A geomorphic history based on topographic map evidence

The Powder River-Little Powder River drainage divide area discussed here is located in Wyoming’s northeast corner and is immediately south of the Montana state line. Although detailed topographic maps of this Powder River-Little Powder 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. This Powder River-Little Powder 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 ended when headward erosion of the north-oriented Powder River valley captured all southeast-oriented flood flow.

Introduction:

• The purpose of this essay is to use topographic map interpretation methods to explore northeast Wyoming  Powder River-Little Powder 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 northeast Wyoming Powder River-Little Powder River drainage divide area landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Powder River-Little Powder River drainage divide location map

Figure 1: Powder River-Little Powder River drainage divide location map. National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a general location map for the Wyoming Powder River-Little Powder River drainage divide area discussed here. The Powder River begins in central Wyoming (southwest of figure 1 map area) and flows east, northeast, and northeast into the state of Montana. The Little Powder River begins near Gillette, Wyoming and flows north to join the Powder River near Broadus, Montana. East of the north-oriented Little Powder River is the northeast-oriented Little Missouri River, which also begins in northeast Wyoming and then flows across the Montana southeast corner to enter the state of South Dakota. East of the Little Missouri River in northeast Wyoming is the northeast-oriented Belle Fourche River, which begins in northeast Wyoming south of the figure 1 map area and flows northeast almost to the Montana state line and then turns abruptly to flow southeast into South Dakota. Other essays discuss northeast Wyoming Little Powder River-Little Missouri River drainage divide evidence and Little Missouri River-Belle Fourche River drainage divide evidence and can be found under Little Missouri River on the sidebar category list. This essay focuses on Powder River-Little Powder River drainage divide evidence south of the Wyoming-Montana state line. A different essay addresses Powder River-Little Powder River drainage divide evidence north of the Wyoming-Montana state line and can be found under Powder River on the sidebar category list. Landform evidence illustrated here is interpreted to have been formed when headward erosion of the north-oriented Little Powder River valley captured multiple southeast-oriented flood flow routes and diverted the flood waters north and then shortly thereafter headward erosion of the northeast-oriented Powder River valley beheaded and captured those same southeast-oriented flood flow routes and in the process created the present-day Powder River-Little Powder River drainage divide. The source of the immense southeast-oriented flood involved cannot be determined from map evidence presented here, however by use of many other essays published on this website it is possible to trace flood waters to a North American ice sheet location. Rapid melting of a large North American ice sheet would provide a logical flood source.

Powder River-Little Powder River Wyoming drainage divide location map

Figure 2: Powder River-Little Powder River Wyoming drainage divide location map. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 2 provides a more detailed map of the Powder River-Little Powder River northeast Wyoming drainage divide area. The Powder River flows north and then northeast in the figure 2 west half while the Little Powder River begins north of Rozet (on highway east of Gillette) and flows north to the figure 2 north edge. The northeast-oriented Little Missouri River begins in the figure 2 east center and the northeast-oriented Belle Fourche River is located in the figure 2 southeast corner. Donkey Creek begins in the Gillette area and flows adjacent to the highways and railroad to join the northeast-oriented Belle Fourche River near Moorcroft, Wyoming (figure 2 southeast corner) and will be important in the figure 10 discussion. Note how almost all Powder River and Little Powder River tributaries from the east are northwest-oriented and how many Powder River and Little Powder River tributaries from the west are southeast-oriented (and how tributaries to the northeast-oriented Powder River and Little Powder River tributaries are usually southeast-oriented). This northwest-southeast tributary drainage alignment is evidence the Little Powder River and the Powder River valleys were eroded headward across multiple southeast-oriented flood flow routes, probably across a southeast-oriented anastomosing channel complex, and will be further illustrated and discussed in the detailed maps and discussions below. This essay begins by viewing The Powder River- Olmstead Creek (a Little Powder River tributary) drainage divide area near the Wyoming-Montana state line and will progress south along the Powder River-Little Powder River drainage divide. Second the Powder River-Elk Creek (a Little Powder River tributary) drainage divide will be viewed. Third will be the Chicken Creek divide area near Spotted Horse. Fourth will be the Powder River-Horse Creek drainage divide area. Fifth will be a view of the Horse Creek-Wildcat Creek drainage divide and confluence area and the Horse Creek-Little Powder River confluence area. Sixth will be a view of the Powder River-Wildcat Creek drainage divide area. Seventh will be a view of the Powder River-Rawhide Creek drainage divide area. And eighth, the essay concludes with a view of the Little Powder River source area and the Little Powder River-Donkey Creek drainage divide.

