Abstract:

Topographic map evidence in the Sweetwater River-Lost Creek drainage divide area near Green Mountain in Wyoming is illustrated and discussed to determine the origin of the regional erosional landforms, including drainage routes and water and wind gaps. Green Mountain is a northwest to southeast oriented mountain south of the east oriented Sweetwater River drainage basin and north of the south oriented Lost Creek drainage basin with the Lost Creek drainage basin being located in the present day Great Divide Basin, which has no exterior drainage. The Sweetwater River flows to the north and southeast oriented North Platte River with water eventually reaching the Gulf of Mexico. South of the Great Divide Basin is the southwest oriented Little Snake River drainage basin, which drains to the Yampa River with the Yampa River draining to the Green River and then the Colorado River. West of Green Mountain is Crooks Mountain and south, northwest, north, and northeast oriented Crooks Creek flows in a north direction through Crooks Gap, which is a deep water gap between the two mountains. West of Crooks Gap south oriented Lost Creek headwaters originate on Crooks Mountain and appear to have beheaded an east and north oriented Crooks Creek tributary. East of Crooks Gap the Green Mountain southwest margin is drained by northwest oriented Crooks Creek, although immediately to the south and west are headwaters of southwest oriented Lost Creek tributaries. A deep northeast to southwest oriented through valley crosses the Green Mountain east end and links the south-southwest oriented Crooks Creek headwaters valley with the northeast oriented Willow Creek valley with Willow Creek flowing to the east oriented Sweetwater River. Topographic map evidence is interpreted in the context of immense melt water floods flowing from the western margin of a thick North American ice sheet in western Canada to and across Wyoming. Initially floodwaters flowed across the Green Mountain region on an erosion (deposition?) surface at least as high as the present day Green Mountain top, although crustal warping since that time probably have altered regional elevations. Floodwaters were flowing across Green Mountain and Crooks Mountain into and across the present day Great Divide Basin to actively eroding Little Snake River tributary valleys. Headward erosion of the much deeper east oriented Sweetwater River valley and its northeast oriented tributary valleys beheaded the south oriented flood flow channels in sequence from east to west. When a major flood flow channel on the Crooks Gap alignment was beheaded by headward erosion of deeper northeast oriented Sweetwater River tributary valley floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Crooks Creek drainage route. The newly reversed Crooks Creek drainage route then captured floodwaters south of Green Mountain and south of the Crooks Mountain east end, while floodwaters further to the south continued to drain in a southwest and south directions to a south oriented flood flow channel on the Lost Creek alignment, which was also still being fed by south oriented floodwaters crossing the present day Crooks Mountain west end. Headward erosion of the deep Sweetwater River valley across south oriented flood flow routes eventually beheaded and reversed flood flow routes across the Crooks Mountain location and also deeply eroded regions north of Green and Crooks Mountains.

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 Sweetwater River-Lost Creek (Great Divide Basin) drainage divide area landform origins near Green 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 Sweetwater River-Lost Creek (Great Divide Basin) drainage divide area landform evidence near Green Mountain, Wyoming will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Sweetwater River-Lost Creek (Great Divide Basin) drainage divide area location map

