Abstract:

This essay uses topographic map evidence to interpret landform origins in the region between the South Fork Shoshone River and Greybull River in Park County, Wyoming. The South Fork Shoshone River and the Greybull Rivers originate in the southern Absaroka Range and flow in a north, north-northeast, and northeast directions between high mountain ridges before entering the Bighorn Basin. Carter Mountain is a high linear mountain located along the drainage divide. The drainage divide at Carter Mountain and elsewhere is crossed by passes, which are interpreted to have been eroded by south and southeast oriented flood flow channels into a surface equivalent in elevation, if not higher, to the present day drainage divide elevation. Floodwaters were derived from the western margin of a thick North American ice sheet and were flowing in south and southeast directions across the Absaroka Range location. At that time the Absaroka Range had not emerged as a high mountain range. A massive flood flow reversal occurred when the much deeper northeast oriented Yellowstone River valley eroded headward across Montana to capture south and southeast oriented melt water flood flow moving into the Bighorn Basin. The Yellowstone River valley eroded headward from space in the deep “hole” the melting ice sheet had formed and occupied and that was being opened up by the ice sheet melting. Floodwaters on the north end of a beheaded flood flow channel through the present day Bighorn Basin reversed flow direction to create the north oriented Bighorn River drainage route, and northeast oriented tributary valleys then eroded headward into the Absaroka Range region to capture south and southeast oriented flood flow still moving west of the actively eroding Yellowstone River valley head. Headward erosion of the Greybull River valley captured the south and southeast oriented flood flow first with headward erosion of the Shoshone and South Fork Shoshone River valley subsequently beheading the south and southeast oriented flood flow routes to the newly eroded Greybull River valley. North oriented tributary and headwaters drainage routes developed in sequence (generally from east to west) by reversals of flood flow on north ends of beheaded flood flow channels. Headward erosion of deep valleys into the Absaroka Range was greatly aided by ice sheet related crustal warping that raised the Absaroka Range region as floodwaters flowed across it. Following the end of all flood flow across the Absaroka Range region and uplift of the Absaroka Range glaciers formed in some of the higher elevation flood eroded valleys and further modified those valley shapes.

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 South Fork Shoshone River-Greybull River drainage divide area landform origins in Park County, 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 South Fork Shoshone River-Greybull River drainage divide area landform evidence in Park County, Wyoming will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

South Fork Shoshone River-Greybull River drainage divide area location map

Figure 1: South Fork Shoshone River-Greybull 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 South Fork Shoshone River-Greybull River drainage divide area in Park County, Wyoming and illustrates a region in northwest Wyoming. The Montana-Wyoming state line is located along the north edge of figure 1 and the Wyoming state line is also located along the west edge of figure 1. Yellowstone National Park is located in the northwest corner of Wyoming. The Absaroka Range extends from north of figure 1 along the eastern boundary of Yellowstone National Park to the Owl Creek Mountains. The Wind River flows in a southeast direction from Togwotee Pass (in southwest quadrant of figure 1) to the south center edge of figure 1 and south of figure 1 turns to flow in a north direction to Boysen Reservoir (near southeast corner of figure 1) and then through Wind River Canyon (unnamed in figure 1, but carved into the Owl Creek Mountains) to near Thermopolis where the river name changes to become the Bighorn River.  The Bighorn River then flows in a north direction from Thermopolis to the north edge of figure 1 (near northeast corner). North of figure 1 the Bighorn River flows in a north-northeast direction to join the northeast oriented Yellowstone River.  The Greybull River originates at the southeast end of the Absaroka Range and flows in a northeast, east-southeast, and northeast direction to join the Bighorn River near the town of Greybull. The Shoshone River is formed at Buffalo Bill Reservoir at the confluence of the east oriented North Fork Shoshone River and the northeast oriented South Fork Shoshone River and then flows in a northeast direction to join the Bighorn River near the north edge of figure 1. The South Fork Shoshone River-Greybull River drainage divide area in Park County, Wyoming is primarily located in the southern Absaroka Range and is bounded on the west and north by the South Fork Shoshone River, on the east by the highway between Cody and Meeteetse, and on the southeast by the Greybull River.

