Snake River-Wind River drainage divide area landform origins along the continental divide in northwest Wyoming, USA

Authors


 

Abstract:

This essay uses topographic map evidence to interpret landform origins in the region between the Snake River and Wind River along the continental divide in northwest Wyoming. The Snake River flows in a south direction from Yellowstone National Park to and through Grand Teton National Park and is joined by west and northwest oriented tributaries including west-oriented Buffalo Fork and its northwest oriented Blackrock Creek tributary and the northwest and southwest oriented Gros Ventre River with water eventually reaching the Pacific Ocean. Togwotee Pass links the northwest oriented Blackrock Creek valley with the southeast oriented Wind River valley. Wind River water eventually reaches the Gulf of Mexico. Other passes, or through valleys, link Buffalo Fork tributary valleys with Wind River tributary valleys and link Wind River tributary valleys with Gros Ventre River tributary valleys. Numerous barbed tributaries provide evidence of drainage direction reversals. The through valleys or passes and barbed tributaries are interpreted to have been formed by diverging and converging southeast and south oriented flood flow channels that once crossed the region. At that time the regional mountains were just beginning to emerge and floodwaters could flow across what are today high mountain ranges. Floodwaters are interpreted to have been derived from the western margin of a thick North American ice sheet and were flowing from western Canada to and across the study region. Headward erosion of the deep south oriented Snake River valley and its southwest and west oriented tributary valleys beheaded southeast and south oriented flood flow channels moving floodwaters to the actively eroding and deep southeast oriented Wind River valley and its actively eroding tributary valleys. Floodwaters on northwest and west ends of beheaded flood flow channels reversed flow direction to create northwest and west oriented Snake River tributary drainage routes. Flood flow captures and flood flow reversals were complex and several examples are illustrated to show some of the complexities. Crustal warping that occurred as floodwaters were flowing across the region and that was related to the thick ice sheet presence north and east of the study region contributed to the flood flow capture and reversal events.

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 Snake River-Wind River drainage divide area landform origins along the continental divide in northwest Wyoming. 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 Snake River-Wind River drainage divide area landform evidence along the continental divide in northwest Wyoming will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Snake River-Wind River drainage divide area location map

Figure 1: Snake River-Wind 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 Snake River-Wind River drainage divide area along the continental divide in northwest Wyoming and shows a region in northwest Wyoming with a thin slice of eastern Idaho located near the west edge of figure 1. The south half of Yellowstone National Park is in the northwest corner of Wyoming. The Snake River originates near the Yellowstone National Park south edge (near Two Ocean Pass) and flows in a northwest direction to near Heart Lake before turning to flow in a south, west, and south direction to Jackson Lake in Grand Teton National Park. From Jackson Lake the Snake River flows in an east direction to Moran and then in a south-southwest, southeast, and southwest direction to Alpine. From Alpine the Snake River turns again to flow in a northwest direction into Idaho. West of figure 1 the Snake River turns to flow in a southwest, northwest, and north direction with water eventually reaching the Pacific Ocean. Major Snake River tributaries of interest are Buffalo Fork, Blackrock Creek (unlabeled northwest and west oriented Buffalo Fork tributary originating near Togwotee Pass), and the Gros Ventre River with its tributary Fish Creek. The Wind River originates near Togwotee Pass and flows in a southeast direction to Riverton in the Wind River Basin where it turns to flow in a northeast and north direction across the Owl Creek Mountains to Thermopolis where it enters the Big Horn Basin (and where it becomes the north oriented Big Horn River). East and north of figure 1 the Big Horn River flows in a north direction to join the northeast oriented Yellowstone River with water eventually reaching the Gulf of Mexico. The Snake River-Wind River drainage divide area investigated in this essay is centered on the Togwotee Pass area and is located south of Buffalo Fork and north and east of the Gros Ventre River. The Absaroka Range is north of the study area and the Wind River Mountains and Gros Ventre Range are the mountains located south of the study area.