Figure 1: Sweetwater River-Lost Creek (Great Divide Basin) 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 Sweetwater River-Lost Creek (Great Divide Basin) drainage divide area near Green Mountain and illustrates a region in south central Wyoming with Colorado and Utah being located south of Wyoming (Utah is in the southwest corner of figure 1). The Great Divide Basin is a region of interior drainage in southern Wyoming. The Sweetwater River originates at the Wind River Range southeast end and flows in a south-southeast direction to near South Pass and then in an east-northeast and east direction north of the Great Divide Basin and between the Granite and the Green Mountains to join the north oriented North Platte River. The North Platte River originates in Colorado (west of Rocky Mountain National Park) and flows into Wyoming in a north-northwest direction between the Medicine Bow Mountains and Sierra Madre Mountains to Pathfinder Reservoir where the Sweetwater River joins it. Note how the Sweetwater River turns to flow in a south direction to join the north oriented North Platte River. North of Pathfinder Reservoir the North Platte River turns to flow in a north-northeast and northeast direction to Casper near the northwest end of the Laramie Range. At Casper the North Platte River turns to flow in an east and southeast direction around the Laramie Range northwest end and then to the east edge of figure 1. East of figure 1 the North Platte River flows into Nebraska with water eventually reaching the Gulf of Mexico. West of the Great Divide Basin is the south oriented Green River drainage basin with the Green River flowing in a south, east, southeast, south, and southwest direction from the town of Green River, Wyoming to and through the Flaming Gorge National Recreation area and Dinosaur National Monument and then to the south edge of figure 1 (in Utah). South and west of figure 1 the Green River joins the southwest oriented Colorado River with water eventually reaching the Pacific Ocean. South of the Great Divide Basin is the Yampa River drainage basin with the Yampa River flowing in a west direction from Steamboat Springs, Colorado to join the Green River in Dinosaur National Park. The Little Snake River is a west and southwest oriented river flowing through Baggs, Wyoming (on Wyoming-Colorado border) to join the Yampa River near the Dinosaur National Monument east boundary. Muddy Creek is a south oriented stream originating along the Great Divide Basin southern rim and joining the Little Snake River near Baggs. North of Muddy Creek is southwest and south oriented Lost Creek, which originates near the west end of Green Mountain (Mountains in figure 1) and which flows into the Great Divide Basin where it ends. Not shown in figure 1 are southwest oriented Lost Creek tributaries originating south of Green Mountain. The Sweetwater River-Lost Creek drainage divide area near Green Mountain investigated in this essay is along the Great Divide Basin northern rim and is south of the east oriented Sweetwater River and north of the Lost Creek headwaters and includes Green Mountain.

Drainage routes in the region seen in figure 1 developed during immense melt water floods from the western margin of a thick North American ice sheet, which flowed from western Canada to and across Wyoming and into Colorado and Utah. At that time mountain ranges in Montana, Wyoming, Colorado, and Utah were in the process of emerging and at first floodwaters could freely flow across what are today major mountain barriers. Mountain ranges emerged as floodwaters deeply eroded surrounding basins and valleys and as ice sheet related crustal warping raised the mountain ranges. The north oriented North Platte River drainage route west of the Laramie Mountains originated as a south oriented flood flow channel. Headward erosion of the much deeper southeast and east oriented North Platte River valley around the Laramie Mountains northwest end beheaded the south oriented flood flow channel and floodwaters on the north end of the beheaded flood flow channel reversed flow direction to flow in a north direction to the deeper east and southeast oriented North Platte River valley and to create the present day North Platte River drainage route. This process actually required multiple steps, and was also greatly aided by ice sheet related crustal warping that was raising mountain ranges in the present day North Platte River headwaters area. The Sweetwater River valley initially eroded headward between the emerging Rattlesnake Hills and Ferris Mountains from the south oriented flood flow channel on the present day north oriented North Platte River alignment and captured south oriented flood flow, which had been moving across the present day Great Divide Basin to actively eroding Little Snake River and tributary valleys, which had eroded headward from the newly eroded Yampa and Green River valleys. Headward erosion of the deep east oriented Sweetwater River valley beheaded south oriented flood flow channels east and west of present day Green Mountain and also flood flow channels crossing Green Mountain. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to create north oriented Sweetwater River tributary drainage routes not seen in figure 1. The Lost Creek drainage route is a relic of a south oriented flood flow route that was beheaded by the reversal of flood flow in the Green Mountain area to create a north oriented Sweetwater River tributary drainage route.

