Cottonwood Creek-Owl Creek drainage divide area landform origins in the Owl Creek Mountains and southern Bighorn Basin, Wyoming, USA

Authors


Abstract:

This essay uses topographic map evidence to interpret landform origins in the region between Cottonwood Creek and Owl Creek in the Owl Creek Mountains and southern Bighorn Basin, Wyoming. Cottonwood Creek and Owl Creek have headwaters in the southern Absaroka Range and then flow in generally east directions along the Owl Creek Mountains north flank and into the southern Bighorn Basin to join the north oriented Bighorn River. Cottonwood Creek is north of Owl Creek. Barbed tributaries, elbows of capture, and through valleys or passes crossing drainage divides provide evidence of earlier drainage history. The earlier drainage history is interpreted to have begun with massive south and southeast oriented floods that initially flowed on a high-level erosion surface as high, if not higher, than high Absaroka Range drainage divides today. These immense south and southeast oriented floods were captured by headward erosion of deep east oriented valleys from a south oriented flood flow channel on the present day north oriented Bighorn River alignment. Floodwaters are interpreted to have been derived from a thick North American ice sheet and were flowing from western Canada to and across the study region. Ice sheet related crustal warping and deep glacial erosion created a deep “hole” in which the ice sheet was located and the crustal warping raised the Absaroka Range and Owl Creek Mountains as floodwaters flowed across them. Ice sheet melting opened up space in the deep “hole” south end and the deep northeast oriented Yellowstone River valley then eroded headward from that space across Montana to capture the southeast and south oriented floods and beheaded a south oriented flood flow channel to the Bighorn Basin. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Bighorn River drainage route. Reversed flood flow on the Bighorn River alignment and headward erosion of deep northeast oriented Greybull River and tributary valleys then captured south and southeast oriented still moving west of the actively eroding Yellowstone River valley head into the study region eventually ended all south and southeast oriented melt water flood flow to the study region.

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

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

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

Cottonwood Creek-Owl Creek drainage divide area location map

Figure 1: Cottonwood Creek-Owl 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 Cottonwood Creek-Owl Creek drainage divide area in the southern Bighorn Basin and illustrates the Wyoming southern Bighorn Basin region. The Yellowstone National Park southeast corner region can be seen in the northwest corner of figure 1 with north-northwest oriented Yellowstone River headwaters flowing into the Park. North and west of figure 1 the Yellowstone River flows primarily in a northwest direction into Montana where it turns to flow in more of an east and then northeast direction across the region north of figure 1. The Wind River originates near Togwotee Pass (south of the Yellowstone River headwaters) and flows in a southeast direction to Riverton where it turns to flow in a northeast and north direction to Boysen Reservoir. From Boysen Reservoir the Wind River flows in a north direction through Wind River Canyon (not labeled in figure 1, but a deep canyon where the Wind River crosses the Owl Creek Mountain) and then changes its name to become the Bighorn River. From Thermopolis on the north side of Wind River Canyon the Bighorn River flows in a generally north direction to the north edge of figure 1 (east of center). North of figure 1 the Bighorn River flows in a north and north-northeast direction to join the northeast oriented Yellowstone River. The Bighorn Basin is located north of the Owl Creek Mountains, west of the Bighorn Mountains (near east edge of figure 1), east of the Absaroka Range (the mountain range extending from northwest corner of figure 1 to Owl Creek Mountains), and south of the Beartooth and Pryor Mountains (north of figure 1). Owl Creek is a labeled east oriented stream on the north side of the Owl Creek Mountains and originates near Washakie Needles and joins the north oriented Bighorn River near Thermopolis. The Owl Creek headwaters include a North Fork and a South Fork. Cottonwood Creek is the unlabeled southeast and east-northeast oriented stream immediately north of Owl Creek and joins the Bighorn River near the town of Winchester. The Cottonwood Creek-Owl Creek drainage divide investigated in this essay is located west of the Bighorn River, south of Cottonwood Creek, and north of Owl Creek.

