A geomorphic history based on topographic map evidence

The Yellowstone River-Beaver Creek drainage divide area discussed here is located in eastern Montana and western North Dakota, USA and straddles the Montana-North Dakota state line. Although detailed topographic maps of this Yellowstone River-Beaver Creek drainage divide area have been available for more than fifty years detailed map evidence has not previously been used to interpret the region’s geomorphic history. The interpretation provided here is based entirely on topographic map evidence. This Yellowstone River-Beaver Creek drainage divide area is interpreted to have been eroded during immense southeast-oriented flood events, the first of which flowed on a topographic surface at least as high as the highest points in the present-day drainage divide area. Flood erosion ended when headward erosion of the northeast-oriented Yellowstone 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 the Yellowstone River-Beaver Creek drainage divide area landform origins. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays 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 the immense meltwater 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 Yellowstone River-Beaver Creek drainage divide area landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Yellowstone River-Beaver Creek drainage divide area location map

Figure 1: Yellowstone River-Beaver Creek 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 location map for the Yellowstone River-Beaver Creek drainage divide area. The Yellowstone River flows from the figure 1 southwest corner in a northeast direction through eastern Montana to the figure 1 center top where after entering North Dakota it joins the east and southeast-oriented Missouri River. The Yellowstone-Missouri River confluence is located just north of Cartwright, North Dakota and Lake Sakakawea (figure 1 northeast corner) is a large reservoir flooding the southeast-oriented Missouri River valley.  Beaver Creek is the unnamed north and northeast-oriented Little Missouri River tributary located east of the Yellowstone River and flowing north through Wibaux, Montana and then northeast into North Dakota where it joins the Little Missouri River. The Little Missouri River in figure 1 flows north through the North Dakota badlands area and north of the Beaver Creek mouth turns east and with some jogs north and southeast flows to the Missouri River. East of the north-oriented Little Missouri River valley are southeast-oriented headwaters of east-oriented Missouri River tributaries. Essays for nearby drainage divide areas discuss Yellowstone River-Little Missouri River drainage divide evidence north of the Beaver Creek-Little Missouri River confluence and Beaver Creek drainage basin evidence and can be found under Little Missouri River on the sidebar category list. Note northwest-oriented Yellowstone River tributaries flowing from the Yellowstone River-Beaver Creek drainage divide and southeast-oriented Yellowstone River tributaries from the west. This northwest-southeast oriented drainage alignment is evidence the north-oriented Little Missouri River valley and Beaver Creek valley and northeast-oriented Yellowstone River valley captured in sequence multiple southeast-oriented flow routes such as would be found in a flood formed southeast-oriented anastomosing channel complex. Detailed maps in this essay provide additional evidence to support this interpretation. The flood water source cannot be determined from evidence presented here, although by using evidence from other essays published on this website flood waters can be traced headward to a North American ice sheet location. Rapid melting of a thick North American ice sheet, which through its weight and erosive actions created a “hole” in the North American continent and caused significant crustal warping elsewhere, would be a logical flood water source.

Detailed Yellowstone River-Beaver Creek drainage divide area location map

Figure 2: Detailed Yellowstone River-Beaver Creek drainage divide area location map. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 2 provides a more detailed location map for the Yellowstone River-Beaver Creek drainage divide area. The Yellowstone River flows northeast through Dawson County, Montana. Beaver Creek begins just south of Wibaux County, Montana and flows north through Wibaux County before turning northeast to flow through Golden Valley County, North Dakota to its confluence with the Little Missouri River near the corner shared by Golden Valley, Billings, and McKenzie Counties, North Dakota. The previously mentioned northwest-southeast oriented drainage alignment is illustrated on figure 2 especially with northwest- and southeast-oriented Yellowstone River tributaries and northwest-oriented Little Missouri River tributaries in northern Billings County. This northwest-southeast oriented drainage alignment is evidence the north-oriented Little Missouri River valley eroded headward across a southeast-oriented anastomosing channel complex to capture an immense southeast-oriented flood and to divert flood water north and east. Following headward erosion of the Little Missouri River valley the Beaver Creek valley eroded southwest and south across the same anastomosing channel complex to capture flood water and divert the flood water north and northeast along a more westerly route. Subsequently the northeast-oriented Yellowstone River valley eroded headward across the same anastomosing channel complex to capture the flood water and divert the flood water further north and northeast. Maps presented here provide evidence to support this interpretation. The maps begin at the north end of the Yellowstone River-Beaver Creek drainage divide and progress southwest and south to the Yellowstone River-Beaver Creek drainage divide south end. First is a map illustrating the Yellowstone River-Beaver Creek drainage divide in the Beaver Creek-Little Missouri confluence area. Next will be a map illustrating the drainage divide between northwest-oriented Smith Creek and Beaver Creek. Continuing south the drainage divide between northwest-oriented Cottonwood Creek and Beaver is looked at next. Still further south two maps illustrate the drainage divide in the area between west and northwest-oriented Glendive Creek and Beaver Creek. The following two maps illustrate the drainage divide between northwest-oriented Cabin Creek and Beaver Creek. The final map illustrates the south end of the Yellowstone River-Beaver Creek drainage divide where headward erosion of a Little Missouri River tributary valley has truncated it.

