Abstract:

This essay uses topographic map evidence to interpret landform origins in the region between South Piney Creek and North Clear Creek in the Wyoming Bighorn Mountains. North Clear Creek originates east of Florence Pass in the high Bighorn Mountains and flows in an east direction to near the Bighorn Mountains east slope base where North Clear Creek joins South Clear Creek and once in the Powder River Basin Clear Creek turns to flow in a northeast direction to join the north oriented Powder River. South Piney Creek originates a short distance north of the North Clear Creek headwaters and flows in a northeast and north-northeast direction to the Bighorn Mountains east slope base before joining North Piney Creek to form southeast, northeast, and east oriented Piney Creek, which then flows to northeast oriented Clear Creek. The Piney Creek-Clear Creek drainage divide area investigated in this essay extends from the high Bighorn Mountains crest ridge to valleys along the base of the Bighorn Mountains eastern slope. Through valleys or mountain passes link the South Piney Creek valley and tributary valleys with the North Clear Creek, Clear Creek, and tributary valleys. The through valleys cross drainage divides at all elevations from the highest Bighorn Mountains crest ridge to drainage divides at the Bighorn Mountains eastern slope base. The through valleys along with elbows of capture, barbed tributaries, valley orientations, and evidence of anastomosing channel complexes are interpreted to have developed during immense melt water floods at a time when the Bighorn Mountains had not emerged. Floodwaters are interpreted to have been derived from the western margin of a thick North American ice sheet and were flowing from western Canada in south and southeast directions to and across the present day Bighorn Mountains region. Headward erosion of east and southeast oriented valleys from south oriented flood flow channels in the present day Powder River Basin first captured south and southeast oriented flood flow in the emerging Bighorn Mountains. The Bighorn Mountains are interpreted to have emerged as floodwaters deeply eroded surrounding regions and as ice sheet related crustal warping raised the Bighorn Mountains. Flood flow routes were beheaded in sequence from east to west and from south to north and floodwaters on north ends of beheaded flood flow routes reversed flow direction to create north oriented drainage routes, which then captured southeast and south oriented flood flow still moving further to the west. The Bighorn Mountains are located along what could be considered to be a segment of the deeply eroded and warped southwest rim of the deep “hole” in which the massive ice sheet was located. A massive flood flow reversal in the Powder River Basin occurred when ice sheet melting opened up space at the south end of the deep “hole” and deep northeast and north oriented valleys eroded headward from that space to capture the immense south and southeast oriented melt water floods. Subsequently headward erosion of the deep northeast oriented Yellowstone River valley north of the Bighorn Mountains beheaded all flood flow routes across the emerging Bighorn Mountains and triggered a massive flood flow reversal in the Bighorn Basin to the west of the Bighorn Mountains. Alpine glaciation in the high Bighorn Mountains occurred after the Bighorn Mountains had emerged as a high mountain range, which was all melt water floods across the region had ended.

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 Piney Creek-Clear Creek drainage divide area landform origins in the Wyoming Bighorn Mountains, 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 Piney Creek-Clear Creek drainage divide area landform evidence in the Wyoming Bighorn Mountains will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Piney Creek-Clear Clear drainage divide area location map

Figure 1: Piney Creek-Clear Creek 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 Piney Creek-Clear Creek drainage divide area in the Wyoming Bighorn Mountains and illustrates a region in north central Wyoming. The Montana-Wyoming state line is located near the north edge of figure 1. The Bighorn Mountains extend from the northwest corner of figure to the south center edge of figure 1. The Bighorn Basin is located west of the Bighorn Mountains and the Powder River Basin is located east of the Bighorn Mountains. The Powder River flows from the south edge of figure 1 (east half) to the northeast corner of figure 1 and flows in a north and northeast direction. Clear Creek originates in the Bighorn Mountains (south of Cloud Peak) and flows in an east direction to Buffalo, Wyoming and then turns to flow in a northeast direction to join the Powder River. Piney Creek is shown, but not labeled in figure 1 and originates in the Bighorn Mountains east of Cloud Peak and flows in a north-northeast direction to Story, Wyoming. From Story Piney Creek flows in a southeast, northeast and east direction to join northeast oriented Clear Creek. Today most drainage routes seen in figure 1 are oriented in north directions and all drainage routes flow to north oriented rivers, yet there are a few south oriented drainage routes shown. The North Fork Powder River originates near Powder River Pass and flows in a south and southeast direction to the south center edge of figure 1. Two unnamed southwest oriented streams are shown originating west of the Piney Creek and Clear Creek headwaters and flow to the northwest oriented Nowood River in the Bighorn Basin with the Nowood River flowing to the north oriented Bighorn River. And of greatest interest in this essay Piney Creek flows in a southeast direction along the Bighorn Mountains east base between Story and Lake De Smet. The Piney Creek-Clear Creek drainage divide area investigated in this essay is located south and east of Piney Creek and north and west of Clear Creek and is primarily located in or adjacent to the Bighorn Mountains.