While today the Bighorn River is a north oriented drainage route it began as a south oriented flood flow channel, which converged south of Wind River Canyon with a southeast oriented flood flow channel, which was located on the southeast oriented Wind River alignment. The floodwaters were derived from the western margin of a thick North American ice sheet and were flowing in south and southeast directions from western Canada to and across the figure 1 region. At that time mountain ranges surrounding the Bighorn Basin had not yet emerged and floodwaters could freely flow across what are today high mountain ranges. The mountain ranges emerged as floodwaters flowed across them and south oriented floodwaters flowing across the emerging Owl Creek Mountains were gradually funneled into fewer and fewer channels until a south oriented flood flow channel on the present day north oriented Wind River Canyon alignment was the only south oriented exit for all floodwaters entering the Bighorn Basin. East and southeast oriented tributary valleys eroded headward in sequence (from south to north) from this south oriented flood flow channel to capture south and southeast oriented flood flow (e.g. Owl Creek, Cottonwood Creek, Gooseberry Creek, and Fifteenmile Creek). The thick ice sheet was located in a deep “hole”, which was formed by a combination of deep glacial erosion and of crustal warping that was raising mountain ranges, including the mountain ranges seen in figure 1. In time ice sheet melting began to open up space at the deep “hole” south end and deep northeast oriented valleys then eroded headward from that space to capture the south and southeast oriented melt water flood flow. The captured floodwaters were diverted to the deep “hole” and then for a significant period of time were drained in a south direction on flood flow channels located east of figure 1. Headward erosion of the deep northeast oriented Yellowstone River valley was one of the valleys eroding headward from the deep “hole” south end and it beheaded a south oriented flood flow channel to the Bighorn Basin. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Bighorn River drainage route. Reversed flood flow on the Bighorn River alignment then captured southeast and south oriented flood flow channels west of the Bighorn River alignment, including the southeast oriented flood flow channel on the Wind River alignment. These captured flood flow channels were fed by south and southeast oriented floodwaters moving west of the actively eroding Yellowstone River valley head. Eventually Yellowstone River valley headward erosion beheaded these western flood flow channels and floodwaters on the northwest end of the final major beheaded southeast oriented flood flow channel reversed flow direction to create the northwest oriented Yellowstone River headwaters drainage route.

Detailed location map for Cottonwood Creek-Owl Creek drainage divide area

Figure 2: Detailed location map Cottonwood Creek-Owl 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 Cottonwood Creek-Owl Creek drainage divide area in the Owl Creek Mountains and southern Bighorn Basin. Green colored areas are National Forest lands and in figure 2 are generally located in the Absaroka Range, which continues in a southeast and east direction as the Owl Creek Mountains. The brown shaded areas are Wind River Indian Reservation lands, which include the Owl Creek Mountains west of Wind River Canyon. The southeast oriented Wind River (not labeled in figure 2) flows across the southwest corner of figure 2. South of figure 2 the Wind River changes direction to flow to Boysen Reservoir, which is located near the southeast corner of figure 2. The Wind River then flows in a north direction from Boysen Reservoir through Wind River Canyon (where the Wind River flows across the Owl Creek Mountains) to Thermopolis where the river name changes to become the Bighorn River. From Thermopolis the Bighorn River flows in a north and northeast direction to the northeast corner of figure 2. Cottonwood Creek originates in the Absaroka Range (in northwest quadrant of figure 2) and flows in a southeast and east-northeast direction in the region north of the Owl Creek Mountains before turning to flow in a southeast direction to join the northeast oriented Bighorn River near Winchester (near northeast corner of figure 2). Owl Creek headwaters originate near Washakie Needles (near southeast end of green colored area) and flow in southeast directions before converging to form an east-northeast, east-southeast, east, and northeast oriented drainage route, which joins the Bighorn River north of Thermopolis. Note the southeast oriented Cottonwood Creek and Owl Creek headwaters and tributaries. Also note Bighorn River tributaries between Cottonwood Creek and Owl Creek in the northeast quadrant of figure 2. These tributaries include northeast and east-southeast oriented Sand Draw and east and east-northeast oriented Coal Draw. The numerous southeast and south oriented drainage routes flowing to the south edge of figure 2 are tributaries to the Wind River, which today turns to flow in a north direction. These numerous southeast and south oriented drainage routes are evidence the region was once crossed by southeast and south oriented flood flow channels that were captured by a massive flood flow reversal and diverted to flow in a north direction.

