Abstract:

This essay uses topographic map evidence to interpret landform origins in the region between Middle Fork Powder River and Buffalo Creek in the Wyoming southern Bighorn Mountains. The Middle Fork Powder River originates in the southern Bighorn Mountains along the asymmetric Bighorn River-Powder River drainage divide and flows in a north, northeast, east, and northeast direction to join the north oriented Powder River east of the Bighorn Mountains. The Middle Fork Powder River has eroded a deep canyon across the Bighorn Mountains upland surface. Buffalo Creek headwaters are located immediately south of the Middle Fork Powder River headwaters and also are located along the asymmetric Bighorn River-Powder River drainage divide. Buffalo Creek flows in a southeast, northeast, north-northeast, and north-northwest direction to join the northeast oriented Middle Fork Powder River. Through valleys link the Middle Fork Powder River headwaters valleys with the Buffalo Creek headwaters valleys and also with valleys of west, northwest, and north oriented Bighorn River tributaries. Through valleys also link Buffalo Creek headwaters valleys with west oriented streams south of the mountains and with southeast oriented streams to the north-northeast oriented South Fork Powder River. The through valleys, asymmetric drainage divide, barbed tributaries, and deep canyons are interpreted to have been formed by a complex of east oriented diverging and converging flood flow channels crossing the southern Bighorn Mountains. Floodwaters were derived from the western margin of a thick North American ice sheet and were flowing from western Canada to and across Wyoming. Initially the Bighorn Mountains had not emerged and floodwaters could freely flow what is today a high mountain range. The Bighorn Mountains emerged as floodwaters deeply eroded surrounding regions and as ice sheet crustal warping raised the Bighorn Mountains. Ice sheet related crustal warping created a deep “hole” in which the ice sheet was located and the Bighorn Mountains region could be considered a warped and deeply eroded segment of the deep “hole’s” southwest rim.  Ice sheet melting opened up space in the deep “hole’s” southern end and the deep northeast oriented Yellowstone River valley then eroded headward across Montana from that newly opened up space to capture the south and southeast oriented flood flow. Floodwaters on north ends of beheaded flood flow routes reversed flow direction to create north oriented drainage routes. Yellowstone River valley headward erosion beheaded flood flow routes in sequence and flood flow in the Powder River Basin was beheaded and reversed first and the reversed flood flow captured south oriented flood flow still moving west of the emerging Bighorn Mountains. This captured flood flow then moved in an east direction across the southern Bighorn Mountains to the newly created and much deeper north oriented Powder River drainage system. Headward erosion of the Yellowstone River valley subsequently beheaded and reversed flood flow in the Bighorn Basin, which captured south oriented flood flow from still further west. The reversed flood flow created the north oriented Bighorn River drainage basin and created the present day asymmetric Bighorn River-Powder River drainage divide, which ended all east oriented flood flow to the Powder River drainage basin.

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 Middle Fork Powder River-Buffalo Creek drainage divide area landform origins in the Wyoming southern 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 Middle Fork Powder River-Buffalo Creek drainage divide area landform evidence in the Wyoming southern Bighorn Mountains will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

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

Figure 1: Middle Fork Powder River-Buffalo 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 Middle Fork Powder River-Buffalo Creek 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 near the south edge of figure 1. The Bighorn Mountains extend in a north to south direction from north of the north center edge of figure 1 to south of Buffalo Creek. The Bighorn Basin is located west of the Bighorn Mountains and is drained by the north oriented Bighorn River. The Powder River Basin is located east of the Bighorn Mountains and is drained by the north oriented Powder River. The Powder River is formed east of Kaycee at the confluence of the southeast oriented North Fork Powder River and northeast oriented Middle Fork Powder River and the flows in an east direction and is joined by the north-northeast oriented South Fork Powder River before turning to flow in a north direction to the north edge of figure 1. North of figure 1 the Powder River joins the northeast oriented Yellowstone River in southeast Montana. The Middle Fork Powder River originates near the south end of the Bighorn Mountains and flows in a northeast direction to join the North Fork Powder River near Kaycee. Buffalo Creek is a Middle Powder River tributary and originates slightly south of the Middle Fork Powder River headwaters and then flows in an east-southeast, northeast, and north direction to join the Middle Powder River. West of the Middle Powder River headwaters is the northeast, north-northwest, and northwest oriented Nowood River, which flows to the north oriented Bighorn River. Slightly south and west of the Buffalo Creek headwaters are headwaters of an unnamed southwest, northwest, southwest oriented stream flowing to near Lyesite where it joins a west oriented stream flowing to the north oriented Wind River at Boysen Reservoir (the Wind River becomes the Bighorn River near Thermopolis). The Middle Fork Powder River-Buffalo Creek drainage divide area investigated in this essay is located south and east of the Middle Fork Powder River and north and west of Buffalo Creek.