Yellowstone River-Beaver Creek drainage divide near Beaver Creek-Little Missouri River confluence

Figure 3: Yellowstone River-Beaver Creek drainage divide near Beaver Creek-Little Missouri River confluence. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 3 illustrates the Yellowstone River-Beaver Creek and Yellowstone River-Little Missouri River drainage divide area west of the Beaver Creek-Little Missouri River confluence. The Little Missouri River valley is located along the figure 3 east edge (center). Beaver Creek flows northeast from the figure 3 south center to join the north-oriented Little Missouri River near the common boundary of McKenzie, Golden Valley, and Billings Counties, North Dakota. The western third of the figure 3 map area is an upland surface drained primarily to the west by the northwest-oriented North and South Forks of Smith Creek. The southwest-oriented creek in the figure 3 northwest corner is a North Fork Smith Creek tributary. Smith Creek is a northwest-oriented Yellowstone River tributary. Southeast-oriented Horse Creek in the figure 3 southwest corner flows to the northeast-oriented Beaver Creek valley. Note the many southeast-oriented Little Missouri River and Beaver Creek tributaries flowing from the Yellowstone River-Little Missouri River and Yellowstone River-Beaver Creek drainage divide. Events recorded by figure 3 evidence begin with southeast-oriented flood water flowing across the entire figure 3 map area. The deep Little Missouri River and Beaver Creek valleys did not exist and flood water was flowing on a topographic surface at least as high as the highest points along the present day Yellowstone River-Little Missouri River (and Beaver Creek) drainage divide. Headward erosion of the deep north-oriented Little Missouri River valley followed by headward erosion of the deep northeast-oriented Beaver Creek captured the southeast-oriented flood flow, which began to erode multiple southeast-oriented tributary valleys headward into the newly eroded Little Missouri River-Beaver Creek west valley wall. Before the west valley wall could be deeply eroded headward erosion of the deep Yellowstone River valley beheaded  southeast-oriented flood flow to the figure 3 map area. Flood flow northwest of the newly eroded Little Missouri River-Beaver Creek west valley wall reversed flow direction and flowed northwest to the deeper and newly eroded Yellowstone River valley and in the process eroded the northwest-oriented Smith Creek drainage basin and created the present-day Yellowstone River-Little Missouri River and Beaver Creek drainage divide.

Smith Creek-Beaver Creek drainage divide area

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

Figure 4 illustrates a Yellowstone River-Beaver Creek drainage divide region southwest of the figure 3 map area and includes some overlap (see South Fork Smith Creek and Horse Creek in figure 4 northwest quadrant and figure 3 southwest area). Figure 4 evidence is similar to the figure 3 evidence. Multiple short southeast-oriented Beaver Creek tributaries have begun to erode headward into the northwest Beaver Creek wall. The upland surface northwest of the northwest Beaver Creek valley wall is drained by various streams to the figure 4 northwest corner and then to northwest-oriented Smith Creek. Southwest and then northwest-oriented C S Creek flows to northwest-oriented Smith Creek and the northeast-oriented Yellowstone River. Events recorded by the figure 4 evidence again begin with southeast-oriented flood water flowing across the entire figure 4 map region (the northeast-oriented Beaver Creek valley did not exist). Flood water was flowing on a topographic surface at least as high as the highest figure 3 map area elevations today. Next headward erosion of the deep northeast-oriented Beaver Creek valley captured the southeast-oriented flood flow and flood waters began to erode southeast-oriented tributary valleys into the newly eroded northwest Beaver Creek valley wall. However, before headward erosion of those southeast-oriented Beaver Creek tributaries could progress very far headward erosion of the deep Yellowstone River valley (northwest of figure 4) beheaded the southeast-oriented flood flow routes to the figure 4 map region. Flood waters between the newly eroded Yellowstone River valley and the Beaver Creek northwest valley wall reversed flow direction to flow northwest to the newly eroded northeast-oriented Yellowstone River valley and in the process to erode the northwest-oriented Smith Creek drainage basin and to create the present day figure 4 Yellowstone River-Beaver Creek drainage divide.