Cottonwood Creek-Sand Draw drainage divide area near the Bighorn River

Figure 3: Cottonwood Creek-Sand Draw drainage divide area near the Bighorn River. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of the Cottonwood Creek-Sand Draw drainage divide area near the Bighorn River. The Bighorn River flows in a north-northwest and northeast direction near the east edge of figure 3. Cottonwood Creek flows in an east-northeast and southeast direction to join the Bighorn River just east of the east edge of figure 3. Grass Creek is the southeast oriented tributary joining Cottonwood Creek in the northwest quadrant of figure 3. Sand Draw drains in a northeast direction from the west edge of figure 3 (south half) and then turns to drain in an east-southeast and northeast direction to join the Bighorn River. Coal Draw drains in a northeast direction to the Bighorn River near the southeast corner of figure 3. North Fork (Coal Draw) drains in an east and east-southeast direction near the south edge of figure 3. Note how the east-southeast oriented Sand Draw valley segment is linked by through valleys with the southeast oriented Grass Creek valley in the northwest and with the north oriented Bighorn River valley in the southeast. The map contour interval for figure 3 is 50 meters and the through valley floor elevation in the northwest is between 1450 and 1500 meters. Elevations north and south of the through valley rise to more than 1550 meters suggesting the through valley is at least 50 meters deep. A similar northwest-to-southeast oriented through valley can be seen linking the east-northeast oriented Cottonwood Creek valley with the northeast oriented Sand Draw valley and then with the east-southeast oriented North Fork (Coal Draw) valley. These through valleys provide evidence of southeast oriented flood flow routes prior to headward erosion of the Sand Draw and Cottonwood Creek valleys. The southeast oriented flood flow was probably moving to a south oriented flood flow channel on the present day north oriented Bighorn River alignment. Headward erosion of the northeast oriented Coal Draw valley first captured the southern southeast oriented flood flow channel. Perhaps the Coal Draw valley eroded headward at the time flood flow on the Bighorn River alignment was reversed. Headward erosion of the Cottonwood Creek valley from a previously eroded southeast oriented flood flow channel beheaded the southeast oriented flood routes to the North Fork (Coal Draw) valley and to the Sand Draw valley and diverted the flood flow in an east-northeast and the southeast direction to the Bighorn River.

Cottonwood Creek-Owl Creek drainage divide area near Hamilton Dome

Figure 4: – Cottonwood Creek-Owl Creek drainage divide area near Hamilton Dome. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a topographic map of the Cottonwood Creek-Owl Creek drainage divide area near Hamilton Dome and is located west and south of figure 3 and includes an overlap area with figure 3. Owl Creek is formed south of Hamilton Dome at the confluence of its east-northeast oriented South Fork (which flows from near the southwest corner of figure 4) and its east oriented North Fork (which flows from the east edge of figure 1-south half) and then flows in an east-southeast direction to the southeast corner of figure 4. Cottonwood Creek (unlabeled in figure 4) flows in a northeast direction from the west center edge of figure 4 to the north edge of figure 4 (east of center) and is located on the south side of Wagonhound Bench. A through valley west of figure 4 (and seen in figure 5) links the northeast and east oriented tributary on the north side of Wagonhound Bench with the Cottonwood Creek valley. Sand Draw originates east of Hamilton Dome and drains in a northeast direction to near the northeast corner of figure 4. A northwest-to-southeast oriented through valley on the southwest side of Hamilton Dome links the Cottonwood Creek valley with the east-southeast oriented Owl Creek valley. The map contour interval for figure 4 is 50 meters and the through valley floor elevation is between 1650 and 1700 meters. Elevations greater than 1800 meters can be found on either side of the valley suggesting the valley is at least 100 meters deep. Hamilton Dome by its name suggests there is a northwest-to-southeast oriented geologic structure on the through valley northeast side. The through valley orientation may be related to the underlying geologic structure, although it is also a water-eroded valley. Prior to headward erosion of the east-northeast oriented Cottonwood Creek valley southeast oriented flood flow moved in the through valley to the east-southeast oriented Owl Creek valley. Headward erosion of the Cottonwood Creek valley beheaded the southeast oriented flood flow. Floodwaters on the northwest end of the beheaded flood flow channel reversed flow direction to create the northwest oriented Cottonwood Creek tributary drainage route seen today.

