Big Dry Creek-Prairie Elk Creek and Redwater River drainage divide area landform origins in northeast Montana, USA

Authors

A geomorphic history based on topographic map evidence

Abstract:

The Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater River drainage divide area discussed here is located in northeast Montana, USA. Although detailed topographic maps of the Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater 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 Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater 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 deep Missouri 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 northeast Montana Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater 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 Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater River drainage divide area landform evidence in northeast Montana will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater River drainage divide area location map

Figure 1: Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater 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 Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater River drainage divide area location map and illustrates a region in northeastern Montana and a small region in western North Dakota (along the figure 1 east edge). The Missouri River flows east from the figure 1 west center edge to Fort Peck Lake and then east to Wolf Point, Poplar, Brockton, and Culbertson, Montana before flowing to North Dakota and the figure 1 east edge. The Yellowstone River flows northeast from the figure 1 map south edge (center east) to Terry, Glendive and Sidney before entering North Dakota and joining the Missouri River. The Redwater River originates northwest of Terry, Montana and flows northwest and then northeast to Brockway and Circle, before gradually turning north-northwest and then turning northeast to join the Missouri River near Poplar, Montana. North-oriented Prairie Elk Creek is located between Fort Peck Lake and the Redwater River and flows to join the Missouri River near Oswego. Big Dry Creek originates in the figure 1 southwest quadrant and flows northeast to Jordan, Montana and after joining north-oriented Little Dry Creek flows north to join the Missouri River at Fort Peck Lake. The Big Dry Creek-Prairie Elk Creek drainage divide area discussed here includes the area between Fort Peck Lake and Prairie Elk Creek. The Prairie Elk Creek-Redwater River drainage divide area discussed here includes the drainage divide between Little Dry Creek and the Redwater River. Based on evidence from the hundreds of Missouri River drainage basin landform origins research project essays published on this website landform evidence illustrated here is interpreted in the context of an immense southeast-oriented flood flowing across the figure 1 map area and which was systematically captured and diverted northeast by headward erosion of deep valleys eroded into a topographic surface at least as high as the figure 1 region highest elevations today. The north-oriented Big Dry Creek, Prairie Elk Creek, and Redwater River valleys eroded south to capture southeast-oriented flood water and diverted the flood flow to the north and northeast. First, the deep Redwater River valley head eroded south and southwest to capture southeast-oriented flood waters and to divert flood waters to the north and northeast. Flood waters on the northwest ends of beheaded flood flow routes reversed flow direction to flow northwest to the newly eroded Redwater River valley. By doing so reversed flood flow eroded many northwest-oriented tributary valleys. Subsequently the Prairie Elk Creek valley eroded south to capture the southeast-oriented flood flow. Next the Big Dry Creek valley eroded south. The Prairie Elk Creek-Redwater Creek drainage divide area essay, the Missouri River-Yellowstone River drainage divide area essay, the northeast end of the Redwater River-Yellowstone River drainage divide area essay, and the southwest end of the Redwater River-Yellowstone River drainage divide area essay, all of which are located east or southeast of the Big Dry Creek-Prairie Elk Creek and Redwater River drainage divide area and also in the Big Dry Creek-Yellowstone River drainage divide area, which is located south of the Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater River drainage divide area describe nearby drainage divide areas and can be found under appropriate river names on the sidebar category list.

Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater River drainage divide area detailed location map