Today the Powder River and the Bighorn River are north oriented rivers flowing to the northeast oriented Yellowstone River in Montana (north of figure 1). While most drainage routes seen in figure 1 are north oriented barbed tributaries flow in southeast directions to join both the north oriented Powder River and Bighorn River. These barbed tributaries provide evidence the north oriented drainage systems evolved during a reversal of south and southeast oriented flood flow across the region. The south and southeast oriented floodwaters were derived from the western margin of a thick North American ice sheet and were flowing from western Canada to and across the region in figure 1. Initially the Bighorn Mountains and other regional mountain ranges had not emerged and floodwaters could easily flow across what are today high mountain barriers. The Bighorn Mountains emerged as deep south-oriented flood flow channels eroded headward into the Powder River Basin to the east and subsequently into the Bighorn Basin to the west. Also ice sheet related crustal warping raised the Bighorn Mountains as floodwaters flowed across them. The crustal warping occurred as the ice sheet created a rim around the deep “hole” in which the ice sheet was located. The region in figure 1 could be considered to be a segment of the deep “hole’s” warped and deeply eroded southwest rim. The flood flow reversal occurred when ice sheet melting began to open up space at the south end of the deep “hole”, which was initially drained in a south direction along 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 the south and southeast oriented melt water floods moving across Montana. Flood flow routes to Wyoming were beheaded by headward erosion of the much deeper Yellowstone River valley in sequence from east to west with flood flow routes to the Powder River Basin being beheaded first. Floodwaters on north ends of the beheaded flood flow routes reversed flow direction to create north oriented drainage routes, which then captured south and southeast oriented flood flow from west of the actively eroding Yellowstone River valley head. The Powder River drainage route captured south and southeast oriented flood flow still moving across what were then the emerging Bighorn Mountains and the southeast oriented North Fork Powder River provides evidence of that capture. The north oriented Powder River also captured east oriented floodwaters flowing south of the emerging Bighorn Mountains. Today one of those former east oriented flood flow routes is shown by the west oriented Wind River tributary flowing from Arminto to Lyesite and then to Boysen Reservoir. Flow along that tributary’s alignment was reversed when Yellowstone River valley headward erosion beheaded and reversed flood flow routes crossing the Bighorn Basin, which created the north oriented Bighorn River drainage route, which in turn captured various southeast oriented flood flow on the southeast oriented flood flow channels as well as beheading and reversing the east oriented flood flow channel to the north-northeast oriented South Fork Powder River valley.