Cottonwood Creek-North Fork Owl Creek drainage divide area near Putney Flat

Figure 5: Cottonwood Creek-North Fork Owl Creek drainage divide area near Putney Flat. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Cottonwood Creek-North Fork Owl Creek drainage divide area near Putney Flat and is located west of figure 4 and includes an overlap area with figure 4. Cottonwood Creek flows in a southeast direction from the west edge of figure 5 (near northwest corner) to near Putney Flat and then turns to flow in a northeast, east-southeast, and northeast direction to the northeast corner of figure 5. Twentyone Creek is the southeast oriented tributary joining Cottonwood Creek on the north side of Putney Flat.  The stream originating south of the north center edge of figure 5 and flowing in a southeast direction to Crater Sink and then turning to flow in a northeast direction is the Cottonwood Creek tributary in figure 4 on the north side of Wagonhound Bench. Note how that stream flows on the alignment of the northeast oriented Cottonwood Creek valley segment as it continues on the north side of Putney Flat. This Cottonwood Creek tributary is flowing in what was once a diverging and converging flood flow channel, which was a component of a larger-scale northeast oriented anastomosing channel complex crossing the region. North Fork Owl Creek flows from the west edge of figure 5 (south half) in an east-southeast, east-northeast, and east direction to join the South Fork Owl Creek near the east edge of figure 5 (just south of center). The South Fork Owl Creek flows from the southwest corner of figure 5 in an east, northeast, east, and east-northeast direction to join the North Fork Owl Creek. Note how in the region south and west of Putney Flat North Fork Owl Creek tributaries are linked by shallow through valleys with Cottonwood Creek tributaries. These linkages suggest the diverging and converging flood flow channels were not limited to the Cottonwood Creek valley, but also incorporated flood flow moving in the North Fork Owl Creek valley. What appears to have occurred here is a northeast oriented anastomosing channel complex has captured a southeast oriented anastomosing channel complex. Evidence for the southeast oriented anastomosing channel complex is the southeast oriented streams flowing to the northeast oriented Cottonwood Creek valley segment, including the southeast oriented Cottonwood Creek headwaters stream. Also near the southwest corner of figure 5 drainage to the east-northeast oriented North Fork Owl Creek valley segment is generally in a southeast direction.

