Abstract:

This essay uses topographic map evidence to interpret landform origins in the region between Buffalo Creek and the South Fork Powder River along the south and southeast flank of the Wyoming Bighorn Mountains. Buffalo Creek is a southeast, northeast, and north-northwest oriented tributary to the northeast oriented Middle Fork Powder River. The Middle Fork Powder River joins the southeast oriented North Fork Powder River and the north-northeast oriented South Fork Powder River to form the north oriented Powder River, which flows to Montana and the northeast oriented Yellowstone River. Significant segments of the Buffalo Creek valley are located in strike valleys bounded by hogback ridges, although Buffalo Creek and Buffalo Creek tributaries have eroded water gaps across some of those hogback ridges. Multiple dry valleys or through valleys link the Buffalo Creek valley with southeast oriented headwaters of South Fork Powder River tributaries. These South Fork Powder River tributaries have also eroded water gaps across hogback ridges. Valley orientation direction changes and barbed tributaries provide additional evidence of multiple capture events. The through valleys, barbed tributaries, valley orientations,valley orientation changes, and water gaps are interpreted in the context of massive south and southeast oriented floods flowing from the Bighorn Basin across the south end of were at that time the emerging Bighorn Mountains to a much deeper north-northeast oriented South Fork Powder River valley. Headward erosion of the deep northeast oriented Middle Fork Powder River beheaded south-southeast oriented flood flow on the present day north-northwest oriented Buffalo Creek segment and floodwaters on the north end of the beheaded flood flow route reversed flow direction to create the north-northwest oriented Buffalo Creek drainage route. The northeast oriented Buffalo Creek valley then eroded headward from this reversed flood flow channel to capture south and southeast oriented flood flow moving west of the actively eroding Middle Fork Powder River valley head. Headward erosion of the northeast oriented Buffalo Creek valley beheaded south and southeast oriented flood flow routes to the north-northeast oriented South Fork Powder River valley. 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 Wyoming at a time when the Bighorn Mountains were emerging. Headward erosion of the deep northeast oriented Yellowstone River valley in Montana beheaded the south and southeast oriented flood flow routes to Wyoming in sequence from east to west. Floodwaters crossing the Powder River Basin were beheaded first and reversed flow direction to create the north oriented and much deeper Powder River drainage system while south and southeast oriented floodwaters still flowed across the emerging Bighorn Mountains and Bighorn Basin to the west. The new and much deeper north oriented Powder River drainage system captured the south and southeast oriented floodwaters crossing the Bighorn Mountains and Bighorn Basin. Subsequently Yellowstone River valley headward erosion beheaded and reversed flood flow across the Bighorn Mountains and in the Bighorn Basin to create the north oriented Bighorn River drainage system and ended all flood flow to the Powder River drainage system. Bighorn Mountains emergence as floodwaters crossed the region probably contributed to flood flow reversal events and to the numerous captures of flood flow channels as this flood flow reversal process took place.

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 Buffalo Creek-South Fork Powder River drainage divide area landform origins in the southern Bighorn Mountains, Wyoming, USA. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big-picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain Buffalo Creek-South Fork Powder River drainage divide area landform evidence in the southern Bighorn Mountains will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Buffalo Creek-South Fork Powder River drainage divide area location map

Figure 1: Buffalo Creek-South Fork Powder 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 Buffalo Creek-South Fork Powder River drainage divide area in the Wyoming southern Bighorn Mountains and illustrates a region in central Wyoming. Casper is the largest city shown and is located in the southeast quadrant of figure 1. The Bighorn Mountains extend in a north to south direction from just north of the Montana border (north of figure 1) into the north center area of figure 1. West of the Bighorn Mountains is the Bighorn Basin, which is drained by the north oriented Bighorn River. The Bighorn River originates as the southeast oriented Wind River, which flows from the west center edge of figure 1 to Riverton and then which turns to flow in a north direction across the east end of the Owl Creek Mountains to enter the Bighorn Basin and to become the Bighorn River. The basin south of the Owl Creek Mountains is known as the Wind River Basin. East of the Bighorn Mountains is the Powder River Basin, which is drained by the north oriented Powder River. The Powder River is formed near Kaycee (north of Casper) at the confluence of the southeast oriented North Fork Powder River and northeast oriented Middle Fork Powder River and then flows in an east direction to be joined by the north-northeast oriented South Fork Powder River. Once formed the Powder River quickly turns to flow in a north direction through the Powder River Basin to the north edge of figure 1 and north of figure 1 in Montana joins the northeast oriented Yellowstone River. Buffalo Creek is an east-southeast, northeast, and north oriented Middle Fork Powder River tributary. The Buffalo Creek-South Fork Powder River drainage divide area investigated in this essay is located along the southeast margin of the Bighorn Mountains and is south and east of Buffalo Creek and west and north of the South Fork Powder River.

