A geomorphic history based on topographic map evidence

The Prairie Elk Creek-Redwater River drainage divide area discussed here is located in northeast Montana, USA. Although detailed topographic maps of the Prairie Elk 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 Prairie Elk 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:

Introduction:

• The purpose of this essay is to use topographic map interpretation methods to explore northeast Montana Prairie Elk 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 Prairie Elk 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.

Prairie Elk Creek-Redwater River drainage divide area location map

Figure 1: Prairie Elk 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 Prairie Elk 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, Montana before gradually turning to flow 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, Montana. The Prairie Elk Creek-Redwater River drainage divide area discussed here is located north of a line between Circle, Montana and the Prairie Elk Creek headwaters area and is south of the Missouri 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 Prairie Elk Creek and Redwater River valleys were two deep valleys that 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. 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 describe drainage divide areas which are located east of the Prairie Elk Creek-Redwater River drainage divide area discussed here and the essays can be found under appropriate river names on the sidebar list (use MT Missouri River for Montana Missouri River).

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

Figure 2: Prairie Elk 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 Prairie Elk Creek-Redwater River drainage divide area discussed here. Mc Cone and Richland Counties are located in Montana. Dawson County is the unnamed county in the figure 2 southeast corner. The Missouri River flows east from Fort Peck Lake in the figure 2 north half and is located south of Frazer, Oswego, Wolf Point, Poplar, Brockton, and Fort Kipp 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. Between north-oriented Prairie Elk Creek and the north-oriented Redwater River is north-oriented Sand Creek, which joins the Missouri River south of Wolf Point. This essay first illustrates evidence in the Sand Creek-Redwater River drainage divide area and then looks at evidence in the Prairie Elk Creek-Sand Creek drainage divide area before looking at evidence south of the Sand Creek headwaters in the Prairie Elk 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 the 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 Sand Creek-Redwater River drainage divide area

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

Figure 3 illustrates the north end of the Sand Creek-Redwater River drainage divide. The east-oriented Missouri River is located in the figure 3 north half. Sand Creek flows north along the figure 3 west edge to join the Missouri River south of Wolf Point. The Redwater River flows northwest from the figure 3 southeast corner area and then in the figure 3 east center turns northeast and joins the Missouri River east of the figure 3 map area. Northwest and west-oriented Rock Creek is located in the figure 3 southwest corner and flows to Sand Creek. Sheep Creek originates near the highway in the figure 3 south center area and flows east and northeast to the Redwater River. Note how a west-oriented Rock Creek tributary is linked by a through valley with northeast and east-oriented Sheep Creek. Through valleys such as this one provide evidence water once flowed east across what are now drainage divides. Further note the northwest-southeast orientation of tributary valleys and/or valley segments that suggests at least some of the major valleys eroded across multiple channels of southeast-oriented flood flow. For example, the northeast-oriented Missouri River valley southeast wall in the figure 3 northwest quadrant has numerous northwest-oriented tributary valleys eroded into it. These northwest-oriented tributaries suggest headward erosion of the Missouri River valley beheaded multiple southeast-oriented flood flow routes and flood waters on the northwest ends of those flood flow routes reversed direction to flow northwest into the newly eroded Missouri River valley. Northwest-oriented Rock Creek and the northwest-oriented Redwater River valley segment may also have been eroded by reversed flood flow on the northwest ends of beheaded southeast-oriented flood flow routes. Nickwall Creek is the northeast-oriented Missouri River tributary located south of the Missouri River in the figure 3 north center area and has a number of southeast-oriented tributaries. The southeast-oriented tributaries suggest the northeast-oriented Nickwall Creek valley eroded southwest to capture multiple southeast-oriented flood flow routes that were subsequently beheaded by headward erosion of the deeper Missouri River valley to the north. Note how headwaters of northeast-oriented Nickwall Creek are linked by a through valley with headwaters of a northwest-oriented Missouri River tributary. This through valley like the through valley linking the Rock and Sheep Creek valleys provides evidence that water once flowed east across present day drainage divide. The multiple through valleys suggest an anastomosing complex of channels, although a look at evidence further south on the drainage divide is needed before drawing too many conclusions.

