A geomorphic history based on topographic evidence

The Powder River-Boxelder Creek drainage divide area discussed here is located in eastern Montana, USA. Although detailed topographic maps of the Powder River-Boxelder Creek 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 Powder River-Boxelder Creek 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 deep 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 southeast Montana  Powder River-Boxelder Creek 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.

• 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 southeast Montana Powder River-Boxelder Creek drainage divide area landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Powder River-Boxelder Creek location map

Figure 1: Powder River-Boxelder Creek 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 southeast Montana’s Powder River-Boxelder Creek drainage divide area. The Powder River begins in central Wyoming and flows northeast into southeast Montana where northeast of Broadus, Montana (figure 1 south center) it turns to flow north-northwest to the northeast oriented Yellowstone River. Boxelder Creek originates southeast of Broadus, near Hammond, Montana, and flows northeast to join the northeast and north-oriented Little Missouri River near the Montana, South Dakota, and North Dakota common corner. In other words the Powder River-Boxelder Creek drainage divide is also the Yellowstone River-Little Missouri River drainage divide. East of the northeast and north-oriented Little Missouri River are southeast-oriented headwaters of east-oriented tributaries to the south-oriented Missouri River (the Missouri River is not shown on figure 1). The Powder River-O’Fallon Creek drainage divide area essay addresses the region north of the Powder River-Boxelder Creek drainage divide area the Little Powder River-Little Missouri River drainage divide area essay addresses the region to the south (both essays can be found under Powder River on the sidebar category list). West of the northeast and north-northwest-oriented Powder River drainage basin is the northeast and northwest-oriented Tongue River drainage basin. This essay presents detailed topographic map evidence suggesting southeast-oriented flood flow once flowed on a topographic surface at least as high as the highest points in the Powder River-Boxelder Creek drainage divide area today and moved across the entire Powder River-Boxelder Creek drainage divide area. This immense southeast-oriented flood was captured by headward erosion of a deep northeast-oriented Boxelder Creek valley and subsequently flood flow to the newly eroded Boxelder Creek valley was beheaded and captured by headward erosion of the deeper Powder River valley, with flood waters already between the Boxelder Creek valley and the newly eroded and deeper Powder River valley being reversed to flow northwest, which resulted in the erosion of northwest-oriented Powder River tributary valleys and in the creation of the present day Powder River-Boxelder Creek drainage divide.

Powder River-Boxelder Creek detailed location map

Figure 2: Powder River-Boxelder Creek 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 Powder River-Boxelder Creek drainage divide area. Almost all tributaries flowing to the northeast oriented Powder River from the Powder River-Boxelder Creek drainage divide area are northwest-oriented and almost all tributaries flowing from the same drainage divide area to northeast oriented Boxelder Creek are either southeast-oriented or have significant southeast-oriented segments. Most Boxelder Creek tributaries from the east are northwest-oriented and most Little Missouri River tributaries from the west are southeast-oriented. A similar northwest-southeast drainage alignment can be seen in tributaries to north-oriented Mizpah Creek west of the northeast oriented Powder River. This northwest-southeast oriented drainage alignment is evidence an immense southeast-oriented flood flowed across the entire region prior to headward erosion of present day northeast- and north-oriented valleys. If this interpretation is correct the northeast-oriented Little Missouri River valley eroded southwest first to capture the southeast-oriented flood flow and to divert the water northeast and north. Headward erosion of the northeast-oriented Boxelder Creek valley next beheaded southeast-oriented flood flow to the northeast-oriented Little Missouri valley and diverted the water northeast to the Little Missouri River valley further to the north. Next headward erosion of the northeast-oriented Powder River valley beheaded southeast-oriented flood flow to the northeast-oriented Boxelder Creek valley and diverted the water north and north-northwest to the northeast-oriented Yellowstone River valley. Finally headward erosion of the north-oriented Mizpah Creek valley beheaded southeast-oriented flood flow to the northeast-oriented Powder River valley and diverted the water north to the north-northwest-oriented Powder River valley and the Yellowstone River.