Cottonwood Creek-North Fork Owl Creek drainage divide area near Cottonwood Peak

Figure 6: Cottonwood Creek-North Fork Owl Creek drainage divide area near Cottonwood Peak. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the Cottonwood Creek-North Fork Owl Creek drainage divide area near Cottonwood Peak and is located west and north of figure 5 and there is an overlap area with figure 5. Cottonwood Peak is a labeled mountain in the west half of figure 6 (slightly north of center). Cottonwood Creek originates near Cottonwood Peak and flows in a northeast direction before turning to flow in a southeast direction to the east edge of figure 6 (south half).  The North Fork Owl Creek originates east of the west center edge of figure 6 and flows in a southeast direction to the south center edge of figure 6. The South Fork North Fork Owl Creek flows in a southeast direction across the southwest corner of figure 6. The north-northwest oriented streams near the northwest corner of figure 6 are tributaries of the north-northeast oriented South Fork Wood River, which flows to the northeast oriented Wood River and then Greybull River. Sugarloaf Mountain is a labeled mountain near the center of figure 6. Sugar Loaf Creek is a southeast and northeast oriented Cottonwood Creek tributary originating near Sugarloaf Mountain. Meadow Creek is a south oriented North Fork Owl Creek tributary originating south of Sugar Loaf Creek. At first glance the high mountain ridges in this region appear to be the last places to look for evidence of flood flow channels. Yet there are notches, passes, or gaps in the high drainage divides linking the Cottonwood Creek and North Fork Owl Creek valleys. For example the north oriented Sugar Loaf Creek valley is linked by a pass with the south oriented Meadow Creek valley. The map contour interval for figure 6 is 50 meters and the pass elevation is between 2500 and 2550 meters. Drainage divide elevations to the east rise to more than 2600 meters and elevations on Sugarloaf Mountain to the west rise to more than 3000 meters.  These elevations suggest the pass is at least 50 meters deep. The pass was eroded by south oriented flood flow moving to the North Fork Owl Creek valley prior to headward erosion of the Cottonwood Creek valley and its tributary Sugar Loaf Creek valley. Headward erosion of the northeast oriented Sugar Loaf Creek valley from the actively eroding Cottonwood Creek valley captured the south oriented flood flow and diverted the floodwaters to the newly eroded Cottonwood Creek valley. Even more intriguing are notches, passes, or gaps in the drainage divide between the north-northwest oriented South Fork Wood River tributaries and the southeast oriented North Fork Owl Creek valley. These notches, passes, or gaps today have elevations of approximately 3200 meters and were eroded by southeast oriented flood flow channels moving floodwaters to the actively eroding southeast oriented North Fork Owl Creek valley. At that time there was no deep South Fork Wood River valley west and north of figure 6 and floodwaters were flowing on an erosion surface equivalent in elevation to the highest drainage divides seen in figure 6 today. Headward erosion of the deep north-northeast oriented South Fork Wood River valley west of figure 6 beheaded flood flow channels to the actively eroding southeast oriented North Fork Owl Creek valley. Probably crustal warping has significantly raised the region and elevations at that time were not the same as they are today.

Detailed map of Sugar Loaf Creek-Meadow Creek drainage divide area

Figure 7: Detailed map of Sugar Loaf Creek-Meadow Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 provides a detailed topographic map of the Sugar Loaf Creek-Meadow Creek drainage divide area seen in less detail in figure 6. The map contour interval for figure 7 is 40 feet. Sugar Loaf Mountain is the labeled mountain near the northeast corner of section 17 and reaches an elevation of 9912 feet. Squaw Teat Butte is a labeled high point in section 16 and reaches an elevation of 9671 feet. The North Fork Owl Creek can be seen flowing in a southeast direction across the southwest corner of figure 7. Sugar Loaf Creek flows from section 16 (east of Sugar Loaf Mountain and Squaw Teat) into the northwest corner of section 15 and then turns to flow in a northeast direction through section 10 to the north edge of figure 7 (east of center) and joins southeast oriented Cottonwood Creek north of figure 7. Meadow Creek originates near the south center edge of section 15 and flows in a south and south-southwest direction to the south edge of figure 7 (west of center) and joins the North Fork Owl Creek south of figure 7. A well-defined pass in section 15 links the northeast oriented Sugar Loaf Creek valley with the south oriented Meadow Creek valley. The pass elevation is between 8320 and 8360 feet. Elevations east of the pass rise to 8564 feet, which means the pass is at least 100 feet deep. Actually the pass is even deeper (more than 200 feet deep) because in section 26 near the south edge of figure 7 there is an elevation of 8672 feet, which suggests the pass was simply a deeper channel in a much broader south oriented valley. That south oriented valley was eroded into an erosion surface at least as high as the drainage divide today, although crustal warping has probably altered elevations since that time. The pass does indicate that south oriented flood flow did cross this high drainage divide ridge. The south oriented flood flow was captured by headward erosion of the deep southeast oriented North Fork Owl Creek valley and the south oriented Meadow Creek valley eroded headward from newly eroded North Fork Owl Creek valley along the captured south oriented flood flow channel. Next headward erosion of the deep Cottonwood Creek valley and its northeast oriented Sugar Loaf Creek valley captured the south oriented flood flow and beheaded the flood flow channel to the actively eroding Meadow Creek valley.