Sand Creek-Wolf Creek drainage divide area north of Wolf Creek

Figure 4: Sand Creek-Redwater River drainage divide area north of Wolf Creek. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 4 illustrates the Sand Creek-Redwater River drainage divide area south of the figure 3 map area and includes overlap areas with figure 3. The Redwater River flows north along the figure 4 east edge and turns to flow northwest in the figure 4 northeast corner area. Northwest-oriented Rock Creek flows to north oriented Sand Creek in the figure 4 northwest corner. South of Rock Creek northwest-oriented Long Branch Creek flows to north oriented Sand Creek and south of Long Branch Creek is northwest-oriented Coal Creek, which flows to the northwest-oriented East Fork Sand Creek (seen in the figure 4 southwest corner). Wolf Creek flows northeast in the figure 4 south center and then east to join the Redwater River. Wolf Creek has several southeast-oriented tributaries including Gady Coulee and also several northwest-oriented tributaries. The southeast-northwest orientation of tributary valleys is much more apparent in figure 4 than in figure 3 and provides evidence the major north- and northeast-oriented valleys eroded headward across multiple southeast-oriented flood flow routes. Further, through valleys link headwaters of southeast-oriented Wolf Creek tributaries with valleys of northwest-oriented Sand Creek tributaries. These through valleys provide evidence multiple southeast-oriented flood flow channels once moved southeast-oriented flood flow across the present day Sand Creek-Redwater River drainage divide. Northwest-oriented tributary valleys were eroded by reversed flood flow on the northwest ends of beheaded southeast-oriented flood flow routes. Flood waters originally flowed on a topographic surface at least as high as the highest figure 4 elevations today. Headward erosion of the north-oriented Redwater River valley first captured the southeast-oriented flood flow and diverted the flood waters north. The Wolf Creek valley then eroded west and southwest to capture southeast-oriented flood flow moving to the newly eroded Redwater River valley. Next headward erosion of the north-oriented Sand Creek valley captured the southeast-oriented flood waters and diverted the flood flow north. Flood flow to the Sand Creek valley was subsequently beheaded by headward erosion of the deep east-oriented Missouri River valley.

Wolf Creek-Redwater River drainage divide area north of Cow Creek

Figure 5: Wolf Creek-Redwater River drainage divide area north of Cow Creek. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 5 illustrates the Wolf Creek-Redwater River drainage divide area south of the figure 4 map area and includes overlap areas with figure 4. The north-northeast oriented Redwater River is located in the figure 5 southeast corner. Northeast-oriented Wolf Creek flows through the figure 5 north center area to the figure 5 north edge. Cow Creek is the southeast-oriented Redwater River tributary flowing across the figure 5 south center area to join the Redwater River just south of the figure 5 southeast corner area. Northwest-oriented Coal Creek and East Fork flow to join the north-oriented Middle Fork of Sand Creek in the figure 5 northwest corner. Note how Redwater River tributaries are predominately southeast-oriented. Also note through valleys linking those southeast-oriented tributaries with northwest-oriented Wolf Creek tributary valleys. The Gold Gulch through valley linking the Wolf Creek valley with the Redwater River is particularly easy to identify. In addition note multiple shallow through valleys linking the north-oriented Middle Fork Sand Creek valley with the southeast-oriented Cow Creek valley. These through valleys and the dominant northwest-southeast orientation of tributary valleys provides strong evidence the major northeast and north-oriented valleys eroded headward to capture multiple channels of southeast-oriented flood flow such as might be found in a southeast-oriented anastomsing channel complex. Flood waters originally flowed southeast on a topographic surface at least as high as the highest figure 5 elevations today. What was at that time the deep north-northeast oriented Redwater River valley eroded south-southwest to capture the southeast-oriented flood waters and to divert the flood flow north. Headward erosion of the northeast-oriented Wolf Creek valley next captured the southeast-oriented flood flow. Headward erosion of the north-oriented Sand Creek valley next beheaded flood flow routes moving water to the actively eroding Wolf Creek valley head and then eroded south to behead southeast-oriented flood flow routes to what was then the newly eroded southeast-oriented Cow Creek valley.