Detailed location map for Sweetwater River-Lost Creek (Great Divide Basin) drainage divide area

Figure 2: Detailed location map Sweetwater River-Lost Creek (Great Divide Basin) 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 Sweetwater River-Lost Creek (Great Divide Basin) drainage divide area near Green Mountain. The Sweetwater River flows in an east-northeast direction from the west edge of figure 2 (north half) to Sweetwater Station and then to near edge of figure 2 where it turns to flow in a southeast, east, southeast, and east direction to the east edge of figure 2 (north half). The Granite Mountains are located along the north edge of figure 2 and the Sweetwater River route is along and through the Granite Mountains southern margin. The labeled dashed line extending from the west edge of figure 2 (south of center) to the east edge of figure 2 (slightly south of center) is Great Divide Basin north rim. North of the dashed line streams drain to the Sweetwater River with the water eventually reaching the Gulf of Mexico. South of the dashed line streams drain into the Great Divide Basin and then end as surface drainage routes. North of the dashed line and south of the Sweetwater River are several west to east oriented mountains starting in the west with Crooks Mountain and then continuing to Green Mountain and ending with the Ferris Mountains straddling the east edge of figure 2. The region immediately south of Crooks Mountain is drained by west-northwest East Alkali Creek, which flows to north-northwest oriented Alkali Creek, which in turn flows to the east-northeast oriented Sweetwater River. The area immediately south of Green Mountain is drained by northwest, north, and northeast oriented Crooks Creek, which flows between Crooks Mountain and Green Mountain toward the east oriented Sweetwater River. Willow Creek in a northeast and north-northeast oriented Sweetwater River tributary originating near the Green Mountain east end. The region immediately south of the Ferris Mountains is drained by west-northwest, north, and northeast oriented Muddy Creek, which flows through Muddy Gap between Green Mountain and the Ferris Mountains to reach the east oriented Sweetwater River. South of the Great Divide Basin north rim Lost Creek originates south of Crooks Mountain and flows in a southwest and south direction to Lost Creek Lake (near south edge of southwest quadrant of figure 2). Lost Creek Lake has no outlet. Arapahoe Creek originates on the east end of Crooks Mountain and flows in a south and southwest direction to join south oriented Lost Creek. Osborne Draw originates south of the Green Mountain east end and drains in a west-southwest and west direction to join south oriented Lost Creek. The Great Divide Basin north rim was created by reversals of flood flow that occurred as the deep east oriented Sweetwater River valley eroded headward across the region and beheaded south oriented flood flow routes that had been flowing across the Great Divide Basin to the actively eroding Little Snake River and tributary valleys. Gaps between Crooks Mountain and Green Mountain and between Green Mountain and the Ferris Mountains were initially eroded by south oriented flood flow channels, but were reversed by headward erosion of the much deeper Sweetwater River valley and its tributary valleys. Reversed flood flow moving through those gaps to the much deeper Sweetwater River valley created deeper north oriented valleys south of the Crooks Mountain, Green Mountain, and the Ferris Mountains that beheaded and reversed east-southeast and southeast oriented flood flow routes developing south of the mountains.

