Cheyenne River-North Platte River drainage divide area landform origins, eastern Wyoming, USA

· Cheyenne River, North Platte River, Wyoming
Authors

A geomorphic history based on topographic map evidence

Abstract:

The Cheyenne River-North Platte River drainage divide area is located in eastern Wyoming, USA and is actually the drainage divide area between a Cheyenne River tributary, Lightning Creek, and the North Platte River. Although detailed topographic maps of the Lightning Creek-North Platte River drainage divide area have been available for more than fifty years detailed map evidence has not previously been used to interpret the region’s geomorphic history. The interpretation provided here is based entirely on topographic map evidence. The Lightning Creek-North Platte River drainage divide area is interpreted to have been eroded during immense southeast-oriented flood events, the first of which flowed on a topographic surface at least as high as the highest points in the present-day drainage divide area. Flood erosion across the drainage divide ended when headward erosion of the northeast-oriented Lightning Creek valley and the southeast-oriented North Platte River valley captured all southeast-oriented flood flow.

Preface:

The following interpretation of detailed topographic map evidence is provided as evidence in the Missouri River drainage basin landform origins research project, which is compiling similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with and within certain adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored geomorphology paradigm, which is briefly described in the introduction below. 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 Wyoming Cheyenne River-North Platte River drainage divide area landform origins. 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 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 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 similar essays is a thick North American ice sheet, comparable in thickness to the present day Antarctic ice sheet, occupied approximately the North American region usually recognized to have been glaciated and through its weight and erosive actions created a “deep” North American “hole”, 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 Cheyenne River-North Platte River drainage divide area landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Lightning Creek-North Platte River drainage divide area location map

Figure 1: Lightning Creek-North Platte River drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a general location map for the eastern Wyoming Cheyenne River (Lightning Creek)-North Platte River drainage divide area. The state of Nebraska is enclosed by the yellow boundary line in the figure 1 southeast quadrant, the state of South Dakota is enclosed by the red boundary line in the northeast quadrant, and the state of Wyoming is in the figure 1 west half and is west of the purple boundary line. Lightning Creek, which is the Cheyenne River tributary of concern here, originates north of Douglas, Wyoming and flows in a northeast direction to join Lance Creek, which in turn flows to the Cheyenne River, which flows around the Black Hills south end and then turns northeast. The North Platte River flows north and northeast to Casper, Wyoming (figure 1 west center) and then east and southeast through Douglas, Glendo, Guernsey, Fort Laramie, Lingle and Torrington, Wyoming and to Morrill, Mitchell, and Scottsbluff, Nebraska. The Lightning Creek-North Platte River drainage divide area discussed here is located south of the Lightning Creek source northwest of Douglas, Wyoming and continues east to approximately the location of a north-south line running through Manville, Wyoming. North and west of the Lightning Creek-North Platte River drainage divide area is the Cheyenne River drainage basin, which bounded to the northwest by the Powder River drainage basin and to the north by the Belle Fourche River drainage basin (see essays under Powder River and Belle Fourche River on sidebar category list for evolution of those drainage basins). North-oriented Lance Creek is the easternmost Lightning Creek tributary discussed here and is located immediately west of the Niobrara River source area (see essays under Niobrara River on sidebar category list for Niobrara River drainage basin evolution). Landform evidence illustrated here is interpreted in the context of an immense southeast oriented flood flowing across the entire figure 1 map area and which was systematically captured and diverted east and northeast by headward erosion of deep valleys eroded into a topographic surface at least as high as the figure 1 region highest elevations today. In the figure 1 map region headward erosion of the North Platte River valley captured southeast-oriented flood flow at approximately the same time as headward erosion of the east, southeast and northeast-oriented Cheyenne River and its tributary Lightning Creek valley eroded southwest to capture the same southeast-oriented flood flow. Detailed maps below provide evidence supporting this interpretation.