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

Figure 6: North end of Prairie Elk Creek-Sand Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 6 illustrates the north end of the Prairie Elk Creek-Sand Creek drainage divide area west of figures 3 and 4 and includes overlap areas with figures 3 and 4. The east-northeast oriented Missouri River is located in the figure 6 northwest quadrant. Sand Creek flows north near the figure 4 east edge and then turns northwest to join the Missouri River as a barbed tributary (just north of the figure 6 map area). Note other northwest-oriented Missouri River tributaries. Prairie Elk Creek flows north in the figure 6 west half to join the Missouri River. Note the predominance of northwest-oriented Prairie Elk Creek tributaries from the east. Also note the predominance of southeast-oriented Sand Creek tributaries from the west. There are exceptions to this northwest-southeast orientation of tributary valleys. One such exception is northeast-oriented Crow Creek flowing from the figure 6 center area to join northwest-oriented Sand Creek. Note how headwaters of an east-oriented Crow Creek tributary are linked by a through valley to headwaters of northwest-oriented Spring Coulee. This through valley is evidence that headward erosion of the northeast-oriented Crow Creek valley and its east-oriented tributary valley captured southeast-oriented flood flow moving on the Spring Coulee alignment. This capture probably took place after headward erosion of the deep east-oriented Missouri River valley beheaded and reversed southeast-oriented flood flow on the northwest-oriented Sand Creek valley segment, but before headward erosion of the deep east-oriented Missouri River valley beheaded southeast-oriented flood flow moving on the Spring Coulee alignment. Headward erosion of the deep east-oriented Missouri River valley subsequently did behead and reverse southeast-oriented flood flow on the Spring Coulee alignment and the resulting flood flow reversal eroded the northwest-oriented Spring Coulee valley and created the present day Spring Coulee-Crow Creek drainage divide. Further south along the Prairie Elk Creek-Sand Creek drainage divide is the drainage divide between northwest-oriented Mud Creek and Little Mud Creek and southeast-oriented Antelope Creek, O’Dell Coulee, and Browns Coulee. Through valleys across this divide are not as obvious, although they are present on more detailed maps. Evidence available in figure 6 suggests headward erosion of the north-oriented Sand Creek valley captured southeast-oriented on flood flow routes that eroded the southwest oriented Antelope Creek, O’Dell Coulee, and Browns Coulee valleys headward into a topographic surface at least as high as the present day drainage divide. Subsequently headward erosion of the north-oriented Prairie Elk Creek valley beheaded the southeast-oriented flood flow routes from north to south. Reversed flood flow on the northwest ends of the beheaded flood flow routes eroded the northwest-oriented Mud Creek. Little Mud Creek and Emily Coulee valleys. Because flood waters were moving in anastomosing (or interconnected) channels reversed flood flow on one channel could capture yet to be beaded flood flow from channels further to the south. Such captures of yet to be beheaded flood flow provided the necessary volumes of reversed flood flow water needed to erode the northwest-oriented valleys.

Prairie Elk Creek-West Fork Sand Creek drainage divide area

Figure 7: Prairie Elk Creek-West Fork Sand Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 7 illustrates the Prairie Elk Creek-West Fork Sand Creek drainage divide area south of the figure 6 map area and includes overlap areas with figure 6. North-northwest and north oriented Prairie Elk Creek is located in the figure 7 west half. The West Fork Sand Creek flows north from the figure 7 southeast quadrant to the O’Dell Reservoir area in the figure 7 northeast quadrant. Porcupine Creek flows north-northeast to join the north-oriented West Fork. The north-northwest oriented East Fork Sand Creek can be seen along the figure 7 east edge (north half) and is joined by north- and northeast-oriented Middle Fork Sand Creek near the figure 7 east edge center. A prominent west to east oriented through valley in the figure 7 center area links the north-oriented Prairie Elk Creek valley with north-oriented West Fork Sand Creek valley. The through valley is drained on the west end by Sadie Coulee, which flows northwest into the through valley and then turns southwest to drain to an unnamed northwest-oriented tributary to north-oriented Prairie Elk Creek. The unnamed northwest-oriented tributary valley is on the same northwest-southeast alignment as the southeast-oriented Cow Creek valley seen in figure 5 above. Today north-northeast oriented Porcupine Creek is located between headwaters of the northwest-oriented Prairie Elk Creek tributary and southeast-oriented Cow Creek (see figure 8 below). This relationship suggests headward erosion of the Porcupine Creek valley captured southeast oriented flood flow to the southeast-oriented Cow Creek valley segment. Northeast-oriented John Coulee appears to have eroded southwest from the newly eroded Porcupine Creek valley to also capture the southeast-oriented flood flow. At the same time an east-oriented valley apparently eroded west from the newly eroded north-oriented Sand Creek valley along the present day through valley alignment to capture a surge of flood flow moving north in the newly eroded Prairie Elk Creek valley (see figure 10 below for evidence of this flood flow surge). The southwest-oriented Sadie Coulee valley alignment was eroded by this surge of north-oriented flood water, some of which was captured by north-oriented Sand Creek. Note evidence of erosional residuals suggesting anastomosing channels within the Prairie Elk Creek valley. This evidence suggests the surge of north-oriented flood flow took place shortly before flood flow across the figure 7 map area ceased.