Arapahoe Creek-Crooks Creek drainage divide area

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

Figure 3 provides a topographic map of Arapahoe Creek-Crooks Creek drainage divide area and shows the east half of Crooks Mountain. The map contour interval for figure 3 is 20 meters. East Alkali Creek is located in the southwest quadrant of figure 3 and flows in a southwest and northwest direction to the east edge of figure 3 (slightly south of center). West of figure 3 East Alkali Creek flows in a west-northwest direction to join northeast oriented West Alkali Creek and to form north-northwest oriented Alkali Creek, which flows to the east-northeast oriented Sweetwater River (which is located north of figure 3). Haypress Creek is a north oriented stream originating on Crooks Mountain and flows in a north direction to the north edge of figure 3 (west of center). North of figure 3 Haypress Creek flows toward the Sweetwater River, but ends as a surface stream. The north oriented Haypress Creek valley is linked by a through valley across Crooks Mountain with the valley of a southwest oriented East Alkali Creek tributary. The through valley floor elevation is shown as 2261 meters. East of the through valley Crooks Mountain elevations rise to more than 2520 meters. West of the through valley elevations rise to 2362 meters suggesting the through valley is at least 100 meters deep. Prior to headward erosion of the much deeper east oriented Sweetwater River valley (north of figure 3) the through valley was eroded by south oriented flood flow. East of the through valley on the south side of Crooks Mountain are headwaters of south oriented Arapahoe Creek, which south of figure 3 flows in a southwest direction to join south oriented Lost Creek, which then ends at Lost Creek Lake. Note how headward erosion of the east-southeast oriented West Arapahoe Creek valley has beheaded flood flow to the southwest oriented East Alkali Creek headwaters valley.  The Lost Creek headwaters are located south of the East Alkali Creek elbow of capture and probably the southwest oriented East Alkali Creek headwaters route converged with a southeast oriented flood flow channel on the present day northwest oriented East Alkali Creek alignment to form a south oriented flood flow channel on the Lost Creek alignment. Southeast oriented flood flow on the East Alkali Creek alignment was beheaded and reversed by headward erosion of the deep Sweetwater River valley to create the north-northwest oriented Alkali Creek drainage route and the northwest oriented East Alkali Creek drainage route. East of Crooks Mountain and near the east edge of figure 3 is north oriented Crooks Creek, which flows through Crooks Gap (near east center edge of figure 3) to the north edge of figure 3. North of figure 3 Crooks Creek flows in a northeast direction toward the east oriented Sweetwater River, but is lost as a surface stream before reaching the Sweetwater River. Sheep Mountain is the upland immediately east of Crooks Gap and Green Mountain is east of Sheep Mountain (figures 5 and 6 also illustrate the Crooks Gap area). West Fork Crooks Creek originates near the south oriented Arapahoe Creek valley and flows in a southeast and northeast direction to join north oriented Crooks Creek. The West Fork Crooks Creek U-turn is evidence of how the reversal of flood flow through Crooks Gap captured south oriented flood flow still moving across Crooks Mountain just a short distance to the west. This evidence suggests the deep Sweetwater River valley was being eroded headward into an erosion surface at least as high as the top of Crooks Mountain and floodwaters deeply eroded the regions surrounding Crooks Mountain.

Detailed map of Arapahoe Creek-West Fork Crooks Creek drainage divide area

Figure 4: Detailed map of Arapahoe Creek-West Fork Crooks 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 Arapahoe Creek-West Fork Crooks Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 20 feet. Arapahoe Creek flows in a south-southeast, south, and south-southeast direction from the north edge of figure 4 (near northwest corner) to Hadsell Reservoir (in northeast corner of section 21) and then in a south direction to the south edge of figure 4. South of figure 4 Arapahoe Creek flows in a south and southwest direction to join south oriented Lost Creek (which flows into the Great Divide Basin and then ends). The West Fork Crooks Creek originates in section 15 (north and east of Hadsell Reservoir) and flows in a west and north direction to the north edge of figure 4 (near northeast corner). North and east of figure 4 West Fork Crooks Creek joins north and northeast Crooks Creek, which flows toward the east oriented Sweetwater River. While surface water does not today normally reach the Sweetwater River, if water did reach the Sweetwater River the water would eventually reach the Gulf of Mexico. West of the south oriented Arapahoe Creek valley near the west edge of section 8 are headwaters of a west oriented tributary to west and northwest oriented East Alkali Creek, which west and north of figure 4 joins north-northwest oriented Alkali Creek to flow to the east-northeast and east oriented Sweetwater River. The southwest oriented stream in section 20 flows to southwest and south oriented Lost Creek. South oriented flood flow probably first crossed Crooks Mountain and the north oriented West Fork Crooks Creek alignment along the east edge of figure 4 probably originated as a south oriented flood flow channel. Headward erosion of the deep Sweetwater River valley north of figure 4 beheaded the south oriented flood flow channel on the present day north oriented West Fork Crooks Creek alignment. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to flow to the much deeper Sweetwater River valley. A shallow east oriented valley then eroded headward from the newly reversed flood flow channel along the Crooks Mountain south margin to capture south oriented flood flow still crossing Crooks Mountain. Headward erosion of the slightly deeper south oriented Arapahoe Creek valley along a south oriented flood flow route then beheaded the east oriented West Fork Crooks Creek headwaters, although at that time the south oriented flood flow channel diverged in region near the corner of sections 8,9, 16, and 17 with one of diverging flood flow channels flowing in a south and southwest direction (along the present day Arapahoe Creek alignment) and the other diverging flood flow channel flowing in a southwest and south direction (along the present day Lost Creek alignment) before the two diverging flood flow channels converged again to flow in a south direction on the south oriented Lost Creek alignment. The flood flow channels diverged on an alluvial fan, which was deposited by the south oriented flood flow. Apparently flood flow across the east end of Crooks Mountain ended almost as soon as the south oriented Arapahoe Creek valley had beheaded the east oriented West Fork Crooks Creek headwaters valley.