Before and while the present day drainage system was formed the region in figure 1 was crossed by massive south and southeast oriented melt water floods from the western margin of a thick North American ice sheet. At least initially the Absaroka Range and the Owl Creek Mountains had not emerged as mountain ranges and the melt water floods flowed across what are today high mountain regions. The mountains emerged as ice sheet related crustal warping raised them and as deep valleys eroded headward into them. The deep valleys eroded headward into the emerging mountain ranges to capture the massive south and southeast oriented flood flow. The present day Bighorn River is located on the alignment of what began as a major south oriented flood flow channel, which south of figure 1 converged with the southeast oriented Wind River flood flow channel. Flood flow on the Bighorn River alignment was reversed when headward erosion of the much deeper northeast oriented Yellowstone River valley from space in the deep “hole” the melting ice sheet had once occupied beheaded the south oriented Bighorn River flood flow channel. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Bighorn River drainage route, which then captured the southeast oriented Wind River flood flow channel. Deep northeast oriented valleys also eroded headward from the newly reversed Bighorn River flood flow channel to capture south and southeast oriented flood flow still moving west of the actively eroding Yellowstone River valley head. The deep northeast oriented Greybull River valley captured southeast and south oriented flood flow in the Absaroka Range first and subsequently South Fork Shoshone River valley headward erosion captured the southeast and south oriented flood flow. What are today high mountain ridges were carved by systematic headward erosion of these deep valleys and their tributary valleys to capture the immense south and southeast melt water flood flow.

Detailed location map for South Fork Shoshone River-Greybull River drainage divide area

Figure 2: Detailed location map South Fork Shoshone River-Greybull 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 South Fork Shoshone River-Greybull River drainage divide area in Park County, Wyoming. Green areas in the west half of figure 2 are National Forest lands and are generally located in the Absaroka Range. East of the Absaroka Range is the Bighorn Basin. The Bighorn River flows in a north direction near the east edge of figure 2. The South Fork Shoshone River originates near the southwest corner of figure 2 and flows in a north-northeast and northeast direction to join the east oriented North Fork Shoshone River at Buffalo Bill Reservoir and to form the northeast oriented Shoshone River, which flows to Cody, the north center edge of figure 2, and to the Bighorn River north of figure 2. Carter Creek is a north oriented Shoshone River tributary flowing from near Foster Reservoir to Buffalo Bill Reservoir. Rock Creek is a north-northwest oriented South Fork Shoshone River tributary south and west of Carter Creek. Carter Mountain is a labeled mountain located south of the Carter and Rock Creek headwaters. Boulder Creek in a north and northwest oriented South Fork Shoshone River tributary located near the small town of Valley. Needle Creek is a north and west oriented South Fork Shoshone River tributary located south of the Boulder Creek headwaters. The town of Meeteetse is located south of the center of figure 2. The Greybull River originates in the southwest quadrant of figure 2 (south of Carter Mountain) and flows in a north-northwest, east, and northeast direction to Meeteetse. From Meeteetse the Greybull River flows in a northeast, east-southeast, and northeast direction to join the Bighorn River near the town Greybull (near northeast corner of figure 2). Meeteetse Creek is an east-northeast and east-southeast oriented stream originating near the Rock Creek headwaters and flowing to the Greybull River downstream from Meeteetse. Note southeast and east-southeast oriented tributaries flowing to the Greybull River in the region between Carter Mountain and Meeteetse. Also note how these Greybull River tributaries are aligned with northwest oriented South Fork Shoshone River tributaries on the other side of Carter Mountain. While today Carter Mountain forms a high ridge at one time southeast oriented flood flow channels crossed that high ridge. At that time Carter Mountain had not yet emerged as the high mountain it is today. Headward erosion of the deep Greybull River valley captured the southeast oriented flood flow channels first. Later headward erosion of the deep South Fork Shoshone River valley captured the southeast oriented flood flow and beheaded the flood flow channels to the newly eroded Greybull River valley. Headward erosion of these deep valleys, plus headward erosion of their deep tributary valleys, played significant roles in the emergence of Carter Mountain as the high mountain it is today. Probably ice sheet related crustal warping also raised the Absaroka Range region as floodwaters flowed across it.