Figure 2: Big Dry Creek-Prairie Elk Creek and Big Dry Creek-Redwater River drainage divide area detailed location map. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 illustrates a somewhat more detailed map of the Big Dry Creek-Prairie Elk Creek drainage divide area and the Big Dry Creek-Redwater River drainage divide area discussed in this essay. Mc Cone County is located in Montana. The Missouri River flows east from Fort Peck Lake in the figure 2 north half and is located south of Frazer, Oswego, Wolf Point, and Poplar as it flows to the figure 2 east edge. The Redwater River flows northeast from Circle near the figure 2 south center edge (in eastern Mc Cone County) into Dawson County before turning north, northwest and northeast to join the Missouri River near Poplar. Prairie Elk Creek originates south of Weldon (located in central Mc Cone County between Circle and Fort Peck Lake) and flows north to join the Missouri River near Oswego. Big Dry Creek originates southwest of the figure 2 map area and flows northeast through Jordan, Montana (located in the figure 2 southwest corner) to join north-oriented Little Dry Creek near the highway intersection south of the flooded north-south oriented arm of Fort Peck Lake. Big Dry Creek, after joining Little Dry Creek, flows north to join the Missouri River at Fort Peck Lake and the north-south arm of Fort Peck Lake is the flooded Big Dry Creek valley. Between Big Dry Creek and Prairie Elk Creek is a Hungry Creek, which is a north-oriented Missouri River tributary. This essay first illustrates evidence in the Hungry Creek-Prairie Elk Creek drainage divide area and then looks at evidence in the Big Dry Creek-Hungry Creek drainage divide area before looking at evidence in the Bear Creek-Shade Creek drainage divide area. Next evidence in the McGuire Creek-Prairie Elk Creek drainage divide area is observed and the essay concludes by looking at evidence in the Nelson Creek (Big Dry Creek)-Cotter Creek (Redwater River) drainage divide area. Figure 2 shows numerous southeast and northwest-oriented Redwater River tributaries. This southeast and northwest drainage alignment is evidence the northeast and north-oriented Redwater River valley eroded headward to capture southeast-oriented flood flow. The southeast-oriented tributary valleys were eroded by southeast-oriented flood flow moving into the newly eroded valleys and the northwest-oriented tributary valleys were eroded by reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow routes. Because flood waters move in and erode anastomosing (or inter-connected) channels reversed flood flow on a beheaded flood flow route could capture flood flow from yet to be beheaded flood flow routes. Such captures of yet to be beheaded flood flow could enable reversed flood flow routes to erode much deeper and larger northwest-oriented valleys than might otherwise be possible. Often evidence for such flow reversals and captures can be found on detailed topographic maps such as those illustrated below.

North end of Hungry Creek-Prairie Elk Creek drainage divide area

Figure 3: North end of Hungry Creek-Prairie Elk Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 illustrates the north end of the Hungry Creek-Prairie Elk Creek drainage divide area. The east-oriented Missouri River valley is located in the figure 3 north half. Prairie Elk Creek flows north in the figure 3 southeast quadrant and joins the Missouri River south of Oswego, Montana. Hungry Creek flows northeast, northwest, and north-northeast to join the Missouri River near the figure 3 west edge. Remuda Creek flows east, northeast, and southeast near the figure 3 south center edge and then flows east to join  north-oriented Prairie Elk Creek. North of Remuda Creek is east-southeast oriented Turtle Creek, which also flows to north-oriented Prairie Elk Creek. Note southeast oriented tributaries to Remuda Creek such as southeast oriented Green Coulee. Also note northwest-oriented Missouri River and Prairie Elk Creek tributaries such northwest-oriented Pasture Creek (located just east of Hungry Creek), Camp Creek (a tributary to Pasture Creek), Spring Coulee (located near the figure 3 east center edge) and Big and Little Mud Creeks (located in the figure 3 southeast corner). The southeast and northwest oriented tributaries provide evidence the major trunk stream valleys eroded headward across multiple southeast-oriented flood flow routes such as might be found in a southeast-oriented anastomosing channel complex. Through valleys link headwaters of northwest-oriented tributaries with headwaters of southeast-oriented tributaries. Figure 3 map quality is poor and figure 3a below illustrates a detailed map of one such through valley linking northwest-oriented Camp Creek with southeast-oriented Green Coulee. The through valleys also provide evidence that flood water once moved southeast across the region. In the case of figure 3a flood water moved from what is today the Camp Creek and Pasture Creek drainage basin to what was then the actively eroding Green Coulee and Remuda Creek drainage basin. Probably the Remuda Creek-Green Coulee valley was being eroded headward along a southeast-oriented flood flow channel that had been captured by headward erosion of the north-oriented Prairie Elk Creek valley. Probably the Prairie Elk Creek valley was eroding south from what was then the actively eroding east-oriented Missouri River valley head (meaning the Missouri River valley in the figure 3 northwest quadrant area did not yet exist). Southeast-oriented flood flow to the actively eroding Remuda Creek drainage basin was beheaded and captured by headward erosion of the east-oriented Missouri River valley. Flood waters on the northwest ends of the beheaded flood flow reversed flow direction to flow northwest into the newly eroded and deeper east-oriented Missouri River valley. This reversal of flood flow eroded the northwest-oriented Pasture Creek and Camp Creek valleys and created the Camp Creek-Green Coulee drainage divide.