The north oriented drainage systems seen in figure 1 evolved during a systematic and massive reversal of immense south oriented melt water floods that flowed across the entire region seen in figure 1. The floodwaters were derived from the western margin of a thick North American ice sheet and were flowing from western Canada to and across the Bighorn Mountains regions. At least initially the Bighorn Mountains had not emerged as a mountain range and floodwaters could freely flow across what is today a major mountain barrier. The Bighorn Mountains emerged as floodwaters deeply eroded the surrounding regions and as ice sheet related crustal warping raised mountain ranges and other regions to form a rim around the deep “hole” in which the ice sheet was located. The region seen in figure 1 could be considered to be a segment of the warped and deeply eroded deep “hole” southwest rim. Initially deep south and southeast oriented flood flow channels captured flood flow moving across the Bighorn Mountains by eroding headward into the Powder River Basin and the Bighorn Basin. Southeast and east oriented valleys eroded headward into the emerging Bighorn Mountains from deep south oriented flood flow channels in the Powder River Basin and southwest and west oriented valleys eroded headward into the emerging Bighorn Mountains from the deep south oriented flood flow channels in the Bighorn Basin. Subsequently headward erosion of the deep northeast oriented Yellowstone River valley across Montana (north of figure 1) was responsible for a systematic and massive flood flow reversal. The Yellowstone River valley eroded headward from space at the south end of the deep “hole” being opened up by the ice sheet melting. At first this newly opened up space drained in south directions using flood flow channels east of figure 1. Headward erosion of the deep northeast oriented Yellowstone River valley beheaded the south oriented flood flow channels moving floodwaters to and across the region seen in figure 1 in sequence from east to west. Flood flow channels to the Powder River Basin were beheaded first. Floodwaters on north ends of the beheaded flood flow routes reversed flow direction to create the north oriented Powder River drainage system, which then captured the southeast and east oriented flood flow still moving from the emerging Bighorn Mountains into the Powder River Basin. In time Yellowstone River valley headward erosion beheaded and reversed flood flow in the Bighorn Basin to create the north oriented Bighorn River drainage system, which captured southeast oriented flood flow channels from west of the actively eroding Yellowstone River valley head (see southeast oriented Bighorn River tributaries near southwest corner of figure 1) and which also captured drainage in what had been the southwest and west oriented flood flow channels from the Bighorn Mountains (but which by that time no longer contained flood flow).

