A geomorphic history based on topographic map evidence

The Peoples Creek-Missouri River drainage divide area is located in Blaine County, Montana, USA. Although detailed topographic maps of the Peoples Creek-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. Peoples Creek is a Milk River tributary and the Peoples Creek-Missouri River drainage divide is the divide between the east oriented Milk River drainage basin to the north and the east oriented Missouri River drainage basin to the south, with the Milk River joining the Missouri River east of the study region. The Peoples Creek-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 across the drainage divide ended when headward erosion of the Milk River valley captured all southeast-oriented flood flow.

Preface:

Introduction:

• The purpose of this essay is to use topographic map interpretation methods to explore Peoples Creek-Missouri River drainage divide area landform origins in Blaine County, Montana. 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 Peoples Creek-Missouri River drainage divide area landform evidence in Blaine County, Montana will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm. This essay is included in the Missouri River drainage basin landform origins research project essay collection.

Peoples Creek-Missouri River drainage divide area location map

Figure 1: Peoples Creek-Missouri 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 Peoples Creek-Missouri River drainage divide area location map. Figure 1 illustrates a region in north central Montana and the US-Canada border is located along the figure 1 north edge. The Missouri River flows northeast, southeast, and east-southeast from the figure 1 west edge to Fort Peck Lake, which continues to the figure 1 east edge. The lake is a large reservoir impounded behind Fort Peck Dam, which is located east of the figure 1 map area. The Milk River flows southeast from Canada (in the figure 1 northwest corner) to Fresno Reservoir, Havre, Chinook, Harlem, Dodson, Malta, Saco, and Hinsdale. Peoples Creek originates in the Bears Paw Mountains and flows northeast, southeast, northeast, and north to join the Milk River near Dodson. The Peoples Creek-Missouri River drainage divide area discussed here is located south of Peoples Creek and west of the Little Rocky Mountains. Based on evidence from the hundreds of Missouri River drainage basin landform origins research project essays published on this website landform evidence illustrated in this essay 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 Milk River valley eroded northwest and west to capture southeast-oriented flood water and to divert flood flow to the newly eroded Missouri River valley east of Nashua, Montana (located east of figure 1. Northeast, east, and north-oriented tributary valleys eroded headward from the newly eroded north-oriented Milk River valley. One such tributary valley was the Missouri River valley, which eroded southwest, west, northwest, and southwest to capture southeast-oriented flood flow that had not yet been captured by headward erosion of the Milk River valley to the north. Another such tributary valley was the Peoples Creek valley, which eroded south, southwest, southeast, and southwest from the newly eroded Milk River valley to capture southeast-oriented flood water that had been moving to the newly eroded Missouri River valley. Detailed maps below illustrate evidence that flood waters crossed the Bearpaw Mountains. Subsequently, as the deep Milk River valley eroded further west it captured southeast-oriented flood flow moving to the newly eroded Peoples Creek valley. Flood waters on the ends of beheaded southeast-oriented flood flow routes reversed flow direction and eroded the present day northwest and north-oriented tributary valleys. The Milk River-Peoples Creek drainage divide area essay, the Peoples Creek-Beaver Creek drainage divide area essay, the Beaver Creek-Missouri River drainage divide area essay, Milk River-Missouri River drainage divide area between Beaver Creek and Larb Creek essay, the Milk River-Missouri River drainage divide area east of Larb Creek essay, and the Missouri River-Musselshell River drainage divide area essay describe other Milk River-Missouri River drainage divide areas east and west of this essay’s study region and can be found under Milk River or MT Missouri River on the sidebar category list.