Figure 3a: detailed map Camp Creek-Green Coulee drainage divide area (see figure 3 discussion above). United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Missouri River-Hungry Creek drainage divide area

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

Figure 4 illustrates the Missouri River-Hungry Creek drainage divide area west of the figure 3 map area and includes overlap areas with figure 3. The flooded Missouri River channel is marked along the figure 4 west edge and enters the figure 4 map area at the figure 4 west center edge and then heads north to Fort Peck Dam. North of Fort Peck Dam the Missouri River is located in the figure 4 northwest corner and north of figure 4 turns southeast to enter the figure 4 northeast quadrant. Bear Creek is a northwest-oriented Missouri River tributary flowing from the figure 4 southeast quadrant to join the Missouri River at Fort Peck Lake. Bear Creek Bay is the flooded northwest-oriented Bear Creek valley. The northwest-oriented Bear Creek valley was eroded by reversed flood flow on the northwest end of a beheaded flood flow route that was moving southeast-oriented flood waters to what was then the newly eroded north-oriented Prairie Elk Creek valley. Figures 5 and 6 below illustrate the present day Hungry Creek-Remuda Creek and Bear Creek-Shade Creek drainage divide areas and provide additional evidence that southeast-oriented flood flow once moved across present day drainage divides. Hungry Creek flows north, northwest, and north along the figure 4 east edge to join the Missouri River in the figure 4 northeast corner area and the Hungry Creek valley eroded south from what was then the actively eroding Missouri River valley head to capture southeast-oriented flood flow moving to the newly eroded north-oriented Prairie Elk Creek valley. The northeast-oriented West Fork of Hungry Creek is located in the figure 4 east center area. Northwest of the West Fork Hungry Creek is Lost Creek which flows north-northeast from the figure 4 to join the Missouri River and the Lost Creek valley eroded south-southwest from what was then the actively eroding Missouri River valley head to capture southeast-oriented flood flow moving to the newly eroded north-oriented Hungry Creek valley. Note Hungry Creek Pass linking Lost Creek with the West Fork of Hungry Creek. Figure 4a below provides a detailed map of this northwest-southeast oriented through valley. This northwest-southeast oriented through valley was eroded by southeast-oriented flood flow moving to what was then the newly eroded north-oriented Hungry Creek valley. In figure 4a below the northwest-southeast oriented through valley continues southeast of the northeast-oriented West Fork Hungry Creek valley to Sids Flat, indicating that headward erosion of the northeast-oriented West Fork Hungry Creek valley captured the southeast-oriented flood flow and diverted the flood waters northeast into the north-oriented Hungry Creek valley. Subsequently headward erosion of the north-northeast oriented Lost Creek valley captured the southeast-oriented flood flow. The sequence of flood flow captures illustrated in figures 4 and 4a is consistent with headward erosion of the deep east-oriented Missouri River valley head.

Figure 4a: Detailed map Hungry Creek Pass area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Hungry Creek-Remuda Creek drainage divide area

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

Figure 5 illustrates a detailed map of the Hungry Creek-Remuda Creek drainage divide area southwest of the figure 3 map area and southeast of the figure 4 map area. Remuda Creek flows north from the figure 5 center area to the figure 5 northeast quadrant where it flows east, northeast, and east to the figure 5 northeast corner. The Middle Fork Remuda Creek originates in the figure 5 east center area and flows east and northeast to the figure 5 east edge. South of the Middle Fork Remuda Creek in the figure 5 southeast quadrant are southeast and east oriented headwaters of the West Fork of Remuda Creek. West of the Remuda Creek headwaters is a southeast and south-southwest oriented tributary to northwest, north, and northwest oriented Hungry Creek, which flows to the figure 5 north edge and then to the Missouri River (north of figure 5). Note the Hungry Creek headwaters area and the link between Hungry Creek and Remuda Creek. Also note the through valley linking Remuda Creek headwaters with Hungry Creek headwaters and how that through valley is linked to the east and northeast-oriented Middle Fork Remuda Creek headwaters. For a time southeast-oriented flood flow was captured by headward erosion of the Remuda Creek valley and was moving northeast from what is today the northwest-oriented Hungry Creek valley segment (in the figure 5 southwest quadrant) to what were then the northeast-oriented Remuda Creek and Middle Fork Remuda Creek valleys and the east-oriented West Fork Remuda Creek valley, suggesting a northeast-oriented anastomosing channel complex was perhaps capturing a southeast-oriented anastomosing channel complex. Headward erosion of the deeper Remuda Creek valley probably beheaded flood flow to the West Fork Remuda Creek valley and the Middle Fork Remuda Creek valley, which would be typical of how ever-changing anastomosing channel complexes evolve. Headward erosion of the deep east-oriented Missouri River valley (north of figure 5) next beheaded and reversed the southeast-oriented flood flow so flood waters on the northwest ends of beheaded flood flow routes reversed flow direction and flowed north to the actively eroding Missouri River valley head. The reversed flood flow eroded the Hungry Creek valley and created the present day Hungry Creek-Remuda Creek drainage divide.