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

Figure 2: Detailed location map Middle Fork Powder River-Buffalo 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 Middle Fork Powder River-Buffalo Creek drainage divide area in the Wyoming southern Bighorn Mountains. The southern end of the Bighorn Mountains extends from near the southwest corner of figure 2 to the north edge of figure 2 and is labeled. Kaycee is a town located near the northeast corner of figure 2. The Middle Fork Powder River flows in an east and northeast direction from the Bighorn Mountains to Kaycee and then turns to flow in an east direction to join the southeast oriented North Fork Powder River near the east edge of figure 2. Beaver Creek is a northeast, southeast, south-southeast, and east oriented stream originating north of the Middle Fork Powder River in the Bighorn Mountains and flows through the town Barnum. Blue Creek is an east oriented tributary also originating in the Bighorn Mountains and joins Beaver Creek near Barnum. Buffalo Creek originates in the Bighorn Mountains in the southwest quadrant in figure 2 at the confluence of its North Fork (labeled N Fk), Middle Fork (Mid Fk), and South Fork (S Fk) and then flows in an east-southeast direction to be joined by southeast and northeast oriented Baker Creek and then to flow in a northeast, north, and northeast direction to join the Middle Fork Powder River south of Barnum. Badwater is a town located near the southwest corner of figure 2. Badwater Creek flows in a southwest, northwest, and west direction through the town of Badwater to the east edge of figure 2 (just north of Cedar Ridge) and west of figure 2 flows to the north oriented Wind River (which becomes the north oriented Bighorn River). South of the Baker Creek headwaters (which are immediately east of the Badwater Creek headwaters and south of the Buffalo Creek headwaters are headwaters of southeast oriented North Fork Cottonwood Creek, which flows to the north-northeast oriented South Fork Powder River. The unlabeled northeast and north oriented river flowing from the west center edge of figure 2 to the north edge of figure 2 (west of the Bighorn Mountains) is the Nowood River, which north of figure 2 turns to flow in a northwest direction to join the north oriented Bighorn River. While this essay focuses on the region between the Middle Fork Powder River and Buffalo Creek it is important to recognize that the reversal of flood flow in the Powder River Basin east of the Bighorn Mountains occurred before the reversal of flood flow in the Bighorn Basin to the west. The newly reversed and much deeper north oriented Powder River drainage route was able to capture significant volumes of floodwaters from the west of what were at that time the emerging Bighorn Mountains. At first these captured floodwaters flowed across the south end of the Bighorn Mountains to erode the Middle Fork Powder River and Buffalo Creek valleys. As the Bighorn Mountains emerged a deeper east oriented flood flow channel at the south end of the Bighorn Mountains moved floodwaters in an east direction on the present day west oriented Badwater Creek alignment to the North Fork Cottonwood Creek alignment (and also along flood flow channels south of figure 2) to reach what was then the actively eroding north-northeast oriented South Powder River valley.

Beaver Creek-Middle Fork Powder River drainage divide area

Figure 3: Beaver Creek-Middle Fork Powder River 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 Beaver Creek-Middle Fork Powder River drainage divide area. The map contour interval for figure 3 is 20 meters. The deeply eroded Bighorn Mountains upland surface is located in the west half of figure 3 with high elevations generally in the 2300 to 2400 meter range. Bighorn Mountains north of figure 3 are generally higher with the highest Bighorn Mountains peaks approximating 4000 meters in height. East of the Bighorn Mountains upland surface is the east-facing Bighorn Mountains slope (probably reflecting the dip of sedimentary strata) with elevations in the north to south oriented through valley at the base being approximately 1600 meters. The Middle Fork Powder River flows in an east and east-northeast direction from the west edge of figure 3 (near southwest corner) to a deep canyon between the North River Slope and the South River Slope before turning to flow in a northeast direction between Castle Rock and Steamboat Rock to the east edge of figure 3 (north of center). The north-northwest oriented stream joining the Middle Fork Powder River near Steamboat Rock is Buffalo Creek. The southeast oriented stream flowing from the west edge of figure 3 to join the Middle Fork Powder River is Sullivan Creek. North of the Sullivan Creek headwaters are headwaters of northeast oriented Beaver Creek, which flows to the north center edge of figure 3 and which then turns to flow in a southeast and south-southeast direction to Barnum where it turns to flow in an east direction to join the Middle Fork Powder River near the east edge of figure 3. Blue Creek originates as a southeast oriented stream between the Beaver Creek and Sullivan Creek headwaters and then turns to flow in a northeast, east, and east-northeast direction (just south of Horse Pasture Ridge) to join Beaver Creek near Barnum. Note how through valleys link the diverging Beaver Creek, Blue Creek, and Middle Fork Powder River valleys in the southwest quadrant of figure 3. Also note how these diverging valleys then converge near Barnum and east of Barnum. These diverging and converging valleys form what was at one time an east oriented anastomosing channel complex moving floodwaters from west of the Bighorn Mountains to east of the Bighorn Mountains. What is even more intriguing is this convergence ignores a deep north-northwest to south-southeast oriented through valley drained north of Barnum by south-southeast oriented Beaver Creek segment and drained south of Steamboat Rock by north-northwest oriented Buffalo Creek. The through valley is a strike valley probably eroded along a nonresistant stratigraphic unit, but is also a water-eroded valley and was eroded by south-southeast oriented flood flow. The south-southeast oriented flood flow was captured by headward erosion of Middle Fork Powder River valley and floodwaters on the north-northwest end of the beheaded flood flow channel reversed flow direction to create the north-northwest oriented Buffalo Creek drainage route. After some steps omitted in this brief overview headward erosion of the east oriented Beaver Creek valley captured the south-southeast oriented flood flow and beheaded the south-southeast oriented flood flow channel. These captures may have been aided by crustal warping that was raising the Bighorn Mountains as floodwaters flowed across the region and/or the captures could reflect the shorter route the Middle Fork Powder River valley has to reach the north oriented Powder River valley than the route floodwaters moving along other routes had to take. In either case at the time the captures took place large volumes of water were flowing in an east direction across the Bighorn Mountains to the converge in the Middle Fork Middle Powder River valley east of the emerging mountains.