Sweetwater River-Crooks Creek drainage divide area

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

Figure 5 illustrates the Sweetwater River-Crooks Creek drainage divide area east and slightly south of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 20 meters. The Crooks Mountain southeast end is located in the northwest corner of figure 5. Arapahoe Creek flow in a south direction near the west edge of figure 5 before turning in a southwest direction to flow to the southwest corner of figure 5. West and south of figure 5 Arapahoe Creek flows to south oriented Lost Creek. Green Mountain is labeled and is located in the east half of figure 5. Crooks Creek originates on Green Mountain near the east edge of figure 5 and flows in a south and south-southwest direction before turning to flow in a northwest and north direction to Crooks Gap and then to the north edge of figure 5 (west of center). North of figure 5 Crooks Creek turns to flow in a northeast direction toward the east oriented Sweetwater River, but disappears as a surface stream before reaching the Sweetwater River. Crooks Gap is a deep water gap eroded between Crooks Peak to the west and Sheep Mountain to the east and is more than 400 meters deep. The water gap probably originated as a deep south-oriented flood flow channel prior to headward erosion of the deeper east oriented Sweetwater River valley north of figure 5. At that time floodwaters were flowing on an erosion surface equivalent in elevation to the present day tops of Crooks Mountain and Green Mountain and the deep south-oriented south flow channel had been eroded into that erosion surface. As south oriented flood flow crossed the region floodwaters deeply eroded the region south of Crooks and Green Mountains to produce the erosion surface seen today (floodwaters probably deposited sediments in the Great Divide Basin, although evidence from sources other than topographic maps is needed to distinguish between an erosion surface and deposition surface). Several hundred meters of bedrock material were probably stripped from much of the Great Divide Basin region to the south, although the topographic map evidence is not adequate to determine whether uplift was raising the Crooks Mountain and Green Mountain as mountain blocks while lowering elevations in the regions to the north and south. Headward erosion of the deep east oriented Sweetwater River valley north of figure 5 was also into that high level erosion surface and headward erosion of deep northeast oriented valleys from the actively eroding Sweetwater River valley head deeply eroded the region north of Green and Crooks Mountain. Headward erosion of a deep northeast oriented Sweetwater River tributary valley (now the northeast oriented Crooks Creek route north of figure 5) beheaded the deep south-oriented flood flow channel through Crooks Gap. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to flow to the much deeper northeast oriented Sweetwater River tributary valley and created the north and northeast oriented Crooks Creek drainage route, which then beheaded and reversed a southeast oriented flood flow channel on the present day northwest oriented Crooks Creek segment to create the northwest, north, and northeast oriented Crooks Creek drainage route seen today.

