Abstract:

This essay uses topographic map evidence to interpret landform origins in the region between the Greybull River and Fifteenmile Creek in the Wyoming Bighorn Basin. The Greybull River originates in the Absaroka Range and flows to Meeteetse in the Bighorn Basin before turning to flow in a northeast, east-southeast, and northeast direction to join the north oriented Bighorn River near the town of Greybull. Fifteenmile Creek originates south and east of Meeteetse and flows in an east and southeast direction to join the north oriented Bighorn River as a barbed tributary near the town of Worland. Between the Greybull River and Fiftennmile Creek is Tatman Mountain, which stands approximately 400 meters higher than the adjacent valleys. Numerous south-southeast oriented tributaries flow on south-southeast oriented slopes to east and southeast oriented Bighorn River tributaries east of Tatman Mountain, while immediately to the north there are numerous north-northwest oriented Greybull River tributaries. Passes are eroded across the high Tatman Mountain upland surface while west of Tatman Mountain northwest-to-southeast oriented through valleys link northwest oriented Greybull River tributary valleys with southeast oriented Fifteenmile Creek tributary valleys. The barbed tributaries, through valleys, and sloping erosion surfaces are interpreted to have formed during massive southeast oriented floods, which flowed across the Bighorn Basin. 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 the Bighorn Basin. At that time mountain ranges surrounding the Bighorn Basin had not emerged and floodwaters were flowing on routes now blocked by high mountains. Headward erosion of a Fifteenmile Creek valley at least 400 meters deep from a south oriented flood flow channel on the present day north oriented Bighorn River alignment captured south-southeast oriented flood flow to what was then a newly eroded and deep east-oriented Gooseberry Creek valley to the south. Headward erosion of other southeast and east oriented valleys in the region east of Tatman Mountain captured in sequence the southeast oriented flood flow and beheaded flood flow routes to the newly eroded valley immediately to the south. Flood flow on the Bighorn River alignment was reversed when headward erosion of the much deeper northeast oriented Yellowstone River valley in Montana beheaded a south oriented flood flow channel supplying floodwaters to the Bighorn River flood flow channel. The deep Yellowstone River valley is interpreted to have been eroding headward from a deep “hole” the melting ice sheet had occupied and that was being opened up by ice sheet melting. Reversal of flow on the Bighorn River alignment caused the northeast oriented Greybull River valley to erode headward across the southeast oriented flood flow routes to the newly eroded Fifteenmile Creek valley.

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 Greybull River-Fifteenmile Creek drainage divide area landform origins in the Wyoming Bighorn Basin. 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 Greybull River–Fifteenmile Creek drainage divide area landform evidence in the Wyoming Bighorn Basin will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Greybull River-Fifteenmile Creek drainage divide area location map

Figure 1: Greybull River-Fifteenmile 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 Greybull River-Fifteenmile Creek drainage divide area in the Wyoming Bighorn Basin and illustrates the Wyoming Bighorn Basin region. The southeast corner of Yellowstone National Park can be seen in the northwest corner of figure 1. The Yellowstone River headwaters flow in a north-northwest direction into Yellowstone National Park to Yellowstone Lake and then continue in a generally northwest direction into Montana before turning to flow in more of an east direction across south central Montana (north of figure 1) and then in a northeast direction to join the Missouri River. South of the Yellowstone River headwaters the Wind River originates near Togwotee Pass 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 through the Owl Creek Mountains in deep Wind River Canyon before entering the Bighorn Basin near Thermopolis. Upon entering the Bighorn Basin the Wind River name changes to the Bighorn River and the Bighorn River flows in a north direction to the towns of Worland and Greybull and the north edge of figure 1. North of figure 1 the Bighorn River flows in a north and north-northeast direction to eventually join the Yellowstone River in Montana. The Greybull River originates near Francs Peak (west of center of figure 1) and flows in a north-northwest, east, and northeast direction to Meeteetse. From Meeteetse the Greybull River flows in a northeast, east-southeast, and northeast direction to join the Bighorn River near the town of Greybull. Fifteenmile Creek originates near the town of Meeteetse and flows in an east-northeast, east, and southeast direction to join the north oriented Bighorn River as a barbed tributary near the town of Worland. Tatman Mountain is the labeled high point located between the Greybull River and Fifteenmile Creek. The Greybull River-Fifteenmile Creek drainage divide area investigated in this essay is located south of the Greybull River between the towns of Meeteetse and Greybull and north of Fifteenmile Creek between the towns of Meeteetse and Worland.