Detailed map of Blue Creek-Middle Fork Powder River drainage divide area

Figure 4: Detailed map of Blue Creek-Middle Fork Powder River 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 Blue Creek-Middle Fork Powder River drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 40 feet. Sullivan Creek flows in a southeast direction across the southwest corner of figure 4 and joins the Middle Fork Powder River just south of figure 4. The Middle Fork Powder River flows in an east-northeast and east direction from the south edge of figure 4 (in section 21) to the east edge of figure 4 (near southeast corner). Blue Creek flows in a southeast direction from the northwest corner of figure 4 into section 9 and then turns to flow in a northeast direction to the north edge of figure 4 (north of section 10). The South Prong flows in a northeast direction from section 17 to join Blue Creek in section 9. An unnamed east oriented Middle Fork Powder River tributary flows from section 17 to the east edge of section 15 and then turns to flow in a south direction to join the Middle Fork Powder River in section 22. A north to south oriented through valley in sections 9 and 16 links the east and south oriented Middle Fork Powder River tributary valley with the Blue Creek U-turn. The through valley floor elevation at the lowest point is between 7280 and 7320 feet. Elevations west of the through valley rise to more than 8040 feet while elevations east of the through valley exceed 7600 feet. These elevations suggest the through valley is approximately 300 feet deep. The through valley is a water-eroded valley and provides evidence of diverging and converging flood flow channels at what is today the west end of the Middle Fork Powder River drainage basin. Remember from figure 3 how in this area the Blue Creek valley is linked to the Beaver Creek valley and how east of the Bighorn Mountains east-facing slope Beaver Creek and Blue Creek converge and then converge with the Middle Fork Powder River.

Middle Fork Powder River-Eagle Creek drainage divide area

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

Figure 5 illustrates the Middle Fork Powder River-Eagle Creek drainage divide area south and slightly west of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 20 meters. The deeply eroded Bighorn Mountains upland surface is located in the west half of figure 5 and east of that upland surface is the Bighorn Mountains eastern slope. The Middle Fork Powder River flows in a northeast direction from the west center edge of figure 5 and the turns to flow in an east-northeast, east, and east-northeast direction to near the northeast corner of figure 5. Bar C Creek is the northwest oriented tributary joining Middle Fork Powder near the west center edge of figure 5. Note the deep Middle Fork Powder River canyon eroded into the Bighorn Mountains upland surface. Bachaus Creek is an east, north, and northeast oriented tributary flowing to the east oriented Middle Fork Powder River canyon. Buffalo Creek flows in a northeast, east, north and northeast direction in the southeast corner region of figure 5 and then reappears in figure 5 and flows in a north-northwest direction near the northeast corner of figure 5 and joins the Middle Fork Powder River just north of figure 5. Eagle Creek originates near Kidd Flat (north of southwest corner of figure 5) and flows in an east direction to join Buffalo Creek near the southeast corner of figure 5. Poker Creek is an east, northeast, east, and northeast oriented Buffalo Creek tributary originating south of the Bachaus Creek headwaters and flowing to the north-northwest oriented Buffalo Creek segment near the northeast corner of figure 5. Note how a through valley links the north oriented Bachaus Creek valley with the east oriented Poker Creek valley. The through valley floor elevation is between 2320 and 2340 meters. Elevations on both sides of the through valley exceed 2400 meters suggesting the through valley is at least 60 meters deep. Even more intriguing are through valleys near Kidd Flat linking the northwest oriented Bar C Creek valley with the east oriented Eagle Creek valley (west of Kidd Flat and not seen in figure 5 is a through valley linking the Eagle Creek valley with a north oriented Middle Fork Powder River tributary valley, which is seen in figure 6). The through valley floor elevation at the road intersection is 2454 meters. Immediately to the east elevations rise to at least 2600 meters and west of figure 5 elevations rise to more than 2600 meters suggesting the through valley is approximately 150 meters deep. The through valley provides further evidence of what was once a large east oriented anastomosing channel complex crossing the southern Bighorn Mountains. Floodwaters were flowing from the Bighorn Basin west of the what were then the emerging Bighorn Mountains to the much deeper northeast oriented Middle Fork Powder River valley, which was being eroded headward from the newly created north oriented Powder River valley, which had eroded headward along a reversed flood flow channel from the deep northeast oriented Yellowstone River valley. The deep Yellowstone River valley eroded headward from space in the deep “hole” the melting ice sheet had opened up and which (at least at first) was draining in a south direction using flood flow channels east of the study region.