Before looking at detailed maps a brief look at the regional drainage history will help in understanding map interpretations given here. Drainage routes shown in figure 1 developed as immense south and southeast oriented melt water floods flowed across the region and later as crustal warping raised the Yellowstone Plateau, Absaroka Range, Wind River Range, Gros Ventre Range, and other regional mountain ranges. Floodwaters were derived from the west margin of a melting thick North American ice sheet and were flowing from western Canada to and across the region shown in figure 1. Initially the deep river valleys, basins, mountain ranges, and high plateaus did not exist and floodwaters could freely flow to and across the region seen in figure 1. Crustal warping related to the thick ice sheet presence raised mountain ranges and high plateau areas in figure 1 as floodwaters flowed across them and as the ice sheet created a deep “hole” in which it was located. Headward erosion of deep valleys between and around the rising mountain ranges over time captured the southeast and south oriented melt water floods. The southeast oriented Wind River valley eroded headward between the rising Owl Creek Mountains and the Wind River Range and was joined near the southeast corner of figure 1 by a south oriented flood flow channel located on the present day north oriented Big Horn River alignment. Headward erosion of the deep northeast oriented Yellowstone River valley (in Montana north of figure 1) from space in the deep “hole” the melting ice sheet was opening up beheaded the south oriented flood flow channel flowing through the Big Horn Basin. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Big Horn River drainage route and captured the southeast oriented Wind River flood flow channel near the southeast corner of figure 1.

At about the same time a south oriented flood flow channel eroded headward on the south oriented Snake River alignment between the rising Teton Range and Gros Ventre Range and beheaded southeast oriented flood flow channels flowing to the actively eroding southeast oriented Wind River valley. This south oriented flood flow channel converged with a southeast oriented flood flow channel on the present day northwest oriented Snake River alignment in eastern Idaho to form a south oriented flood flow channel west of the rising Salt River Range (note north oriented Snake River tributary joining the Snake River near Alpine). Floodwaters on west and northwest ends of the beheaded flood flow channels reversed flow direction to create the northwest and west oriented Snake River tributary drainage routes seen today. These northwest and west oriented Snake River tributaries include the northwest oriented Gros Ventre River and northwest oriented Hoback River and northwest and west oriented Fish Creek and Blackrock Creek-Buffalo Fork. Headward erosion of the deep southwest oriented Snake River valley (west of figure 1) beheaded the southeast oriented flood flow channel on the present day northwest oriented Snake River alignment (west of Alpine). Floodwaters on the northwest end of the beheaded flood flow channel reversed flow direction to create the northwest oriented Snake River drainage route (in eastern Idaho) and the north oriented Snake River tributary drainage route (south of Alpine) and captured the south oriented flood flow channel between the Teton Range and the Gros Ventre Range. These massive flood captures and flood flow direction reversals were aided by on-going crustal warping that was raising mountain ranges and forming intervening basins and valleys. In time headward erosion of the deep Yellowstone River valley across southern Montana (north of figure 1) beheaded and reversed all south oriented flood flow routes to the present day Snake River and Wind River headwaters regions and ended flood flow to the region seen in figure 1.