Powder River-Olmstead Creek drainage divide area

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

Figure 3 illustrates the Powder River-Olmstead Creek drainage divide area near the Montana-Wyoming state line. Northwest-oriented streams in the figure 3 west half are Powder River tributaries. The three major northwest-oriented Powder River tributaries from north to south are Buffalo Creek, Dry Creek, and Bitter Creek. Armstrong Prong flows west-northwest to northwest-oriented Bitter Creek and Corral Creek flows southeast and then south to join Armstrong Prong. The east-oriented Olmstead Creek drainage system flows to the north-oriented Little Powder River. Note how many Olmstead Creek tributaries and Olmtead Creek headwaters are southeast oriented indicating the Olmstead Creek valley eroded west from what was probably a newly eroded Little Powder River valley to capture southeast oriented flood flow moving on several different flood flow routes. North-northwest-oriented Cromack Draw provides evidence flood water on the northwest end of a beheaded and captured southeast-oriented flood flow route reversed flow direction to flow northwest and with assistance from flood flow captured from southeast-oriented flood flow routes further to the  southwest eroded a northwest-oriented tributary valley to the east-oriented Olmstead Creek valley. Subsequent to Olmstead Creek capture events the northeast-oriented Powder River valley eroded southwest and beheaded and captured southeast-oriented flood flow routes carrying flood water across the figure 3 region. Flood flow routes were beheaded in sequence with southeast-oriented flood flow on the Buffalo Creek alignment beheaded first, flood flow on the Dry Creek alignment beheaded second, and flood flow on the Bitter Creek alignment  beheaded third. In each case flood water on the northwest ends of beheaded flood flow routes reversed flow direction to flow northwest to the newly eroded Powder River valley and by doing so created the Powder River-Little Powder River drainage divide and also eroded the present day northwest-oriented Powder River tributary valleys. Erosion of the northwest-oriented tributary valleys was aided by flood water captured from yet to be beheaded southeast-oriented flood flow routes further to the southwest. The present day southeast- and south-oriented Corral Creek valley to the west-northwest-oriented Armstrong Prong valley alignment probably is a reversal of flow on a route captured flood waters from the yet to beheaded Bitter Creek flood flow route used to reach reversed flow on the newly beheaded Buffalo Creek and Dry Creek flood flow routes.

Powder River-Elk Creek drainage divide area

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

Figure 4 illustrates a Powder River-Little Powder River drainage divide region south of the figure 3 area and includes an area of overlap. The north-oriented Little Powder River is located a short distance east of the figure 4 map area. Major east-oriented drainage routes to the Little Powder River from north to south are east-oriented Olmstead Creek with north-northwest Cromack Draw flowing to it, southeast-oriented Elk Creek with its southeast-oriented North Fork, and southeast-oriented White Tail Creek. Bitter Creek is the major northwest-oriented drainage system flowing to the northeast-oriented Powder River, although in the figure 4 southwest corner S A Creek also flows northwest to the Powder River. In addition to the northwest-southeast oriented drainage alignment as evidence multiple southeast-oriented flood flow routes once crossed the present day Powder River-Little Powder drainage divide there are shallow through valleys linking headwaters of the northwest-oriented streams with headwaters of the southeast-oriented streams. These through valleys are further evidence flood water was flowing in multiple channels typical of an anastomosing channel complex. Careful study of through valleys (which are better observed on mosaics of detailed topographic maps) reveals how reversed flood flow on beheaded flood flow routes captured flood water from yet to be beheaded flow routes. Evidence of such a capture by northwest-oriented Bitter Creek is seen on figure 4 where  northwest and north-oriented Bitter Creek headwaters are linked by high level through valleys to northwest-oriented S A Creek. Those through valleys are evidence flood flow was moving over a topographic surface at least as high as the highest figure 4 region elevations today and that flood waters eroded the present day landscape before all flood water drained from the region. The north-oriented Bitter Creek headwaters segment was eroded south by flood waters captured from a yet to be beheaded southeast-oriented flood flow route using the northwest-oriented Bitter Creek headwaters segment alignment (and also White Tail Creek alignment) to reach reversed flood flow on the beheaded northwest-oriented Bitter Creek-East Fork valley alignment.