Today the Powder River and Bighorn River are north oriented drainage systems, although both rivers have barbed southeast oriented tributaries. The southeast oriented tributaries provide evidence  the Powder River and the Bighorn River drainage systems were both formed during the reversals of immense south and southeast oriented floods. Floodwaters were derived from the western margin of a thick North American ice sheet and were flowing from western Canada to and across Wyoming. At that time mountain ranges seen in figure 1 had not emerged and at least initially floodwaters could freely flow across what are today major mountain barriers. The mountain ranges emerged as floodwaters flowed across them and as the floodwaters deeply eroded surrounding regions. In addition ice sheet related crustal warping uplifted the mountain ranges as the massive ice sheet created a deep “hole” in which the ice sheet was located. In time ice sheet melting opened up space at the south end of the deep “hole”, which drained initially in a south direction using flood flow routes east of figure 1. The deep northeast oriented Yellowstone River valley then eroded headward from the newly opened up space to capture south and southeast oriented melt water floods flowing across Montana (north of figure 1). Headward erosion of the deep northeast oriented Yellowstone River valley beheaded south and southeast oriented flood flow routes to Wyoming in sequence from east to west. Flood flow routes to the emerging Powder River Basin were beheaded before flood flow routes crossing the emerging Bighorn Mountains and Bighorn Basin were beheaded. Floodwaters on north ends of the beheaded flood flow routes reversed flow direction to create north oriented drainage routes and the deep Yellowstone River valley knick point then eroded headward (or in a south direction) along those reversed flood flow channels. The much deeper north oriented valleys then captured south and southeast oriented flood flow moving west of the actively eroding Yellowstone River valley head. The southeast oriented North Fork Powder River provides evidence the newly reversed Powder River drainage route captured southeast oriented flood flow still crossing the emerging Bighorn Mountains. In time Yellowstone River valley headward erosion beheaded and reversed flood flow routes crossing the emerging Bighorn Mountains and Bighorn Basin. Floodwaters on north ends of those beheaded flood flow routes reversed flow direction to create the north oriented Bighorn River drainage route, which captured southeast oriented flood flow channels filled with floodwaters still moving in a south direction west of the actively eroding Yellowstone River valley head (see southeast oriented Wind River and other southeast oriented tributaries in Wind River Basin and in Bighorn Basin).

Detailed location map for Buffalo Creek-South Fork Powder River drainage divide area

Figure 2: Detailed location map Buffalo Creek-South Fork Powder 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 Buffalo Creek-South Fork Powder River drainage divide area in the southern Bighorn Mountains. Kaycee, Wyoming is located near the north edge of the northeast quadrant of figure 2. Barnum is a town west and south of Kaycee also in the northeast quadrant of figure 2. The towns of Madden and Arminto are located along the railroad in the southwest quadrant of figure. The Bighorn Mountains south end is north of railroad and the Bighorn Mountains extend northward from near Cedar Ridge to the north edge of figure 2 and then into southern Montana. The South Fork Powder River flows in a northeast and north-northeast direction from the south center edge of figure 2 to join the east oriented Powder River east of Kaycee. The Powder River then flows to the east edge of figure 2 and just east of figure 2 turns to flow in a north direction. The Middle Fork Powder River originates in the Bighorn Mountains and flows in an east and northeast direction (south of Barnum) to Kaycee where it is joined by the southeast oriented North Fork Powder River to form the east oriented Powder River. Buffalo Creek headwaters are in the Bighorn Mountains (north of Arminto) and include a southeast oriented North Fork (N Fk), east-southeast oriented Middle Fork (Mid Fk), and northeast oriented South Fork (S Fk).  Once formed Buffalo Creek flows in an east-southeast direction and then makes a jog to the south before being joined by northeast oriented Baker Creek and then turning to flow in a northeast, north-northeast, and north-northwest direction to join the Middle Fork Powder River south of Barnum. Spring Creek is a north oriented Buffalo Creek tributary located south of Barnum. Baker Creek is an east-northeast oriented Buffalo Creek tributary and a southeast oriented tributary originates south of South Fork Buffalo Creek. The southeast oriented stream originating directly south of the southeast oriented Baker Creek tributary is the North Fork Cottonwood Creek, which after being joined by the east-southeast oriented South Fork Cottonwood Creek becomes Cottonwood Creek. Cottonwood Creek joins the northeast oriented South Fork Powder River in the south center area of figure 2. Indian Creek is a southeast oriented South Fork Powder River tributary north of Cottonwood Creek. Further north and east Willow Creek is a southeast, north-northeast, and northeast oriented South Fork Powder River tributary with east and northeast oriented Alkali Creek as a tributary. Hackett Creek is an east oriented Alkali Creek tributary. Posey Creek and Murphy Creek are east and northeast oriented South Fork Powder River tributaries north of Willow Creek. West of the North Fork Cottonwood Creek, Baker Creek, and South Fork Buffalo Creek headwaters are the headwaters of southwest, northwest, and southwest oriented Badwater Creek, which flows to the towns of Badwater and Lost Cabin and west of figure 2 flows in a west direction to join the north oriented Wind River (which becomes the Bighorn River). North and west of the Bighorn Mountains in the northwest region of figure 2 is the southern end of the north and northwest oriented Nowood River drainage basin. North and west of figure 2 the Nowood River joins the Bighorn River. The Bighorn Mountains as seen in figure 2 form the drainage divide between the Powder River drainage basin to the east and south and the Bighorn River drainage basin to the west and north.