Lightning Creek-North Platte River drainage divide area detailed location map

Figure 2: Lightning Creek-North Platte River drainage divide area detailed location map. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a detailed location map for the Lightning Creek-North Platte River drainage divide area. Converse and Niobrara Counties are located in Wyoming. Lightning Creek originates northwest of Douglas, Wyoming and flows northeast to join north-oriented Lance Creek near Cow Creek, Wyoming in the figure 2 northeast quadrant. The North Platte River enters the figure 2 map area in the west center and flows east before turning southeast to flow through Douglas and to the Glendo Reservoir. The Lightning Creek-North Platte River drainage divide area discussed here is located west of the highway extending north from Manville to Lance Creek and Cow Creek, Wyoming. Note the northeast and southwest-oriented tributaries flowing to the east-oriented North Platte River. These northeast and southwest-oriented tributary valleys were probably initiated as interconnected channels in a large northeast-oriented anastomosing channel complex formed during an immense flood, which was first captured by headward erosion of the Cheyenne River-Lightning Creek (and tributary) valleys and subsequently captured by headward erosion of the North Platte River valley. North and east of this figure 2 map region tributary orientations primarily have northwest and southeast-orientations, which has been interpreted in hundreds of other Missouri River drainage basin landform origins research project essays as evidence for an immense southeast-oriented flood. While evidence presented here is not adequate to determine the flood source, using the other essays as group enables flood waters to be traced headward to what was probably a rapidly melting thick North American ice sheet located in a deep “hole” occupying approximately the North American region usually recognized to have been glaciated. However, readers may question how flood waters from such an ice sheet (which would have been located north and east of the figure 2 map area) could be flowing northeast from Wyoming’s Laramie Range, which is located in the figure 2 southwest corner. While not obvious from figure 2 evidence the detailed maps shown here demonstrate the northeast-oriented Lightning Creek valley and tributary valleys eroded headward across southeast-oriented flood flow and the southwest-oriented North Platte River tributary valleys also were eroded across southeast-oriented flood flow. Based on other essay interpretations figure 2 evidence does make a case for northeast-oriented flood flow from the Laramie Range, which is south and west of Lightning Creek-North Platte River drainage divide area discussed here. For purposes of this essay the question of how and why melt water floods flowed northeast from the Laramie Range will not be answered, although other essays are needed to document routes continental ice sheet melt water floods took west and south of this figure 2 region.

Lightning Creek-Lost Creek-Lance Creek drainage divide area

Figure 3: Lightning Creek-Lost Creek-Lance Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 illustrates the Lightning Creek-Lance Creek drainage divide area northeast of Lost Springs, Wyoming. Lance Creek flows north-northeast in the figure 3 northeast corner. Note how Lance Creek tributaries include southeast oriented Golden Draw and Sothman Draw and northwest-oriented Bills Creek and present day Lance Creek headwaters in the figure 3 southeast quadrant are both southeast oriented and northwest oriented. The southeast and northwest-orientations of tributaries and headwaters are evidence the north-northeast oriented Lance Creek valley eroded south-southwest to capture multiple southeast-oriented flood flow routes, such as might be found in a southeast-oriented anastomosing channel complex. Headward erosion of the Lance Creek valley captured the southeast-oriented flood flow and diverted the water to the Cheyenne River valley. Note how west of Lance Creek along the figure 3 north edge is northeast-oriented Little Lightning Creek, which has east-southeast oriented tributaries and headwaters. West and south of Little Lightning Creek are northwest-oriented tributaries flowing to north-northwest, north-northeast and northeast oriented Twentymile Creek, which can be seen in the figure 3 west center and northwest corner. The northwest-oriented tributaries and headwaters are evidence headward erosion of the Twentymile Creek valley beheaded multiple southeast-oriented flood flow routes and flood waters on the northwest ends of those beheaded flood flow routes reversed flow direction to flow northwest into the newly eroded northeast-oriented Twentymile Creek valley. Southeast of the north-northwest oriented Twentymile Creek headwaters is southeast-oriented Dip Creek, which flows to southwest-oriented Lost Creek, which after flowing through Lost Springs flows to the southeast-oriented North Platte River. Note how Lost Creek has several other southeast-oriented tributaries including Stevenson Draw and Watkins Draw. These southeast-oriented tributaries are evidence the southwest-oriented Lost Creek valley was eroded headward across multiple southeast-oriented flood flow routes and diverted the water southwest to the newly eroded southeast-oriented North Platte River valley. Note also how Lost Creek headwaters are linked by a through valley to east-southeast and northeast-oriented Sothman Draw and the north-northeast oriented Lance Creek valley. It is possible the southwest-oriented Lost Creek valley originated as a southwest extension of an earlier and higher level Lance Creek valley that was eroded southwest across the figure 3 map area to southwest of the present day North Platte River valley. Headward erosion of the deeper North Platte River valley then beheaded northeast-oriented flood flow moving in that early Lance Creek valley, causing a reversal of flow on the southwest end of the earlier Lance Creek valley that eroded the present day southwest-oriented Lost Creek valley.