What is today the north oriented Bighorn River drainage system originated during massive south and southeast oriented melt water floods that crossed the entire region seen in figure 1. 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 region seen in figure 1. At that time the Absaroka Range (mountain range in eastern Yellowstone National Park), the Bighorn Mountains (mountains along east edge of figure 1), the Owl Creek Mountains, and the Wind River and Gros Ventre Ranges (both in the southwest quadrant of figure 1) had not emerged as high mountain ranges and floodwaters could flow freely across what are today high mountain barriers. The mountains emerged as ice sheet related crustal warping raised them and as deep valleys eroded headward into them. Ice sheet related crustal warping combined with deep glacial erosion created a deep “hole” in which the thick ice sheet was located. South and southeast oriented flood flow channels eroded headward into the southwest rim of this deep “hole”, which is where the region in figure 1 is located. The present day north oriented Bighorn River drainage route originated as a south oriented flood flow channel that south of Boysen Reservoir converged with a southeast oriented flood flow channel on the southeast oriented Wind River alignment. The north-northwest oriented Greybull River segment and the north-northwest Yellowstone River segments seen in figure 1 are located on alignments that originated as south-southeast oriented flood flow channels. In time ice sheet melting opened up space in the deep “hole”, especially in the south, and deep northeast oriented valleys eroded headward from that space to capture the south and southeast oriented melt water floods flowing across Montana. Headward erosion of the deep northeast oriented Yellowstone River valley across Montana was one of those deep valleys. Captured floodwaters were diverted in a northeast direction into the deep “hole” where at first the floodwaters drained in a south direction on routes east of figure 1. Headward erosion of the deep Yellowstone River valley beheaded a south oriented flood flow channel supplying floodwaters to the south oriented flood flow channel on the Bighorn River alignment. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Bighorn River drainage route seen today, which captured floodwaters still moving in south and southeast directions west of the actively eroding Yellowstone River valley head including southeast oriented flood flow channels on the Fifteenmile Creek and Wind River alignments. Also deep northeast oriented valleys eroded headward from the newly reversed Bighorn River flood flow channel to capture south and southeast flood flow still moving west of the actively eroding Yellowstone River valley head. Headward erosion of the deep east and northeast oriented Greybull River valley beheaded and reversed a south-southeast oriented flood flow channel in what was then the emerging Absaroka Range to create the north-northwest oriented Greybull River headwaters drainage route.

Detailed location map for Greybull River-Fifteenmile Creek drainage divide area

Figure 2: Detailed location map Greybull River-Fifteenmile 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 Greybull River-Fifteenmile Creek drainage divide area in the Wyoming Bighorn Basin. The Bighorn River flows in a north direction near the east edge of figure 2 to the town of Greybull near the north edge of figure 2. Meeteetse is a town near the southwest corner of figure 2 and the Greybull River flows in a northeast direction from the west edge of figure 2 (near Meeteetse) to the small town of Fenton and then makes an east-southeast jog before resuming its northeast direction to join the Bighorn River near the town of Greybull (do not confuse the river with the irrigation canals in the lower Greybull River valley region). Fifteenmile Creek originates a short distance south and east of Meeteetse and flows in an east-northeast, east, and southeast direction to join the north oriented Bighorn River a short south of the southeast corner of figure 2. Note the large number of south oriented drainage routes in what is today a north oriented drainage basin. These south oriented drainage routes are relics of the south oriented flood flow channels that once crossed the region. For example,  Fifteenmile Creek has numerous southeast and south-southeast oriented tributaries and the north oriented Bighorn River has other southeast oriented barbed tributaries including Fivemile Creek and Tenmile Creek. Elk Creek is a southeast, east-northeast, east-southeast, and east-northeast oriented Bighorn River tributary originating near Sheep Mountain. Also note how west of Tatman Mountain there are several north and north-northwest oriented Greybull River tributaries. The southeast oriented tributaries are on alignments of southeast oriented flood flow channels captured by headward erosion of the deeper Fifteenmile Creek valley. The north-northwest and north oriented tributary drainage routes were formed by reversals of flood flow on south and southeast oriented flood flow channels beheaded by headward erosion of the much deeper northeast oriented Greybull River valley.