South Fork Sage Creek-Meeteetse Creek drainage divide area

Figure 3: South Fork Sage Creek-Meeteetse 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 South Fork Sage Creek-Meeteetse Creek drainage divide area. The map contour interval for figure 3 is 50 meters except in the eastern fourth where the contour interval is 20 meters. Foster Reservoir is a small lake near the west center edge of figure 3. West of Foster Reservoir is Carter Mountain with elevations more than 500 meters higher than the elevation at Foster Reservoir. Meeteetse Creek flows in an east and southeast direction from the west edge of figure 3 (south of Foster Reservoir) to the south center edge of figure 3. South of figure 3 Meeteetse Creek joins the northeast oriented Greybull River as a barbed tributary. Note how Meeteetse Creek flows near the edge of Meeteetse Rim, which in the south center area of figure 3 is a rim along the south margin of a deep north oriented drainage basin. The north oriented drainage basin has been eroded by east and northeast oriented South Fork Sage Creek, which originates at Foster Reservoir and which joins northeast oriented Sage Creek to form north oriented Sage Creek. North of figure 3 Sage Creek flows to the northeast oriented Shoshone River. What has happened to form the Meeteetse Rim is south oriented flood flow on the present day north oriented Sage Creek alignment (east of Carter Mountain) converged with east oriented flood flow moving in the Meeteetse Creek valley (from west of figure 3) to form a major southeast oriented flood flow channel on the Meeteetse Creek alignment. Floodwaters south and east of figure 3 were first captured by headward erosion of the deep northeast oriented Greybull River valley. At that time there was no Shoshone River valley north of figure 3 and the deep northeast oriented South Fork Shoshone River valley west of Carter Mountain did not exist. Floodwaters were apparently flowing across what is today the high Carter Mountain drainage divide ridge to reach the actively eroding Meeteetse Creek valley. Headward erosion of the much deeper northeast oriented Shoshone River valley north of figure 3 beheaded the south oriented flood flow channel on the Sage Creek alignment. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Sage Creek drainage route, which captured some, but not all of the flood flow moving in an east direction from west of figure 3. This captured flood flow eroded the deep north oriented South Fork Sage Creek drainage basin seen north of Meeteetse Rim while some of the east oriented flood flow continued to flow in a southeast direction to the previously eroded northeast oriented Greybull River valley. Headward erosion of the deep South Fork Shoshone River valley west of Carter Mountain next beheaded the southeast oriented flood flow moving across Carter Mountain and ended all flood flow to the region seen in figure 3. The figure 3 landscape since that time has not significantly changed although crustal warping may have raised the region.

Detailed map of South Fork Sage Creek-Meeteetse Creek drainage divide area

Figure 4: Detailed map of South Fork Sage Creek-Meeteetse 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 South Fork Sage Creek-Meeteetse Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 40 feet. Meeteetse Creek flows in an and east-southeast direction from the west edge of figure 4 (south half) to the south edge of figure 4 (east of center) and south and east of figure 4 joins the northeast oriented Greybull River as a barbed tributary. The South Fork Sage Creek originates at Foster Reservoir west of figure 4 and flows from the west center edge of figure 4 to the unnamed lake near the center of figure 4 before turning to flow in a north-northeast direction to the north edge of figure 4 (east half). North of figure 4 the South Fork Sage Creek joins Sage Creek, which then flows in a north direction to join the northeast oriented Shoshone River. Meeteetse Rim is located north of Meeteetse Creek in the south half of figure 4. Meeteetse Rim is the rim of the deep east-southeast and north-northeast oriented South Fork Sage Creek drainage basin. Elevations along Meeteetse Rim in section 34 are approximately 700 feet higher than the unnamed lake level in section 27. Note how Meeteetse Creek flows along the edge of the north-facing Meeteetse Rim escarpment in a relatively shallow valley. How was the South Fork Sage Creek able to erode a much deeper valley than Meeteetse Creek? The north-facing escarpment is a water-eroded landform and was eroded by floodwaters flowing from the northeast and east oriented Meeteetse Creek valley west of figure 4. Today such an interpretation may defy logic because west of figure 4 is Carter Mountain where elevations are generally greater than 10,000 feet and in places exceed 11,000 feet. Yet at the time floodwaters were crossing what is today Carter Mountain. Prior to Shoshone River valley headward erosion north and west of figure 4 those east oriented floodwaters were converging with south oriented floodwaters in the south center area of figure 4 and then flowing to the newly eroded northeast oriented Greybull River valley. Headward erosion of the much deeper (than the Meeteetse Rim elevation) Shoshone River valley north of figure 4 beheaded the south oriented flood flow route. Floodwaters on the north end of the beheaded flood flow route reversed flow direction to create the north oriented Sage Creek drainage route, which then captured some, but not all of the east oriented flood flow moving across Carter Mountain. The captured floodwaters eroded the deeper South Fork Sage Creek valley while floodwaters that were not captured continued to flow to the Greybull River along the present day Meeteetse Creek drainage route.  Figures 5 and 6 illustrate regions west of figures 3 and 4.