Drainage divides in the Harney Hills area

Figure 4: Drainage divides in the Harney Hills area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates in more detail the Twentymile Creek-Lance Creek drainage divide area in the Harney Hills area, which was seen in less detail in figure 3 above. Little Lightning Creek flows east-southeast and northeast in the figure 4 northeast quadrant. To the south are east-southeast oriented Golden Draw and Sothman Draw, which flow to north-northeast oriented Lance Creek, which is located east of figure 4. Northwest-oriented Harney Creek and East Harney Creek have eroded valleys (water gaps) across the Harney Hills and flow to northeast-oriented Twentymile Creek, which is located northwest of the figure 4 map area. Note the unnamed East Harney Creek tributary, which has also eroded a valley (or water gap), across the Harney Hills. The present day northwest-oriented Harney Creek, East Harney Creek, and unnamed East Harney Creek tributary valleys or water gaps eroded across the Harney Hills were probably eroded by southeast-oriented flood flow routes moving flood waters to what was then the newly eroded north-northeast oriented Lance Creek valley (along the Sothman Draw valley route just prior to being reversed). Flood flow reversal occurred when the deep Twentymile Creek valley eroded southwest and beheaded the southeast-oriented flood flow routes. Flood waters on the northwest ends of the beheaded flood flow routes reversed flow direction and flowed northwest to the newly eroded and deeper Twentymile Creek valley. The flood flow reversals occurred in sequence from the northeast to the southwest. Because flood waters were flowing in anastomosing channels (or interconnected channels) reversed flood flow on one route often captured southeast-oriented flood flow on yet to be beheaded flood flow routes. Such captures enabled the reversed flood flow channels to erode deeper valleys than would otherwise have been possible. The northeast-oriented Little Lightning Creek valley eroded southwest into the figure 4 map region between the time the Lance Creek valley eroded southwest into the region and the time headward erosion of the Twentymile Creek valley beheaded southeast-oriented flood flow to the Sothman Draw valley. Note how Little Lightning Creek headwaters are east-southeast oriented indicating headward erosion of the Little Lightning Creek valley captured southeast-oriented flood flow.