Greybull River-Elk Creek drainage divide area

Figure 3: Greybull River-Elk Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of the Greybull River-Elk Creek drainage divide area. The town of Basin is located near the northeast corner of figure 3. The Bighorn River is the north oriented river seen near Basin. Antelope Creek is the southeast, northeast, and east-southeast stream joining the north oriented Bighorn River just south of Basin. The Greybull River flows in an east and northeast direction across the northwest corner of figure 3 and joins the Bighorn River north of figure 3. Elk Creek flows in an east-northeast, east-southeast, and northeast direction from the west edge of figure 3 (near southwest corner) to join the Bighorn River just east of the east edge of figure 3 (south half). The South Fork Elk Creek is located south of Elk Creek and flows in a southeast, east-northeast, and north-northwest direction to join Elk Creek. While today the Bighorn River is a north oriented river system the predominant tributary direction seen in figure 3 is southeast. Antelope Creek headwaters and tributaries flow in southeast directions. Elk Creek tributaries are oriented in southeast directions. South Fork Elk Creek headwaters and tributaries are oriented in southeast directions. These numerous southeast oriented tributaries suggest the South Fork Elk Creek valley eroded headward across southeast oriented flood flow and next the Elk Creek valley eroded headward across the same southeast oriented flood flow and beheaded southeast oriented flood flow routes to the newly eroded South Fork Elk Creek valley. Floodwaters on the north end of a beheaded flood flow route reversed flow direction to create the north-northwest oriented South Fork Elk Creek drainage segment. The Antelope Creek valley next eroded headward to capture southeast oriented flood flow before headward erosion of the Greybull River valley beheaded southeast oriented flood flow to the newly eroded Antelope Creek valley and (west of Antelope Creek) to the newly eroded Elk Creek valley. Floodwaters on north-northwest ends of beheaded flood flow routes reversed flow to create the north-northwest oriented Greybull River tributary drainage routes. Further evidence supporting this interpretation is the northwest-to-southeast oriented through valley south of Jones Reservoir in the west center area of figure 3, which links the Greybull River valley with the Elk Creek valley.

Elk Creek-Fivemile Creek drainage divide area

Figure 4: Elk Creek-Fivemile Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a topographic map of the Elk Creek-Fivemile Creek drainage divide area south of figure 3 and includes a significant overlap area with figure 3. Elk Creek flows in an east, east-northeast, east-southeast, and northeast direction from the west edge of figure 4 (north half) to near the northeast corner of figure 4 and joins the north oriented Bighorn River east of figure 4. The South Fork Elk Creek originates in the north center area of figure 4 and flows in a southeast and east-northeast direction to near the east edge of figure 4 (north half). Fivemile Creek flows in a southeast direction from slightly west of the center of figure 4 to the east edge of figure 4 (near southeast corner). The map contour interval for figure 4 is 20 meters. Note how the south wall of the Elk Creek valley in the northwest quadrant of figure 4 is a north-facing escarpment approximately 100 meters high. South of that escarpment near the west edge of figure 4 is a south-southeast oriented slope drained by south-southeast oriented streams flowing to the south edge of figure 4 and then to Fifteenmile Creek (south of figure 4 and seen in figure 5). The south-southeast oriented drainage orientation for the secondary streams seen in figure 3 predominates again in figure 4 and suggests headward erosion of the southeast oriented Fivemile Creek valley and of the Elk Creek valley (west of the Fivemile Creek valley) beheaded south-southeast oriented flood flow routes to the newly eroded Fifteenmile Creek valley south of figure 4. Evidence for south-southeast and southeast oriented flood flow across this region is excellent even though today the Bighorn River flows in a north direction. This evidence suggests the Bighorn River valley is located on the alignment of what was once a major south oriented flood flow channel, which was reversed to create the present day north oriented drainage route.