Rock Creek-Meeteetse Creek drainage divide area

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

Figure 5 illustrates the Rock Creek-Meeteetse Creek drainage divide area west and slightly south of figure 3 and includes an overlap area with figure 3. The South Fork Shoshone River flows in a northeast direction across the northwest corner of figure 5. Carter Mountain is the high ridge extending from near the southwest corner of figure 5 to the northeast quadrant of figure 5. Note the location of Foster Reservoir in the northeast quadrant of figure 5 and remember the east-southeast oriented headwaters of the South Fork Sage Creek originate at Foster Reservoir. Meeteetse Creek originates on the southeast side of Carter Mountain (south of the center of figure 5) and flows in an east-northeast and east direction to the east center edge of figure 5 and east of figure 5 turns to flow in a southeast direction to join the Greybull River. Rock Creek is the north and north-northwest oriented stream originating on the north side of Carter Mountain in the southwest quadrant of figure 5 and joins the South Fork Shoshone River near the north edge of figure 5. The map contour interval for figure 5 is 50 meters. Note how the northwest oriented East Fork Rock Creek headwaters and the northeast oriented Meeteetse Creek headwaters are linked by a pass or notch cut across Carter Mountain. The elevation at the pass is between 3250 and 3300 meters. Elevations on Carter Mountain to the northeast rise to more than 3450 meters while Carter Mountain elevations to the southwest rise much higher. These elevations suggest the pass is at least 150 meters deep. The pass was eroded by southeast oriented flood flow moving to what at that time was the actively eroding east-northeast Meeteetse Creek valley. At that time the deep northeast oriented South Fork Shoshone River valley did not exist and floodwaters could flow in a southeast direction to and across Carter Mountain. East of figure 5 as seen in figures 3 and 4 some of the floodwaters flowed in a southeast direction to the newly eroded Greybull River valley while other floodwaters flowed in a north direction on the Sage Creek alignment to the what at that time was actively eroding northeast oriented Shoshone River valley.

Detailed map of Rock Creek-Meeteetse Creek drainage divide area

Figure 6: Detailed map of Rock Creek-Meeteetse 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 Rock Creek-Meeteetse Creek drainage divide area seen in less detail in figure 5. Carter Mountain is the high ridge extending from the west edge of figure 6 (near southwest corner) to the north edge of figure 6 (east half). North and west of Carter Mountain drainage flows to the northeast oriented South Fork Shoshone River. The East Fork Rock Creek originates in the northeast corner of section 12 near the center of figure 6 and flows in northwest direction to the north edge of figure 6 (near northwest corner) and north and west of figure 6 joins north-northwest oriented Rock Creek, which then flows to the South Fork Shoshone River. Meeteetse Creek originates in the northwest corner of section 7 (immediately east of the East Fork Rock Creek origin) and then flows in an east-northeast direction to the east edge of figure 6. East of figure 6 Meeteetse Creek turns to flow in a southeast direction to the northeast oriented Greybull River. Note in the northwest corner of section 7 a pass or gap linking the Meeteetse Creek headwaters valley with the East Fork Rock Creek valley. The map contour interval for figure 6 is 40 feet and the pass elevation is between 10,720 and 10,760 feet. Carter Mountain in the northwest quadrant of section 7 (north of the pass) reaches an elevation of more than 11,240 feet while in section 12 (south of the pass) Carter Mountain elevations exceed 11,420 feet. These elevations suggest the pass is at least 480 feet deep. The pass is a water-eroded landform and was eroded by southeast oriented flood flow moving to what was at that time the actively eroding Meeteetse Creek valley. At that time there was no deep South Fork Shoshone River valley north and west of Carter Mountain and floodwaters were flowing on a surface equivalent in elevation, if not higher, to the top of Carter Mountain today. Probably crustal warping has raised the entire region since that time and obviously the deep northeast oriented South Fork Shoshone River valley has eroded headward into that former high-level surface. However, the pass provides evidence the southeast oriented flood flow did move across Carter Mountain, which today is one of the higher mountains in the Absaroka Range. Figures 7 and 8 illustrate additional evidence that floodwaters flowed across Carter Mountain to reach the newly eroded Greybull River valley.