Antelope Creek-Shawnee Creek drainage divide area

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

Figure 5 illustrates a region west and slightly south of the figure 3 map area and includes some overlap area with figure 3. North-northwest and north-northeast oriented Twentymile Creek is located in the figure 5 northeast corner. The West Fork Twentymile Creek originates as a northwest-oriented stream and then turns northeast to flow to Twentymile Creek in the figure 5 northeast corner. Southwest-oriented drainage west of the highway in the figure 5 northwest corner is the head of southwest-oriented Antelope Creek, which flows to the southeast-oriented North Platte River at Douglas, Wyoming. Draining to the figure 5 south edge (east half) are the southeast-oriented West Fork, south-southwest oriented Middle Fork, and southwest-oriented East Fork of Shawnee Creek, which south of figure 5 flows southwest on the East Fork alignment to te southeast-oriented North Platte River. Northeast-oriented drainage along the figure 5 north center edge is flowing to northeast-oriented Walker Creek, which is a Lightning Creek tributary. Note how the West Fork of Shawnee Creek has multiple southeast-oriented tributaries, the Middle Fork of Shawnee has southeast-oriented tributaries, and the East Fork of Shawnee Creek also has southeast-oriented tributaries. Also note how the South Fork of Walker Creek has northwest-oriented tributaries and an unnamed southwest-oriented Antelope Creek tributary (located immediately southeast of the highway) has northwest-oriented tributaries. Further, note how the northeast-oriented West Fork Twentymile Creek has southeast-oriented tributaries. The southeast-oriented tributaries and the northwest-oriented tributaries are evidence the Shawnee Creek, Twentymile Creek, Walker Creek, and Antelope Creek valleys were eroded across multiple southeast-oriented flood flow routes, such as might be expected in a southeast-oriented anastomosing channel complex. The northwest-oriented tributary valleys were eroded by reversed flood flow on the northwest ends of beheaded southeast-oriented flood flow routes. It is possible the southwest-oriented Shawnee Creek and East Fork Shawnee Creek valley originated as a southwest extension of an earlier Twentymile Creek valley, when that earlier (and probably deep) Twentymile Creek valley eroded southwest across the figure 3 map area, and then headward erosion of the much deeper North Platte River valley beheaded northeast-oriented flood flow moving in that early Twentymile Creek valley, causing a reversal of flow on the southwest end of the earlier Twentymile Creek valley that eroded the present day southwest-oriented Shawnee Creek and East Fork Shawnee Creek valley. It is also possible the southwest-oriented Antelope Creek valley originated as a southwest extension of an earlier Walker Creek valley, when that earlier (and probably deep) Walker Creek valley eroded southwest across the region, and then headward erosion of the much deeper North Platte River valley beheaded northeast-oriented flood flow moving in that early Walker Creek valley, causing a reversal of flow on the southwest end of the earlier Walker Creek valley that eroded the present day southwest-oriented Antelope Creek valley.

West Fork Twentymile Creek-East Fork Shawnee Creek drainage divide area

Figure 6: West Fork Twentymile Creek-East Fork Shawnee Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates a detailed map of West Fork Twentymile Creek-East Fork Shawnee Creek drainage divide area seen in less detail in figure 5 above. Headwaters of several East Fork Shawnee Creek tributaries originate just east of Flat Top and flow southeast to the figure 6 south center edge. Headwaters of several West Fork Twentymile Creek tributaries originate at the spring just north of Flat Top and flow north-northwest to the figure 6 north edge (west half). North-northwest oriented Twentymile Creek is located in the figure 6 northeast corner and north-oriented Sawmill Canyon drains north to the figure 6 north center (east half) edge and then to north-oriented Twentymile Creek. Note the high level through valleys eroded across the ridge just west of Flat Top that today represents the drainage divide between north-northwest oriented West Fork Twentymile Creek headwaters and southeast-oriented East Fork Shawnee Creek headwaters. Those through valleys were eroded by southeast-oriented flood flow moving from what is today the Twentymile Creek (and Cheyenne River drainage basin) to what is today the Shawnee Creek (and North Platte River drainage basin). Similar high level through valleys link the north-oriented Sawmill Canyon valley with valleys of south-oriented East Fork Shawnee Creek tributaries and provide evidence that at one time flood waters moved across the Sawmill Canyon-East Fork Shawnee drainage divide as well. The multiple through valleys provide evidence the flood waters were eroding deep anastomosing channels into the regional landscape. The anastomosing channels were almost certainly interconnected and constantly changing as one channel eroded deeper and captured flood flow from other channels. Such captures often resulted in reversals of flood flow on the ends of beheaded flood flow channels. Flood waters initially were flowing southeast, probably to an actively eroding North Platte River valley headcut southeast of the figure 6 map area. Subsequently the flood waters were captured by headward erosion of the northeast-oriented Lightning Creek-Twentymile Creek valley to the north and at about the same time by headward erosion of the deeper North Platte River valley to the southwest. Those captures resulted in flood flow reversals that resulted in the present day drainage pattern.