Prairie Elk Creek and Sand Creek-Cow Creek drainage divide area

Figure 8 illustrates the Prairie Elk Creek and Sand Creek-Cow Creek drainage divide area south of the figure 7 map area and includes overlap areas with figure 7 (and also with figure 5). Cow Creek flows northeast from the figure 8 south center edge and then north-northeast before turning southeast in the figure 8 southeast quadrant. North-oriented Prairie Elk Creek is located along the figure 8 west edge. Previously mentioned Sadie Coulee is located in the figure 8 northwest corner. North-northeast oriented Porcupine Creek flows to the figure 8 north center edge. Northwest-oriented and north-oriented East Fork Sand Creek is located in the figure 8 northeast quadrant and flows to the figure 8 north edge (east half). Northwest-oriented Coal Creek flows to the north-oriented East Fork from the east and northeast-oriented Middle Fork flows to the East Fork from the west. Headwaters of northeast-oriented Wolf Creek are located in the figure 8 northeast quadrant close to the figure 8 east edge. Note how southeast-oriented tributary valleys link the southeast-oriented Cow Creek valley segment with northwest and north-oriented headwaters of the East Fork Sand Creek, the Middle Fork Sand Creek, and Porcupine Creek. These linkages provide evidence headward erosion of the north-oriented East Fork Sand Creek beheaded and captured southeast-oriented flood flow that had been moving to the southeast-oriented Cow Creek valley and then to the north-oriented Redwater River valley. The linkages also provide evidence headward erosion of the Porcupine Creek valley (and West Fork Sand Creek valley) beheaded and captured southeast-oriented flood flow routes to the southeast-oriented Cow Creek valley segment. Further note northwest-oriented tributary valleys to north-oriented Prairie Elk Creek. North of the Porcupine Creek headwaters these northwest-oriented Prairie Elk tributaries provide evidence the north-oriented Prairie Elk Creek valley beheaded and captured southeast-oriented flood flow that had been moving to what was then the newly eroded Porcupine Creek valley. South of the Porcupine Creek headwaters these northwest-oriented Prairie Elk Creek tributary valleys provide evidence headward erosion of the north-oriented Prairie Elk Creek valley beheaded and captured southeast-oriented flood flow to what was then the newly eroded northeast and north-northeast oriented Cow Creek valley segment.