Middle Fork Powder River-Murphy Creek drainage divide area

Figure 3: Middle Fork Powder River-Murphy Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of Middle Fork Powder River-Murphy Creek drainage divide area. The map contour interval for figure 3 is 20 meters. The east-facing Bighorn Mountains slope can be seen near the west edge of figure 3 with a north-northwest to south-southeast oriented through valley located along its base. The town of Barnum is located in the through valley. Buffalo Creek flows in a north-northwest direction from the south edge of figure 3 in the through valley to near Steamboat Rock where it joins the northeast oriented Middle Fork Powder River. Beaver Creek flows in a southeast direction from the northwest corner of figure 3 to the through valley and then flows in a south-southeast direction on the through valley floor to Barnum where it turns to flow in an east direction to join the Middle Fork Powder River. Blue Creek flows in an east and northeast direction from the west edge of figure 3 (north of center) to join Beaver Creek near Barnum. Sheep Creep flows in an east-southeast direction from the west center edge of figure 3 to the through valley and then flows in a northeast direction to join the Middle Fork Powder River near Castle Rock. The Middle Fork Powder River flows in an east-northeast direction from the west edge of figure 3 to the through valley near Steamboat Rock and then turns to flow in a northeast, east, and northeast direction to the northeast corner of figure 3. Today the through valley is crossed by several streams and is also used by streams flowing in opposite directions, yet it is a continuous through valley. While the through valley follows the strike of a nonresistant stratigraphic layer the through valley is also a water-eroded valley and was eroded by south-southeast oriented flood flow prior to headward erosion of the Middle Fork Powder River valley. Headward erosion of the Middle Fork Powder River valley and its tributary valleys (especially the Beaver Creek valley) captured the south-southeast oriented flood flow. Floodwaters on the north end of the beheaded south-southeast oriented flood flow channel reversed flow direction to flow to the deeper northeast oriented Middle Fork Powder River valley and to form the north-northwest oriented Buffalo Creek drainage route. Murphy Creek flows in a northeast direction near the southeast corner of figure 3 and east of figure 3 joins the north-northeast oriented South Fork Powder River. Note how north to south oriented through valleys link the northeast oriented Middle Fork Powder River valley with the northeast oriented Murphy Creek valley. These through valleys are also located between hogback ridges, but they are water-eroded valleys and were eroded by south oriented flood flow captured by headward erosion of the Murphy Creek valley. Later Middle Fork Powder River valley headward erosion beheaded the flood flow channels to the newly eroded Murphy Creek valley and floodwaters on north ends of the beheaded flood flow routes reversed flow direction to create north oriented Middle Fork Powder River tributary routes.