Detailed map of Bear Creek-Shade Creek drainage divide area

Figure 6: Detailed map of Bear Creek-Shade Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the drainage divide area between northwest oriented Bear Creek (flowing to Missouri River at Fort Peck Lake), north-oriented Hungry Creek (flowing to Missouri River north of figure 6), southeast-oriented North Prong Shade Creek (flowing to north-oriented Prairie Elk Creek), and southeast-oriented North Fork Rock Creek (flowing to Big Dry Creek at Rock Creek Bay at Fort Peck Lake-see figure 2 for Rock Creek route). Northwest-oriented Bear Creek is located in the figure 6 north center area and flows to the figure 6 north edge. North and northwest oriented Hungry Creek is located in the figure 6 northeast quadrant and also flows to the figure 6 north edge. The North Prong Shade Creek originates in the figure 6 center area and flows northwest, northeast and then turns southeast to flow to the figure 6 southeast corner. The North Fork Rock Creek flows southeast in the figure 6 south center area to the figure 6 south edge. Figure 6 illustrates through valleys linking the north-oriented Hungry Creek valley with the southeast-oriented North Prong Shade Creek valley, the northwest oriented Bear Creek valley with the southeast-oriented North Prong Shade Creek valley, and the northwest-oriented Bear Creek valley with the southeast-oriented North Fork Rock Creek valley. Briefly figure 6 evidence can be explained in the context of a southeast-oriented flood moving across the entire figure 6 map area on a topographic surface at least as high the highest figure 6 elevations today. Headward erosion of what was then a deep southeast-oriented North Prong Shade Creek valley into the figure 6 map area captured the southeast-oriented flood flow and eroded a deep south and southeast-oriented valley headward along what is today the northwest- and north-oriented Hungry Creek valley alignment. Also, a deep southeast-oriented valley eroded headward from the east-oriented Shade Creek valley (see figure 7 below) along what is today the southeast-oriented North Fork Rock Creek valley alignment. Headward erosion of the deep east-oriented Missouri River to the north of figure 6 then beheaded and reversed the southeast-oriented flood flow causing flood flow in the present day Hungry Creek drainage basin to flow north to the newly eroded Missouri River valley and flood flow in the Bear Creek drainage basin to flow northwest to newly eroded Missouri River valley. In the figure 7 map area located south of the figure 6 map area the southeast-oriented North Fork Rock Creek was captured by reversed flood flow moving to the west-oriented Rock Creek and north-oriented Big Dry Creek. Before that capture, but after the Bear Creek drainage basin flood flow reversal, the North Fork Rock Creek valley was north-oriented and moved large quantities of captured yet to be beheaded and reversed southeast-oriented flood flow into the figures 6 and 7 map areas. The final reversal of flood waters occurred when the deep Big Dry Creek valley eroded south and beheaded and reversed all southeast-oriented flood flow routes supplying yet to be beheaded flood flow to the figures 6 and 7 map areas.