Fivemile Creek-Fifteenmile Creek drainage divide area

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

Figure 5 illustrates the Fivemile Creek-Fifteenmile Creek drainage divide area south and slightly east of figure 4 and includes a significant overlap area with figure 4. Fivemile Creek flows in a southeast and east-southeast direction from the north edge of figure 5 (slightly west of center) to the east edge of figure 5 (north half). South of Fivemile Creek is southeast, northeast, and southeast oriented Sixmile Creek, which flows to the east edge of figure 5 (slightly north of center). Tenmile Creek is formed at the confluence of its south-southeast oriented Middle and North Forks and then flows in a southeast direction to the southeast corner of figure 5. Fifteenmile Creek can be seen in the southwest corner of figure 5 flowing in a southeast direction. All of the streams east of figure 5 flow to the north oriented Bighorn River as barbed tributaries. Note also the south-southeast oriented slope drained by south-southeast oriented streams flowing to the Fifteenmile Creek valley in the west half of figure 5 and to the Tenmile Creek valley in the east half of figure 5. The major southeast oriented Bighorn River tributary valleys were eroded headward across south-southeast oriented flood flow in sequence from south to north. In other words headward erosion of the Fifteenmile Creek valley captured the south-southeast oriented flood flow first. Next headward erosion of the Tenmile Creek valley captured the south-southeast oriented flood flow in the east half of figure 5. Headward erosion of the Sixmile Creek valley then captured south-southeast oriented flood flow to the newly eroded Tenmile Creek valley. Fivemile Creek valley headward erosion then captured south-southeast oriented flood flow to the newly eroded Sixmile Creek valley. Headward erosion of these southeast oriented valleys to capture south-southeast oriented flood flow was from a south oriented flood flow channel on the present day north oriented Bighorn River alignment. Subsequently south oriented flood flow on the Bighorn River alignment was beheaded and reversed by headward erosion of the much deeper northeast oriented Yellowstone River valley (in Montana-well north of figure 5), which had eroded headward from space in the deep “hole” the ice sheet had occupied and which was being opened up by the ice sheet melting.

Greybull River-Badger Creek drainage divide area

Figure 6: Greybull River-Badger Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the Greybull River-Badger Creek drainage divide area west of the previous figures and there is no overlap area with previous figures. The Greybull River flows in a northeast direction across the northwest corner of figure 6. In the northwest quadrant of figure 6 McGee Gulch and Mackey Gulch are north-northwest oriented Greybull River tributaries and Blackstone Gulch is a north-northeast oriented Greybull River tributary. Fifteenmile Creek flows in northeast direction to join east-southeast oriented Parker Gulch near the south edge of figure 6 (west of center) and then flows in an east direction to the east edge of figure 6 (near southeast corner). Labeled Fifteenmile Creek tributaries include southeast oriented Sand Spring Draw and Badger Creek and south-southeast oriented Badger Gulch and Blackburn Gulch. Note other unlabeled southeast and south-southeast oriented Fifteenmile Creek tributaries. The map contour interval for figure 6 is 20 meters. Tatman Mountain is the high point between the Greybull River and Fifteenmile Creek and while showing rugged topography on its sides has a relatively flat top suggesting the presence of an erosion surface and/or of horizontal strata. Elevations at the top of Tatman Mountain reach 1900 meters, which is more than 400 meters higher than the Fifteenmile Creek valley elevation to the south or the Greybull River valley elevation to the north. Fenton Pass is a north-to-south pass eroded across the top of Tatman Mountain. East of Fenton Pass is a deeper and wider northwest-to-southeast oriented pass eroded across Tatman Mountain. Note how these two passes link north oriented Greybull River tributary valleys with south-southeast oriented Fifteenmile Creek tributary valleys. South oriented flood flow channels eroded the passes at a time when floodwaters were flowing on a surface at least as high as the top of Tatman Mountain. Floodwaters were flowing to the 400-meter deep east and southeast oriented Fifteenmile Creek valley, which was eroding headward into the region to capture south and south-southeast oriented flood flow. At that time there was no deep Greybull River valley to the north of Tatman Mountain. Instead there was a surface at least as high as the top of Tatman Mountain. Headward erosion of the 400-meter deep Greybull River valley north of Tatman Mountain captured the south oriented flood flow. Floodwaters on north ends of beheaded flood flow channels reversed flow direction to create north oriented Greybull River tributary drainage routes. West of Tatman Mountain floodwaters apparently flowed in more of a southeast direction to reach the east oriented Fifteenmile Creek valley until being beheaded by Greybull River valley headward erosion.

