A geomorphic history based on topographic map evidence

The Little Powder River-Little Missouri River drainage divide area discussed here is located in Montana’s southeast corner and Wyoming’s northeast corner, near where Wyoming, South Dakota and Montana meet. Although detailed topographic maps of this Little Powder River-Little Missouri 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 Little Powder River-Little Missouri 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 Little Powder 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 Little Powder River-Little Missouri 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 Little Powder River-Little Missouri River drainage divide area landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Little Powder River-Little Missouri River drainage divide location map

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

The Little Powder River begins in northeast Wyoming and flows north-northwest and north to join the northeast-oriented Powder River near Broadus, Montana. The Little Missouri River begins in northeast Wyoming and flows in a northeast direction across Montana’s southeast corner and into South Dakota. The Little Powder River-Little Missouri River drainage divide area addressed here is the drainage divide area south of Hammond, Montana. Boxelder Creek is a northeast-oriented Little Missouri River tributary, and a different essay addresses Little Powder River-Boxelder Creek drainage divide area landform evidence and can be found under Powder River or Little Missouri River on the sidebar category list. South of Hammond in figure 1 is an unnamed Little Missouri River tributary flowing southeast and then northeast across the Montana-Wyoming state line. That tributary is Thompson Creek. Immediately south of Thompson Creek is an unnamed east-oriented Little Missouri River tributary. That tributary is the North Fork Little Missouri River. Further south two unnamed branches join to form the northeast-oriented Little Missouri River. The eastern branch is the Little Missouri River headwaters and the western branch, which flows northwest before turning northeast, is Prairie Creek. East of the northeast-oriented Little Missouri River is the northeast-oriented Belle Fourche River, which just south of the Wyoming-Montana state line abruptly turns to the southeast. Landform evidence in the Little Missouri River-Belle Fourche River drainage divide area is illustrated and discussed in a separate essay found under Little Missouri River and Belle Fourche River on the sidebar category list. Evidence presented here documents immense southeast-oriented floods that flowed over the entire Little Powder River-Little Missouri River drainage divide area as discussed here and was captured first by Little Missouri River valley headward erosion and second by Little Powder River valley headward erosion. Evidence presented here is not adequate to determine the flood source, although by using many other essays published on this website it is possible to trace flood waters headward to a North American ice sheet location. Rapid melting of a large North American ice sheet would be a logical source.

Detailed Little Powder River-Little Missouri River drainage divide location map

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

Figure 2 provides a more detailed location map for the Little Powder River-Little Missouri River drainage divide area discussed here. The discussion here begins in the Hammond, Montana area where the drainage divide between the northwest-oriented East Fork Little Powder River and southeast-oriented Willow Creek headwaters will be illustrated. Next the essay discussion moves south to look at the Little Powder River-Thompson Creek drainage divide area. Continuing south the essay next illustrates the Little Powder River-Gammon Creek drainage divide area. Moving still further south the Little Powder River-North Fork Little Missouri River drainage divide area will be illustrated and discussed. After a detailed map view of the Dry Creek-Driscoll Creek drainage divide the essay discussion proceeds to the Duck Creek-Prairie Creek drainage divide area and to the Little Powder River-Prairie Creek drainage divide south of that. Finally the essay concludes with a discussion of Spring Creek-Little Missouri River drainage divide area evidence. Figure 2 illustrates a pronounced northwest-southwest drainage alignment present in the Little Powder River-Little Missouri River drainage divide area and also in adjacent drainage basins. This northwest-southeast-oriented oriented drainage alignment is evidence the northeast-oriented Little Missouri River valley eroded headward across multiple southeast-oriented flood flow routes to capture flood water and divert the flood water northeast. Subsequently the Little Powder River valley eroded south to behead and capture those same southeast-oriented flood flow routes and diverted the flood water north to the Powder River. The multiple southeast-oriented flood flow routes probably were multiple channels in what was an immense southeast-oriented flood formed anastomosing channel complex. Detailed map evidence below will further support this interpretation.