Detailed location map for Piney Creek-Clear Creek drainage divide area

Figure 2: Detailed location map Piney Creek-Clear Creek 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 Piney Creek-Clear Creek drainage divide area in the Wyoming Bighorn Mountains. The green colored areas are National Forest lands, which are located in the Bighorn Mountains. Cloud Peak is a labeled high point in the Bighorn Mountains near the west edge of figure 2. The east oriented stream originating south of Cloud Peak is North Clear Creek (not French Creek as figure 2 implies, but which is correctly labeled further to the east) and flows in an east direction (south of the correctly labeled French Creek) to join northeast oriented South Clear Creek and to form east oriented Clear Creek, which then flows to Buffalo. French Creek joins Clear Creek near Buffalo. From Buffalo Clear Creek flows in a north-northeast direction to Ucross and then flows in a northeast direction to Clearmont and the north edge of figure 2. South Rock Creek flows in a northeast direction from near the North Clear Creek headwaters to near Saddlestring where it joins north-northeast and southeast oriented North Rock Creek to form southeast oriented Rock Creek, which joins Clear Creek east of Buffalo. South Piney Creek originates north of the South Rock Creek headwaters and flows in a north-northeast and northeast direction to join (south of Banner) north-northeast and east oriented North Piney Creek and to form Piney Creek, which then flows in a southeast, northeast, and east direction to join Clear Creek near Ucross. Lake De Smet is located south of the Piney Creek U-turn (where southeast oriented Piney Creek turns to flow in a northeast direction). The greater detail seen in figure 2 shows more south oriented drainage routes than were seen in figure 1. Of greatest interest in this essay are the southeast oriented Rock Creek and Piney Creek segments. Flood flow in the southeast oriented Rock Creek valley was captured by headward erosion of the deeper north-northeast oriented Clear Creek valley. Flood flow in the southeast oriented Piney Creek valley was captured by headward erosion of the northeast and east oriented Piney Creek valley, which eroded headward from the newly eroded northeast oriented Clear Creek valley. The northeast and north-northeast oriented Clear Creek valley eroded headward from a newly reversed flood flow channel on the Powder River alignment and captured east and southeast oriented flood flow channels flowing from the emerging Bighorn Mountains near Buffalo. The east and southeast oriented flood flow channels had been supplying floodwaters to south and southeast oriented flood flow channels, which were beheaded by headward erosion of the deeper Clear Creek valley. South and southeast oriented streams seen in figure 2 south of Buffalo provide evidence of those former south and southeast oriented flood flow channels. Headward erosion of the deep Clear Creek valley and captures of the various southeast and east oriented flood flow channels coming from the emerging Bighorn Mountains took place during the systematic reversal of the immense south oriented melt water flood flow so as to divert the floodwaters in north and northeast directions to space in the south end of the deep “hole” the melting ice sheet was opening up.

Piney Creek-Rock Creek drainage divide area east of Bighorn Mountains

Figure 3: Piney Creek-Rock Creek drainage divide area east of Bighorn Mountains. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of Piney Creek-Rock Creek drainage divide area east of the Bighorn Mountains. Piney Creek flows in a southeast direction from the north edge of figure 3 (west of center) to near the north end of Lake De Smet and then turns to flow in a northeast direction to the north edge of figure 3 (near northeast corner). Lake De Smet is located in the east half of figure 3. North Rock Creek flows in a north-northeast direction from the west edge of figure 3 (south half) and near the west center edge of figure 3 is joined by east oriented Ditch Creek at which point North Rock Creek turns to flow in a southeast direction. South Rock Creek flows in a north direction from the south edge of figure 3 (west half) to near Stone Mountain and then turns in a northeast direction to join southeast oriented North Rock Creek and to form southeast oriented Rock Creek, which then flows to the south edge of figure 3 (east half) and south of figure 3 joins north-northeast oriented Clear Creek. Lake De Smet is located in a northwest to southeast oriented through valley linking the southeast oriented Piney Creek valley with the Clear Creek valley (south of figure 3). South of the Clear Creek valley the through valley continues and links the Clear Creek valley with southeast oriented Crazy Woman Creek tributary valleys. The map contour interval for figure 3 is 20 meters and the Lake De Smet normal pool elevation shown in figure 3 is 1392 meters. Elevations in the through valley south and east of Lake De Smet are between 1400 and 1420 meters. East of the through valley elevations in a few places are more than 1500 meters although elevations are more commonly in the 1440 to 1460 meter range. These elevations suggest the through valley may be as much as 80 meters deep when compared with elevations to the east. The through valley provides evidence of a southeast oriented flood flow channel that was first captured by headward erosion of the deeper north-northeast oriented Clear Creek valley (south of figure 3). Headward erosion of the northeast oriented Piney Creek valley subsequently captured the southeast oriented flood flow and beheaded the flood flow channel to the newly eroded Clear Creek valley. The region east of Lake De Smet was probably deeply eroded by southeast oriented flood flow that was first captured by headward erosion of the deeper north-northeast oriented Clear Creek valley and was later captured by headward erosion of the northeast and east oriented Piney Creek valley. Probably the southeast oriented flood flow stripped significant thicknesses of bedrock from the Powder River Basin so the depth of the Lake De Smet through valley was probably much greater than present day elevations show.