Detailed map of Crooks Gap area

Figure 6: Detailed map of Crooks Gap area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed topographic map of the Crooks Gap area seen in less detail in figure 5. The map contour interval for figure 6 is 20 feet. Crooks Gap is located on the boundary between sections 29 and 30 near the center of figure 6 and is located between Crooks Peak to the west and Sheep Mountain to the east. North and north-northeast oriented West Fork Crooks Creek joins north-northwest oriented Crooks Creek south of Crooks Gap (in section 31) and Crooks Creek then flows in a north direction to the north edge of figure 6. North of figure 6 Crooks Creek turns to flow in a northeast direction toward the east oriented Sweetwater River. The West Fork Crooks Creek valley is just as deep as the Crooks Creek valley, which suggests significant volumes of north oriented (or reversed) flood flow moved in the West Fork Crooks Creek valley. As seen in figures 3 and 4 the West Fork Crooks Creek valley originated south of the Crooks Mountain east end and may have been supplied by southeast oriented flood flow on the present day northwest oriented East Alkali Creek alignment before headward erosion of the south oriented Arapahoe Creek valley ended that flow. In any case floodwaters were probably still moving across the Crooks Mountain south end to the West Fork Crooks Creek valley at the time floodwaters moving through Crooks Gap were beheaded and reversed to flow in a north direction to the deeper northeast oriented Crooks Creek valley, which had eroded headward from the actively eroding Sweetwater River valley head. Crooks Creek crosses the 6700-foot contour line in section 31. Crooks Peak to the west rises to 7707 feet and Crooks Mountain west of figure 6 rises to 8310 feet. Sheep Mountain to the east of Crooks Gap rises to 7895 feet and Green Mountain east of figure 6 rises to more than 9000 feet. These elevations suggest Crooks Gap is as much as 1600 feet deep. The Crooks Gap location may be related to regional geologic structures although Crooks Gap is a water-eroded feature and was not eroded by present day Crooks Creek or West Fork Crooks Creek. Large volumes of floodwaters, first moving in a south direction and then moving in a north direction were responsible for eroding the deep Crooks Gap valley. Flood flow across Green Mountain probably ended while flood flow was still moving across Crooks Mountain. This observation is consistent with the interpretation that floodwaters were beheaded by headward erosion of the deep east oriented Sweetwater River valley and its northeast oriented tributary valleys (north of figure 6).

Crooks Creek-Osborne Draw drainage divide area

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

Figure 7 illustrates the Crooks Creek-Osborne Draw drainage divide area south and slightly east of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 20 meters. Green Mountain is in the northeast corner of figure 7. Crooks Creek originates on Green Mountain and flows in a south and southwest direction on the northwest side of Stratton Rim and then makes a U-turn to flow in a northwest, west-northwest, and north direction to the north edge of figure 7 (west half). West Fork Crooks Creek flows in an east and north direction to the north edge of figure 7 (near northwest corner) and joins Crooks Creek north of figure 7. Bare Ring Slough is a west and northwest oriented Crooks Creek tributary north and west of Bare Ring Butte. Osborne Draw drains in a west-southwest direction across the south center area of figure 7 and south and west of figure 7 joins south oriented Lost Creek. Southwest oriented Osborne Draw tributaries originate west of the Bare Ring Slough headwaters and south of the Crooks Creek U-turn. The drainage divide between southwest and northwest oriented Crooks Creek and southwest oriented Osborne Draw tributaries is a low relief drainage divide and is difficult to identify with a 20-meter contour interval. Apparently southwest oriented flood flow crossed Green Mountain moving toward a south oriented flood flow channel on the present day Lost Creek alignment and the reversal of flood flow on the Crooks Gap alignment enabled the relatively shallow northwest oriented Crooks Creek valley (and its northwest oriented tributary Bare Ring Slough valley) to erode headward across what were then newly beheaded southwest oriented flood flow channels that had been moving floodwaters across Green Mountain. Flood flow routes across Green Mountain were beheaded before flood flow in the Crooks Gap valley was beheaded and reversed. Once flood flow through Crooks Gap was beheaded and reversed south oriented flood flow still moved across Crooks Mountain on the Arapahoe Creek alignment to a south oriented flood flow channel on the Lost Creek alignment. Apparently there was enough flood water in the region south of Green Mountain at that time that shallow northwest oriented valleys could erode headward from the Crooks Gap region to drain water south of Green Mountain in a north direction to the deeper Sweetwater River valley while further to the south the remaining floodwaters drained in southwest directions to the still active south oriented flood flow channel on the Lost Creek alignment. As floodwaters drained either northward through Crooks Gap or southward to the Lost Creek flood flow channel all floodwaters drained from the region and the landscape probably has changed little since. However, it is possible crustal warping continued after flood flow region ended and some elevations have been altered.