Antelope Creek-West Fork Shawnee Creek drainage divide area

Figure 7: Antelope Creek-West Fork Shawnee Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Antelope Creek-West Fork Shawnee Creek drainage divide area northeast of Douglas, Wyoming and includes significant overlap areas with figure 5 above. Antelope Creek flows southwest along the highway to join the southeast oriented North Platte River, which is located just southwest of the figure 7 map area. Southwest-oriented East Antelope Creek is located to the southeast of Antelope Creek and flows through Douglas to the North Platte River. Northwest of Antelope Creek are other southwest-oriented drainage routes, which flow to the North Platte River valley (west of Douglas the North Platte River is east-oriented and then turns  to flow in a southeast direction-see figures 1 and 2 above). The West Fork Shawnee Creek flows southeast to join the south-oriented Middle Fork Shawnee Creek in the figure 7 southeast corner and to flow as southwest-oriented Shawnee Creek to the southeast oriented North Platte River. Northeast-oriented headwaters of northeast-oriented Walker Creek are located in the figure 7 north center. Note northwest-oriented Antelope Creek tributary valleys, which were eroded by reversed flood flow on northwest ends of southeast-oriented flood flow routes beheaded by headward erosion of the Antelope Creek valley. The southeast-oriented flood flow routes had been moving flood waters to southeast-oriented West Fork Shawnee Creek tributary valleys, which in turn moved the water to southwest-oriented Shawnee Creek and what was then was probably the newly eroded southeast-oriented North Platte River valley head. The southwest-oriented Antelope Creek valley eroded headward (perhaps along a valley alignment originally established by headward erosion of an earlier and higher level northeast-oriented Walker Creek valley) to behead the southeast-oriented flood flow routes to Shawnee Creek and to divert the flood waters southwest to what was then the newly eroded southeast-oriented North Platte River valley head. Reversed flood on the northwest ends of the beheaded flood flow routes moved flood water northwest to the newly eroded and deeper southwest-oriented Antelope Creek valley. Note the location of southeast- and southwest-oriented Simpson Draw-Walker Creek drainage divide area, located in the southwest section of the figure 7 northeast quadrant, which figure 8 illustrates in detail.

Walker Creek-Antelope Creek-Simpson Draw drainage divide area

Figure 8: Walker Creek-Antelope Creek-Simpson Draw drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the drainage divide between northeast-oriented Walker Creek and southwest-oriented Antelope Creek and between an east and northeast-oriented Walker Creek tributary and southeast-oriented Simpson Draw, which flows to the West Fork Shawnee Creek. Most of the figure 8 map area is illustrated in less detail along the north edge of figure 7 above. Northeast oriented Walker Creek headwaters are located in the figure 8 northwest corner. South and southwest-oriented Antelope Creek headwaters are located along the figure 8 west edge south of Walker Creek. An unnamed east-northeast oriented Walker Creek tributary originates in the figure 8 center and flows toward the figure 8 northeast corner. Southeast-oriented Simpson Draw is located in the figure 8 southeast quadrant. Note how the unnamed east- and northeast-oriented Walker Creek tributary valley is eroded deeper than the Simpson Draw valley. The deeper erosion indicates flood flow to the unnamed Walker Creek tributary valley continued longer than it did to the Simpson Draw valley. This probably means the southwest-oriented Antelope Creek valley beheaded southeast-oriented flood flow to the Simpson Draw valley before the northeast-oriented Walker Creek valley beheaded southeast-oriented flood flow to the unnamed Walker Creek tributary valley. The Simpson Draw valley and the unnamed Walker Creek tributary valley were components of an ever-changing southeast-oriented anastomosing channel complex, which was being captured by headward erosion of the northeast-oriented Lightning Creek-Walker Creek valley to the north and headward erosion of the deep southeast-oriented North Platte River valley to the south and the Walker Creek-Shawnee Creek, Antelope Creek-Shawnee Creek, and Walker Creek-Antelope Creek drainage divides were developed as the southeast-oriented flood waters were captured by one or the other of the two major competing valley systems. Drainage patterns today are almost precisely the same as when flood waters were captured by Powder River valley headward erosion and ceased to flow across the region.