Detailed map of Piney Creek-Lake De Smet drainage divide area

Figure 4: Detailed map of Piney Creek-Lake De Smet 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 Piney Creek-Lake De Smet drainage divide area seen in less detail in figure 3. The north end of Lake De Smet can be seen in the southeast quadrant of figure 4. Piney Creek flows in a southeast direction from the north edge of figure 4 (west half) and then turns to flow in an east and northeast direction to near the northeast corner of figure 4. Little Piney Creek is the east oriented Piney Creek tributary joining Piney Creek near Kearney in section 26. Diverging and converging through valleys typical of an anastomosing channel complex cross the region between Piney Creek and Lake De Smet and between Little Piney Creek and Lake De Smet. Between at least some of the shallow diverging and converging through valleys are streamlined erosional residuals suggesting the anastomosing channel complex was eroded by southeast oriented flood flow from the southeast oriented Piney Creek valley moving in a southeast direction across the Lake De Smet basin to the Clear Creek valley (and perhaps further to the southeast). Figure 4 shows no dam impounding Lake De Smet suggesting Lake De Smet is a natural lake (other sources indicate Lake De Smet is a natural lake, but the level has been raised by a dam at the north end and has been used as a reservoir for irrigation and other purposes with water coming from Piney Creek). The map contour interval for figure 4 is 20 feet and the Lake De Smet surface elevation shown in figure 4 is 4568 feet. The northwest to southeast oriented through valley at the south end of the Lake De Smet basin (not seen in figure 4) has an elevation of between 4580 and 4600 feet. The region east of the through valley looks like the region between Piney Creek and Lake De Smet and is crossed by diverging and converging shallow through valleys with streamlined erosional residuals in between. Elevations on the highest of the erosional residuals in this southeast oriented anastomosing channel complex exceed 4900 feet suggesting the Piney Creek-Clear Creek through valley at Lake De Smet is at least 300 feet deep. While this region is east of the Bighorn Mountains and is much lower in elevations than regions further to the west figures 3 and 4 have been included in this essay to document southeast oriented flood flow in the Powder River Basin that preceded the reversal of flood flow and headward erosion of the north-northeast oriented Clear Creek valley.

South Piney Creek-North Rock Creek drainage divide area

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

Figure 5 illustrates the South Piney Creek-North Rock Creek drainage divide area west of figure 3 and there is a significant overlap area with figure 3. Piney Creek flows across the northeast corner of figure 5 in a southeast direction. South Piney Creek flows from the south edge of figure 5 (west half) in a north-northeast direction to Willow Park Reservoir (in southwest quadrant of figure 5) and then in a north-northeast and northeast direction to the north edge of figure 5. Kearney Lake Reservoir straddles the west edge of figure 5 (south half) and Kearney Creek flows in a northeast direction from Kearney Lake Reservoir to join north-northeast oriented South Piney Creek. North Piney Creek originates north of Kearney Creek and flows in a north-northeast direction to the north center edge of figure 5. North of figure 5 North Piney Creek turns to flow in an east direction to join South Piney Creek and to form southeast oriented Piney Creek. Stone Mountain is a labeled high point near the south edge of the southeast quadrant of figure 5. South Rock Creek flows in a north direction from the south edge of figure 5 (just west of Stone Mountain) and then turns to flow in an east-northeast direction to join southeast oriented North Rock Creek and to form southeast oriented Rock Creek, which then flows to the east edge of figure 5 (near southeast corner) and then to join north-northeast oriented Clear Creek. North Rock Creek originates north of the south center edge of figure 5 and flows in a north-northeast direction before turning to flow in a southeast direction. Ditch Creek is the east oriented stream joining North Rock Creek at its elbow of capture (where north-northeast oriented North Rock Creek turns to flow in a southeast direction). Ditch Creek gets its name from an irrigation ditch that extends from near the Willow Park Reservoir on South Piney Creek to the headwaters of east oriented Ditch Creek. The irrigation ditch uses a through valley to cross the South Piney Creek-North Rock Creek drainage divide. The map contour interval for figure 5 is 20 meters and the through valley floor elevation is between 2500 and 2520 meters. Elevations along the drainage divide north of the through valley rise to more than 2600 meters. South of the through valley elevations rise much higher. These elevations suggest the through valley is at least 80 meters deep. The through valley was eroded by east oriented flood flow at a time when the deeper north-northeast oriented South Piney Creek valley did not exist. Floodwaters were flowing to what was then the actively eroding southeast oriented North Rock Creek and Rock Creek valley (which was probably eroding headward from a south oriented flood flow channel in the Powder River Basin). Headward erosion of the deeper north-northeast oriented South Piney Creek valley beheaded the east oriented flood flow to the North Rock Creek valley and diverted the floodwaters to the southeast oriented Piney Creek valley north of figure 5.