Castle Creek-Eleanor Creek drainage divide area

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

Figure 7 illustrates the Castle Creek-Eleanor Creek drainage divide area west and south of figure 5 and there is an overlap area with figure 5. Carter Mountain is the high drainage divide between the South Fork Shoshone River valley to the northwest and the Greybull River valley to the southeast. The South Fork Shoshone River flows in a north-northeast direction across the northwest corner of figure 7. Boulder Creek flows in a north, north-northeast, and north-northwest direction from near the southwest corner of figure 7 to join the South Fork Shoshone River near the north edge of figure 7. Castle Creek is a north oriented Boulder Creek tributary originating in the southwest quadrant of figure 7. The Greybull River flows in a north, northeast, and east-northeast direction from the south edge of figure 7 (east of center) to the east edge of figure 7 (south of center). Note southeast oriented streams flowing from the Carter Mountain area to join the Greybull River as barbed tributaries. Eleanor Creek is an east-northeast and east oriented Greybull River tributary in the south center region of figure 7. Note how a pass links an east-southeast oriented Eleanor Creek tributary valley with a northwest oriented Castle Creek tributary valley. The map contour interval for figure 7 is 50 meters and the pass elevation is between 3200 and 3250 meters. Elevations north of the pass on Carter Mountain rise to 3628 meters and south of the pass near the south edge of figure 7 elevations along the drainage divide rise to more than 3550 meters. These elevations suggest the pass is at least 375 meters deep. The pass and other similar passes cut across Carter Mountain were eroded by southeast oriented flood flow moving to what was at that time the newly eroded Greybull River valley. At that time the deep north-northeast oriented South Fork Shoshone River valley did not exist. If a valley existed on the South Fork Shoshone River alignment the valley was at that time being used as a south oriented flood flow channel.

Detailed map of Castle Creek–Eleanor Creek drainage divide area

Figure 8: Detailed map of Castle Creek-Eleanor 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 Castle Creek-Eleanor Creek drainage divide area seen in less detail in figure 7. The South Fork Shoshone River-Greybull River drainage divide serves as the ranger district boundary and is the high ridge extending in a northeast direction from near the southwest corner of figure 8 to the north edge of figure 8 (east of center). Eleanor Creek originates near the south edge of figure 8 (west half) and flows in an east-northeast and east direction to the east edge of figure 8 and joins the Greybull River east of figure 8. A southeast oriented Eleanor Creek tributary originates in section 29 and is located north of the Boulder Basin Trail, which is on the drainage divide between the tributary and Eleanor Creek. The northwest oriented stream originating in section 20 (north of section 29) flows to north oriented Castle Creek, which then flows to the north edge of figure 8 (west half). North of figure 8 Castle Creek flows to Boulder Creek, which then flows to the South Fork Shoshone River. Note on the boundary between sections 20 and 29 a pass linking the northwest oriented Castle Creek tributary valley with the southeast oriented Eleanor Creek tributary valley. The Boulder Basin Trail crosses the drainage divide at the pass. The map contour interval is 40 feet and the pass elevation is between 10,600 and 10,640 feet. Elevations in section 36 to the southwest of the pass rise to 11,602 feet and in section 16 to the northeast of the pass elevations rise to more than 11,720 feet. These elevations suggest the pass is at least 960 feet deep. While today the pass crosses a high mountain ridge the pass was originally eroded as a southeast oriented flood flow channel at a time when the regional topography looked very different from how it looks today. At that time there was no deep South Fork Shoshone River valley north and west of figure 8 and floodwaters flowed in a south direction on the present day north oriented Castle Creek alignment and then turned to flow in a southeast direction to what was probably an actively eroding Eleanor Creek valley. Whether the Eleanor Creek valley at that time was eroding headward from a newly eroded Greybull River valley or from a south oriented flood flow channel is difficult to determine, however south of figure 8 the Greybull River flows in a north and even north-northwest direction suggesting its alignment in that region originated as a south oriented flood flow channel. If so headward erosion of a much deeper northeast oriented Greybull River 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 and north-northwest oriented Greybull River drainage route.