Detailed map of Spring Creek-Eagle Creek drainage divide area

Figure 6: Detailed map of Spring Creek-Eagle 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-Eagle Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet. The Middle Fork Powder River flows in a northeast direction across the northwest corner of figure 6. Kidd Flat is located in sections 22 and 23 in the southwest quadrant of figure 6.  A Spring Creek tributary originates near the south edge of section 23 and flows in a north and northwest direction to Kidd Flat and then in a west direction to join north oriented Spring Creek, which flows from the south edge of figure 6 to join the Middle Fork Powder River in section 9 (near northwest corner of figure 6). Bar C Creek originates near the northeast corner of section 23 and flows in a west direction before turning to flow in a north direction and then a northwest direction to join the Middle Fork Powder River just north of figure 6. Eagle Creek originates as a north oriented stream near the south edge of section 23 (next to the north oriented Spring Creek headwaters) and turns to flow in an east-southeast and east direction to the east edge of figure 6 (near southeast corner). Note how the Eagle Creek, Spring Creek, and Bar C Creek valleys are linked by through valleys and how the Eagle Creek and Spring Creek headwaters flow almost adjacent to each other before turning to flow in opposite directions. Remember, Spring Creek and Bar C Creek flow to the Middle Fork Powder River valley, which is located in a northwest of Kidd Flat while Eagle Creek flows to the Buffalo Creek valley, which then flows to the Middle Fork Powder River valley. In other words these are converging or diverging valleys depending on how they are viewed. Converging southeast oriented flood flow channels eroded the Spring Creek and Bar C Creek prior to headward erosion of the deeper northeast oriented Middle Fork Powder River valley. Floodwaters were flowing to what was then the actively eroding Eagle Creek valley and were coming from areas in the Bighorn Basin now drained by north oriented Nowood River tributaries. Headward erosion of the deeper northeast oriented Middle Fork Powder River valley captured the southeast oriented flood flow and floodwaters on the north and northwest ends of the beheaded flood flow channels reversed flow direction to create the Spring Creek and Bar C Creek drainage routes. The Spring Creek-Eagle Creek drainage divide elevation is 8066 feet. Elevations to the north rise to 8555 feet while elevations to the south rise to 8656 feet suggesting the Kidd Flat through valleys are approximately 500 feet deep.

Eagle Creek-Buffalo Creek drainage divide area

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

Figure 7 illustrates the Eagle Creek-Buffalo Creek drainage divide area south and west of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 20 meters. Note the southeast oriented slope near the southeast corner of figure 7 and how elevations decrease near the west edge of figure 7 and especially in the northwest corner of figure 7. Kidd Flat is located near the north center region of figure 7. The Middle Fork Powder River originates west of Kidd Flat on the west edge of the Bighorn Mountains upland surface and flows in a north, north-northeast, east, and north-northeast direction to the north center edge of figure 7. Through valleys link the Middle Fork Powder River headwaters valley with valleys of north and northwest oriented Nowood River tributaries west of the Bighorn Mountains upland surface west edge. The deepest through valley is defined by seven contour lines on a side and is at least 120 meters deep. The through valleys provide evidence of east oriented flood flow from the present day north oriented Nowood River drainage basin with water moving to the Middle Fork Powder River valley. Buffalo Creek originates just north of the south center edge of figure 7 at the confluence of its east oriented South Fork, east and southeast oriented Middle Fork, and southeast and south-southeast oriented North Fork and then flows in an east and east-southeast direction to the south edge of figure 7 (east half). Remember after turning to flow in a northeast and north direction Buffalo Creek eventually joins the Middle Fork Powder River. Eagle Creek flows in an east-southeast, northeast, and east direction from near Kidd Flat to the east edge of figure 7 (near county line) and east of figure 7 joins Buffalo Creek. Note how a through valley links the south oriented headwaters valley of southeast and south-southeast oriented North Buffalo Creek and with the northeast and north oriented Spring Creek valley. The through valley floor elevation is between 2560 and 2580 meters. Elevations greater than 2700 meters can be found on either side of the through valley suggesting the through valley is at least 120 meters deep. The through valley is also linked by a through valley with the north oriented Middle Fork Powder River headwaters valley. These through valleys provide evidence of linkages between the Middle Fork Powder River valley and the Buffalo Creek valley, which further strengthens the case for an east oriented anastomosing channel complex crossing the southern Bighorn Mountains prior to the reversal of flood flow in the Nowood River drainage basin west of figure 7.