Detailed map of Crooks Creek-Osborne Draw drainage divide area

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

Figure 8 provides a detailed topographic map of the Crooks Creek-Osborne Draw drainage divide seen in less detail in figure 7. The map contour interval for figure 8 is 20 feet. Crooks Creek flows in a southwest direction from the northeast corner of figure 8 into section 33 where it turns to flow in a northwest direction across the northeast corner of section 32 and then to the north center edge of figure 8. North and west of figure 8 Crooks Creek turns to flow in a north direction through Crooks Gap and then in a northeast direction toward the east oriented Sweetwater River. Southwest oriented Crooks Creek tributaries include First Creek and Daniels Creek. The west-northwest and northwest oriented drainage route to the northwest corner of figure 8 is Bare Ring Slough, which north and west of figure 8 drains to Crooks Creek. A shallow northeast to southwest oriented through valley in section 32 links the Crooks Creek elbow of capture, (where Crooks Creek turns from flowing in a southwest direction to flowing in a northwest direction) with the southwest and west oriented Bare Ring Slough headwaters valley. The through valley floor elevation is between 7480 and 7500 feet. Elevations northwest of the through valley rise to at least 7580 feet while to the southeast elevations rise to at least 7620 feet suggesting the through valley is at least 80 feet deep. The through valley provides evidence headward erosion of the northwest oriented Crooks Creek valley captured southwest oriented flood flow that had been moving further to the southwest. Southwest and west oriented drainage routes south of the Fremont-Sweetwater County line drain to Osborne Draw, which drains in a west-southwest and west direction to south oriented Lost Creek (see figure 2). In section 1 a northeast to southeast oriented through valley links the southwest oriented Bare Ring Slough headwaters valley with a southwest oriented Osborne Draw tributary valley. The through valley floor elevation is between 7360 and 7380 feet. Elevations west of the through valley rise to 7432 feet and east of the through valley elevations rise much higher suggesting the through valley is at least 53 feet deep. West of figure 8 is Bare Ring Butte, which rises to 7529 feet. If the Bare Ring Butte elevation is used the through valley depth is more than 149 feet deep. Whichever depth is used the through valley provides evidence floodwaters once flowed from the present day northwest oriented Crooks Creek drainage basin to the present day south oriented Lost Creek drainage basin and that headward erosion of the northwest oriented Bare Ring Slough valley first captured the southwest oriented flood flow with headward erosion of the northwest oriented Crooks Creek valley next capturing the southwest oriented flow. The low relief along the drainage divides suggests floodwaters were draining from the region and were not actively eroding deep valleys headward into the region.