Boulder Creek-Needle Creek drainage divide area

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

Figure 9 illustrates the Boulder Creek-Needle Creek drainage divide area and is located south and slightly west of figure 7 and includes a significant overlap area with figure 7. The Greybull River flows in a north-northwest, north-northeast, and northeast direction from the south edge of figure 9 (near southeast corner) to the east edge of figure 9 (east half). Eleanor Creek originates slightly north of the center of figure 9 and flows in an east-northeast and east direction to join the northeast oriented Greybull River. Anderson Creek is a northeast oriented stream joining Eleanor Creek shortly before joining the Greybull River. The South Fork Shoshone River flows in a north-northeast, north, and north-northeast direction from near the southwest corner of figure 9 to the north edge of figure 9 (west half). Needle Creek is a north and west oriented stream flowing from the south edge of figure 9 to join the South Fork Shoshone River in the southwest quadrant of figure 9. Boulder Creek is the north and north-northeast oriented stream originating north of the Needle Creek elbow capture (where Needle Creek turns to flow in a west direction) and flows to the north edge of figure 9 (west of center). North of figure 9 Boulder Creek joins the South Fork Shoshone River. Note how the north oriented Needle Creek valley segment is located on approximately the same alignment as the north oriented Boulder Creek valley. Also note the south oriented Needle Creek tributary on the same alignment, which flows to the Needle Creek elbow of capture as a barbed tributary.  A pass links that south oriented Needle Creek tributary valley with the north oriented Boulder Creek valley and provides evidence of a former south oriented flood flow channel that existed prior to the flood flow reversals that created the present day north oriented drainage systems. The map contour interval for figure 9 is 50 meters and the pass elevation is between 3350 and 3400 meters. Elevations west of the pass rise to 3610 meters and elevations greater than 3600 meters can be found east of the pass. These elevations suggest the pass is at least 200 meters deep. The present day west oriented Needle Creek valley segment probably originated as an east oriented diverging flood flow channel from a south oriented flood flow channel on the present day north oriented South Fork Shoshone River alignment and converged with the south oriented flood flow channel on the present day north oriented Boulder Creek and Needle Creek alignments at the Needle Creek elbow of capture location. Headward erosion of the much deeper northeast oriented South Fork Shoshone River valley (north of figure 9) beheaded the south oriented flood flow channel on the Boulder Creek alignment. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Boulder Creek drainage route. Floodwaters on the north end of the south oriented flood flow channel on the present day north oriented South Fork Shoshone River alignment next reversed flow direction and also reversed flow direction on the present day north and west Needle Creek alignment. For a time southeast oriented flood flow from west of the newly reversed South Fork Shoshone River valley was captured south of figure 9 and these captured floodwaters helped erode the deep Needle Creek valley seen today.

Detailed map of Boulder Creek-Needle Creek drainage divide area

Figure 10: Detailed map of Boulder Creek-Needle 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 Boulder Creek-Needle Creek drainage divide area seen in less detail in figure 9. Needle Creek flows in a northwest and west direction from the south edge of figure 10 (slightly west of center) to the west edge of figure 10 (near southwest corner) and west of figure 10 joins the north oriented South Fork Shoshone River (not seen in figure 10, although the east side of the South Fork Shoshone River valley is seen along the west edge of figure 10). Boulder Creek headwaters flow in a north direction to the north center edge of figure 10 and north of figure 10 converge to form north oriented Boulder Creek, which eventually joins the South Fork Shoshone River. North oriented basins in which the north oriented Boulder Creek headwaters streams originate are cirques and were carved by glacial erosion. Glaciation occurred after the north oriented valleys had been formed and after all flood flow across the region had ended. Note in section 9 a pass linking the center north oriented Boulder Creek headwaters valley with a south oriented Needle Creek tributary valley. The map contour interval for figure 10 is 40 feet and the pass elevation is between 11,080 and 11,120 feet. Needle Mountain to the west (in southeast corner of section 6) reaches 12,108 feet while an elevation of 12,095 feet is found in section 2 to the east. These elevations suggest the pass is approximately 1000 feet deep.  While not deep compared to the 3000-foot plus Needle Creek valley depth the pass is evidence of a south oriented flood flow channel that was eroded into a high-level surface equivalent in elevation, if not higher, to the highest points seen in figure 10. Headward erosion of deep valleys from space in the deep “hole” the melting ice sheet had occupied captured the immense south and southeast oriented melt water floods and systematically eroded the deep north and west oriented Needle Creek valley to the south, the deep Boulder Creek valley to the north, and the deep South Fork Shoshone River valley to the west. Headward erosion of these deep valleys was aided by ice sheet related crustal warping that raised the Absaroka Range as the immense melt water floods flowed across it.

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.