Detailed map of Fenton Draw-Blackburn Gulch drainage divide area

Figure 7: Detailed map of Fenton Draw-Blackburn Gulch 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 Fenton Draw-Blackburn Gulch drainage divide area seen in less detail in figure 6. The top of Tatman Mountain is the flat-topped upland seen near the center of figure 7 and also in the northeast quadrant of figure 7 with Fenton Pass being located near the center of figure 7. The map contour interval for figure 7 is 20 feet and the highest point on Tatman Mountain is west of Fenton Pass and reaches 6229 feet. Elevations on the top of Tatman Mountain west of Fenton Pass are slightly higher than 6200 feet and decrease very gradually toward the east or toward Fenton Pass. Elevations on the Tatman Mountain upland immediately east of Fenton Pass range from more than 6180 feet at the west end to between 6120 and 6140 feet at the east end. Elevations on the upland top in the northeast quadrant of figure 7 range from 6115 feet at the west end to between 6040 and 6060 feet at the east end. These elevations define what was probably an erosion surface with a gentle slope to the east that existed prior to the flood erosion that removed the material surrounding Tatman Mountain. The Bench Mark at Fenton Pass has an elevation of 5998 feet suggesting that Fenton Pass is 160 to 180 feet deep. Note how Fenton Pass links the north oriented Fenton Gulch valley with the valley of a south-southeast oriented Blackburn Gulch tributary valley. In the northwest quadrant of section 21 and the southwest quadrant of section 16 there are unnamed northwest-to-southeast oriented passes linking a northwest oriented Fenton Gulch tributary valley with a southeast oriented valley. The elevation of the section 21 pass is between 5800 and 5820 feet while the elevation of the section 16 pass is between 5840 and 5860 feet. These elevations suggest the passes are between 255 and 295 feet deep. These passes across Tatman Mountain were eroded by south oriented flood flow moving to what was then the actively eroding Fifteenmile Creek valley. Today the Fifteenmile Creek valley elevation south of figure 7  is in the 4700-4800 foot range, which means it is approximately 1400 feet lower than the top of Tatman Mountain. It is possible floodwaters were eroding a 1400-foot deep Fiftennmile Creek valley headward across the region. At that time there was no Greybull River valley to the north and floodwaters were flowing on a surface at least as high as the top of Tatman Mountain today. The Greybull River valley to the north of figure 7 is as deep as the Fifteenmile Creek valley and headward erosion of the 1400-foot deep Greybull River valley north of figure 7 captured the south oriented flood flow and ended all flood flow across Tatman Mountain to the newly eroded Fifteenmile Creek valley.

Detailed map of McGee Gulch-Badger Gulch drainage divide area

Figure 8: Detailed map of McGee Gulch-Badger Gulch 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 McGee Gulch-Badger Gulch drainage divide area seen in less detail in figure 6 and is located west of figure 7 (there is no overlap area with figure 7). The Greybull River flows in a northeast direction across the northwest corner of figure 8. McGee Gulch is a north-northwest oriented Greybull River tributary originating near Beaver Slide and draining to the north edge of figure 8 (east of center). Blackstone Gulch has headwaters north and west of the Beaver Creek Basin and then drains in a north and north-northeast direction to the north edge of figure 8 (west of center). The Badger Creek Basin is a southeast oriented escarpment-surrounded basin where Badger Creek originates. Badger Creek flows from Badger Creek Basin in a southeast direction to join east oriented Fifteenmile Creek. The map contour interval for figure 8 is 20 feet and the Badger Creek Basin escarpment generally ranges from 100 to 200 feet in elevation although some higher sections can be found. Badger Creek Basin is an abandoned headcut that was being eroded headward (in a northwest direction) by southeast oriented flood flow moving to what was then the actively eroding Fifteenmile Creek valley. At that time there was no northeast oriented Greybull River valley to the northwest and floodwaters were stripping the landscape as they eroded the headcut headward to the northwest. Headward erosion of the deeper northeast oriented Greybull River valley captured the southeast oriented flood flow and ended flood flow to the Badger Creek Basin headcut. Floodwaters on the northwest end of the beheaded flood flow route reversed flow direction to create northwest oriented Blackstone Gulch tributary drainage routes and the north and north-northeast oriented Blackstone Gulch drainage route. The Devils Slide area illustrates another north-northwest to south-southeast oriented through valley or pass across the Greybull River-Fifteenmile Creek drainage divide. The unimproved road crosses the drainage divide at an elevation of 5310 feet. In the southwest quadrant of section 3 elevations rise to 5742 feet and higher elevations on Tatman Mountain can be found just east of figure 8. These elevations suggest the Devils Slide through valley depth is at least 400 feet. The through valley was eroded by south-southeast oriented flood flow moving to the actively eroding Fifteenmile Creek valley. Headward erosion of the much deeper northeast oriented Greybull River valley north and west figure 8 beheaded the south-southeast oriented flood flow channel. Floodwaters on the north-northwest end of the beheaded flood flow channel reversed flow direction to create the north-northwest oriented McGee Gulch drainage route.