Detailed map of Middle Fork Powder River-North Fork Buffalo Creek drainage divide area

Figure 8: Detailed map of Middle Fork Powder River-North Fork Buffalo 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 Middle Fork Powder River-North Fork Buffalo Creek drainage divide seen in less detail in figure 7 above. The map contour interval for figure 8 is 20 feet. Note the steep west-facing slope near the west edge of figure 8 along the west edge of the deeply eroded Bighorn Mountains upland surface. Drainage on that west-facing slope is to west, northwest, and north oriented Nowood River tributaries with the Nowood River flowing in a north and northwest direction to eventually join the north oriented Bighorn River. Drainage on the east side of the asymmetric drainage divide is to the Middle Fork Powder River drainage basin, which north and east of figure 8 eventually flows to the north oriented Powder River. The Middle Fork Powder River headwaters are located in section 25 near the north edge of figure 8 and flow in an east, northeast, and north direction to the north edge of figure 8 (in section 30). Spring Creek originates near the southeast corner of section 31 and flows in a northeast direction to the east edge of figure 8 and east of figure 8 turns to flow in a north direction to the Middle Fork Powder River (see figure 6). The North Fork Buffalo Creek originates a short distance south of figure 8 (west half) and flows in a northeast direction into section 1 where it turns to flow in a southeast and south direction to the south edge of figure 8 (east half). South of figure 1 North Fork Buffalo Creek joins with the Middle and South Forks of Buffalo Creek to form Buffalo Creek, which eventually joins the Middle Fork Powder River. A west to east oriented through valley in sections 2 and 36 links west oriented Nowood River tributary valleys with the southeast oriented North Fork Buffalo Creek valley and the northeast oriented Spring Creek valley. The through valley floor elevation at its deepest point in section 36 is between 8600 and 8620 feet. Elevations near the northwest corner of section 36 rise to more than 8960 feet while elevations south of the Carlson Cabin in section 11 rise to 9066 feet. These elevations suggest the through valley is at least 340 feet deep. While today it seems almost impossible the through valley was eroded by east oriented flood flow moving from what is now the much deeper north oriented Nowood River drainage basin to the east oriented Middle Fork Powder River drainage basin. Floodwaters flowed in diverging and converging flood flow channels with the southeast oriented North Fork Buffalo Creek valley and the northeast oriented Spring Creek valley being diverging flood flow channels. Floodwaters at that time were flowing to the much deeper north oriented (or reversed) flood flow channels in the Powder River basin located east and north of figure 8. A massive reversal of flood flow in the Bighorn Basin west of the Bighorn Mountains created the north oriented Nowood River drainage basin and deeply eroded the area west of figure 8 and ended all flood flow across the southern Bighorn Mountains.