Peoples Creek-Missouri River drainage divide area detailed location map

Figure 2 illustrates a somewhat more detailed map of the Peoples Creek-Missouri River drainage divide area discussed in this essay. Blaine and Chouteau Counties is located in Montana (Phillips County is located east of Blaine County). The eastern red shaded area is the Fort Belknap Indian Reservation and the western red shaded area is the Rocky Boys Indian Reservation. Peoples Creek originates in the Bearpaw Mountains southwest of Cleveland (located north of the “S” in Bearpaw Mountains) and flows northeast, southeast and northeast and finally turns north to join the southeast-oriented Milk River west of Dodson. The southeast-oriented Milk River is located in the figure 2 northeast quadrant. The Missouri River flows south-southeast and southeast from the figure 2 west center edge and then forms the southern boundary of Chouteau, Blaine and Phillips Counties as flows east-northeast, southeast, and east across the figure 2 lower half. The Little Rocky Mountains are located in the indentation in the southern Fort Belknap Indian Reservation border. The Peoples Creek-Missouri River drainage divide discussed here is located west of the Little Rocky Mountains and south of Peoples Creek. The major Missouri River tributaries discussed below are Cow Creek and Lion Coulee. Cow Creek has many tributaries and tributaries discussed here include Suction Creek, Little Suction Creek, Gap Creek, and Als Creek. Bullwhacker Coulee is the major Lion Coulee tributary discussed below. Note the large number of southeast-oriented Missouri River tributaries and of southeast-oriented tributaries to other trunk streams, especially in eastern Blaine County and in Phillips County. This southeast drainage alignment is evidence the Missouri River valley and other major trunk stream valleys eroded headward across and/or along multiple southeast-oriented flood flow channels such as might be found in a large southeast-oriented anastomosing channel complex. As previously mentioned this essay interprets Peoples Creek-Missouri River drainage divide evidence in the context of an immense southeast-oriented flood, which crossed the entire figure 2 map area. Headward erosion of the east-oriented Missouri River valley first captured the southeast-oriented flood flow, although headward erosion of the Milk River valley to the Dodson region probably occurred at about the same time and the Peoples Creek then eroded south, southwest, west-northwest to capture the southeast-oriented flood flow moving to the newly eroded Missouri River valley. Soon thereafter headward erosion of the Milk River valley beheaded southeast-oriented flood flow routes to the newly eroded Peoples Creek valley. Topographic maps below illustrate how southeast-oriented Missouri River tributary valleys eroded northwest into the Bearpaw Mountain region to capture southeast-oriented flood flow, which was subsequently beheaded by headward erosion of the Peoples Creek valley. Evidence presented here requires flood waters to have originally flowed across a topographic surface at least as high as the highest figure 2 elevations today (including Bearpaw Mountain elevations), although it is possible the Bearpaw Mountain region was being uplifted while flood erosion was taking place. An alternate possibility is the Bearpaw Mountain region and the Milk River-Peoples Creek drainage divide area were surrounded by sedimentary rocks and/or ice, which were removed by flood water erosion. Detailed maps tell the story better.

Little Suction Creek-Little Peoples Creek drainage divide area

Figure 3: Little Suction Creek-Little Peoples Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 illustrates the Little Suction Creek-Little Peoples Creek drainage divide area along the Little Rocky Mountain west side. Little Peoples Creek flows in the figure 3 southeast corner northwest to the north-south highway and then follows the highway north and northwest to the figure 3 north edge. North of figure 3 Little Peoples Creek turns northeast and eventually joins Peoples Creek and flows to the Milk River. Little Suction Creek flows northeast and north from the figure 3 southwest quadrant to the east end of Timber Ridge (located in the figure 3 west center) and then turns northwest to join south and south-southwest oriented Suction Creek in the figure 3 northwest corner area (southeast oriented Rattlesnake Creek also joins Suction Creek in the northwest corner area). Note northwest-oriented tributaries to the northeast and north-oriented Little Suction Creek valley segments. These northwest-oriented tributaries include Warneke Coulee, Running Crow Creek, Crazyman Coulee, and Matador Coulee. These northwest-oriented Little Suction Creek tributaries provide evidence headward erosion of what is now the northeast and north-oriented Little Suction Creek valley beheaded southeast oriented flood flow routes and flood waters on the northwest ends of the beheaded flood flow routes reversed flow direction to erode northwest-oriented valleys. In the case of Warneke Coulee and Running Crow Creek southeast oriented flood flow routes had been moving flood waters southeast along the present day Bradley Canyon alignment into the western Little Rocky Mountains. At first southeast-oriented flood water went south and southeast across Little Rocky Mountain passes to south- and southeast-oriented Missouri River tributaries (see Peoples Creek-Beaver Creek drainage divide area and Beaver Creek-Missouri River drainage divide area essays). However, headward erosion of what was then the deep northeast-oriented Little Peoples Creek valley north of the figure 3 map area beheaded southeast-oriented flood flow on what is today the northwest-oriented Little Peoples Creek valley alignment. Flood waters on the northwest end of the beheaded flood flow route reversed flow direction to flow northwest to the newly eroded and deeper northeast-oriented Little Peoples Creek valley. Reversed flood flow in the newly created Little Peoples Creek drainage basin captured yet to be beheaded southeast-oriented flood flow moving along the Bradley Canyon alignment. With aid of the yet to be beheaded flood flow moving along the Bradley Canyon alignment the newly reversed Little Peoples Creek was able to erode a significant northwest-oriented valley. Shortly thereafter headward erosion of the southeast- and south-oriented Cow Creek-Suction Creek valley from the Missouri River valley beheaded southeast-oriented flood flow routes supplying water to the newly reversed Little Peoples Creek drainage basin. Flood waters on the northwest ends of the beheaded flood flow routes reversed flow direction to erode the northwest-oriented Warneke Coulee, Running Crow Creek valley, and other valleys.