Chicken Creek divide area

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

Figure 5 illustrates the Powder River-Little Powder River drainage divide area south of the figure 4 map area and again provides overlap with figure 3. Bar Creek flows northwest to the figure 5 northwest corner and northwest oriented S A Creek is east of that and still further east are northwest-oriented Bitter Creek headwaters. West of Spotted Horse northwest-oriented Spotted Horse Creek begins along the figure 5 west edge. Chicken Creek Draw is a northwest, west, and southwest-oriented Spotted Horse Creek tributary. Southeast-oriented White Tail Creek is located in the figure 5 northeast corner and northeast-oriented Horse Creek flows across the figure 5 southeast corner. Horse Creek tributaries shown from north to south are southeast-oriented Spring, Squaw, and Hay Creeks. Note multiple through valleys linking headwaters of  northwest-oriented Powder River tributaries with headwaters of southeast-oriented Little Powder River tributaries. For example the highway east of Spotted Horse and south of Chicken Creek Divide is located in a well-defined through valley linking northwest-oriented Chicken Creek Draw headwaters with southeast-oriented Hay Creek headwaters. This through valley and the Chicken Creek Draw valley orientation suggests southeast-oriented flood flow on the Spotted Horse Creek alignment was captured by headward erosion of the Little Powder River-Horse Creek-Hay Creek valley prior to beheading of southeast-oriented flood flow on the Spotted Horse Creek route. This capture of Spotted Horse Creek alignment southeast-oriented flood flow by southeast-oriented Hay Creek may have become a primary southeast-oriented flow route and may have beheaded flow routes such as the T D Southwest Draw and Box Draw flood flow routes, causing flood waters on northwest ends of those routes to reverse flow direction to create northwest-oriented Chicken Creek Draw tributary valleys.  In any case the Powder River-Little Powder River drainage divide area in the Chicken Creek Draw area provides evidence a southeast-oriented anastomosing channel complex once crossed the divide.

Powder River-Horse Creek drainage divide area

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

Figure 6 illustrates the Powder River-Little Powder River drainage divide region south of the figure 5 map area again with overlap. Chicken Creek Draw flowing to northwest-oriented Spotted Horse Creek is located in the figure 6 north center. Horse Creek flows northeast to the figure 6 east center edge and Hay Creek and Gas Draw are the major southeast-oriented Horse Creek tributaries shown while Ruff Draw, Gibbon Draw, and Box Elder Draw flow north, north-northeast and north-northwest to reach northeast-oriented Horse Creek. South of Horse Creek in the figure 6 southeast corner Lone Tree Draw flows east to northeast-oriented Wildcat Creek (not visible in figure 6). The northwest-oriented stream beginning in the figure 6 south center and flowing to the figure 6 west center is the Middle Prong of Wild Horse Creek. The multiple northwest-oriented tributaries flowing to the northwest-oriented Spotted Horse Creek headwaters including (from northeast to southwest) Chicken Creek Draw, T D Southwest Draw, Rose Creek, Washout Draw, and Box Draw provide evidence the Little Powder River-Horse Creek valley eroded headward or southwest to capture southeast-oriented flood waters flowing in a southeast-oriented anastomosing channel complex. Deeper erosion on the Hay Creek-Chicken Creek Draw probably enabled that route to capture flood flow going to the T D Southwest Draw, Rose Creek, Washout Draw, and Box Draw routes causing a reversal of flood flow on those routes to create the present day drainage divide with Horse Creek. Subsequently headward erosion of the Powder River valley beheaded southeast-oriented flood flow on the Spotted Horse Creek route and caused a reversal of flood flow on the northwest end of that route to create the Chicken Creek Draw-Hay Creek drainage divide. Through valleys that link northwest-oriented Spotted Horse Creek tributaries with northwest-oriented Middle Prong Wild Horse Creek tributaries provide evidence reversed flood flow on the Spotted Horse Creek route captured yet to be beheaded southeast-oriented flood flow on the Middle Prong Wild Horse Creek route. For example, south-southwest oriented North Washout Draw is linked by a through valley to north-northeast and north-northwest oriented Linn Draw. As the northeast-oriented Powder River valley eroded southwest, southeast-oriented flood flow on the Middle Prong Wild Horse Creek route was beheaded and flow on that route was also reversed.