Detailed map of Chimney Creek-North Fork Owl Creek drainage divide area

Figure 8: Detailed map of Chimney Creek-North Fork Owl 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 Chimney Creek-North Fork Owl Creek drainage divide area seen in less detail in figure 6. The map contour interval for figure 8 is 40 feet. Cottonwood Peak is located in section 35 near the center of figure 8 and has an elevation of 10,919 feet. Chimney Creek originates on the Cottonwood Peak northwest side and flows in a northwest and north-northwest direction to the north edge of figure 8 (west half). North of figure 8 Chimney Creek joins the north-northeast oriented South Fork Wood River with water eventually reaching the northeast oriented Greybull River, which eventually flows to the north oriented Bighorn River. Cottonwood Creek originates in section 35 (northeast from Cottonwood Peak) and flows in a northeast and east direction to the east edge of figure 8 (north half). The North Fork Owl Creek (not labeled in figure 8) originates in section 4 (in southwest quadrant of figure 8) and flows in a southeast direction to the south center edge of figure 8. The well-marked red wilderness area boundary follows the high Wood River drainage divide with Cottonwood and Owl Creeks, which today is a major topographic feature and barrier. In the southeast corner of section 5 (near the southwest corner of figure 8) elevations on the high drainage divide reach 11,180 feet and an even higher elevation of 11,379 feet is found a short distance south of figure 8. Between these 11,000-foot plus high elevations and Cottonwood Peak the drainage divide dips several hundred feet to a low elevation of between 10,520 and 10,560 feet near the south edge of section 34. That low elevation is almost 800 feet lower than the high point south of figure 8 and suggests a northwest-to-southeast valley at least 800 feet deep once crossed the region. At that time elevations west of the drainage divide were at least as high as the drainage divide, which means there was no deep north-northeast oriented South Fork Wood River valley west of figure 8 (nor were there any other deep north and northeast oriented valleys further to the west). Floodwaters responsible for eroding that high-level southeast oriented valley were flowing on an erosion surface equivalent in elevation to some of the highest drainage divides in the present day Absaroka Range. Probably the Absaroka Range has been uplifted since that time and since that time the deep north-northeast oriented Wood and Greybull River headwaters and tributary valleys have definitely eroded headward across the southeast oriented flood flow route in sequence (from east to west) to capture the massive southeast oriented flood flow and to divert the floodwaters in a north and northeast direction to the north oriented Bighorn River. In other words, evidence for a massive flood flow reversal in the Bighorn Basin can be seen along this high Absaroka Mountain drainage divide.