East Fork Little Powder River-Willow Creek drainage divide area

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

Figure 3 illustrates the East Fork Little Powder River-Willow Creek drainage divide area south of Hammond, Montana. The East Fork Little Powder River flows northwest in the valley immediately north of Belcher Mountain (figure 3 southwest corner). Note other northwest-oriented Little Powder River tributaries along the figure 3 west edge. Southeast-oriented Wolf Creek and Camp Creek (north of highway and southeast of Hammond) flow to southeast-oriented North Fork Willow Creek, which flows to the northeast-oriented Little Missouri River. Note in the figure 3 east half other southeast-oriented streams flowing to the Little Missouri River. The north-northeast-oriented West Fork west of Hammond is the West Fork of northeast-oriented Boxelder Creek, which flows to the Little Missouri River. North and northwest-oriented Little and Big Goat Creeks (figure 3 north center) are Boxelder Creek tributaries. The Little Powder River-Little Missouri River drainage divide here is an asymmetric drainage divide, providing evidence the Little Powder River drainage basin was eroded into a pre-existing Little Missouri River eroded drainage basin surface. Southeast-oriented Little Missouri River tributaries flowing to the northeast-oriented Little Missouri River are barbed tributaries, providing evidence the Little Missouri River valley eroded southwest to capture multiple southeast-oriented flow routes. The northwest-oriented Little Powder River tributaries provide evidence that when the deeper Little Powder River valley was eroded into the region it beheaded multiple southeast-oriented flow routes and there was enough water present that water already on the northwest ends of beheaded flow routes was able to reverse flow direction and erode northwest-oriented valleys. The best explanation for this evidence is the multiple southeast-oriented flow routes were components of an immense southeast-oriented and probably ever-changing flood formed anastomosing channel complex that was captured first by Little Missouri River valley headward erosion and subsequently by Little Powder River valley headward erosion.

Little Powder River-Thompson Creek drainage divide area

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

Figure 4 depicts a Little Powder River-Little Missouri River drainage divide area south of the figure 3 map area (there is some overlap). Northwest-oriented streams west of the drainage divide include the East Fork Little Powder River and its tributary Blow Out Creek (figure 3 north center), Belle Creek (northwest corner), Wright Creek and South Fork Wright Creek (south of Belle Creek), and Ranch Creek (southwest quadrant). East of the drainage divide from north to south are northeast-oriented headwaters of southeast-oriented tributaries to southeast-oriented Willow Creek (northeast quadrant) and then the Thompson Creek drainage basin, with southeast-oriented North Fork Thompson Creek and Thompson Creek being the two most prominent streams. This region, like the region to the north, is characterized by an asymmetric drainage divide and a pronounced northwest-southeast oriented drainage alignment. Close study of the map or of more detailed maps of this same area reveals northwest-oriented Little Powder River tributaries are linked by through valleys with  southeast-oriented Little Missouri River tributaries. Through valleys are evidence the multiple channels once carried water southeast across what is now the Little Powder River-Little Missouri River drainage divide. Again the evidence can be best explained by Little Missouri River valley headward erosion capturing multiple southeast-oriented flood flow routes or channels and then Little Powder River valley headward erosion beheading and capturing the multiple southeast-oriented flood flow routes to create what is today the Little Powder River-Little Missouri River drainage divide. Note many northwest-oriented Little Powder River tributaries have north-oriented headwaters. These north-oriented tributaries are evidence reversed flood flow on the northwest end of a beheaded southeast-oriented flood flow route captured flood flow from yet to be beheaded (by the Little Powder River valley) flood flow routes further to the south.

Little Powder River-Gammon Creek drainage divide area

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

Figure 5 depicts a region south of the figure 4 map area again with some overlap. The Montana-Wyoming state line follows the west-east county line, with Powder River and Carter Counties in Montana and Campbell and Crook Counties in Wyoming. Most figure 5 evidence is similar to figure 3 and 4 evidence and includes an asymmetric drainage divide, northwest-southeast oriented drainage alignment and through valleys across the drainage divide, although in figure 5 a southwest to northeast-oriented upland is located along the Little Powder River-Little Missouri River drainage divide. The upland appears flat-topped suggesting some type of resistant cap rock is present, although the upland surface appears to have a slight slope to the northeast. How that slope developed cannot be determined from map evidence. Shallow northwest-southeast oriented through valleys are cut across the upland top and provide evidence multiple southeast-oriented flood flow routes crossed the upland surface, meaning flood water once flowed on a topographic surface at least as high as the topographic surface defined by the upland’s present day highest elevations and subsequent flood water erosion removed surrounding bedrock materials both southeast and northwest of the upland to create the topographic surface that exists today. The upland’s elevation above the prevailing present-day topographic surface provides a minimum estimate of the amount of flood erosion that occurred. Note how the upland’s northwest side, which was eroded by reversed flow on the northwest ends of beheaded flood flow routes has not been eroded as cleanly as the upland’s southeast side, which was eroded by southeast-oriented flood waters that were being captured to flow to the northeast-oriented Little Missouri River. More on this capture and the upland southeast escarpment in the figure 6 discussion below.

