lankin Dome to the west rises to more than 2300 meters while McIntosh Peak to the east rises to 2458 meters. These elevations suggest Lankin Gap is more than 300 meters deep. Lankin Gap was eroded by southwest oriented flood flow moving to south oriented flood flow channels at the western end of the emerging Green Mountains (and between the Green Mountains and Crooks Mountain). In the east half of figure 10 a southwest to northeast oriented road travels through Beef Gap and a south-southwest to north-northeast road travels through an unnamed gap west of Beef Gap. Converging southwest oriented flood flow channels eroded these two present day wind gaps. The southwest oriented flood flow appears to been headed toward the emerging Green Mountains south of figure 10, although deep present day north oriented water gaps are located at both ends suggesting a reversal of flood flow south of figure 10 as the Green Mountains emerged. The east oriented Sweetwater River eroded headward across the southwest oriented flood flow channels to capture the southwest oriented flood flow that probably was being blocked to the south by the Green Mountains emergence.

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.