Cottonwood Creek-Beaver Creek drainage divide area

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

Figure 5 illustrates the Yellowstone River-Beaver Creek drainage divide in a region southwest of the figure 4 map area (there is overlap in the figure 5 northeast corner and figure 4 southwest corner). Note the Beaver Creek valley is becoming shallower to southwest and south. Northwest-oriented drainage in the figure 5 northwest corner is to northwest-oriented Cottonwood Creek, which flows to the northeast-oriented Yellowstone River. Northwest-oriented drainage in the figure 5 southwest corner is to northwest-oriented Box Elder Creek, which also flows to the northeast-oriented Yellowstone River. Again short southeast-oriented Beaver Creek tributaries drain the northwest Beaver Creek valley wall. Events recorded by the figure 5 evidence are similar to events recorded by the figure 3 and 4 evidence and begin with southeast-oriented flood water flowing across the entire figure 5 map area (the northeast-oriented Beaver Creek valley and drainage route did not exist). Headward erosion of the northeast-oriented Beaver Creek valley then captured the southeast-oriented flood water and diverted the flood water northeast to the deep and newly eroded Little Missouri River valley. Southeast-oriented flood water began to erode southeast-oriented Beaver Creek tributary valleys into the newly eroded northwest Beaver Creek valley wall, but before there was adequate time for that erosion to progress very far headward erosion of the deep northeast-oriented Yellowstone River valley (northwest of the figure 5 map area) beheaded the southeast-oriented flood flow that was moving across the figure 5 map area. Flood waters already between the newly eroded Yellowstone River valley and the Beaver Creek northwest valley wall rim reversed flow direction and flowed to the northwest to the deeper and newly eroded Yellowstone River valley and by doing so eroded the northwest-oriented Cottonwood Creek and Box Elder Creek drainage basins and also created the present day Yellowstone River-Beaver Creek drainage divide.

Glendive Creek-Beaver Creek drainage divide area near Wibaux

Figure 6: Glendive Creek-Beaver Creek drainage divide area near Wibaux. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 6 illustrates the Yellowstone River-Beaver Creek drainage divide region southwest of the figure 5 map area (there is no overlap). Northwest-oriented drainage in the figure 6 north center flows to northwest-oriented Box Elder Creek and the northeast-oriented Yellowstone River. The northwest-oriented stream paralleling the highway in the figure 6 northwest quadrant is Krug Creek, which is a tributary of west and northwest-oriented Glendive Creek, which flows to the northeast-oriented Yellowstone River. West-oriented Hodges Creek in the figure 6 southwest quadrant also is a west and northwest-oriented Glendive Creek tributary. The Beaver Creek valley at Wibaux is much shallower than further to the north and southeast-oriented Beaver Creek tributaries flow from the west while northwest-oriented Beaver Creek flow from the east. While Beaver Creek has not eroded a deep valley here the figure 6 evidence and events recorded by that evidence are similar to the previous figure evidence and events. Before the north-oriented Beaver Creek drainage system existed southeast-oriented flood waters flowed across the entire figure 6 map area. Headward erosion of the shallow Beaver Creek valley beheaded southeast-oriented flood flow routes and water on the northwest ends of those beheaded flood flow routes reversed flow direction to flow to the newly eroded Beaver Creek valley and in the process erode the northwest-oriented Beaver Creek tributary valleys. Almost as soon as the Beaver Creek valley eroded headward across the figure 6 map area the deep northeast-oriented Yellowstone River valley eroded headward to the northwest of the figure 6 map area and beheaded the southeast-oriented flood flow to the figure 6 map region. Flood waters between the newly eroded Beaver Creek valley and the much deeper and newly eroded Yellowstone River valley reversed flow direction to flow west and northwest to the deep Yellowstone River valley and in the process eroded the west and northwest-oriented Glendive Creek drainage basin and also created the present day Yellowstone River-Beaver drainage divide.