Fogarty Coulee-Suction Creek drainage divide area

Figure 4: Fogarty Coulee-Suction Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates the Fogarty Coulee-Suction Creek drainage divide area north and west of the figure 3 map area. Fogarty Coulee drains east, southeast and northeast across the figure 4 north edge area and northeast of figure 4 flows to Peoples Creek and then to the Milk River. Suction Creek is located along the figure 4 south edge (west half) and turns south to flow to south-southeast oriented Cow Creek and then to the Missouri River. The lake in the figure 4 south center is Putnam Lake, which drains to Suction Creek. Note the east-oriented arc-shaped escarpment surrounded basin in which there is today a maze of interconnected dry (or through) valleys, some of which link the Fogarty Coulee valley (Milk River drainage basin) with the Suction Creek valley (Missouri River drainage basin). The east-oriented arc-shaped escarpment-surrounded basin is an abandoned headcut eroded by southeast oriented flood flow that was beheaded by headward erosion of the east-oriented Fogarty Coulee valley (from the northeast-oriented Peoples Creek valley). Before Fogarty Coulee captured the southeast oriented flood flow significant volumes of south-oriented flood water flowed across the figure 4 map area and eroded the maze of north to south oriented through valleys linking the Fogarty Coulee valley with the Suction Creek valley. Anastomosing complexes of channels provide evidence of large floods, although the anastomosing channel complex in figure 4 is small compared to anastomosing channel complexes seen in figures below. In fact the entire Peoples Creek-Missouri River drainage divide area was eroded by an ever-changing southeast oriented anastomosing channel complex of which the Suction Creek valley was just one of many southeast and south oriented channels. Headward erosion of the Milk River-Peoples Creek valley system beheaded the southeast-oriented flood flow routes and diverted the flood waters to what was then the newly eroded Milk River valley.

Peoples Creek-Cow Creek drainage divide area near Thunder Butte

Figure 5: Peoples Creek-Cow Creek drainage divide area near Thunder Butte. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