Powder River-Little Beaver Creek-Boxelder Creek drainage divide area

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

Figure 3 illustrates the Powder River-Boxelder Creek drainage divide north end. Beaver Flats in the figure 3 northeast quadrant is drained by northeast-oriented Little Beaver Creek. Little Beaver Creek flows northeast to the Little Missouri River and is the major northeast-oriented Little Missouri River tributary immediately north and west of northeast-oriented Boxelder Creek (see figure 1). The Powder River is located in the figure 3 northwest corner and the figure 3 location is near the Powder River elbow of capture where the northeast-oriented Powder River turns to flow north-northwest. The area of southeast-oriented drainage southeast of Chalk Buttes (figure 3 southeast corner) drains to northeast-oriented Boxelder Creek. The rim of the southwest and northwest-facing escarpment serves as the Powder River-Little Missouri River drainage divide and the escarpment face is drained by northwest-oriented Powder River tributaries. Erosion of the deep Powder River valley has truncated what had been eroded as a deep northeast-oriented Little Beaver Creek valley, which is discussed in the Powder River-O’Fallon Creek drainage divide essay, the O’Fallon Creek-Little Beaver Creek drainage divide essay, and the Little Beaver Creek-Boxelder Creek drainage divide essay. Note the Boxelder Creek drainage basin area is slightly lower in elevation than the Little Beaver Creek headwaters area. The lower Boxelder Creek drainage basin elevation suggests the Boxelder Creek drainage basin continued to be eroded by northeast-oriented flood flow after flood flow responsible for eroding the Little Beaver Creek drainage basin had been beheaded. Such a situation would logically occur if headward erosion of the deep Yellowstone River-Powder River valley was responsible beheading southeast-oriented flood flow to both the northeast-oriented Little Beaver Creek valley and to the northeast-oriented Boxelder Creek valley. The Boxelder Creek valley extends southwest from the figure 3 location for a considerable distance and at the time headward erosion of the deep Powder River valley reached the figure 3 location yet to be beheaded flood flow routes further south were still flowing to what would have been the actively eroding Boxelder Creek valley.

Spring Creek-Buffalo Creek drainage divide near Chalk Buttes

Figure 4: Spring Creek-Buffalo Creek drainage divide near Chalk Buttes. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates the Powder River-Boxelder Creek drainage divide region south of the figure 3 map area and provides a thin overlap strip. Northwest-oriented drainage flows down the northwest-facing escarpment to the Powder River. Those northwest-oriented Powder River tributary valleys were eroded by reversals of flood flow on the northwest ends of beheaded southeast oriented flood flow routes. Prior to being beheaded the flood flow routes had been carrying flood water to the newly eroded northeast-oriented Boxelder Creek valley and Boxelder Creek tributary valleys. It is probable flood flow from yet to be beheaded southeast oriented flood flow routes further to the southwest moved northeast in the newly eroded Boxelder Creek and tributary valleys and was captured by reversed flow on some of the beheaded flood flow routes. Such captures of northeast-oriented flood flow would have provided significant additional amounts of flood water needed to erode the northwest-oriented Powder River tributary valleys that exist today. Northeast-oriented Buffalo Creek in the figure 4 southeast corner turns to flow southeast (east of the figure 4 map area) and flows to northeast-oriented Boxelder Creek. Chalk Buttes is probably capped by a resistant cap rock and is an erosional residual. Note southeast oriented Buffalo Creek tributaries flowing from Chalk Buttes and northwest-oriented Powder River tributaries also flowing from Chalk Buttes. These southeast- and northwest-oriented streams suggest flood waters originally flowed on a topographic surface at least as high as the present day Chalk Buttes highest elevations. If so, the northeast-oriented Buffalo Creek valley was probably eroded headward into that higher level topographic surface (as was the parallel northeast-oriented Boxelder Creek valley) and Chalk Buttes may be all that remains of what was at one time the northwest wall of a newly eroded Buffalo Creek valley. Southeast-oriented flood water captured by the newly eroded and northeast-oriented Buffalo Creek and Boxelder Creek valleys removed all other evidence (at least in the figure 4 map area) of the higher level topographic surface and headward erosion of the deep Powder River valley removed all evidence of the higher level topographic surface northwest of the present day figure 4 Powder River-Boxelder Creek drainage divide.