Glendive Creek-Beaver Creek drainage divide area south of Wibaux

Figure 7: Glendive Creek-Beaver Creek drainage divide area south of Wibaux. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 7 illustrates the Yellowstone River-Beaver Creek drainage divide region south of the figure 6 map area (there is a small strip of overlap). Note the west-facing escarpment separating the Beaver Creek drainage basin from the deeply eroded Glendive Creek drainage basin to the west. Also note well-defined through valleys linking the east and southeast-oriented Beaver Creek tributaries from the west with northwest-oriented Glendive Creek tributaries draining the west-facing escarpment face. In addition note northwest-oriented Beaver Creek tributaries from the east. Further note north-oriented Horse Creek flowing along the west-facing escarpment base to northwest-oriented Glendive Creek and  north-northeast-oriented Eastman Creek also flowing to Glendive Creek (northwest corner figure 7). Evidence shown here in figure 7 is different from evidence shown in the previous figures, however figure 7 evidence can be explained by the previously described sequence of events. The event sequence begins with southeast-oriented flood water flowing across the figure 7 map area on a topographic surface at least as high the highest present day figure 7 elevations (Beaver Creek did not exist nor did the west-facing escarpment or the deeply eroded Glendive Creek drainage basin). The next significant event was headward erosion of the north-oriented Beaver Creek valley to capture the southeast-oriented flood flow. While the valley looks shallow today it was at least as deep as the elevations of the highest buttes in the figure 7 map area and flood water erosion removed most evidence of the valley walls. Flood water on northwest ends of beheaded flood flow routes reversed flow direction to create  northwest-oriented Beaver Creek tributaries. Southeast-oriented flood water west of the west-facing escarpment was first captured by a southeast-oriented flood flow route on the Cabin Creek alignment (see figure 8, 9 and 10) which was eroding a deep valley around the south of the present-day Beaver Creek drainage basin. Headward erosion of this deep valley reached to what was then a southeast-oriented flood flow route using the present day northwest-oriented Glendive Creek alignment and began to erode a deep valley, the west wall of which is the figure 7 west-facing escarpment. Soon thereafter the northeast-oriented Yellowstone River valley eroded headward and beheaded southeast-oriented flood moving on the present day northwest-oriented Glendive Creek alignment. Flood water between the newly eroded Yellowstone River valley and Beaver Creek valley began to erode the northwest-oriented Glendive Creek drainage basin, which for a time captured significant flood flow from yet to be beheaded (by Yellowstone River valley headward erosion) flood low routes further to the southwest. Evidence of those captures is in the form of the present day north-oriented Horse Creek and north-northeast-oriented Eastman Creek, tributaries to northwest-oriented Glendive Creek. Continued headward erosion of the deep Yellowstone River valley soon beheaded all flood flow routes eroding the figure 7 region and the present day Yellowstone River-Beaver Creek drainage divide was created.

Cabin Creek-Beaver Creek drainage divide area north of Cabin Creek

Figure 8: Cabin Creek-Beaver Creek drainage divide area north of Cabin Creek. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 8 illustrates the Yellowstone River-Beaver Creek drainage divide region south of the figure 7 map area (there is no overlap and there is gap between the two figures). Beaver Creek is the north-oriented stream along the figure 8 east edge. Cabin Creek is the northwest-oriented Yellowstone River tributary flowing along the base of the southwest facing escarpment. The Yellowstone River-Beaver Creek drainage divide is located along the escarpment rim. Note several of the Beaver Creek tributaries are northeast oriented. Figure 8 events can best be understood by also looking at figure 9 and 10 evidence below. Events recorded by the figure 8 evidence again begin with southeast-oriented flood water flowing across the entire region and Beaver Creek, the escarpment, and the deeply eroded Cabin Creek drainage basin did not exist. The flood water was flowing on a topographic surface at least as high as the highest figure 8 elevations today. Headward erosion of the north-oriented Beaver Creek valley captured the southeast-oriented flood flow routes. Northeast-oriented Beaver Creek tributaries were probably initiated as routes used by some of the captured southeast-oriented flood flow to reach the actively eroding Beaver Creek valley head. Southeast-oriented flood flow on the Cabin Creek alignment was captured at what is today the south end of the Beaver Creek drainage basin (see figure 10 below) by headward erosion of a deep northeast-oriented Little Missouri River valley tributary. This capture enabled southeast-oriented flow on the Cabin Creek alignment to begin to erode a deep southeast-oriented valley west of the north-oriented Beaver Creek valley and the present day southwest-facing escarpment is the northeast wall of what was initiated as a southeast-oriented Cabin Creek valley carrying flood water to the deep north-oriented Little Missouri River valley, which had been eroding south slightly faster than the shallower Beaver Creek valley. However, headward erosion of the even deeper northeast-oriented Yellowstone River valley beheaded southeast-oriented flood flow on the Cabin Creek alignment and caused flood waters on the northwest end of that route to reverse flow direction and to erode the present day northwest-oriented Cabin Creek drainage basin and to create the present day Yellowstone River-Beaver Creek drainage divide.