Little Powder River-North Fork Little Missouri River drainage divide area

Figure 6: Little Powder River-North Fork Little Missouri River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the region south of figure 5 and provides areas of overlap along the figure 6 north edge and figure 5 south edge. Again much of the figure 6 evidence is similar to previously discussed evidence. Note the North Fork Little Missouri River flowing northeast and then southeast in the figure 6 area east of Rockypoint. The North Fork Little Missouri River flows east from the figure 6 map area to join the northeast-oriented Little Missouri River. Southeast-oriented streams in figures 5 and 6 east and southeast of the forested upland are North Fork Little Missouri River tributaries. The North Fork Little Missouri River drainage basin including its associated tributary valleys was probably eroded west and northwest along southeast-oriented flood flow routes in the form of large-scale southeast-oriented headcut being carved into the high level topographic surface defined by the present day upland flat top (or even higher). The upland’s present day southeast-oriented escarpment is probably the abandoned headcut face, that ceased to be actively eroded when southeast-oriented flood water eroded deeper flow routes around the upland resistant cap rock mass. The northeast-oriented North Fork Little Missouri River headwaters probably are evidence the North Fork Little Missouri River valley captured southeast-oriented flood flow that had eroded deeper valleys around the resistant cap rock and across the upland’s southwest end. Northwest-oriented McKim Draw flowing to the northeast-oriented North Fork Little Missouri River segment probably formed as a reversal of flood flow on one of those deeper flow routes that was beheaded and captured by North Fork Little Missouri River headward erosion. The northwest-oriented Dry Creek and southeast-oriented Driscoll Creek alignment, just southwest of McKim Draw, probably was carved as an even deeper flood flow route (east of figure 6 Driscoll Creek does flow to the east-oriented North Fork Little Missouri River). Note how just east of Bowman Hill a north-northeast oriented stream flows to northwest-oriented Dry Creek and is linked by a through valley with a south-southwest-oriented flows to northwest-oriented Duck Creek (see southwest corner of figure 6). The through valley was carved by yet to be beheaded flood water still moving southeast on the Duck Creek alignment that was captured by reversed flow on the northwest end of the newly beheaded Dry Creek flood flow route.

Detail map of Dry Creek-Driscoll Creek drainage divide area

Figure 7: Detail map of Dry Creek-Driscoll Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 provides a detailed map of the drainage divide between northwest-oriented Dry Creek and southeast oriented Driscoll Creek headwaters, which also is the Little Powder River-Little Missouri River drainage divide. Note how a shallow through valley crosses the present-day Little Powder River-Little Missouri River drainage divide. Also note in the figure 7 north center northwest-oriented McKim Draw flowing to the northeast-oriented North Fork Little Missouri River headwaters (that downstream turn southeast and east) and the through valley to an unnamed southeast oriented stream just north of Driscoll Creek (figure 7 east edge center). That unnamed stream flows to Driscoll Creek and Driscoll Creek after flowing southeast turns to flow northeast to join the east-oriented North Fork Little Missouri River. In other words, the Little Powder River-Little Missouri River drainage divide is located between northwest-oriented McKim Draw and northwest-oriented Dry Creek. Further, note north and northeast-oriented valleys leading to the Dry Creek and Driscoll Creek headwaters areas. Those valleys provide evidence that both reversed flood flow on the newly beheaded Dry Creek alignment and continuing southeast and east oriented flood flow on the Driscoll Creek valley route captured flood water from yet to be beheaded southeast oriented flood flow further to the southwest.