Detailed location map for Snake River-Wind River drainage divide area

Figure 2: Detailed location map Snake River-Wind 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 Snake River–Wind River drainage divide area in northwest Wyoming. Grand Teton National Park is labeled and is located in the west half of figure 2. The Snake River flows in a south direction to Jackson Lake and then in an east direction to Moran. From Moran the Snake River flows in a south-southwest direction to the southwest corner of figure 2. Buffalo Fork is a west-southwest and west oriented stream joining the Snake River near Moran. Blackrock Creek originates near Togwotee Pass and flows in a northwest and west direction to join west oriented Buffalo Fork (the highway west of Togwotee Pass follows the Blackrock Creek valley). The Gros Ventre River flows in a northwest direction from the south edge of figure 2 (west of center) to Lower Slide Lake and then turns to flow in a southwest direction to join the Snake River south of the southwest corner of figure 2. The east-west continental divide is shown with a dashed line and extends from the north edge of figure 2 to Kingfisher Mountain and Yellow Mountain and then to Togwotee Pass and finally to the south edge of figure 2 (east half). The Wind River originates at Togwotee Pass and flows in a southeast direction to the southeast corner of figure 2. The south-southeast oriented Wind River tributary west of Pinnacle Buttes (near Togwotee Pass) is Brooks Lake Creek. North of Brooks Lake Creek is west and northwest oriented Cub Creek, which flows to southwest oriented South Buffalo Fork and west oriented Buffalo Fork. Du Noir Creek is a south-southeast oriented Wind River tributary just east of Pinnacle Buttes. Warm Springs Creek is an east and east-southeast oriented stream located south of the southeast oriented Wind River headwaters and south of Pinnacle Buttes. West of the Warm Springs Creek headwaters and of the continental divide is northwest and southwest oriented Fish Creek, which flows to the northwest oriented Gros Ventre River. The North Fork Fish Creek flows in a south-southwest direction from near Togwotee Pass while Cottonwood Creek is a south oriented stream flowing to the Gros Ventre River just west of the North Fork Fish Creek. Other drainage routes in the study region are unlabeled and will be noted as they appear in detailed maps.

Cub Creek-Brooks Lake Creek drainage divide area

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

Figure 3 provides a topographic map of the Cub Creek-Brooks Lake Creek drainage divide area. The east-west continental divide is shown with a labeled dashed line and extends from near the northeast corner of figure 3 to near the southwest corner of figure 3. Togwotee Pass is near the southwest corner of figure 3 and the Wind River flows in a southeast direction from Togwotee Pass to the south edge of figure 3 (near highway) with water eventually reaching the Gulf of Mexico. Brooks Lake Creek is located east of the continental divide and flows in a south direction from Upper Brooks Lake (south of Bear Cub Pass) to Brooks Lake and then to the south edge of figure 3 and joins the Wind River south of figure 3. South Buffalo Fork flows in a southwest direction across the northwest corner of figure 3 and then joins south oriented North Buffalo Fork to form west oriented Buffalo Fork with water eventually reaching the Pacific Ocean. Cub Creek flows just north of the continental across the center region of figure 3 and north of Bear Cub Pass turns to flow in a northwest direction to join South Buffalo Fork. The map contour interval for figure 3 is 50 meters and the Bear Cub Pass elevation at the continental divide is between 2750 and 2800 meters. Elevations along the continental divide to the southwest rise to more than 3250 meters and elevations along the continental to the east rise to more than 3300 meters. These elevations suggest Bear Cub Pass is at least 450 meters deep. Bear Cub Pass is a water-eroded feature and was eroded by southeast oriented flood flow moving on the present day northwest oriented Cub Creek alignment to the south oriented Brooks Lake Creek valley and then to the southeast oriented Wind River valley. Flood flow across Bear Cub Pass ended when headward erosion of the much deeper west and southwest oriented (South) Buffalo Fork valley captured the south oriented flood flow and diverted the floodwaters to the south oriented Snake River valley. Floodwaters on the northwest end of the beheaded flood flow channel reversed flow direction to create the northwest oriented Cub Creek drainage segment seen in figure 3. Headward erosion of the west oriented Cub Creek valley segment captured or had already captured south oriented flood flow from flood flow channels east of Bear Cub Pass and was captured by the reversed flow on the present day northwest oriented Cub Creek valley segment.