Horse Creek-Wildcat Creek drainage divide and confluence area

Figure 7: Horse Creek-Wildcat Creek drainage divide and confluence area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 7 illustrates an area east of figures 5 and 6 and overlap is provided. The north-northwest and north-oriented Little Powder River is located in the figure 7 northeast corner. Northeast and east oriented Horse Creek flows to northeast-oriented Wildcat Creek and then the Little Powder River. Major southeast-oriented Horse Creek tributaries (from northeast to southwest) are the previously mentioned Spring Creek, Squaw Creek, and Hay Creek. The Horse Creek-Wildcat Creek drainage divide area is located between the two northeast-oriented streams. Note most Horse Creek tributaries flowing from the Horse Creek-Wildcat Creek drainage divide are northwest-oriented and most Wildcat Creek tributaries flowing from the Horse Creek-Wildcat Creek drainage divide are southeast-oriented. Also note shallow through valleys linking the northwest-oriented Horse Creek tributaries with southeast-oriented Wildcat Creek tributaries. Further, note northwest-oriented tributaries flowing from the southeast to northeast-oriented Wildcat Creek. The barbed tributaries, the northwest-southeast-oriented tributary drainage alignment, and the through valleys crossing the Horse Creek-Wildcat Creek drainage divide all provide evidence the Wildcat Creek valley eroded southwest to capture southeast oriented flood flow moving along multiple southeast oriented flood flow routes and subsequently the east and northeast-oriented Horse Creek valley eroded west and southwest to capture the same southeast oriented flood flow routes. The north-northwest oriented Little Powder River valley segment suggests that segment developed as a reversal of flood flow on a beheaded southeast-oriented flood flow route.

Powder River-Wildcat Creek drainage divide area

Figure 8: Powder River-Wildcat Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 8 depicts a Powder River-Little Powder River drainage divide region south of the figure 6 map area and provides overlap. The northeast-oriented Wildcat Creek drainage basin occupies most of the figure 8 east half although in the figure 8 southeast corner headwaters of southeast and east-oriented Hay Creek (unnamed in figure 8) flow to the north-oriented Little Powder River. The Middle Prong of Wild Horse Creek flows northwest in the figure 8 northwest corner to northwest oriented Wild Horse Creek and subsequently to the northeast-oriented Powder River. Twentymile Creek, which flows to northwest oriented Wild Horse Creek, crosses the figure 8 southwest corner. Note how Wildcat Creek tributaries from the northwest are oriented in a southeast direction and are also linked to northwest-oriented Horse Creek tributaries. For example southeast oriented Homestead Draw is linked to an unnamed northwest-oriented Horse Creek tributary and northwest-southeast oriented erosional residuals are located between the northwest and southeast oriented tributaries. Also note how Wildcat Creek tributaries from the south are oriented in north-northwest direction and are linked by through valleys with the southeast- and east-oriented Hay Creek headwaters. For example, north-northwest-oriented Mumma Draw (flowing to northeast-oriented Wildcat Creek) is linked by a through valley to the southeast-oriented oriented Hay Creek headwaters. In addition note high level shallow through valleys linking northwest-oriented Middle Prong Wild Horse Creek tributaries with headwaters of various Wildcat Creek tributaries. Finally note how southeast-oriented North Fork Wildcat Creek is aligned with the northwest-oriented Middle Prong Wild Horse Creek. All of this evidence suggests the Little Powder River-Wildcat Creek valley eroded headward or southwest to capture multiple southeast-oriented flood flow routes moving across a topographic surface at least as high as the highest figure 8 elevations today and subsequently the northeast-oriented Powder River valley eroded headward to capture those same southeast-oriented flood flow routes and to cause a reversal of flood flow on the northwest ends of beheaded flood flow routes that eroded the northwest-oriented tributary valleys and to create the Powder River-Little Powder River drainage divide.