Buffalo Creek-South Fork Powder River drainage divide area

Figure 4: Buffalo Creek-South Fork Powder River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a topographic map of the Buffalo Creek-South Fork Powder River drainage divide area south and east of figure 3 and includes an overlap area with figure 3. The map contour interval for figure 4 is 20 meters. The through valley at the base of the Bighorn Mountains eastern slope is located west of the Red Wall seen near the west margin of figure 4. Beaver Creek flows in a northeast direction from the west center edge of figure 4 to the through valley and then turns to flow in a north-northwest direction to the northwest corner of figure 4. Spring Creek originates at Lake Spring in the through valley (near south edge of figure 4) and flows in a north direction to join Buffalo Creek. The South Fork Powder River flows (meanders) in a north and north-northeast direction from the south edge of figure 4 (east half) to near the northeast corner of figure 4. Willow Creek flows in a north-northeast, east, north, east, and northeast direction from the south edge of figure 4 (west of center) to join the north oriented South Fork Powder River. North of Willow Creek Posey Creek originates east of the Red Wall and flows in an east direction (just south of the center of figure 4) to join the north oriented South Fork Powder River. North of Posey Creek Murphy Creek originates north of the words “Hole-in-the-Wall” and flows in an east-northeast and northeast direction to the north edge of figure 4 and joins the South Fork Powder River north and east of figure 4. Note the broad north-to-south oriented through valley extending from the north edge of figure 4 to the south edge of figure 4 in the east half of figure 4. The South Fork Powder River flows in a north direction along that through valley’s east wall, but then turns to flow in a north-northeast direction through a water gap eroded across the north end of Tisdale Mountain. Frewens Castle is on the northwest side of the water gap. The water gap is more than 160 meters deep and the through valley linking the northeast oriented Murphy Creek valley and the north-northeast oriented South Fork Powder River valley is approximately 200 meters deep (based on present day nearby elevations). The through valley provides evidence of converging south oriented flood flow channels prior to the reversal of flood flow that created the north and north-northeast oriented South Fork Powder River drainage route. Reversed flood flow on the north-northeast oriented South Fork Powder River segment then captured southeast oriented flood flow in the through valley west of Frewens Castle. Headward erosion of the northeast oriented Murphy Creek valley then captured the flood flow with headward erosion of the Middle Fork Powder River valley (north of figure 4) capturing the flood flow and ending flood flow to the newly created Murphy Creek valley.

Willow Creek-South Fork Powder River drainage divide area

Figure 5: Willow Creek-South Fork Powder River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Willow Creek-South Fork Powder River drainage divide area south of figure 4 and there is an overlap area with figure 4. The map contour interval for figure 5 is 20 meters. Note how the hogback ridges are curving in the southwest quadrant of figure 5. The South Fork Powder River flows in a north direction near the east edge of figure 5. The Red Wall is located in the northwest quadrant of figure 5. Spring Creek flows in a north direction from Lake Spring in the valley directly west of the Red Wall. South of Lake Spring the through valley is drained by a south oriented tributary to east, southeast, and south oriented Lost Creek, which joins Willow Creek near the Landing Strip. South and east oriented Big Willow Creek joins southeast and northeast oriented Little Willow Creek near the Landing Strip to form Willow Creek. Once formed Willow Creek flows in an east direction through a water gap eroded across the hogback ridge forming the through valley east wall and is joined by north-northeast oriented Alkali Creek before Willow Creek turns to flow in a north-northeast, east, north-northeast, east, and northeast direction to the north edge of figure 5. Willow Creek has eroded additional water gaps across hogback ridges in the north center area of figure 5. These water gaps provide evidence the Willow Creek alignment was established at a time when the hogback ridges did not exist. Either the hogback ridges were buried under easily eroded bedrock material that has since been eroded away or the regional structures responsible for the hogback ridges were formed as the floodwaters flowed across the region. Floodwaters initially flowed in a south direction and the north-northeast oriented Alkali Creek-Willow Creek valley segment was initially a south-southwest oriented flood flow channel. The through valley west of the Red Wall was a converging south oriented flood flow channel and the South Fork Powder River valley in the east half of figure 5 also originated as a south oriented flood flow channel. The reversal of flood flow in the Powder River Basin (caused by headward erosion of the deep northeast oriented Yellowstone River valley from space being opened up in the deep “hole” the melting ice had occupied) first reversed flood flow on the South Fork Powder River alignment. That reversal of flood flow led to the reversal of flood flow on the Willow Creek and Alkali Creek alignments and the reversed flood flow then captured south and southeast oriented flood flow on the Big and Little Willow Creek headwaters alignments. Included in that captured flood flow was south oriented flood flow on the present day north oriented Spring Creek (and Buffalo Creek north of figure 5) alignment. Headward erosion of the Middle Fork Powder River valley north of figure 4 (see figure 3) beheaded and reversed the flood flow route on the Buffalo Creek-Spring Creek alignment to create the north oriented Spring Creek and Buffalo Creek drainage routes seen today. Crustal warping was probably occurring as these flood flow captures took place and may have aided in the flood flow reversals.