North Fork Rock Creek-Shade Creek drainage divide area

Figure 7: North Fork Rock Creek-Shade Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 


Figure 7 illustrates the North Fork Rock Creek-Shade Creek drainage divide area south of the figure 6 map area and includes overlap areas with figure 6. Shade Creek flows east to the figure 7 east center edge. Southeast oriented North Fork Rock Creek flows from the figure 7 north edge to the figure 7 center area and then turns southeast to flow south-southwest to the figure 7 south edge. Figure 7 evidence can be explained by southeast-oriented flood flow moving across the entire figure 7 map area on a topographic surface at least as high as the highest figure 7 elevations today. Headward erosion of what was then a deep east-oriented Shade Creek valley (probably from what was then the newly eroded north-oriented Prairie Elk Creek valley) captured southeast-oriented flood flow. The southeast-oriented North Fork Rock Creek valley segment was eroded headward from the newly eroded Shade Creek valley to capture southeast-oriented flood flow moving in what is today the northwest-oriented Bear Creek drainage basin. A north-northeast oriented tributary valley eroded headward from the newly eroded Shade Creek valley along what is today the south-southwest oriented North Fork Rock Creek valley segment. Headward erosion of the deep east-oriented Missouri River valley next beheaded and reversed flood flow in the present day Bear Creek drainage basin. The flood flow reversal resulted in the erosion of the northwest-oriented Bear Creek valley. For a time (until the deep north-oriented Big Dry Creek valley could erode south to behead southeast-oriented flood flow being captured and moving northeast to Shade Creek drainage basin) the north-northeast oriented Shade Creek valley continued to capture yet to be beheaded southeast-oriented and that flood flow moved north-northeast into the figure 7 map area with some flood flow moving northwest along the present day southeast-oriented North Fork Rock Creek valley segment to the newly reversed northwest-oriented Bear Creek valley, some of the flood flow went east in the Shade Creek valley to the north-oriented Prairie Elk Creek valley, and some flood flow may have spilled north in the figure 7 northeast quadrant to help erode figure 6 landscapes, including the deep north-oriented Hungry Creek valley. Headward erosion of the deep Big Dry Creek valley then beheaded and reversed southeast-oriented flood flow moving to the north-northeast valley now used by south-southwest oriented North Fork Rock Creek. That flood flow reversal captured what is today the southeast-oriented Rock Creek valley segment.

McGuire Creek-Middle Fork Prairie Elk Creek drainage divide area

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

Figure 8 illustrates the McGuire Creek-Prairie Elk Creek drainage divide area south of previous figures and there are no overlap areas with previous figures. Northwest-oriented Nelson Creek is located in the figure 8 southwest corner and flows to Nelson Creek Bay. Northwest-oriented McGuire Creek flows across the figure 8 center area to McGuire Creek Bay located along the figure 8 west edge (north half). Nelson Creek Bay and McGuire Creek Bay are the flooded valleys of Nelson Creek and McGuire Creek where they enter what is today the flooded valley of north-oriented Big Dry Creek. Valleys have been flooded by Fort Peck Dam and are part of the Fort Peck Lake seen in figures 1 and 2. McGuire Creek is formed at the confluence of northwest-oriented Middle Fork McGuire Creek and southeast and southwest-oriented Upper McGuire Creek in the figure 8 east center area. Southeast and north-northeast oriented Middle Fork (Prairie Elk Creek) is located in the figure 8 northeast corner and is linked by a well-defined through valley with Upper McGuire Creek. The Middle Fork Prairie Elk Creek-Upper McGuire Creek drainage divide is illustrated in more detail in figure 9 below. Figure 8 evidence is explained by southeast-oriented flood flow moving across the figure 8 map area on a topographic surface at least as high as the highest figure 8 elevations today. Flood waters were captured east of the figure 8 map area by headward erosion of what was then the deep northeast and north-oriented Redwater River valley. Subsequently headward erosion of the deep north-oriented Prairie Elk Creek valley  captured some southeast-oriented flood flow moving on the present day northwest-oriented McGuire Creek alignment and a deep valley eroded southwest and then northwest to initiate a deep northwest-southeast oriented valley on the present day McGuire Creek alignment. Headward erosion of the deep east-oriented Missouri River valley and the north-oriented Big Dry Creek valley then beheaded and reversed southeast-oriented flood flow on the McGuire Creek alignment. Flood waters on the northwest end of the beheaded flood flow route reversed flow direction and flowed northwest into the newly eroded and deeper north-oriented Big Dry Creek valley and by doing so eroded the northwest-oriented McGuire Creek valley.