Buffalo Creek-Baker Creek drainage divide area

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

Figure 9 illustrates the Buffalo Creek-Baker Creek drainage divide area south and slightly east of figure 7 and includes an overlap area with figure 7. The map contour interval for figure 9 is 20 meters. The Bighorn Mountains are curving to the west of figure 9 and west oriented streams flowing to the west edge of figure 9 drain to south-southwest and west oriented Badwater Creek with water flowing south of the mountains to the north oriented Wind River (which becomes the north oriented Bighorn River). The one exception is the west and northwest oriented stream flowing to the northwest corner of figure 9, which is a tributary to the north oriented Nowood River. West of figure 9 north-to south oriented through valleys link north oriented Nowood River tributary valleys with south oriented Badwater Creek tributary and headwaters valleys. Willow Creek in the southwest quadrant of figure 9 flows in a south, south-southeast, and south direction to join west-southwest oriented Dry Fork (Badwater Creek), which flows to the southwest corner of figure 9. The North Fork, Middle Fork, and South Fork of Buffalo Creek meet near the north center area of figure 9 and form east-southeast and southeast oriented Buffalo Creek, which flows to the east center edge of figure 9. Baker Creek is the northeast oriented tributary joining Buffalo Creek near the east center edge of figure 9. Baker Creek originates in the south center region of figure 9. First Water Creek is a southeast oriented tributary originating south of the South Fork Buffalo Creek and joining Baker Creek near the Baker Creek headwaters. Note the north to south oriented through valley linking the east oriented South Fork Buffalo Creek valley with the southeast oriented First Water Creek valley. The through valley is defined by at least seven contour lines on each side. The through valley is seen in more detail in figure 10. Immediately west of the Baker Creek headwaters is southeast oriented Sanchez Creek, which flows to southeast, northeast, and southeast oriented North Fork Cottonwood Creek, which flows to the south edge of figure 9 and south of figure 9 joins southeast oriented Cottonwood Creek. Cottonwood Creek originates near the south center edge of figure 9 and south of figure 9 flows to the north-northeast oriented South Fork Powder River. Cottonwood Creek, the North Fork Cottonwood Creek, and Baker Creek all flow along segments of the same northeast oriented through valley, which is a strike valley between hogback ridges. East and north of figure 9 this same through valley is used by north-northeast oriented Buffalo Creek before Buffalo Creek cuts across hogback ridges to enter another through valley and then to flow in a north-northwest direction to join the Middle Fork Powder River as seen in figure 3. While these through valleys are located along the strike between hogback ridges the through valleys are also water-eroded valleys and were eroded as south oriented flood flow from north and west of figure 9 flowed to the much deeper north oriented (or reversed) Powder River Basin flood flow channels on the east side of the emerging Bighorn Mountains.

Detailed map of South Fork Buffalo Creek-First Water Creek drainage divide area

Figure 10: Detailed map of South Fork Buffalo Creek-First Water 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 Fork Buffalo Creek-First Water Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 20 feet. Badwater Creek originates just north of the northwest corner of figure 10 and flows in a southwest direction across the northwest corner of figure 8. West and south of figure 9 Badwater Creek turns to flow in a west direction and south of the mountains to eventually join the north oriented Wind River (which becomes the north oriented Bighorn River). West oriented streams flowing to the west edge of figure 10 are Badwater Creek tributaries. East of the asymmetric drainage divide the South Fork Buffalo Creek originates in the southwest quadrant of section 23 and flows in a southeast and east direction into section 19 where it turns flow in a northeast and southeast direction to the east edge of figure 10 and east of figure 10 joins the North Fork and Middle Fork of Buffalo Creek to form Buffalo Creek. First Water Creek flows in a south and southeast direction from the northwest corner of section 35 to the south edge of figure 10 (east half) and south and east of figure 10 joins northeast oriented Baker Creek, which then joins Buffalo Creek. A north to south oriented through valley in section 25 links the South Fork Buffalo Creek valley with the southeast oriented First Water Creek valley. The through valley floor elevation is between 8300 and 8320 feet. Elevations in section 26 to the west rise to 8875 feet and elevations along the border between sections 25 and 30 to the east rise to 8741 feet. These elevations suggest the through valley is at least 420 feet deep. The through valley was eroded by south oriented flood flow moving to the southeast oriented First Water Creek valley prior to headward erosion of the South Fork Buffalo Creek valley. Headward erosion of the east oriented South Fork Buffalo Creek valley beheaded the south oriented flood flow to the First Water Creek valley. The through valley provides additional evidence supporting the interpretation that Middle Fork Powder River tributary valleys are linked both in the west where the tributary valleys diverge from the Middle Fork Powder River headwaters valley and then again in the east where the tributary valleys converge to join the Middle Fork Powder River valley. These diverging and converging flood flow channels were eroded as an east oriented anastomosing channel complex across the southern end of the emerging Bighorn Mountains and moved south oriented floodwaters from the yet to be beheaded reversed Bighorn River drainage basin to the west to the newly beheaded and reversed and much deeper north oriented Powder River drainage basin to the east.

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.