Duck Creek-Prairie Creek drainage divide area

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

Figure 8 continues this essay’s journey south along the Little Powder River-Little Missouri River drainage divide and illustrates a region south of the figure 6 map area (again with some overlap). The Little Powder River-Little Missouri River drainage divide roughly separates the figure 8 east and west halves. West of the divide northwest-oriented streams flow to the north oriented Little Powder River, while east of the divide most streams are southeast-oriented, although northeast-oriented Prairie Creek flows across the figure 8 southeast-corner to join with the northeast-oriented Little Missouri River and in the figure 8 northeast corner southeast-oriented Driscoll Creek turns to flow northeast to the east-oriented North Fork Little Missouri River. Duck Creek is the major northwest-oriented Little Powder River tributary flowing from the Duck Creek Breaks area. Note how Duck Creek headwaters include north and northeast-oriented tributaries that originated when reversed flood flow on the northwest end of what was then the newly beheaded southeast-oriented Duck Creek flood flow route captured flood water that was continuing to flow southeast on yet to be beheaded flood flow routes further to the southwest, and caused that captured flood water to make a U-turn and flow northwest to the newly eroded Little Powder River valley (and in the process to erode the northwest-oriented Duck Creek valley). Again note the northwest-southeast oriented drainage alignment, the asymmetric drainage divide, and multiple through valleys linking northwest-oriented Little Powder River tributaries with southeast-oriented Little Missouri River tributaries, all providing evidence flood waters once flowed in multiple southeast-oriented flood flow channels across the entire figure 8 map region. Headward erosion of the northeast-oriented Little Missouri River-Prairie Creek valley first captured the southeast-oriented flood flow and the existence of the present day Little Powder River-Little Missouri River drainage divide is evidence headward erosion of the deeper Little Powder River valley subsequently beheaded and captured all of the southeast-oriented flood flow routes.

Little Powder River-Prairie Creek drainage divide area

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

Progressing still further south along the Little Powder River-Little Missouri River drainage divide figure 9 illustrates an area south of figure 8 (again with overlap). East of the drainage divide Prairie Creek begins as a northwest-oriented stream and then turns northeast to flow to the northeast-oriented Little Missouri River. The northwest-oriented Prairie Creek headwaters segment originated when headward erosion of the northeast-oriented Little Missouri River-Prairie Creek valley beheaded the flood flow route. Note how reversed flood flow captured southeast-oriented flood flow moving on what is today the northwest-oriented Spring Creek route. Spring Creek today flows to join the north-northwest-oriented Little Powder River near Soda Well at the figure 9 west edge. Project the northwest-oriented Prairie Creek headwaters segment northwest to the figure 9 north edge and there is the north-northwest-oriented headwaters of the South Fork of northwest-oriented Duck Creek. In between is the east-oriented Flat Creek valley which eroded headward from the newly eroded Prairie Creek valley to capture southeast-oriented flood waters that had been moving along the Duck Creek-South Fork Duck Creek alignment to what is today the northwest-oriented Prairie Creek headwaters segment. Following capture by Flat Creek valley headward erosion, headward erosion of the Little Powder River valley beheaded and captured flood waters moving southeast on the Duck Creek-South Fork Duck alignment, and flood waters on the northwest end of that beheaded flood flow route reversed flow direction to create the present day Duck Creek-Prairie Creek drainage divide.

Spring Creek-Little Missouri River drainage divide area

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

Figure 10 completes the trip south along the Little Powder River-Little Missouri River drainage divide and with overlap shows the region south of the figure 9 map area. The Little Powder River flows north-northeast at the figure 10 west edge center and turns to flow north-northwest to the figure 10 northwest corner. The northeast-oriented Little Missouri River originates near the figure 10 east edge center just east of Flatiron Butte. Northeast and east-oriented Deadman Creek originates just north of the Little Missouri River source and just west of the Deadman Creek headwaters are headwaters of northwest-oriented Prairie Creek. West of the Little Missouri River-Deadman Creek-Prairie Creek source area are headwaters of the northwest-oriented Spring Creek, which flows to the north-northwest-oriented Little Powder River valley. Headward erosion of the Prairie Creek valley beheaded and captured southeast-oriented flood water that was helping to erode the northeast-oriented Little Missouri River valley headward or southwest. Subsequently Little Powder River valley headward erosion beheaded and captured that same southeast-oriented flood flow route and headward erosion of the Little Missouri River valley ceased. Where was the southeast-oriented flood flow going before it was beheaded and captured by headward erosion of the northeast-oriented Little Missouri River valley? A look at the next major southeast-oriented flood flow route the Little Missouri River valley would have captured had it continued to erode southwest provides an answer. Southwest of the Little Missouri River present day source are headwaters of northwest-oriented Mitchell Creek and east-oriented Cabin Creek. Cabin Creek flows to the northeast-oriented Belle Fourche River. Prior to Little Powder River valley headward erosion the Mitchell Creek-Cabin Creek alignment was being used as a major flood flow route. And then Little Powder River valley headward erosion beheaded that southeast-oriented flood flow route to create what is today the Mitchell Creek-Cabin Creek drainage divide and also the Little Powder River-Belle Fourche River drainage divide.

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.