Prairie Elk Creek and Cow Creek-Redwater River drainage divide area

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

Figure 9 illustrates the Prairie Elk Creek-Cow Creek, the Cow Creek-Redwater River, and the Prairie Elk Creek-Redwater River drainage divide areas southeast of the figure 8 map area and includes overlap areas with figure 8. Northwest-oriented drainage flowing to the figure 9 northwest corner area flows to Prairie Elk Creek. The East Fork of Prairie Elk Creek is the long northwest-oriented stream in the figure 9 west center edge area. Cow Creek originates in the figure 9 northwest quadrant and flows northeast and north-northeast to the figure 9 north edge center. Note northwest-oriented Cow Creek headwaters and also the northwest-oriented Cow Creek tributary originating in the figure 9 center area. Southeast-oriented drainage to the figure 9 east and south edges flows to the northeast oriented Redwater River. Figure 9 evidence can be explained with southeast-oriented flood flow moving across the entire figure 9 map area on a topographic surface at least as high as the highest figure 9 elevations today. Headward erosion of a deep northeast oriented Redwater River valley into the region southeast of the figure 9 map area captured the southeast-oriented flood flow and flood waters eroded deep southeast-oriented tributary valleys northwest from the newly eroded northeast oriented Redwater River valley wall. The Cow Creek valley was one of those southeast-oriented valleys and a northeast-oriented tributary valley to the southeast-oriented Cow Creek valley eroded southwest to capture flood flow moving to some actively eroding southeast-oriented Redwater River tributary valleys. The northwest-oriented Cow Creek headwaters and northwest-oriented Cow Creek tributary provide evidence the northeast-oriented Cow Creek valley did in fact behead and reverse southeast-oriented flood flow moving to the newly eroded Redwater River valley. Apparently southeast-oriented flood moving on the East Fork Prairie Elk Creek alignment was able to erode a deep enough valley on its route to southeast-oriented Denwoody Creek and Horse Creek (which flows to the Redwater River at Circle, Montana) that the Cow Creek valley could not capture that flow. Headward erosion of the north-oriented Prairie Elk Creek valley then beheaded and captured southeast-oriented flood flow to the newly eroded northeast- and southeast-oriented Cow Creek valley and also beheaded and captured the southeast-oriented flood flow on the East Fork Prairie Elk Creek-Denwoody Creek-Horse Creek alignment. Flood waters on the northwest ends of the beheaded flood flow reversed flow to flow northwest into the newly eroded north-oriented Prairie Elk Creek valley. Because the Prairie Elk Creek valley eroded from north to south and flood flow routes were beheaded in that sequence, reversed flow on a newly beheaded flood flow route could capture yet to be beheaded southeast-oriented flood flow from flood flow routes further south. Such captured flood waters helped erode significant northwest-oriented valleys.

Prairie Elk Creek-Redwater River drainage divide area

Figure 10: Prairie Elk Creek-Redwater River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 10 illustrates the Prairie Elk Creek-Redwater River drainage divide area south of the Cow Creek headwaters and includes overlap areas with figure 9. North-northeast oriented Middle Fork Prairie Elk Creek is located in the large north-oriented in the figure 10 northwest corner area. The northwest-oriented East Fork Prairie Elk Creek originates in the figure 10 center and flows to the figure 10 north edge to join the Middle Fork north of the figure 10 map area. Near the figure 10 west center edge southeast-oriented Upper McGuire Creek flows to same large through valley used by the north-northeast oriented Middle Fork Prairie Elk Creek and then turns west to join northwest-oriented Middle Fork McGuire Creek. Northwest oriented McGuire Creek is located in the figure 10 southwest corner. West of figure 10 McGuire Creek flows west-northwest to join north-oriented Big Dry Creek, which flows to the northeast and east-oriented Missouri River. Southeast-oriented drainage flowing to the figure 10 east and south edges flows to the Redwater River. The North Fork Horse Creek flows to the figure 10 south center edge. East of the North Fork Horse Creek is southeast-oriented Denwoody Creek, which is linked by a through valley with the northwest-oriented East Fork Prairie Elk Creek valley. Northwest and northeast-oriented Cow Creek is located in the figure 10 northeast quadrant. Figure 10 evidence tells essentially the same story as figure 9 evidence. Southeast-oriented flood flow to what was then the newly eroded northeast-oriented Redwater River valley was captured by headward erosion of the northeast-oriented Prairie Elk Creek-Middle Fork Prairie Elk Creek valley. Flood waters on the northwest ends of beheaded southeast-oriented flood flow routes reversed flow direction to flow northwest to the newly eroded north-oriented Prairie Elk Creek valley. What was different here was headward erosion of the Prairie Elk Creek valley captured what must have been a major east-southeast oriented flood flow channel and a surge of flood waters moved north in the newly eroded north-oriented Prairie Elk Creek valley. Some of the flood waters were captured by what is today the west to east oriented through valley linking the Prairie Elk Creek valley and the Sand Creek valley seen in figure 7. Those captured flood waters moved east and then north in the Sand Creek valley while remaining flood waters continued north in Prairie Elk Creek valley. Headward erosion of the deep Missouri River valley and its north-oriented Big Dry Creek tributary valley then beheaded and reversed the major flood flow route feeding the newly eroded north-oriented Prairie Elk Creek and Sand Creek valley system. Flood waters on the northwest end of that beheaded flood flow route reversed flow direction to flow west-northwest into the newly eroded north-oriented Big Dry Creek valley and by doing so eroded the McGuire Creek drainage basin and created the present day McGuire Creek-Prairie Elk Creek drainage divide.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic 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.