Detailed map of Upper McGuire Creek-Middle Fork Prairie Elk Creek drainage divide area

Figure 9: Detailed map of Upper McGuire Creek-Middle Fork Prairie Elk Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates in detail the Upper McGuire Creek-Middle Fork Prairie Elk Creek drainage divide area seen in less detail in figure 8 above. The Middle Fork Prairie Elk Creek flows south from the figure 9 north center edge and in the figure 9 center area makes a U-turn and flows north-northeast into the figure 9 northeast corner area. Upper McGuire Creek flows southeast from the figure 9 north edge (west half) and flows adjacent to the Middle Fork Prairie Elk Creek before turning to flow southwest to the figure 9 south edge (west half) and then to northwest-oriented McGuire Creek (see figure 8). The Middle Fork Prairie Elk Creek and Upper McGuire Creek flow in opposite directions in a large southwest to northeast oriented through valley. Tributaries to the through valley from the northwest are southeast oriented, which suggests the valley was eroded across southeast-oriented flood flow. Why do two streams flow parallel and adjacent to each other in the same valley and then diverge and flow in completely opposite directions? As seen in figure 8  above the southwest-northeast oriented through valley links the northwest-oriented McGuire Creek valley with the north-oriented Prairie Elk Creek valley. Also as described in the figure 8 discussion the northwest-oriented McGuire Creek valley was eroded by a reversal of southeast-oriented flood flow that had been captured by headward erosion of the north-oriented Prairie Elk Creek valley. The Prairie Elk Creek eroded south from what was then the actively eroding east-oriented Missouri River valley head (meaning the Missouri River valley further to the west did not yet exist and southeast-oriented flood flow could freely move into the figure 8 and 9 map areas). Headward erosion of the deep east-oriented Missouri River valley and of the north-oriented Big Dry Creek valley (from the newly eroded east-oriented Missouri River valley) next beheaded and reversed southeast-oriented flood flow in the McGuire Creek drainage basin. The drainage divide seen in figure 9 was formed when flood waters captured by the reversal of flood flow in what is today the northwest-oriented McGuire Creek drainage basin separated from flood waters moving north in the Prairie Elk Creek valley. Because headward erosion of the Missouri River valley and the Big Dry Creek valley had beheaded and reversed all flood flow moving to the figure 9 map area the separation of flood flow between the two drainage basins was the final flood event in the figure 9 map area.

Nelson Creek-Cotter Creek drainage divide area

Figure 10: Nelson Creek-Cotter Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 illustrates the Nelson Creek-Cotter Creek drainage divide south of the figure 8 map area. Northwest-oriented Nelson Creek flows to the figure 10 northwest corner and then to Nelson Bay as seen in figure 8 above. Nelson Bay is the flooded Nelson Creek valley where it enters the flooded Big Dry Creek valley, which has been flooded by Fort Peck Dam. Southeast-oriented drainage in the figure 10 east half flows to the northeast oriented Redwater River located southeast of the figure 10 map area. Southeast-oriented Cotter Creek in the figure 10 southeast quadrant joins the Redwater River at Brockway, Montana. Headwaters of north-oriented Prairie Elk Creek are located north of the figure 10 map area. Figure 10 evidence can be explained by southeast-oriented flood flow moving across the entire figure 10 map area to what was then a deep and newly eroded northeast oriented Redwater River valley. Southeast-oriented flood waters then eroded the Redwater River northwest valley wall and eroded southeast-oriented tributary valleys into the erosion surface the southeast-oriented flood waters were creating. The deep northeast and north oriented Redwater River valley eroded south and southwest from what was then the actively eroding east and northeast-oriented Missouri River valley head (meaning the deep Missouri River valley northwest of figure 10 did not yet exist and flood waters could freely move southeast across the region). Subsequently, headward erosion of the deep east-oriented Missouri River valley and the north-oriented Big Dry Creek valley beheaded the southeast-oriented flood flow. Flood waters on the northwest ends of the beheaded southeast-oriented flood flow routes reversed flow direction to flow northwest into the newly eroded and deeper north-oriented Big Dry Creek valley. The reversal of flood flow eroded the present day northwest-oriented Big Dry Creek tributary valleys and created the present day Big Dry Creek-Redwater River drainage divide seen in figure 10.

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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