Powder River-Rawhide Creek drainage divide area

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

Figure 9 illustrates a Powder River-Little Powder River drainage divide region south of the figure 8 map area (there is no overlap area). Section 36 along the figure 9 north center edge is drained to the north by headwaters of the north and northeast-oriented Jamison Prong of northeast-oriented Wildcat Creek. In the figure 9 northwest corner Twentymile Creek flows northwest just east of Twentymile Butte. South of Twentymile Butte the railroad follows the valley of northwest-oriented Wild Horse Creek and its northwest-oriented Hay Creek tributary. South of the Hay Creek-Wild Horse Creek confluence Wild Horse Creek is oriented in a north-northwest direction. The figure 9 east half is drained by north-northwest and northeast-oriented Rawhide Creek and its various tributaries to the north-oriented Little Powder River. Note through valleys crossing the Powder River-Little Powder River drainage divide and also other drainage divides such as between the Wildcat Creek headwaters and the southeast-oriented Rawhide Creek tributaries, among others. For example note how northwest-oriented Barker Draw headwaters are linked to southeast-oriented Road Prong of Rawhide Creek headwaters and how headwaters of northwest-oriented Felix Draw are linked to unnamed Rawhide Creek tributaries. Also note through valleys linking the north-oriented Wildcat Creek headwaters in section 36 with headwaters of southeast-oriented Box Draw, Nine T Bar Creek, and Road Prong Rawhide Creek. Many similar linkages can be found throughout the figure 9 map area. These linkages are evidence the Rawhide Creek drainage basin was eroded headward to capture multiple southeast-oriented flood flow routes and subsequently southeast-oriented flood flow was beheaded by Powder River valley headward erosion, causing a reversal of flood flow on the northwest ends of beheaded flood flow routes that created the Powder River-Little Powder drainage divide and also eroded the northwest-oriented Powder River tributary valleys.

Little Powder River-Donkey Creek drainage divide area

Figure 10: Little Powder River-Donkey Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 10 illustrates a region east and slightly south of the figure 9 map area and does include an overlap area. Northeast-oriented Rawhide Creek flows across the figure 10 extreme northwest corner. Little Rawhide Creek is a Rawhide Creek tributary and begins as a northwest-oriented stream and then turns north to reach northeast-oriented Rawhide Creek. The Little Powder River flows northwest from its source area to the figure 10 north center. Located near the Radio Tower east of Gillette are southeast-oriented headwaters of east-oriented Donkey Creek, which can be seen in figure 10 flowing next to the highway east of Wyodak. Donkey Creek is a tributary to the northeast-oriented Belle Fourche River (see figures 1 and 2). The northwest-oriented Little Powder River headwaters segment is evidence headward erosion of the north-oriented Little Powder River valley beheaded and captured southeast-oriented flood flow routes, causing flood waters on the northwest ends of beheaded flow routes to reverse flow direction and flow northwest to the newly eroded Little Powder River valley. Prior to being beheaded and reversed flood flow on the northwest-oriented Little Powder River headwaters segment had been flowing to east-oriented Donkey Creek and the northeast-oriented Belle Fourche River. The Donkey Creek valley had eroded west to capture that flood flow route and other southeast-oriented flood flow routes now preserved in the figure 10 map evidence in the form of northwest-oriented Little Powder River tributaries. Figure 10 evidence demonstrates Donkey Creek eroded west across an anastomosing complex of southeast-oriented flood flow routes and that had the Little Powder River valley eroded further south it would have next captured flood flow moving east along the Donkey Creek 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 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.