Greybull River-Fifteenmile Creek west end drainage divide area

Figure 9: Greybull River-Fifteenmile Creek west end  drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Greybull River-Fifteenmile Creek drainage divide area near the Fifteenmile Creek headwaters and is located south and west of figure 6 and includes an overlap area with figure 6. The Greybull River flows in a northeast, north-northeast, and northeast direction from the west edge of figure 9 (slightly south of center) to Meeteetse and then to the north edge of figure 9 (west half). Little Buffalo Basin in the southwest quadrant of figure 9 appears to be an eroded dome with hogbacks surrounding a central basin. The central basin was eroded by southeast oriented flood flow prior to headward erosion of the Greybull River valley and today is drained by east oriented Little Buffalo Creek, which flows through a water gap near the south center edge of figure 9 to southeast oriented Buffalo Creek, which south of figure 9 flows to east oriented Gooseberry Creek. South and east of figure 9 Gooseberry Creek flows to the north oriented Bighorn River. Fifteenmile Creek originates north of Little Buffalo Basin and east of Meeteetse and flows in an east-northeast and east direction to the east edge of figure 9 (near northeast corner). A Fifteenmile Creek tributary flows in a southeast direction through the Hole in the Ground before turning to flow in a northeast direction to join Fifteenmile Creek. Jack Sellers Draw near the southeast corner of figure 9 drains to east oriented Gooseberry Creek. The drainage history recorded by drainage routes seen in figure 9 begins with southeast oriented flood flow moving across the region to the actively eroding and deep east oriented Gooseberry Creek valley (south and east of figure 9). Next headward erosion of the deep east oriented Fiftenmile Creek valley almost to the present day location of Meeteetse beheaded the southeast oriented flood flow routes to the newly eroded Gooseberry Creek valley. Headward erosion of the deep northeast oriented Greybull River valley next captured the southeast oriented flood flow and floodwaters on northwest ends of beheaded flood flow routes reversed flow direction to create northwest oriented Greybull River tributary drainage routes (e.g. northwest oriented stream joining Greybull River at Meeteetse). Headward erosion of the Greybull River valley ended all flood flow to the newly eroded Fifteenmile Creek valley. Based on evidence seen in figures 6, 7, and 8 floodwaters removed at least 400 meters of bedrock material from the region seen in figure 9. If the top of Tatman Mountain is an erosion surface formed by earlier flood events the amount of flood erosion may have been much greater than the 400 meters documented by the present day Tatman Mountain erosional residual.

Detailed map of Greybull River-Fifteenmile Creek drainage divide area

Figure 10: Detailed map of Greybull River-Fifteenmile 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 Greybull River-Fifteenmile Creek drainage divide area seen in less detail in figure 9. Meeteetse is located in the northwest corner of figure 10 and the northeast oriented Greybull River is located west and north of figure 10. The northwest oriented stream flowing to Meeteetse is a Greybull River tributary. Buffalo Creek is a southeast oriented stream flowing to the south edge of figure 10 (near southeast corner) and south and east of figure 10 joins east oriented Gooseberry Creek. Note how the northwest oriented stream alignment is the same as the alignment of southeast oriented Buffalo Creek and how a through valley links the two opposing drainage routes. Highway 120 makes use of the through valley as it travels from Meeteetse to the southeast oriented Buffalo Creek valley. A close look at the through valley reveals three streams drain it. At the northwest end is the northwest oriented Greybull River tributary. At the southeast end southeast oriented Buffalo Creek drains the through valley. In the middle (near the center of figure 10) a southeast oriented stream drains the through valley and then turns to flow in a northeast direction to Hole in the Ground where the stream turns to flow in a southeast direction. Just east of figure 10 that stream turns to flow in a northeast direction and then joins or becomes Fifteenmile Creek. The map contour interval for figure 10 is 20 feet and the elevation where the highway crosses the drainage divide between the Fifteenmile Creek headwaters stream and Buffalo Creek is 6178 feet. The elevation where the highway crosses the Greybull River-Fifteenmile Creek drainage divide is 6218 feet. Elevations on the hogback ridge to the west rise to more than 6600 feet while elevations on the hogback ridges to the east rise to more than 6400 feet. These elevations suggest the through valley is approximately 200 feet deep. While the through valley is probably located between two hogback ridges it is also a water-eroded valley and was eroded by southeast oriented flood flow moving to what was then the newly eroded Gooseberry Creek valley. Headward erosion of the east-oriented Fiftennmile Creek valley captured the southeast oriented flood flow and diverted the floodwaters to the actively eroding Fifteenmile Creek valley. Finally headward erosion of the northeast oriented Greybull River valley beheaded the flood flow channel to the newly eroded Fifteenmile Creek valley. Floodwaters on the northwest end of the beheaded flood flow channel reversed flow direction to create the northwest oriented Greybull River drainage route.

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.