Sage Creek-Box Creek and Lightning Creek drainage divide area

Figure 9: Sage Creek-Box Creek and Lightning Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Sage Creek-Box Creek and Lightning Creek drainage divide area northwest of Douglas, Wyoming. Lightning Creek flows northeast in the figure 9 southeast corner. The South Fork of Box Creek flows to the figure 9 northeast corner and the North Fork Box Creek flows from the figure 9 north center to the figure 9 northeast corner. Box Creek is a Lightning Creek tributary and joins Lightning Creek northeast of the figure 9 map area. Sage Creek flows southeast from the figure 9 west edge (north half) and then turns to flow south-southeast to the figure 9 south center edge. Sage Creek flows to the east-oriented North Platte River located south of figure 9 (see figures 1 and 2). Southwest and west-oriented tributaries flow to Sage Creek from the north and east. East and southeast oriented tributaries flow to Sage Creek from the west, although one Sage Creek tributary south of the Box Creek Divide flows southeast before turning south to flow to Sage Creek. The drainage divide between northeast-oriented Lightning Creek and southwest-oriented Sage Creek tributaries is the Sundquist Flats erosion surface, while the drainage divide between Sage Creek and northeast-oriented South and North Forks of Box Creek is the ridge named on figure 9 as the Box Creek Divide. Figure 9 evidence suggests southeast oriented flood water was flowing on topographic surface at least as high as the highest points on the Box Creek Divide and Sundquist Flats area today when what was then the deep Lightning Creek valley eroded into the region to capture the southeast oriented flood flow. Headward erosion of the deep South Fork Box Creek soon followed and headward erosion of the deep North Fork Box Creek valley followed soon after. At about the same time the deeper south-oriented Sage Creek valley eroded north and northwest to capture southeas toriented flood flow routes that were in the process of being captured by headward erosion of the northeast-oriented Lightning Creek and South and North Fork Box Creek valleys. The previously mentioned southeast- and south-oriented Sage Creek tributary provides evidence water flowed southeast along what is today the Box Creek Divide. Some southwest-oriented Sage Creek tributary valleys may have been eroded by reversed flow on beheaded northeast-oriented flood flow routes moving water to the actively eroding northeast-oriented Lightning Creek and South Fork and North Fork Box Creek valleys.

Sage Creek-Box Creek drainage divide at Box Creek Divide

Figure 10: Sage Creek-Box Creek drainage divide at Box Creek Divide. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 illustrates the Sage Creek-Box Creek drainage divide at Box Creek Divide located just east of Taylor Flats and seen in less detail in figure 9 above. Drainage north and east of Taylor Flats and the Box Creek Divide flows to the North Fork Box Creek and eventually reaches the Cheyenne River. Drainage south and west of Taylor Flats and the Box Creek Divide flows to Sage Creek and the North Platte River. Note how multiple southeast oriented streams drain the Taylor Flats southeast end to south-oriented Sage Creek and provide evidence multiple southeast oriented flood flow routes once crossed the Taylor Flats surface and were captured by headward erosion of a south-oriented Sage Creek tributary. Subsequently the southeast oriented flood flow routes were beheaded by headward erosion of the Sage Creek valley (southwest of figure 10) and of the southwest-oriented School Section Draw valley. West and northwest-oriented School Section Draw tributary valleys were probably eroded by reversals of flood flow on beheaded southeast-oriented flood flow routes to the previously mentioned south-oriented Sage Creek tributary valley. North of Box Creek Divide note how Dry Draw (which drains to the North Fork Box Creek) has southeast-oriented headwaters and how there are northwest-oriented tributary valleys to the northeast-oriented North Fork Box Creek valley (located along the figure 10 north edge-west half). The southeast- and northwest-orientations of those North Fork Box Creek tributary valleys is evidence the North Fork Box Creek eroded headward across southeast-oriented flood flow. The Dry Draw valley eroded into the region first to capture southeast-oriented that was subsequently captured by headward erosion of the North Fork Box Creek valley. Flood flow reversals on the northwest ends of beheaded flood flow routes then eroded the northwest-oriented North Fork Box Creek tributary valleys.

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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