Cabin Creek-Beaver Creek drainage divide area south of Cabin Creek

Figure 9: Cabin Creek-Beaver Creek drainage divide area south of Cabin Creek. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 9 illustrates the Yellowstone River-Beaver Creek drainage divide region south of the figure 8 map area (with considerable overlap). Note how the northwest-oriented Middle Fork Cabin Creek is aligned with the truncated headwaters of the northeast-oriented Fork of Beaver Creek, which flows to a northwest-oriented  Beaver Creek valley segment seen in the figure 9 northeast corner. Again the figure 9 evidence can be best understood by also looking at the figure 8 and 10 evidence. Events recorded by figure 9 evidence again begin with southeast-oriented flowing across the entire region on a topographic surface at least as high as the highest figure 9 elevations today. Headward erosion of the north-oriented Beaver Creek valley then captured southeast-oriented flood waters and eroded headward along reversed flow on one beheaded flood flow route to create the northwest-oriented Beaver Creek segment in figure 9. Southeast-oriented flood flow on what is today the northwest-oriented Cabin Creek alignment was captured by the actively eroding Beaver Creek valley and northeast-oriented Beaver Creek tributary valleys, including the truncated Fork of Beaver Creek valley, were probably initiated as the captured flood waters moved to the actively eroding Beaver Creek valley. Southeast-oriented flood flow moving on the Cabin Creek alignment was then captured by a deep northeast-oriented Little Missouri River tributary valley that had eroded around the south end of the actively eroding Beaver Creek valley head. Southeast-oriented flood flow on the Cabin Creek alignment then eroded a deep valley. However, headward erosion of the deeper Yellowstone River valley then beheaded southeast-oriented flood flow on the Cabin Creek alignment causing flood waters on that alignment to reverse flow and to flow northwest to the deeper Yellowstone River valley and in the process to erode the northwest-oriented Cabin Creek drainage basin and to create the present day Yellowstone River-Beaver Creek alignment.

Yellowstone River-Beaver Creek-Little Missouri River drainage divide area

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

Figure 10 illustrates the south end of the Beaver Creek escarpment-surrounded drainage basin. Northwest-oriented Cabin Creek is located in the figure 10 northwest corner. Northwest-oriented Pennel Creek flows to northwest-oriented O’Fallon Creek, which flows to the northeast-oriented Yellowstone River. The figure 10 southeast quadrant drains to the north-oriented Little Missouri River, which flows north in a deep valley east of the shallower north-oriented Beaver Creek valley. Most southeast and east-oriented Little Missouri River tributaries are headwaters of northeast-oriented Cannonball Creek, which after flowing southeast turns and flows northeast along the base of the southeast-facing escarpment to join the Little Missouri River. Events recorded by figure 10 evidence again begin with southeast-oriented flood water flowing across the entire region on a topographic surface at least as high as the highest present day elevations. Next the north-oriented Little Missouri River valley eroded south to capture the southeast-oriented flood water and to divert the flood water north and east. At approximately the same time the Beaver Creek valley eroded southwest and south from the newly eroded Little Missouri River valley to capture the same southeast-oriented flood flow that the Little Missouri River valley was capturing. For reasons not apparent in evidence present here the north-oriented Little Missouri River valley eroded south faster than the Beaver Creek valley and headward erosion of the deep northeast-oriented Cannonball Creek valley from the deep and actively eroding north-oriented Little Missouri River valley head captured southeast-oriented flood flow moving on the Cabin Creek alignment west of the shallower and actively eroding Beaver Creek valley head (and also captured southeast-oriented flood flow moving on the present day O’Fallon Creek-Pennel Creek route). This capture beheaded most flood flow to what is now the Beaver Creek drainage basin and a deep southeast-oriented valley eroded headward along the west side of the Beaver Creek valley. Southeast-oriented flood flow along this Cabin Creek route was beheaded by headward erosion of the even deeper northeast-oriented Yellowstone River valley, which subsequently also beheaded southeast-oriented flood flow on the O’Fallon Creek-Pennel Creek alignment. Reversed flow on the Cabin Creek and O’Fallon-Pennel Creek alignments eroded the present day northwest-oriented Yellowstone River tributary drainage basins and created the present day figure 10 Yellowstone River-Beaver Creek and Yellowstone River-Little Missouri River drainage divides.

Additional information and sources of maps studied

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