• Figure 5 illustrates the Peoples Creek-Cow Creek drainage divide area west of the figure 4 map area. Suction Creek headwaters are in the McDougal Basin southwest of Suction Butte (located in the figure 5 southeast quadrant). Suction Creek then flows northeast to go north around Suction Butte and then turns to flow southeast to the figure 5 east edge. Nicholson Bluff Creek is the northwest-oriented stream flowing from the mountain pass between Thunder Butte and the unnamed butte to the east. Note how that mountain pass provides a through valley linking northwest-oriented Nicholson Bluff Creek with southeast-oriented Suction Creek. Nicholson Bluff Creek flows northwest to join northeast oriented Peoples Creek as a barbed tributary. West of the Suction Creek headwaters, between Rieve Butte and Hansen Butte, are headwaters of north-northwest Rieve Creek, which also flows to northeast oriented Peoples Creek as a barbed tributary. Just south of Rieve Creek headwaters are headwaters of south-southeast oriented Hansen Creek, which with a southwest jog flows to Winters Creek, southeast-oriented Cow Creek and the Missouri River. Note high level through valleys (or mountain passes) linking the north-northwest oriented Rieve Creek valley with the present day northeast and southeast oriented Suction Creek valley (these links are west of McDougal Basin and west of McDonald Basin). Figure 5 evidence can be explained in the context of an immense southeast-oriented flood flowing on a topographic surface at least as high as the highest level figure 5 through valleys today. It is possible the surface was as high as tops of the buttes, however no valleys cross these buttes and based on figure 5 evidence alone it is possible the buttes stood above the topographic surface on which flood waters flowed. Headward erosion of what was then the deep southeast-oriented Suction Creek valley captured the southeast-oriented flood waters and tributary valleys eroded southwest to the McDougal Basin area and west to the McDonald Basin area to capture additional southeast-oriented flood flow. Another tributary valley eroded headward along a southeast-oriented flood flow route using what is today the northwest-oriented Nicholson Bluff Creek alignment. About the same time headward erosion of south-southeast oriented Hansen Creek valley reached the figure 5 map area and eroded a valley headward along what is to today the north-northwest oriented Rieve Creek valley alignment. As these south-oriented valleys were actively eroding the deep Peoples Creek valley beheaded southeast-oriented flood flow on both the south-oriented Nicholson Bluff Creek-Suction Creek valley and the Rieve Creek-Hansen Creek valley routes. Flood waters on northwest ends of the beheaded flood flow routes reversed flow direction to erode present day northwest-oriented valleys. Flood waters on the Nicholson Bluff Creek-Suction Creek valley were beheaded first and for a time yet to be beheaded southeast-oriented flood from the Rieve Creek valley alignment moved into the McDonald and McDougal Basins and then north to join reversed flood flow in the Nicholson Bluff Creek valley and helped erode the northwest-oriented Nicholson Creek valley. By capturing flood waters moving south on the Rieve Creek-Hansen Creek valley alignment reversed flood flow on the Nicholson Bluff Creek-Suction Creek alignment was able to erode a deeper valley, which means the present day Nicholson Bluff Creek-Suction Creek drainage divide is lower in elevation than the Rieve Creek-Hansen Creek drainage divide.

Peoples Creek-Gap Creek drainage divide area

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

Figure 6 illustrates the Peoples Creek-Gap Creek drainage divide area west of the figure 5 map area. Peoples Creek is located along the figure 6 north edge and flows generally east before turning northeast to flow to the figure 6 north edge. Gap Creek is located in the figure 6 center south area and flows east and southeast to the figure 6 south edge. Figure 5 provided evidence southeast-oriented flood waters crossed what are today mountain passes east of the figure 6 map area. Figure 6 illustrates a large north-south through valley linking the Peoples Creek valley with southeast-oriented Gap Creek, which flows to Cow Creek and then to the Missouri River. The floor of this large through valley is more than 100 meters lower in elevation than the floor of the Nicholson Bluff Creek-Suction Creek drainage divide seen in figure 5. The multiple through valleys linking the Peoples Creek valley with the Missouri River valley to the south provide evidence of a large-scale and ever-changing anastomosing complex of south and southeast-oriented channels crossing what is today the Peoples Creek-Missouri River drainage divide area. The anastomosing channel complex was constantly changing and when a channel was able erode deeper than adjacent channels it captured flood flow from the adjacent channels. Apparently headward erosion of the southeast-oriented Gap Creek valley into the figure 6 map area and then west was able to capture significant southeast-oriented flood flow before being captured by headward erosion of the northeast-oriented Peoples Creek valley. In other words, the Peoples Creek valley upstream from this through valley originally drained south along the present day Gap Creek-Cow Creek alignment to what was then the newly eroded Missouri River valley and headward erosion of the northeast-oriented Peoples Creek valley to the figure 6 map area beheaded flood flow to the Gap Creek valley and diverted the flood waters northeast to what was then the newly eroded Milk River valley.