South Fork North Fork Owl Creek-Middle Fork Owl Creek drainage divide area

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

Figure 9 provides a topographic map of the South Fork North Fork Owl Creek-Middle Fork Owl Creek drainage divide area south of figure 6 and includes an overlap area with figure 6. The Holy City is a landform near the north center edge of figure 9. The North Fork Owl Creek flows in a southeast direction from the north edge of figure 9 (just west of the Holy City) to the east center edge of figure 9. The South Fork North Fork Owl Creek flows in a southeast direction from the north edge of figure 9 (near northwest corner) and then turns to flow in an east-northeast and east-southeast direction to join the North Fork Owl Creek south of the Holy City. The South Fork Owl Creek flows in a southeast direction from the west center edge of figure 9 to near the south center edge of figure 9 and then turns to flow in a northeast direction to Anchor Reservoir and the east edge of figure 9 (south half). Middle Fork Owl Creek headwaters are located south and west of the center of figure 9 and flow in a northeast direction to near the center of figure 9. From the center of figure 9 the Middle Fork Owl Creek flows in an east-southeast direction to join the South Fork Owl Creek at Anchor Reservoir near the east edge of figure 9. Note how a northwest-to-southeast oriented through valley links the east-southeast oriented Middle Fork Owl Creek valley with the southeast oriented South Fork North Fork Owl Creek valley to the northwest. The map contour interval for figure 9 is 50 meters and the through valley floor elevation is between 2350 and 2400 meters. Elevations north and east of the through valley rise to more than 2500 meters and much higher elevations can be seen to the southwest. The through valley was eroded by a southeast oriented flood flow channel prior to headward erosion of east-northeast oriented South Fork North Fork Owl Creek valley segment. Erosion of the two diverging valleys is best explained in the context of diverging and converging flood flow channels in a large-scale anastomosing channel complex. Evidence for other diverging and converging flood flow channels can be found in the southwest quadrant of figure 9. Slab Creek is a south-southwest oriented South Fork Owl Creek tributary and a road crosses Slab Creek and then goes in an east and north direction to the Middle Fork Owl Creek headwaters area. That road makes use of a through valley linking the South Fork Owl Creek valley with the Middle Fork Owl Creek valley. The through valley floor elevation is between 2700 and 2750 meters. Elevations south of the through valley rise to 2862 meters and elevations to the north rise even higher. In other words the through valley is more than 100 meters deep. The through valley was eroded by east oriented flood flow diverging from a South Fork Owl Creek valley flood flow channel and then converging with a southeast oriented flood flow channel on the Middle Fork Owl Creek alignment. Since that time a much deeper South Fork Owl Creek valley captured all of the flood flow and crustal warping has probably raised the region so the topography today probably looks different from how it looked when floodwaters eroded the through valley.

Detailed map of South Fork North Fork Owl Creek-Middle Fork Owl Creek drainage divide area

Figure 10: Detailed map of South Fork North Fork Owl Creek-Middle Fork Owl 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 North Fork Owl Creek-Middle Fork Owl Creek drainage divide area seen in less detail in figure 9. The North Fork Owl Creek flows in a southeast direction from the north edge of figure 10 (east half) to the east edge of figure 10 (north of center).  The South Fork North Fork Owl Creek flows in a southeast direction from the northwest corner of figure 10 into section 6 and then turns to flow in an east-northeast direction to the south edge of section 33 where it turns to flow in a southeast direction to join the southeast oriented North Fork Owl Creek in section 3. Northeast and east-northeast oriented Middle Fork Owl Creek headwaters streams (labeled in figure 10) converge in the northeast quadrant of section 17 to form the Middle Fork Owl Creek (not labeled in figure 10), which then flows in an east-southeast direction to near the southeast corner of figure 10. A southeast oriented Middle Fork Owl Creek headwaters stream flows from the northeast corner of section 8 to join the Middle Fork Owl Creek in the northeast corner of section 16. A northwest-to-southeast oriented unimproved road follows that southeast oriented Middle Fork Owl Creek headwaters stream and then continues in a through valley to the South Fork North Fork Owl Creek valley. Note how the southeast oriented South Fork North Fork Owl Creek valley is aligned with the through valley and with the southeast oriented Middle Fork Owl Creek headwaters stream valley. The map contour interval for figure 10 is 40 feet and the through valley elevation at the drainage divide is between 7720 and 7760 feet. Elevations in the northeast corner of section 9 to the east rise to 8330 feet while much higher elevations can be found west of the through valley. These elevations suggest the through valley is at least 770 feet deep. The through valley is a water-eroded landform and was eroded by what was once a diverging flood flow channel from the flood flow channel on the present day South Fork North Fork Owl Creek alignment. At that time the South Fork Owl Creek, Middle Fork Owl Creek, South Fork North Fork Owl Creek, and North Fork Owl Creek valleys were being eroded into a high-level erosion as a complex of diverging and converging flood flow channels. Also at that time the Absaroka Range was being uplifted and the successful of the flood flow channels were being eroded deeper and deeper into the rising mountain mass. In time the deeper flood flow channels beheaded flood flow to the less successful flood flow channels, which is what happened in the case of the South Fork North Fork Owl Creek valley, which beheaded the Middle Fork Owl Creek flood flow channel with the through valley left as evidence.

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.

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