Willow Creek-Crooks Creek drainage divide area

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

Figure 9 illustrates the Willow Creek-Crooks Creek drainage divide area east and somewhat south of figure 7 and there is an overlap area with figure 7. Figure 9 shows Green Mountain in its entirety. The map contour interval for figure 9 is 20 meters. Sheep Mountain is near the northwest corner of figure 9 and Crooks Gap is west of Sheep Mountain (and west of figure 9). Crooks Creek originates on Green Mountain (slightly south of the center of figure 9) and flows in a south and southwest direction to the southwest margin of the Green Mountain upland where Crooks Creek turns to flow in a northwest and west-northwest direction to the west edge of figure 9 (south of center). West of figure 9 Crooks Creek turns to flow in a north direction through Crooks Gap and then in a northeast direction north of figure 9 toward the east oriented Sweetwater River. North-northeast oriented streams flowing from Green Mountain to the north edge of figure 9 (west half) are various forks of Cottonwood Creek, which north of figure 9 flows in a northeast direction to join the east oriented Sweetwater River. Willow Creek originates on Green Mountain north of the Crooks Creek headwaters and flows in a northeast direction to the northeast corner of figure 9. North and east of figure 9 Willows Creek flows to the east oriented Sweetwater River. A northeast to southwest oriented through valley across Green Mountain links the northeast oriented Willow Creek valley with the southwest oriented Crooks Creek valley. The through valley floor elevation is between 2440 and 2460 meters. Whiskey Peak to the east rises to 2812 meters and the high point on Green Mountain to the west is shown as 2768 meters. These elevations suggest the through valley could be as much as 300 meters deep. The through valley appears to be a water-eroded valley and was probably eroded by south oriented flood flow moving from north of Green Mountain to the Great Divide Basin area. At that time elevations north of Green Mountain were at least as high the through valley floor and probably much higher. If correctly interpreted that means several hundred meters of bedrock material were stripped from the region north of Green Mountain as the deep east-oriented Sweetwater River valley eroded headward to capture the south oriented flood flow. The northeast oriented Willow Creek drainage route could have been formed by a reversal of flood flow on the northeast end of a beheaded flood flow channel, although more probably the through valley orientation across Green Mountain was controlled by local geologic structures, and the northeast oriented Willow Creek valley eroded headward across south oriented flood flow channels, which were subsequently beheaded and reversed to create north oriented Sweetwater River tributary drainage routes (e.g. Cooper Creek).

Detailed map of Willow Creek-Crooks Creek drainage divide area

Figure 10: Detailed map of Willow Creek-Crooks 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 Willow Creek-Crooks Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 20 feet. Willow Creek flows in a southeast direction across the northeast quadrant of section 11 and then in section 12 turns to flow in a northeast direction to the north edge of figure 10 (east half). North and east of figure 10 Willow Creek flows in a northeast and north-northeast direction to the east oriented Sweetwater River. Crooks Creek flows in a south-southeast direction across section 15 and in section 22 turns to flow in a south-southwest direction to the south edge of figure 10 (west half). South and west of figure 10 Crooks Creek turns to flow in a northwest direction and west of Green Mountain turns to flow in a north and northeast direction toward the east oriented Sweetwater River. A through valley in the south half of section 14 links the northeast oriented Willow Creek valley with the south-southwest oriented Crooks Creek valley. The through valley floor elevation is between 8140 and 8160 feet. The high point in section 24 to the east is 8706 feet and east of figure 10 Whiskey Peak reaches an elevation of 9225 feet. The high point near East Cottonwood Park west of the through valley has an elevation of 9040 feet and west of figure 10 Green Mountain elevations rise to 9081 feet. These elevations suggest the through valley is between 546 and 900 feet deep depending on which elevations are used. The through valley is a water eroded valley and was probably primarily eroded by south-southwest oriented flood flow moving across present day Green Mountain, although at that time the surface north of Green Mountain was at least as high as Green Mountain. It is possible the final erosion of the through valley was done by southeast oriented flood flow, which moved across the present day Green Mountain top to the southeast and northeast oriented Willow Creek headwaters valley and also to the south-southeast oriented Crooks Creek headwaters valley. If so, the through valley was being eroded into an erosion surface at least as high as the present day Green Mountain top and floodwaters were responsible for eroding regions surrounding Green Mountain. Such erosion would have stripped almost 2000 feet of bedrock from regions south of Green Mountain and even more from the regions north of Green Mountain. Crustal warping may also have played a role in developing the Green Mountain elevation above the surrounding regions, although topographic map evidence suggests deep erosion was the primary factor.

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.