Detailed map of Cub Creek-Brooks Lake Creek drainage divide area

Figure 4: Detailed topographic map of the Cub Creek-Brooks Lake 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 Cub Creek-Brooks Lake Creek drainage divide area seen in less detail in figure 3 above. The east-west continental divide serves as the Ranger District boundary and is shown with a labeled line and extends from the east center edge of figure 4 to the south edge of figure 4 (west half). Areas south and east of the continental divide drain to the Wind River and water eventually reaches the Gulf of Mexico. Areas north and west of the continental divide drain to the Snake River and water eventually reaches the Pacific Ocean. Cub Creek flows in a west and northwest direction from the east edge of figure 4 (north half) to the north edge of figure 4 (west half) and joins southwest and west oriented (South) Buffalo Fork, which flows to west oriented Buffalo Fork and then to the Snake River. Bear Cub Pass is located near the center of figure 4 and south of Bear Cub Pass is Upper Brooks Lake. The south oriented stream flowing from Upper Brooks Lake is Brooks Lake Creek, which flows to the southeast oriented Wind River. The map contour interval for figure 4 is 40 feet and the Bear Cub Pass elevation at the drainage divide is between 9120 and 9160 feet. Elevations along the continental divide to the southwest rise to more than 10,800 feet while elevations along the continental divide to the east rise to more than 11,000 feet. These elevations suggest Bear Cub Pass is at least 1640 feet deep. Bear Cub Pass is actually a much broader north-to-south oriented through valley eroded across the continental divide, which extends from the center of section 12 to the southwest corner of section 11. This broad through valley is a water-eroded feature and was eroded by south oriented flood flow that initially flowed on a surface as high as the highest continental divide elevations today. At that time there was no continental divide (at least in this location) and floodwaters were flowing in a south direction to the actively eroding southeast oriented Wind River valley. Headward erosion of the much deeper west and southwest oriented (South) Buffalo Fork valley from the actively eroding south oriented Snake River valley beheaded the southeast and south oriented flood flow channel. Floodwaters on the northwest end of the beheaded flood flow channel reversed flow direction to create the northwest oriented Cub Creek drainage route segment, which captured the east oriented Cub Creek valley segment and created the Cub Creek-Brooks Lake Creek drainage divide, which is now the continental divide. Crustal warping that raised the region as floodwaters flowed across it probably played a significant role in the flood flow captures and reversals of flow direction.

Blackrock Creek-Wind River drainage divide area

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

Figure 5 illustrates the Blackrock Creek-Wind River drainage divide area west and slightly south of figure 3 and includes a significant overlap area with figure 3. The east-west continental divide is shown with a labeled dashed line and extends in a west direction from the east edge of figure 5 (north half) to Bear Cub Pass and then in a south-southwest direction to Togwotee Pass and finally in south-southeast direction to the south edge of figure 5 (slightly east of center). Togwotee Pass is located near the center of figure 5 and Blackrock Creek flows in a northwest and west direction from Togwotee Pass to near the northwest corner of figure 5 and west of figure 5 joins west oriented Buffalo Fork, which then flows to the Snake River. The Wind River also originates at Togwotee Pass and flows in a southeast direction to the south edge of figure 5 (east half). The map contour interval for figure 5 is 50 meters and the Togwotee Pass elevation at the continental divide is between 2900 and 2950 meters. Two Ocean Mountain to the southwest rises to 3269 meters and the continental divide to the northeast rises to more than 3300 meters suggesting Togwotee Pass is at least 300 meters deep. Togwotee Pass is a water-eroded landform and was eroded by southeast oriented flood flow moving to the actively eroding Wind River valley. At that time the deep south-oriented Snake River valley to the west did not exist and elevations to the west were at least as high as the pass elevation (at that time). Headward erosion of the much deeper south oriented Snake River valley captured the southeast oriented flood flow causing floodwaters on the northwest end of the beheaded flood flow channel to reverse flow direction to create the northwest oriented Blackrock Creek drainage route. The flood flow reversal was greatly aided by crustal warping that was raising the Togwotee Pass region as floodwaters flowed across it. Note other unlabeled passes across the continental divide such as the one southeast of Two Ocean Mountain between northwest and southwest oriented Maverick Creek (which flows to southwest oriented North Fork Fish Creek) and the southeast oriented Wind River. The floor of this unlabeled pass at the continental divide has an elevation of between 2850 and 2900 meters (slightly lower than Togwotee Pass). Elevations on Lava Mountain (just south of figure 5) rise to 3186 meters suggesting this unlabeled pass is also approximately 300 meters deep. This unlabeled pass was eroded by south oriented flood flow moving from the present day southeast oriented Wind River headwaters area to the actively eroding and much deeper south-southwest oriented North Fork Fish Creek valley. These other passes or through valleys provide significant supporting evidence for the flood origin interpretation given here, but also introduce complexities, which suggest multiple stages of flood flow erosion related to the headward erosion of valleys from different directions.