Detailed map of Spring Creek-Lost Creek drainage divide area

Figure 6: Detailed map of Spring Creek-Lost 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 Spring Creek-Lost Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 20 feet. The north to south oriented ridges in figure 6 are hogback ridges formed by resistant stratigraphic units, which are dipping in an east direction, and the region is located along the Bighorn Mountains eastern margin. Lake Spring is located west of the Red Wall in the northwest quadrant of figure 6 and Spring Creek flows in a north direction from Lake Spring to the north edge of figure 6 and joins north-northwest oriented Buffalo Creek north of figure 6. The south oriented stream originating near Lake Spring is a south oriented tributary to Lost Creek, which flows in an east-southeast and south direction from the west edge of figure 6 (south half) to the south edge of figure 6 (in the through valley). South of figure 6 Lost Creek joins east oriented Willow Creek, which after eroding a deep water gap across the hogback ridge forming the Lost Creek valley east wall turns to flow in a north-northeast direction to the south center edge of figure 6 and then to the southwest corner of section 1 (in northeast quadrant of figure 6) where it turns to flow in an east direction across the hogback ridge in the east half of figure 6 before resuming its north-northeast direction to near the northeast corner of figure 6. North and east of figure 6 Willow Creek flows to the north-northeast oriented South Fork Powder River. North of the Willow Creek water gap in section 1 is the Poodle Dog Creek water gap eroded across the same hogback ridge. Poodle Dog Creek is an east oriented Willow Creek tributary and south of Poodle Dog Creek is east oriented Cottonwood Creek, which flows to the north-northeast oriented Willow Creek valley. The east oriented Poodle Dog Creek, Cottonwood Creek, Willow Creek, and other east oriented stream valleys were eroded by east oriented flood flow moving to what was probably a south oriented flood flow channel on the present day north-northeast oriented Willow Creek alignment. At that time the deep through valley west of the Red Wall did not exist. Headward erosion of a deep south-oriented flood flow channel eroded the valley west of the Red Wall. Headward erosion of the deep northeast oriented Yellowstone River valley in Montana beheaded flood flow routes to the Powder River Basin. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to create the north oriented Powder River drainage system. The reversal of flood flow on the South Fork Powder River alignment (east of figure 6) caused the reversal of flood flow on the Willow Creek alignment, which captured south oriented flood flow on the Spring Creek-Lost Creek through valley alignment. Headward erosion of the northeast oriented Middle Fork Powder River valley north of figure 6 (see figure 3) then beheaded the south oriented flood flow channel on the Spring Creek-Lost Creek through valley alignment. Floodwaters on the north end of the beheaded flood channel reversed flow direction to create the Spring Creek-Lost Creek drainage divide seen near Lake Spring in figure 6.

Buffalo Creek-Willow Creek drainage divide area

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

Figure 7 illustrates the Buffalo Creek-Willow Creek drainage divide area west of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 20 meters. The southeast-facing slope in the northwest region of figure 7 is the Bighorn Mountains southeast slope. Buffalo Creek flows in an east-southeast direction from the west edge of figure 7 (south half) to the deep north-northeast oriented valley at the base of the Bighorn Mountains southeast slope and then turns to flow in a north-northeast direction to the north center edge of figure 7. Baker Creek is the east-northeast oriented stream joining Buffalo Creek at the point where Buffalo Creek enters the deep valley on the northwest side of the Grey Wall. The Island is an erosional residual on the east side of the Buffalo Creek valley north of the center of figure 7. Little Willow Creek originates just south of The Island and flows in a southeast, south-southeast, east, and northeast direction to join Big Willow Creek near the Landing Strip (located near the east center edge of figure 7) and to form east and north-northeast oriented Willow Creek. Big Willow Creek originates near Cow Spring Butte (east of The Island) and flows in a south and east direction to join Little Willow Creek and to form Willow Creek. Remember Lost Creek flows in a south direction to join Willow Creek near the Landing Strip and is located in a through valley drained by north oriented Spring Creek (west of the Red Wall near the northeast corner of figure 7). A deep northwest to southeast oriented through valley between the The Island and Cow Spring Butte provides evidence of a southeast oriented flood flow channel that was captured by headward erosion of the Little Willow Creek valley (probably from a reversed flood flow channel on the north-northeast oriented Willow Creek alignment seen in figure 5). The through valley floor elevation is between 1800 and 1820 meters. Cow Spring Butte rises to more than 1980 meters and elevations greater than 2000 meters are found south of The Island. These elevations suggest the through valley is at least 160 meters deep. The shape of landforms in the region surrounding The Island suggests that for a time a northeast oriented flood flow channel may have converged with a south-southwest oriented flood flow to form a southeast and east oriented flood flow channel that supplied floodwaters to the north-northeast oriented Willow Creek valley (seen in figure 5). Other interpretations are possible, but whatever interpretation is used there is no question that large volumes of southeast oriented flood flow once moved from the Buffalo Creek valley to the Little Willow Creek headwaters valley.