Stump Creek-Cabin Creek drainage divide near Saddle Butte

Figure 5: Stump Creek-Cabin Creek drainage divide near Saddle Butte. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Powder River-Boxelder Creek drainage divide region south of the figure 4 map area and provides an overlap area. The rim of the west-facing escarpment is the Powder River-Boxelder Creek drainage divide. Northwest-oriented drainage flows to the northeast-oriented Powder River and the northwest-oriented tributaries were eroded by reversals of flood waters on the northwest ends of southeast-oriented flood flow routes beheaded by headward erosion of the deep Powder River valley. Reversed flood water on these beheaded flood flow routes also captured flood water moving north along the Boxelder Creek valley route that had been captured from yet to be beheaded (by Powder River valley headward erosion) southeast-oriented flood flow routes further to the south. Note in the figure 5 south center how southwest-oriented Keith Creek originates in what is probably a west-facing abandoned headcut that was eroded by flood waters moving from the northeast-oriented Boxelder Creek drainage basin to the northwest-oriented Timber Creek valley. Similar evidence of such captures can be seen all along the Powder River-Boxelder Creek drainage divide. Note also how the present day escarpment or drainage divide has truncated the headwaters of southeast-oriented Boxelder Creek tributaries. Truncation of these southeast-oriented drainage basins is further evidence the deep Powder River valley eroded headward across multiple southeast-oriented flood flow routes and diverted the flood flow to the deep northeast-oriented Yellowstone River valley.

Timber Creek-Corral Creek drainage divide area

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

Figure 6 illustrates the Powder River-Boxelder Creek drainage divide region south of the figure 5 map area and provides an overlap area. Figure 6 better illustrates the northwest-oriented Timber Creek valley and how flood flow from the southeast aided in the erosion of the present day large northwest-oriented Timber Creek valley. Reversed flood flow on beheaded southeast-oriented flood flow routes was augmented by flood flow from the southeast was probably captured from yet to be beheaded flood flow routes south of the actively eroding deep Powder River valley head. At that time the somewhat shallower Boxelder Creek valley was being eroded southwest by yet to be beheaded southeast-oriented flood flow routes and the southeast-oriented flood flow was also removing the northwest Boxelder Creek valley wall almost as fast as the Boxelder Creek valley was being eroded. Loss of that northwest valley wall meant when the parallel and much deeper Powder River valley eroded southwest reversed flood flow on the northwest ends of beheaded flood flow routes was able to capture flood waters moving northeast in the Boxelder Creek valley. In fact there may have been spillage to the northwest from the Boxelder Creek valley all along the present day Powder River-Boxelder Creek drainage divide. However, enough flood flow moved northeast on the Boxelder Creek valley route to maintain the shallower northeast-oriented valley and the truncated Boxelder Creek drainage basin that exists today. The Powder River-Boxelder Creek drainage divide was created when headward erosion of the deep northeast-oriented Powder River valley captured all southeast-oriented flood flow to the figure 6 map area and caused reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow routes, although the present day Powder River-Boxelder Creek drainage divide probably did not really come into existence until all southeast-oriented flood flow to the Boxelder Creek valley had been beheaded and there was no longer sufficient northeast flow for there to be spillage from the Boxelder Creek valley to the Powder River valley.