South Fork Peoples Creek-Cow Creek drainage divide area

Figure 7: South Fork Peoples Creek-Cow Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the South Fork Peoples Creek-Cow Creek drainage divide area west and south of the figure 6 map area and also illustrates the Clear Creek-South Fork Peoples Creek drainage divide area. Figure 7a below illustrates the map area immediately north of the figure 7 map area and shows more of the Clear Creek-Peoples Creek drainage divide area. The South Fork Peoples Creek flows northeast from the Bentel Divide area in the figure 7 northeast corner area. South-southeast oriented North Fork Cow Creek flows from Bentel Divide to the figure 7 southeast corner area. Southeast-oriented drainage at Maddux (in the figure 7 southeast quadrant) flows to the North Fork Cow Creek. Southeast-oriented drainage west of Maddux is the headwaters of southeast-oriented South Fork Cow Creek. Note the drainage divide here because figure 8 below illustrates where the North and South Forks Cow Creek meet. The north-oriented stream in the figure 7 northwest quadrant is Clear Creek, which flows north to the Milk River. The East Fork Clear Creek originates a short distance west of Bentel Divide and flows west and northwest to join Clear Creek a short distance north of the figure 7 map area. The present day north-oriented Clear Creek valley and its tributary northwest-oriented East Fork Clear Creek valley were initiated by southeast-oriented flood flow moving to the western Peoples Creek valley (which originally drained south along the Gap Creek valley to the Missouri River valley). At first flood waters moved south and southeast along the East Fork Clear Creek valley route to the North Fork Cow Creek valley, however headward erosion of the South Fork Peoples Creek valley beheaded that route and diverted the flood waters northeast to the Peoples Creek valley. Next headward erosion of the deep Battle Creek-Peoples Creek through valley seen in figure 7a beheaded flood flow routes to the south causing reversals of flood flow that eroded the present day Clear Creek drainage basin south of Battle Creek, including the northwest-oriented East Fork Clear Creek valley. Subsequently headward erosion of the deep Milk River valley beheaded southeast-oriented flood flow on the Clear Creek-Battle Creek-Peoples Creek valley route and caused a reversal of flood flow that eroded the west-oriented Battle Creek valley and the north-oriented Clear Creek valley and also that created the Battle Creek-Peoples Creek drainage divide.

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

Cow Creek valley at TU Bench

Figure 8: Cow Creek valley at TU Bench. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the Cow Creek valley where the North and South Forks Cow Creek meet west of TU Bench and is located southeast of the figure 7 map area. The North Fork Cow Creek flows southeast from the figure 8 northwest corner area to join southeast and north-oriented South Fork Cow Creek near the figure 8 west center edge and then to flow east across the figure 8 center area to the figure 8 east edge. Cow Creek is the east oriented stream immediately north of TU Bench. Als Creek flows east-southeast from the figure 8 southwest corner along the figure 8 south edge and joins Cow Creek southeast of the figure 8 map area. An unnamed east-southeast oriented Cow Creek tributary originates between Cow Creek and Als Creek in the TU Bench area and also joins Cow Creek east of the figure 8 map area. Also note the unnamed southeast oriented stream flowing to TU Reservoir (located north of TU Bench), which flows to Hedges Creek, which in turn flows to Cow Creek. At first glance these various Cow Creek tributaries appear independent of each other. But, on closer inspection these tributaries are flowing in what was once a southeast oriented anastomosing channel complex. Note the many through valleys connecting the various tributary valleys and also the way the TU Bench area has been eroded. Figure 8 evidence demonstrates immense quantities of southeast and east oriented flood water once flowed across the figure 8 map area. The flood water came southeast across the present day Milk River (Clear Creek)-Missouri River (Cow Creek) drainage divide seen in figure 7 above before headward erosion of the deep Peoples Creek valley captured the southeast-oriented flood flow and diverted the flood waters east and northeast to what was then the newly eroded Milk River valley. Also, this figure 8 map area is west of where southeast-oriented Gap Creek joins Cow Creek (seen in figure 9 below), which means flood waters that flowed southeast across the Peoples Creek-Gap Creek drainage divide (seen in figure 6 above) did not flow across this figure 8 map area. Figures 9 and 10 below follow the Cow Creek valley downstream to see where the southeast-oriented flood waters were headed (and also to see valleys beheaded by headward erosion of the east- and southeast-oriented Cow Creek anastomosing valley complex.