Detailed map of Buffalo Creek-Little Willow Creek drainage divide area

Figure 8: Detailed map of Buffalo Creek-Little Willow 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 Buffalo Creek-Little Willow Creek drainage divide seen in less detail in figure 7 above. The map contour interval for figure 8 is 20 feet. Buffalo Creek flows in a north-northeast direction from near the southwest corner of figure 8 to the north edge of figure 8 (west half). Little Willow Creek originates in the northeast corner of section 21 (south of The Island) and flows in a southeast and south-southeast direction to the south edge of figure 8 (in section 25 near southeast corner of figure 8). A through valley in section 15 (east of The Island) links a northwest oriented Buffalo Creek tributary valley with a south-southeast oriented Little Willow Creek tributary valley. The through valley floor elevation is between 6020 and 6040 feet. Cow Butte in section 14 to the east rises to more than 6500 feet and elevations in section 29 to the southwest rise to 6572 feet (near south edge of figure 8). These elevations suggest the through valley is at least 460 feet deep. The through valley was probably eroded by southeast oriented flood flow moving from the present day north-northeast oriented Buffalo Creek valley to the southeast and south-southeast oriented Little Willow Creek valley. The reversal of flood flow in the Buffalo Creek valley probably ended flood flow to the Little Willow Creek valley. A second through valley can be seen in section 21 south of The Island and also links the Little Willow Creek headwaters with a northwest oriented Buffalo Creek valley. The through valley floor elevation is 6051 feet suggesting the through valley may be as much as 450 feet deep. This second through valley is much narrower and for a time may have been used by east oriented flood flow moving from the Buffalo Creek valley to the Little Willow Creek valley. It is also possible the second through valley was eroded by a diverging and converging southwest oriented flood flow channel on the southeast side of The Island, which was subsequently reversed to flow in an east direction as the deeper Little Willow Creek valley eroded headward into the region and captured the flood flow. Probably the final flood flow movement was to the Little Willow Creek valley and that flood flow ended when headward erosion of the Middle Fork Powder River valley north of figure 8 beheaded and reversed flood flow in the Buffalo Creek valley. The deeper Middle Fork Powder River valley knick point then eroded headward along the reversed Buffalo Creek alignment and beheaded east and southeast oriented flood flow to the Little Willow Creek valley.