Detailed map of South Piney Creek-North Rock Creek drainage divide area

Figure 6: Detailed map of South Piney Creek-North Rock 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 South Piney Creek-North Rock Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet. South Piney Creek flows in a north-northeast direction from the south edge of figure 6 (near southwest corner) into section 13 where it makes a north-northwest, southwest, and north-northwest jog before resuming flow in a north-northeast direction to the north edge of figure 6 (west half). North Rock Creek flows in a north-northeast direction from the south edge of figure 6 (east half) to the east edge of figure 6 (north of center) and east of figure 6 turns to flow in a southeast direction. Ditch Creek originates near the southwest corner of section 8 and flows in an east and east-northeast direction to the east edge of figure 6 (north of North Rock Creek) and joins North Rock Creek east of figure 6. The Rock Creek and Piney Diversion Ditch can be seen extending from South Piney Creek in the southeast corner of section 13 to the Ditch Creek headwaters near the southwest corner of section 8. The Diversion Ditch moves water from South Piney Creek to the Rock Creek valley and crosses the South Piney Creek-North Rock Creek drainage divide via a through valley in the southeast corner of section 7.  The through valley floor elevation is between 8240 and 8480 feet. Elevations in the northwest corner of section 8 rise to more than 8640 feet suggesting the through valley is at least 160 feet deep. The through valley was eroded by east or southeast oriented flood flow moving from north and west of the present day South Piney Creek valley to what was at that time the actively eroding southeast oriented North Rock Creek valley. At that time the South Piney Creek valley did not exist and south and southeast oriented flood flow was still moving across what is now the high Bighorn Mountains upland surface. Evidence of earlier higher level flood flow channels can be seen in section 18 where two notches in the drainage divide provide evidence of former southeast oriented flood flow channels. The northern notch is more than 100 feet deep. Flood flow in those two higher-level notches was probably captured by headward erosion of the deeper Ditch Creek valley and its extension now seen in the through valley used by the Diversion Ditch. Headward erosion of the deep north-northeast oriented South Piney Creek valley beheaded the southeast or east oriented flood flow to the Ditch Creek valley and diverted floodwaters to the southeast oriented Piney Creek valley. Flood flow captures seen in figure 6 probably occurred before the massive flood flow reversals in the Powder River Basin to the east and in the Bighorn Basin to the west.

South Piney Creek-North Clear Creek drainage divide area

Figure 7: South Piney Creek-North Clear Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the South Piney Creek-North Clear Creek drainage divide area south and west of figure 5 and includes an overlap area with figure 5. The dashed line extending from near the northwest corner of figure 7 to the south edge of figure 4 (west half) is a county boundary following the divide between drainage to the Bighorn Basin to the west and to the Powder River Basin to the east. Florence Pass is located near the southwest corner of figure 7 and North Clear Creek originates at Florence Lake just east of Florence Pass. The map contour interval for figure 7 is 20 meters and while hard to read on figure 7 the Florence Pass elevation appears to be between 3360 and 3380 meters. Cloud Peak to the north rises to 4018 meters and Mather Peaks along the south edge of figure 7 rise to 3784 meters. These elevations suggest Florence Pass may be as much as 420 meters deep. Florence Pass links the east oriented North Clear Creek valley with the west oriented Paint Rock Creek headwaters valley and the south oriented West Tensleep Creek valley. Today Florence Pass crosses the high Bighorn Mountains crest ridge and it is difficult to say for certain which direction the water that eroded Florence Pass was moving. One possibility is Florence Pass was eroded by east oriented flood flow moving from what is now the west oriented Paint Rock Creek headwaters valley alignment to what was then the actively eroding North Fork Clear Creek valley. Headwater erosion of the deeper south oriented West Tensleep Creek valley next captured the flood flow and the drainage divide at Florence Pass emerged. South Rock Creek originates in the south center area of figure 7, just north of North Clear Creek, and flows in an east, northeast, north, northeast, north, and northeast direction to the east edge of figure 7 (north half). Bomber Mountain is north of Florence Pass and Diamond Lake is north and east of Bomber Mountain. South Piney Creek originates at Diamond Lake and flows in a northeast and north-northeast direction to Willow Park Reservoir near the north edge of figure 7 (east half). Elk Creek is a north oriented South Piney Creek tributary originating at Elk Lake. A Pack Trail extends from the North Clear Creek valley across the South Rock Creek headwaters and across a pass west of Ant Hill to Elk Lake. THe pass is one of several notches or passes eroded across that drainage divide. The passes west of Ant Hill link the north oriented Elk Creek valley and north-northeast oriented South Piney Creek valley with the east oriented South Rock Creek headwaters valley and the east oriented North Clear Creek valley. While today much lower elevations are located east of Ant Hill at the time the passes were eroded those lower elevations did not exist. Either the region east of Ant Hill has been deeply eroded since that time and/or the Bighorn Mountains have been significantly uplifted since that time to produce the elevation differences seen today. The deepest passes west of Ant Hill have elevations of between 3240 and 3280 meters. Ant Hill rises to 3347 meters suggesting the passes are at least 67 meters deep. South oriented flood flow channels crossing what is today this high Bighorn Mountains region eroded these passes. Study of the high peaks area in the west half of figure 7 reveals many other passes or notches eroded across the high drainage divides. These other passes or notches were also eroded by south and southeast oriented flood flow channels crossing the region at a time when the regional topography looked very different from it does today. Some of the valleys in the high peaks region appear to have been modified by alpine glaciation. The alpine glaciers developed in and modified preexisting valleys after the immense south oriented melt water floods had ended and after the Bighorn Mountains had emerged to become the high mountain range they are today.