Cody Creek-Muskrat Creek drainage divide area

Figure 7: Cody Creek-Muskrat Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Powder River-Boxelder Creek drainage divide region south of the figure 6 map area and provides an overlap area. Northeast-oriented Boxelder Creek flows across the figure 7 southeast corner. Most Boxelder Creek tributaries flowing from the Powder River-Boxelder Creek drainage divide (the escarpment rim) are southeast-oriented or have significant southeast-oriented segments. Headwaters of Powder River tributaries are located west of the escarpment rim (or drainage divide) and are almost always northwest oriented. Events recorded by figure 7 evidence begin with southeast-oriented flood water flowing across a high level topographic that has now been completely removed. Figure 7 contains no evidence of that higher level topographic surface, although Chalk Buttes illustrated in figures 3 and 4 provides evidence that flood flow originally moved on a much higher level topographic surface than the present day Boxelder Creek erosion surface. The southeast-oriented flood flow was probably moving along ever-changing southeast-oriented channels of an immense southeast-oriented anastomosing channel complex. Headward erosion of the northeast and north-oriented Little Missouri River valley systematically captured the southeast-oriented flood flow and diverted the flood water northeast and north. The Boxelder Creek-Little Missouri River drainage divide essay (found under Little Missouri River on sidebar category list) describes what happened immediately southeast of the northeast-oriented Boxelder Creek valley.  Headward erosion of what was then a deep northeast-oriented Boxelder Creek valley next systematically captured the southeast-oriented flood flow, although all evidence of the northwest wall of the deep Boxelder Creek valley was probably removed almost as fast as the valley was eroded. Subsequently headward erosion of the deeper northeast-oriented Powder River valley captured all southeast-oriented flood flow routes moving to the figure 7 map area, although the actively eroding northeast-oriented Boxelder Creek valley was still capturing flood waters from yet to be beheaded (by deep Powder River and tributary valley headward erosion) flood flow routes. In time headward erosion of the deep Powder River and tributary valleys captured all flood flow from those yet to be beheaded flood flow routes and rapid erosion of the figure 7 map area ceased.

Crow Creek-Boxelder Creek drainage divide

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

Figure 8 illustrates the Powder River-Boxelder Creek drainage divide region south of the figure 7 map area and provides a significant overlap area. Crow Creek is a north and northwest-oriented Powder River tributary and flows north and northwest along the figure 8 west edge. Boxelder Creek flows northeast across the figure 8 southeast corner. Note the predominance of southeast-oriented tributaries flowing from the Powder River-Boxelder Creek drainage divide (the escarpment rim) to northeast-oriented Boxelder Creek and the predominance of northwest-oriented drainage west of the escarpment rim (or drainage divide) and also northwest-oriented Boxelder Creek tributaries located in the figure 8 southeast corner. Also note the Soda Creek drainage basin in the figure 8 south center that will be featured in figure 9 below. Events recorded by the figure 8 evidence begin with southeast-oriented flood flow moving across a high level topographic surface at least as high as the highest figure 8 elevations today. The flood waters were probably flowing in channels being eroded as part of an immense southeast-oriented anastomosing channel complex that was being captured by headward erosion of the deep northeast-oriented Little Missouri River valley. The southeast-oriented flood flow was next captured by headward erosion of what was then a deep northeast-oriented Boxelder Creek valley, although southeast-oriented flood flow was removing all evidence of the northwest valley wall almost as fast as the deep northeast-oriented valley was being eroded. Subsequently the deep northeast-oriented Powder River valley eroded southwest and beheaded southeast-oriented flood flow moving to the figure 8 map area. Flood flow on the northwest end of what had been a major southeast-oriented flood flow channel using what is now the northwest-oriented Crow Creek alignment reversed flow direction to flow northwest and to erode the northwest-oriented Crow Creek valley. The north-oriented Crow Creek headwaters probably eroded south to capture southeast-oriented flood water on a yet to be beheaded southeast-oriented flood flow route, and the addition of that captured flood water helped erode the northwest-oriented Crow Creek valley. Headward erosion of the north-oriented Little Powder River valley next beheaded all flood flow to the Crow Creek and Boxelder Creek headwaters and rapid erosion of the figure 8 map area ceased.