Baker Creek-Cottonwood Creek drainage divide area

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

Figure 9 illustrates the Baker Creek-Cottonwood Creek drainage divide area south and west of figure 7 and includes an overlap area with figure 7. The map contour interval for figure 9 is 20 meters. Baker Creek originates in the north center area of figure 9 and flows in an east-northeast direction along the north side of the Red Wall to the north edge of figure 9 (east half). First Water Creek (“Water Creek” in figure 9) is a southeast oriented Baker Creek tributary. West and south of First Water Creek is southeast oriented Sanchez Creek, which joins southeast, east-northeast and southeast oriented North Cottonwood Creek near the Baker Creek headwaters. Cottonwood Creek originates south of North Cottonwood Creek and flows in an east direction until it is joined by southeast oriented North Cottonwood Creek (west of Three Buttes). After being joined by North Cottonwood Creek Cottonwood Creek turns to flow in a south-southeast and south direction and then in a southeast direction (south of Cottonwood Rim) to the east edge of figure 9. East and south of figure 9 Cottonwood Creek joins the north-northeast oriented South Fork Powder River. Headward erosion of the southeast oriented North Fork Cottonwood Creek valley appears to have beheaded the east-northeast oriented Baker Creek valley, which had previously been beheaded by headward erosion of the east oriented Cottonwood Creek valley. The southeast oriented Cottonwood Creek valley and its tributary North Cottonwood Creek valley were probably eroded by southeast oriented flood flow flowing across the south end of the Bighorn Mountains from the Bighorn Basin to the newly reversed and much deeper South Fork Powder River valley. East-northeast oriented flood flow in the Baker Creek valley may have initially flowed to the Little Willow Creek valley as seen in figure 7 and 8. Further complicating flood flow movements in the region seen in figure 9 are drainage routes near the west edge of figure 9. The south oriented stream flowing from near Deadman Butte to the south edge of figure 9 is E K Creek, which south of figure 9 turns to flow in a west and northwest direction as Alkali Creek, which eventually joins west oriented Badwater Creek. Badwater Creek flows south of the mountains in a west direction to the north oriented Wind River, which then flows through Wind River Canyon across the Owl Creek Mountains to the Bighorn Basin where the Wind River names changes to become the Bighorn River. Badwater Creek headwaters are located near the west edge of figure 9 and are flowing in a southwest direction (west of Deadman Butte). The present day west oriented Badwater Creek and Alkali Creek alignments originated as east oriented flood flow routes from the Wind River Basin area (west of figure 9) to the newly reversed and at that time much deeper north oriented Powder River drainage system (which was beheaded and reversed before flood flow in Bighorn and Wind River Basins was beheaded and reversed). At that time south and southeast flood flow was entering the Wind River Basin from the Bighorn Basin and also from west of Bighorn Basin and at least some that flood flow was captured by the reversal of flood flow in the Powder River Basin. Headward erosion of the deep Yellowstone River valley in Montana in time beheaded and reversed the flood flow routes to the Wind River Basin that were moving  across the Bighorn Basin and the Wind River Basin was then drained in a north direction through Wind River Canyon and that reversed flood flow route then captured the large volumes of flood flow still moving into the Wind River Basin area from west of the Bighorn Basin. That flood flow capture by reversed flow through Wind River Canyon resulted in further erosion of the Wind River Basin floor to create the Wind River Basin topography seen today.

Detailed map of Baker Creek-North Fork Cottonwood Creek drainage divide area

Figure 10: Detailed map of Baker Creek-North Fork Cottonwood 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 Baker Creek-North Fork Cottonwood Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 20 feet. This is a region of southeast dipping hogback ridges along the Bighorn Mountains southeast flank. Baker Creek flows in an east direction across the south margin of section 15 and then turns to flow in an east-northeast direction to the northeast corner of figure 10. North Cottonwood Creek flows in a northeast from the west edge of figure 10 (near southwest corner) across section 21 and into section 22 where it turns to flow in a southeast direction to the south edge of figure 10. Note how North Cottonwood Creek has eroded a series of valleys across the hogback ridge south of the northeast oriented North Fork Cottonwood Creek-Baker Creek through valley. Elevations of the North Fork Cottonwood Creek valley floor in the present day water gap range from 6600 feet to 6400 feet. The high point on the hogback ridge in section 23 is 6941 feet and an elevation greater than 6920 feet can be found near the southwest corner of section 22. These elevations suggest the water gap is 300 to 500 feet deep (depending on how it is viewed). Surrounding the present day water gap are several dry through valleys. For example Cottonwood Road is located in a through valley in the east half of section 23. These through valleys provide evidence of multiple south and southeast oriented flood flow channels that once crossed the region. These south and southeast oriented flood flow channels converged in the Cottonwood Creek valley south and east of figure 10, which had eroded valleys across additional hogback ridges south and east of figure 10. The Cottonwood Creek valley and North Cottonwood Creek valleys eroded headward from the deep north-northeast oriented South Fork Powder River valley to capture yet to be beheaded and reversed south and southeast oriented flood flow that had crossed the Bighorn Basin to reach the region seen in figure 10. The south and southeast oriented flood flow was moving across the south end of what were then the emerging Bighorn Mountains to the newly reversed and much deeper north oriented Powder River drainage routes. Headward erosion of the slightly deeper North Fork Cottonwood Creek valley beheaded what was probably a east-northeast diverging flood flow channel on the present day Baker Creek alignment and which was probably moving floodwaters to the southeast oriented Little Willow Creek headwaters area seen in figure 7 and 8.

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.