Detailed map of Blackrock Creek-Wind River drainage divide area

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

Figure 6 illustrates a detailed topographic map of the Blackrock Creek-Wind River drainage divide area seen in less detail in figure 5. The east-west continental divide serves as a Ranger District boundary and is shown with a labeled line extending in a south-southwest and west direction from the north edge of figure 6 (near northeast corner) to Togwotee Pass and then in a southwest and southeast direction to the south edge of figure 6 (east of center). Togwotee Pass is located south and east of the center of figure 6. Blackrock Creek originates north of Togwotee Pass and flows in a north-northwest, west, and northwest direction to the northwest corner of figure 6. The Wind River originates just south of Togwotee Pass and flows in a southeast direction from Togwotee Pass to the south edge of figure 6 (east half). The map contour interval for figure 6 is 40 feet and the Togwotee Pass elevation is shown as being 9544 feet. Two Ocean Mountain to the southwest rises to 10,724 feet while the mountain in the southeast corner of section 21 to the northeast rises 10,775 feet. These elevations suggest Togwotee Pass is almost 1200 feet deep. Togwotee Pass is a water-eroded through valley and was eroded by southeast oriented flood flow moving to what at that time was an actively eroding southeast oriented Wind River valley. Initially floodwaters flowed on a surface at least as high as the high mountain ridge across which the Togwotee Pass through valley has been eroded. In other words, at the time floodwaters first flowed across the region the entire region was at least as high as the highest points in figure 6 today, although there has probably been considerable crustal warping and uplift of the region since that time. Crustal warping probably raised the region as floodwaters flowed across it and contributed to the flood flow reversal that created the northwest oriented Blackrock Creek drainage route and the drainage divide that is today the east-west continental divide. Headward erosion of the much deeper south oriented Snake River valley west of figure 6 was the more direct cause of the flood flow reversal when it beheaded the southeast oriented flood flow channel. Floodwaters on the northwest end of the beheaded flood flow channel reversed flow direction to create the northwest oriented Blackrock Creek drainage route.

North Fork Fish Creek-Sheridan Creek drainage divide area

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

Figure 7 illustrates the North Fork Fish Creek-Sheridan Creek drainage divide area south and slightly east of figure 5 and includes a significant overlap area with figure 5. The east-west continental divide is shown with a labeled dashed line and extends from the north center edge of figure 7 to the south center edge of figure 7. The Wind River flows in a southeast, south-southeast, and southeast direction from the north edge of figure 7 (slightly east of center) to the east edge of figure 7 (south half).  Sheridan Creek is located in the southeast quadrant of figure 7 and flows in a southeast, northeast, and east direction from near the continental divide to join the Wind River near the east edge of figure 7. West of the continental divide the North Fork Fish Creek flows in a south-southwest direction to near the southwest corner of figure 7. South of figure 7 southwest oriented Fish Creek joins the northwest oriented Gros Ventre River, which then flows in a northwest and southwest direction to join the south oriented Snake River. Sheridan Pass is located in the south center area of figure 7 and Squaw Creek originates near Sheridan Pass and flows in a west and northwest direction to join the south-southwest oriented North Fork Fish Creek. The map contour interval for figure 7 is 50 meters and the Sheridan Pass elevation at the drainage divide is between 2800 and 2850 meters. Elevations along the continental divide to the south rise to at least 3000 meters while to the north elevations rise to more than 3100 meters. These elevations suggest Sheridan Pass is at least 150 meters deep. Sheridan Pass was probably initially eroded by southeast and east-southeast oriented flood flow moving from the present day Gros Ventre River drainage basin to the southeast oriented Wind River drainage basin. Headward erosion of the much deeper south-southwest oriented North Fork Fish Creek valley from what was probably a southeast oriented flood flow channel on the present day northwest oriented Gros Ventre River alignment beheaded the flood flow channel moving floodwaters to the Sheridan Pass through valley. Floodwaters on the west end of the beheaded flood flow channel reversed flow direction to create the west-northwest oriented Squaw Creek drainage route and probably captured significant flood flow from east of Sheridan Pass, which then flowed in a west direction to the much deeper south-southwest oriented North Fork Fish Creek valley. Headward erosion of a still deeper southeast oriented valley on the Wind River alignment then captured flood flow east of Sheridan Pass and created the Squaw Creek-Sheridan Creek drainage divide, which today is the west-east continental divide.