Detailed map of Crow Creek-Soda Creek drainage divide area

Figure 9: Detailed map of Crow Creek-Soda Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 provides a detailed map of the Crow Creek-Soda Creek drainage divide area, which is located in the figure 8 south center. Crow Creek flows north along the figure 9 west edge and further north turns northwest (see figure 8 above). Soda Creek begins as a northeast-oriented stream, but turns southeast to flow to northeast-oriented Boxelder Creek. The North Fork Soda Creek is southeast-oriented. Northwest-oriented valleys drain to the north-oriented Crow Creek valley and are linked to Soda Creek headwaters. The northeast-oriented Soda Creek valley segment probably eroded southwest to capture southeast-oriented flood flow moving on the alignment of what is now the northwest-oriented Crow Creek tributary valley located in the figure 9 southwest quadrant. Note northwest-southeast-oriented streamlined residuals between southeast-oriented North Fork Soda Creek and Soda Creek. Events recorded by evidence on this detailed topographic map are similar to events recorded by the less detailed figure 8 map above. Southeast-oriented flood flow initially moved across the figure 9 map region on a topographic surface at least as high as the highest figure 9 elevations today and was captured by headward erosion of what was then a deep northeast-oriented Boxelder Creek valley. Deep southeast-oriented tributary valleys then eroded headward from the newly eroded Boxelder Creek valley and included the Soda Creek and North Fork Soda Creek valleys. The deep Soda Creek valley eroded southwest to capture southeast-oriented flood flow and the northwest wall of the newly eroded Soda Creek valley was removed almost as fast as the valley was eroded. Headward erosion of the deep north-oriented Crow Creek valley next captured the southeast-oriented flood flow and diverted the water north and northwest to the Powder River valley. Flood flow on the northwest ends of beheaded southeast-oriented flood flow routes reversed flow direction to erode northwest-oriented tributary valleys to the Crow Creek valley.

East Fork Little Powder River-West Fork Boxelder Creek drainage divide

Figure 10 illustrates the Powder River-Boxelder Creek drainage divide region south of the figure 8 map area and provides a thin overlap strip. This figure 10 location is the south end of the Powder River-Boxelder Creek drainage divide and is where northeast-oriented Boxelder Creek originates. Southeast-oriented drainage in the figure 10 southeast corner flows to the northeast-oriented Little Missouri River. The Boxelder Creek-Little Missouri River drainage divide is located between the north and northwest-oriented Boxelder Creek tributaries and the headwaters of the southeast-oriented streams. The northwest-oriented East Fork Little Powder River flows across the figure 10 southwest corner. Headwaters of northwest oriented East Fork Little Powder River are linked to headwaters of southeast-oriented Little Missouri River tributaries. The north-northeast-oriented West Fork Boxelder Creek begins southwest of Hammond almost on the rim of the deep north-oriented Little Powder River valley. Northwest-oriented headwaters of Little Powder River tributaries provide evidence the West Fork Boxelder Creek valley eroded southwest to capture southeast-oriented flood routes that were subsequently beheaded and reversed by headward erosion of the deep north-oriented Little Powder River valley. Events recorded by the figure 10 evidence begin with flood water moving across the entire figure 10 map area on a topographic at least as high as the highest figure 10 elevations today. The southeast-oriented flood water was moving to what was probably a deep and newly eroded northeast-oriented Little Missouri River valley, which had eroded headward to capture the flood flow and to divert the water north and northeast. Next headward erosion of what was then a deep northeast-oriented Boxelder Creek valley captured the southeast-oriented flood flow and diverted the flood water northeast along the Boxelder Creek valley route. Probably soon after headward erosion of the deeper northeast-oriented Powder River valley and its north-oriented Little Powder River tributary valley beheaded southeast-oriented flood flow to the Boxelder Creek valley and diverted the flood waters north, northeast, and north-northwest to the northeast-oriented Yellowstone River valley.

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.