Cow Creek valley downstream from TU Bench

Figure 9: Cow Creek valley downstream from TU Bench. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the region immediately east of the figure 8 map area and shows the east end of TU Bench. Hedges Creek flows east from the figure 9 west center edge and is joined by east-northeast Cow Creek, which also flows from the figure 9 west center edge just south of Hedges Creek. Cow Creek is then joined by southeast-oriented Gap Creek, which flows from the figure 9 northwest quadrant. After joining Gap Creek the Cow Creek valley orientation turns southeast and then south-southeast near the figure 9 southeast corner. Als Creek flows east and southeast in the figure 9 southwest corner and joins Cow Creek south of the figure 9 map area. Winters Creek flows south-southeast from the figure 9 north center edge to join south-southeast oriented Cow Creek. Just north of figure 9 Winters Creek is joined by south-oriented Hansen Creek, headwaters of which were seen in figure 5 above. Figure 9 evidence suggests large volumes of flood water moved south on the Winters Creek alignment before headward erosion of the Peoples Creek valley beheaded and reversed the flood flow. The figure 9 evidence is showing how headward erosion of the south-southeast-oriented Cow Creek valley captured an east-oriented anastomosing channel complex that now represents the east-oriented Cow Creek drainage basin west of the figure 9 map area. Flood waters that eroded the figure 9 map region crossed the Peoples Creek-Missouri River drainage divide seen in the previous figures (figures 5, 6 and 7). These flood waters flowed across what is today a high mountain region. To some extent the Bear Paw Mountain region elevation is the result of the erosion of deep valleys around it. Some of the present day elevation probably resulted from localized uplift, which may have been taking place as flood waters eroded the region. The source of the southeast-oriented flood waters cannot be determined from evidence presented here. However, the hundreds of Missouri River drainage basin landform origins research project essays published on this website when taken as a group can be used to trace flood waters both up flood to source areas and down flood to see where flood waters were going. A logical flood water source would be rapid melting of a thick North American ice sheet located in a deep “hole” occupying approximately the North American location usually recognized to have been glaciated. The deep “hole” would have been created by deep glacial erosion and by crustal warping caused by the ice sheet weight. Such a flood water source would not only explain the immense southeast-oriented floods this essay series describes, but would also explain why deep valleys were eroding headward to capture the southeast-oriented flood waters and diverting the flood waters further and further to the northeast and north into space in the deep “hole” the rapidly melting thick ice sheet had once occupied. In addition, such a flood water source may explain uplift of the Bear Paw Mountain region during an immense southeast-oriented flood. A thick North American ice sheet in deep “hole” created in part due to the ice sheet’s weight would probably create crustal warping elsewhere on the continent, especially along ice sheet margins. Further, rapid erosion of significant volumes of overlying material might trigger localized uplifts of what are today high mountain regions.

Lion Coulee-Missouri River drainage divide area

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

Figure 10 illustrates the Lion Coulee drainage basin south of the figures 8 and 9 map areas. The Missouri River is located along the figure 10 south edge. South-southeast oriented Cow Creek flows from the figure 10 northeast corner area to the figure 10 east center edge and then to the Missouri River southeast of the figure 10 map area. Lion Coulee drains southeast from the figure 10 west center and northwest quadrant areas to join the Missouri River in the figure 10 southeast corner. South- and southeast-oriented Bullwhacker Coulee drains from the figure 10 north center and is the major Lion Coulee tributary shown. Evidence presented in this essay suggests the deep Missouri River valley eroded headward into the region to capture southeast-oriented flood flow flowing on a topographic surface now preserved in the high Bear Paw Mountain regions to the north. The south-southeast-oriented Cow Creek valley eroded headward from what was probably the actively eroding and deep Missouri River valley head. As the Missouri River valley head eroded west the south- and southeast-oriented the southeast-oriented Lion Coulee valley eroded northwest and the Bullwhacker Coulee valley eroded north. Headward erosion of the east-oriented Cow Creek valley complex north of the figure 10 map area then beheaded flood flow routes to what was then the actively eroding Bullwhacker Coulee valley system and subsequently to what was then the actively eroding Lion Coulee valley system. Next headward erosion of the Peoples Creek valley systematically beheaded and reversed flood flow routes that had been supplying flood waters to what was then the actively eroding Cow Creek drainage system. Finally, further to the north, headward erosion of the deep Milk River valley beheaded and reversed flood flow routes to what was then the actively eroding Peoples Creek valley. Evidence presented in this essay makes a strong case that southeast-oriented flood waters crossed what are today high Bear Paw Mountain regions. As previously stated it is possible the Bear Paw Mountain region was being uplifted as flood waters eroded the region and the described  drainage changes were taking place. Evidence presented in this essay makes a strong case for the  “thick ice sheet that melted fast” paradigm.

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.