Detailed map of Elk Creek-South Rock Creek drainage divide area

Figure 8: Detailed map of Elk Creek-South Rock 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 Elk Creek-South Rock Creek drainage divide seen in less detail in figure 7 above. The map contour interval for figure 8 is 40 feet. Cloud Peak Reservoir is located in the northwest quadrant of figure 8 and South Piney Creek flows in a northeast direction to and through Cloud Peak Reservoir. North of figure 8 South Piney Creek turns to flow in a north-northeast direction. East of Cloud Peak Reservoir is Elk Lake and Elk Creek flows in a north-northeast direction from Elk Lake. North of figure 8 Elk Creek makes a northwest jog and then flows in a north direction to join north-northeast oriented South Piney Creek. South Rock Creek originates in the northeast corner of section 32 (near southwest corner of figure 8) and then flows in a generally east direction near the south edge of figure 8 before turning in a northeast direction to flow to the east edge of figure 8. North Clear Creek flows in an east direction south of figure 8. Ant Hill is located near the center of figure 8 and reaches an elevation 10,980 feet. The Solitude Trail extends from the south edge of figure 8 (west half) across the South Rock Creek headwaters and then across a pass west of Ant Hill to Elk Lake. The pass west of Ant Hill has an elevation of between 10,600 and 10,640 feet, which is 340 feet lower than the top of Ant Hill to the east. Other passes across the ridge west of Ant Hill are also present. South oriented flood flow channels eroded these passes at a time when Ant Hill did not stand high above surrounding regions. Today east of Ant Hill elevations drop sharply and are less than 8400 feet in places along the east edge of figure 8 and with present day topography water south oriented flood west of Ant Hill does not make sense. Yet the passes provide evidence water once flowed in a south direction before being captured by headward erosion of much deeper east and north-northeast oriented valleys. Headward erosion of the North Clear Creek valley and subsequently of the South Rock Creek valley first captured the south oriented flood flow. Next headward erosion of the north-northeast South Piney Creek valley captured the south oriented flood flow and beheaded the flood flow channels to the newly eroded South Rock Creek valley. Floodwaters on the north ends of the beheaded flood flow channels reversed flow direction to create the north oriented Elk Creek drainage route. Apparently the Bighorn Mountains were being uplifted as these captures were taking place and floodwaters were deeply eroding the emerging Bighorn Mountains eastern slope. Study of drainage divide ridges in figure 8 shows the history was considerably more complex than the brief description provided here, although the description provided here provides a brief outline that hopefully identifies a few of the key regional drainage history events.