Detailed map of Squaw Creek-Sheridan Creek drainage divide area

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

Figure 8 illustrates a detailed topographic map of the Squaw Creek-Sheridan Creek drainage divide area seen in less detail in figure 7. The east-west continental divide serves as a National Forest boundary line and is shown with a labeled line extending from the north edge of figure 8 (east of center) to the south edge of figure 8 (east of center). Sheridan Pass is labeled and is located in the northeast quadrant of section 10. Sheridan Creek flows in a south-southeast direction from the north edge of figure 8 (just east of the continental divide) and near Sheridan Pass turns to flow in an east direction to the east center edge of figure 8. Warm Springs Creek flows in a northeast and east direction near the southeast corner of figure 8 and east and south of figure 8 flows in a southeast direction and eventually joins the southeast oriented Wind River. The North Fork Fish Creek flows in a southwest direction across the northwest corner of figure 8 and west of figure 8 joins northwest oriented South Fork Fish Creek to form southwest oriented Fish Creek, which then flows to the northwest oriented Gros Ventre River. Squaw Creek originates in section 10 near Sheridan Pass and flows in a west-southwest, west-northwest, and northwest direction to join the southwest oriented North Fork Fish Creek. The map contour interval for figure 8 is 40 feet and the Sheridan Pass elevation is 9245 feet. Elevations along the continental divide reach more than 9600 feet in section 33 to the north and reach 9808 feet in section 16 near the south edge of figure 8 suggesting Sheridan Pass may be as much 350 feet deep. Note in the southeast corner of section 10 and the northwest corner of section 15 northwest-to-southeast oriented through valleys linking the west-northwest oriented Squaw Creek valley with then Warm Springs Creek valley. Elevations of these through valleys at the continental divide are between 9360 and 9400 feet, which is more than 100 feet higher than the Sheridan Pass elevation. However these through valleys represent the flood flow channel orientation before being captured by headward erosion of the deeper east oriented Sheridan Creek valley. Capture of the southeast oriented flood flow that had been moving to the actively eroding Warm Spring Creek valley provides evidence of the ever-changing anastomosing flood flow channels, which were changing as flood water eroded deeper channels headward at the expense of less deep flood flow channels. Crustal warping that was raising the regional mountain ranges also contributed to the ever-changing channel pattern.