South Rock Creek-North Clear Creek drainage divide area

Figure 9: South Rock Creek-North Clear Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the South Rock Creek-North Clear Creek drainage divide area east and slightly south of figure 7 and includes a significant overlap area with figure 7. The map contour interval for figure 9 is 20 meters and figure 9 shows a significant segment of the Bighorn Mountains eastern slope with elevations ranging greater than 3500 meters near the west center edge of figure 9 to less than 1600 meters near the northeast corner of figure 9. North Clear Creek flows in an east direction from the west edge of figure 9 (south half) and then makes a southeast jog before turning to flow in an east direction to Lucasta Camp and then to flow near the highway to the east edge of figure 9 (south half). South Rock Creek originates near the west edge of figure 9 (just north of North Clear Creek) and flows in an east, northeast, and north direction to be joined by northeast and southeast oriented Middle Rock Creek and then to flow in a northeast and north direction to the north edge of figure 9 (east of center). North of Lucasta Camp is Hunter Mesa and north of Hunter Mesa are headwaters of east oriented French Creek, which flows to the east center edge of figure 9 and which joins Clear Creek east of figure 9. A north-to-south oriented through valley (north of the Hunter Mesa west end) links a north oriented South Rock Creek tributary valley with the east oriented French Creek valley. The through valley has a floor elevation of between 2380 and 2400 meters. High points on the upland surface east of the through valley reach 2467 meters while elevations west of the through valley rise much higher. These elevations suggest the through valley is at least 67 meters deep. The through valley was probably eroded by south oriented flood flow before the reversal of flood flow on the present day north oriented South Rock Creek alignment (north of the through valley). Flood flow on the south oriented flood flow channel was reversed when headward erosion of the much deeper southeast oriented Rock Creek valley (north and east of figure 9) beheaded the south oriented flood flow channel. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented South Rock Creek drainage route and the north oriented South Rock Creek tributary drainage route. The northeast oriented South Rock Creek valley segment next eroded headward to capture south and southeast oriented flood flow west of the beheaded and reversed flood flow channel alignment. Again this description is simplified and omits a number of steps in the process responsible for various South Rock Creek direction changes and the headward erosion of various South Rock Creek tributary valleys. The Bighorn Mountains were emerging as these flood flow events took place with floodwaters deeply eroding the Bighorn Mountains eastern slope while ice sheet related crustal warping was probably raising the Bighorn Mountains relative to the Powder River Basin floor to the east.

Detailed map of South Rock Creek-French Creek drainage divide area

Figure 10: Detailed map of South Rock Creek-French 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 South Rock Creek-French Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 40 feet. Hunters Mesa is located near the south center edge of figure 10. Paradise Ranch is located in the southwest corner of section 34 north of Hunters Mesa. French Creek flows in an east direction from the Paradise Ranch area to the east edge of figure 10 (south half). South Piney Creek flows in a northeast and north-northeast direction from the west edge of figure 10 (south of center) to the north edge of figure 10 (west of center). Keno Creek originates in section 28 and flows in a north direction to join north-northeast oriented South Piney Creek in section 21. A through valley in the southwest corner of section 27 and the northwest corner of section 34 links the north oriented Keno Creek valley with the east oriented French Creek valley. The through valley floor elevation is between 7840 and 7880 feet. A high point in the southeast corner of section 22 to the northeast reads 8113 feet and elevations in the northeast corner of section 27 exceed 8080 feet suggesting the through valley is at least 100 feet deep and may be even deeper. A subtle northwest to southeast oriented through valley is located in the southeast corner of section 29 and links the South Piney Creek valley with the French Creek valley. This second through valley has a floor elevation of between 8200 and 8240 feet and elevation east of the through valley rise to 8375 suggesting the through valley is at least 135 feet deep. These and similar through valleys in the region appear almost insignificant when compared with the much deeper stream valleys and with the Bighorn Mountains eastern slope. However, these through valleys are water-eroded features and were eroded by south and southeast oriented flood flow that was first captured by headward erosion of the east oriented French Creek valley. At that time the Bighorn Mountains did not stand high above regions the north and west and melt water floods were able to flow to the region in figure 10. The east oriented French Creek valley eroded headward from a deeper south or southeast oriented flood flow channel eroded headward along the Bighorn Mountains eastern flank. Headward erosion of the deep southeast oriented Rock Creek valley next beheaded the south oriented flood flow channel on the present day north oriented Keno Creek-South Piney Creek alignment. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Keno Creek-South Piney Creek drainage route. The northeast oriented South Piney Creek valley (west of Keno Creek) then eroded headward to capture additional south and southeast oriented flood flow moving to what was then the newly eroded and actively eroding French Creek valley. Headward erosion of the northeast oriented South Piney Creek valley ended all flood flow to the French Creek valley.

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.