Warm Springs Creek-South Fork Fish Creek drainage divide area

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

Figure 9 illustrates the Warm Springs Creek-South Fork Fish Creek drainage divide area south and east of the figure 7 and includes an overlap area with figure 7. The east-west continental divide is shown with a labeled dashed line and extends from the north edge of figure 9 (west half) to the south center edge of figure 9. Sheridan Pass is located near the north edge of figure 9. The Wind River flows in an east and southeast direction near the north edge of the northeast quadrant of figure 9. East of figure 9 the Wind River flows in a southeast, south, and southeast direction into the Wind River Basin. Warm Springs Creek originates near the continental divide (south of Sheridan Pass) and flows in a northeast, southeast, and east-southeast direction to the east center edge of figure 9. East of figure 9 Warm Springs Creek flows in a southeast and then northeast direction to join the Wind River. Note north oriented Warm Springs Creek tributaries. For example, Fish Lake Creek flows in a north-northeast direction from Fish Lake (near center of figure 9) to join Warm Springs Creek north of Fish Lake Mountain. The northwest oriented stream flowing across the southwest quadrant of figure 9 is the South Fork Fish Creek, which west of figure 9 joins southwest oriented North Fork Fish Creek to form southwest oriented Fish Creek, which then flows to the northwest oriented Gros Ventre River. Note the south oriented streams flowing to northwest oriented South Fork Fish Creek as barbed tributaries. For example, Leeds Creek flows in a southeast direction along the southwest side of the continental divide until it is south of Fish Lake and then turns to flow in a south direction only to make a U-turn as it enters northwest oriented South Fork Fish Creek. The barbed tributaries alone are evidence the South Fork Fish Creek valley originated as a southeast oriented drainage route, which had captured multiple south oriented flood flow channels. But, for further evidence look at the continental divide between the north-oriented Fish Lake Creek valley and the south-oriented Leeds Creek valley where a north-to-south oriented through valley crosses the continental divide. The map contour interval for figure 9 is 50 meters and the through valley is defined by at least four contour lines on each side suggesting it is at least 150 meters deep. The through valley was eroded by a south oriented flood flow channel moving floodwaters to a southeast oriented flood flow channel on the present day northwest oriented South Fork Fish Creek alignment. Headward erosion of the deeper Warm Springs Creek valley beheaded the south oriented flood flow channel and floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Fish Lake Creek drainage route. The flood flow reversal was probably greatly aided by crustal warping that was raising the entire region as floodwaters flowed across it.

Detailed map of Fish Lake Creek-Leeds Creek drainage divide area

Figure 10: Detailed map of Fish Lake Creek-Leeds 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 Fish Lake Creek-Leeds Creek drainage divide area seen in less detail in figure 9. The east-west continental divide serves as the Ranger District boundary line and is shown with a labeled line extending from the northwest corner of figure 10 to the south edge of figure 10 (east half). Fish Lake is located in section 31 and Fish Lake Creek flows in a north-northeast direction from Fish Lake to the north edge of figure 10 (east of center). North of figure 10 Fish Lake Creek flows to east-southeast-oriented Warm Springs Creek, which eventually joins the Wind River. Leeds Creek originates in the north half of section 35 and flows in a southeast direction along the southwest side of the continental divide to section 6 where it turns to flow in a south direction to join northwest oriented South Fork Fish Creek, which flows to the Gros Ventre River, which then flows to the Snake River. Note the north-to-south oriented through valley in the north half of section 6 and south half of section 31 linking the north oriented Fish Lake Creek valley with the south oriented Leeds Creek valley. The map contour interval for figure 10 is 40 feet and the through valley floor elevation at the drainage divide is between 9360 and 9400 feet. Fish Lake Mountain in section 5 rises to 10, 073 feet and an elevation of 9857 feet can be seen in the northwest corner of section 35 (just west of the Leeds Creek headwaters). These elevations suggest the through valley is at least 450 feet deep. The through valley is a water-eroded feature and was eroded by a south oriented flood flow channel moving floodwaters to a southeast oriented flood flow channel on the present day northwest oriented South Fork Fish Creek alignment. At that time the deep Warm Springs Creek and Wind River valleys to the north did not exist and floodwaters could freely flow across the region. Headward erosion of the deep Warm Springs Creek valley beheaded the south oriented flood flow channel and floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Fish Lake Creek drainage route and the Fish Lake Creek-Leeds Creek drainage divide.

Additional information and sources of maps studied

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

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: