Abstract:

Introduction:

• The purpose of this essay is to use topographic map interpretation methods to explore Wyoming and South Dakota northeast-oriented southeast-oriented Belle Fourche 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 northeast-oriented southeast-oriented Belle Fourche River drainage divide area landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Northeast-oriented southeast-oriented Belle Fourche River drainage divide area location map

Figure 1: Northeast-oriented southeast-oriented Belle Fourche 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 general location map for the northeast-oriented southeast-oriented Bell Fourche River drainage divide area. South Dakota is the state located in the figure 1 east half. Montana is the state located in the figure 1 northwest quadrant and Wyoming is the state located in the figure 1 southwest quadrant. The Belle Fourche River begins near Wright, Wyoming and flows northeast almost to the Montana border and then makes a sharp turn to the southeast and flows southeast along the Black Hills northeast flank before turning east to join the northeast-oriented Cheyenne River. The Belle Fourche River-Belle Fourche River drainage divide area discussed here is located north and west of the northeast-oriented Redwater River (unnamed in figure 1), which flows from the Sundance, Wyoming area to join the southeast-oriented Belle Fourche River near Belle Fourche, South Dakota. West of the northeast-oriented Belle Fourche River is the northeast-oriented Little Missouri River and the north and northeast-oriented Powder River. Other essays address evidence along Wyoming’s Little Missouri-Belle Fourche River drainage divide, along the Little Missouri River-Belle Fourche River drainage divide north of the Belle Fourche River elbow of capture, and the Powder River-Belle Fourche River drainage divide, and along drainage divides further west and northwest. These other essays can be found under appropriate river or region names on the sidebar category list. North of the southeast-oriented Belle Fourche River is the southeast and east-northeast oriented Moreau River. Moreau River drainage basin essays can be found under Moreau River on the sidebar category list. This essay interprets northeast-oriented southeast-oriented Belle Fourche River drainage divide evidence in the context of an immense southeast-oriented flood that flowed over the entire figure 1 map area and was systematically captured by headward erosion of deep east- and northeast-oriented valleys and diverted further and further to the northeast and north. The source of the southeast-oriented flood water cannot be determined from evidence presented here. However, based on collective evidence from numerous other Missouri River drainage basin landform origins research project essays (published on this website) flood waters can be traced headward to a North American ice sheet location and it can be demonstrated the floods occurred before and/or while the Black Hills area was being uplifted. Rapid melting of a thick North American ice sheet located in a deep “hole” would explain the flood water source and also why deep valleys eroded west and southwest to capture southeast-oriented flood waters and diverted the flood water further and further northeast and north into space in the deep “hole” the rapidly melting ice sheet once occupied. In addition, presence of a thick North American ice sheet in a deep “hole” north and east of the Black Hills might explain crustal warping that uplifted the Black Hills during an immense southeast-oriented flood. Uplift of the Black Hills may have been accelerated by crustal unloading as flood waters deeply eroded the region and removed overlying sedimentary layers.

Northeast-oriented southeast-oriented Belle Fourche River drainage divide area detailed location map

Figure 2: Northeast-oriented southeast-oriented Belle Fourche River drainage divide area detailed location map. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 2 provides a detailed location map for the northeast-oriented southeast-oriented Belle Fourche River drainage divide. The northeast-oriented Belle Fourche River flows from the figure 2 southwest corner in Crook County, Wyoming almost to the Montana border and then turns southeast to flow to Belle Fourche, South Dakota and then east to Fruitdale, South Dakota. Redwater River headwaters originate in the Bear Lodge Mountains and flow east and northeast and north to join the southeast-oriented Belle Fourche River near Belle Fourche, South Dakota. Sundance Creek, a Redwater River tributary, originates near Sundance, Wyoming and flows northeast to join the Redwater River. Between the northeast-oriented Belle Fourche River and the southeast-oriented Belle Fourche are the north-south oriented Bear Lodge Mountains, which form the drainage divide between the northeast-oriented and southeast-oriented Belle Fourche River. West of the Bear Lodge Mountains northeast-oriented Belle Fourche River tributaries tend to be northwest-oriented with Beaver Creek, Blacktail Creek, Lytle Creek, and Miller Creek being examples. East of the Bear Lodge Mountains tributaries to the southeast-oriented Belle Fourche River are southeast-oriented, although they turn east and even northeast to join the southeast-oriented Belle Fourche River. Further south is the northeast-oriented Redwater River drainage basin, although northern Redwater River tributaries from the Bear Lodge Mountain area are east-oriented. East and southeast-oriented valleys were eroded headward into the Bear Lodge area along southeast-oriented flood flow routes. Northwest-oriented tributary valleys were initiated by reversed flood flow on northwest ends of beheaded southeast-oriented flood flow routes. Deep northeast-oriented valleys eroded headward across multiple southeast-oriented flood flow channels, such as might be found in an anastomosing channel complex. Detailed maps begin at the Belle Fourche River elbow of capture in the north and proceed south along the northeast-oriented Belle Fourche River-Beaver Creek drainage divide before looking at the Beaver Creek-southeast-oriented Belle Fourche River drainage divide in the Bear Lodge Mountains.

Northeast-oriented southeast-oriented Belle Fourche River elbow of capture area

Figure 3: Northeast-oriented southeast-oriented Belle Fourche River elbow of capture area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 3 illustrates the Belle Fourche River elbow of capture area, which is also the north end of the northeast-oriented southeast-oriented Belle Fourche River drainage divide. The northeast-oriented Belle Fourche River flows from the figure 3 south edge (southwest quadrant) to the figure 3 north center just south of Stoneville Flats and then turns southeast to flow to the figure 3 southeast quadrant and south edge. The northeast-oriented Little Missouri River can be seen in the figure 3 northwest corner. Stoneville Flats is a large northwest-southeast oriented through valley linking the northeast-oriented Little Missouri River valley with the Belle Fourche River elbow of capture. Today Stoneville Flats is drained by northwest-oriented Arkansas Creek, which originates in the intermittent lakes located next to the Belle Fourche River elbow of capture. This evidence suggests water once flowed north in the Stoneville Flats valley, probably from the northeast-oriented Belle Fourche River valley to the northeast-oriented Little Missouri River valley. However, at the same time water must also have been flowing southeast along the present day southeast-oriented Belle Fourche River valley, otherwise the southeast-oriented Belle Fourche River valley would not have been able to capture all flow in the northeast-oriented Belle Fourche River valley. In other words, the best explanation for the Stoneville Flats valley evidence is so much water was moving northeast in the northeast-oriented Belle Fourche River valley the water was able to spill both northwest (probably reverse flow along a former southeast-oriented flood flow channel) into the northeast-oriented Little Missouri River valley and also southeast along the Black Hills northeast flank. The drainage divide between the northeast-oriented and southeast-oriented Belle Fourche provides excellent evidence of southeast-oriented flood flow. Tributaries to the southeast-oriented Belle Fourche River are southeast-oriented. Trouble Creek, Bear Gulch, and Gumbo Creek are examples. They were eroded headward along southeast-oriented flood flow routes. Tributaries to the northeast-oriented Belle Fourche River are northwest-oriented. Ripley Creek and Sand Draw are examples. They were eroded by reversals of flood flow on the northwest ends of flood flow routes beheaded by headward erosion of the deep northeast-oriented Belle Fourche River valley. The multiple tributaries are evidence of multiple flood flow routes or channels, such as would be expected in a flood formed anastomosing channel complex.

Northeast-oriented southeast-oriented Belle Fourche River drainage divide area north of Oak Creek

Figure 4: Northeast-oriented southeast-oriented Belle Fourche River drainage divide area north of Oak Creek. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 4 illustrates the northeast-oriented southeast-oriented Belle Fourche River drainage divide area south of the figure 3 map area and includes overlap areas with figure 3. The northeast-oriented Belle Fourche River is located in figure 4 northwest corner and the southeast-oriented Belle Fourche River is located in the figure 4 northeast corner. Beaver Creek is a north and northwest-oriented Belle Fourche River tributary located in the figure 4 southwest corner. Tributaries to the northeast-oriented Belle Fourche River are northwest-oriented and include Arnold Creek, East Creek, and Beaver Creek and Beaverdam Creek and Spring Creek, which are Beaver Creek tributaries. In figure 4 north most tributaries to the southeast-oriented Belle Fourche River start out as southeast-oriented or have southeast-oriented segments and include Gumbo Creek, Deep Creek, Pine Creek, Alum Creek headwaters ,and Oak Creek, although many of these tributaries turn northeast before joining the southeast-oriented Belle Fourche River. In figure 4 the Bear Lodge Mountain top appears smooth, however in more detailed topographic maps there are ups and downs created by water erosion from multiple flow channels that once flowed across what is now the mountain top. Shallow valleys link headwaters of northwest-oriented tributaries to the northeast-oriented Belle Fourche River with headwaters of tributaries to the southeast-oriented Belle Fourche River and are evidence that at least the northeast-oriented Belle Fourche River valley was eroded into a topographic surface as high as the Bear Lodge Mountain top (the mountain top is about 400 meters higher than the Belle Fourche valley in the figure 4 northeast corner and 300 meters higher than the Belle Fourche River valley in the figure 4 northwest corner). The deep east-oriented tributary valleys to the southeast-oriented Belle Fourche River had to be eroded prior to headward erosion of the deep northeast-oriented Belle Fourche River valley. Headward erosion of the deep northeast-oriented Belle Fourche River valley then beheaded the southeast-oriented flood flow routes responsible for eroding those deep east-oriented tributary valleys. Flood flow on the northwest ends of the beheaded flood flow routes reversed flow direction to flow northwest into the newly eroded deep northeast-oriented Belle Fourche River valley. By reversing flow direction the flood water initiated erosion of northwest-oriented Belle Fourche River tributary valleys and also created the northeast-oriented southeast-oriented Belle Fourche River drainage divide.

Belle Fourche River-Beaver Creek drainage divide area east of Hulett, Wyoming

Figure 5: Belle Fourche River-Beaver Creek drainage divide area east of Hulett, Wyoming. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 5 illustrates the region south of the figure 4 map area and includes overlap areas with figure 4. Hulett, Wyoming is the town located on the northeast-oriented Belle Fourche River in the figure 5 west center. East of Hulett on the highway is the town of Alya, which is located where northwest and north oriented Lame Jones Creek joins northwest, north and northwest oriented Beaver Creek. Northwest-oriented Blacktail Creek flows from the figure 5 south edge to join the Belle Fourche River near Hulett. North-northwest oriented Whitetail Creek is located in the figure 5 southwest corner just west of Blacktail Creek. Belle Fourche River tributaries in this figure 5 map area are predominantly northwest oriented and some have eroded significant northwest oriented valleys. The northwest-oriented valleys were eroded by reversals of flood flow on the northwest ends of beheaded flood flow routes as the deep Belle Fourche River valley eroded headward into the figure 5 map region. Frequently the reversed flood flow captured flood waters from yet to be beheaded flood flow routes further to the south. These flood water captures often provided large amounts of additional water, which helped erode the northwest-oriented valleys. Evidence of such captures of yet to be beheaded southeast-oriented flood flow is often reflected in the present day drainage pattern. For example in the figure 5 south center north and northeast-oriented Slaybaugh Creek flows to northwest- and north-oriented Lame Jones Creek. A northeast-oriented Slaybaugh Creek tributary is linked by a through valley to a southwest-oriented Blacktail Creek tributary. What has happened (and in several other similar situations located in figure 5) is reversed flood water on the Beaver Creek alignment captured southeast-oriented flood water on the yet to be beheaded Blacktail Creek alignment and the captured flood water helped erode the Beaver Creek valley, the Lame Jones Creek valley, and the through valley linking Blacktail Creek and Lame Jones Creek. In fact, the captured flood water may have begun to erode a southeast-oriented valley headward along the Blacktail Creek alignment before headward erosion of the much deeper northeast-oriented Belle Fourche River captured the flow.

Belle Fourche River-Blacktail Creek drainage divide area east of Devils Tower

Figure 6 illustrates the region south and west of the figure 5 map area and includes overlap areas with figure 5. The northeast-oriented Belle Fourche River flows past Devils Tower located along the figure 6 west center edge. Northwest-oriented Lytle Creek flows from the figure southeast quadrant to join the Belle Fourche River near Devils Tower. Northwest-oriented Blacktail Creek flows to the figure 6 north center edge. North-northwest oriented Whitetail Creek is located between Blacktail Creek and the Belle Fourche River. Northwest-oriented Beaver Creek is located in the figure 6 northeast corner and east of figure 6 it flows north just east of Taylor Divide (see figure 6 east center edge area). Northwest-oriented Miller Creek is located in the figure 6 southwest corner. The northwest-oriented tributary valleys to the northeast-oriented Belle Fourche River valley originated with reversals of flood flow on the northwest ends of beheaded flood flow routes. As previously mentioned these flow reversals often captured flood waters from yet to be beheaded flood flow further to the south. Figure 6 illustrates locations of a number of such captures. For example, in the figure 6 southeast corner is northeast-oriented Togus Creek, which flows to the north and northwest-oriented Beaver Creek. Just to the north is Ellsbury Divide. Note the through valley that connects Togus Creek with headwaters of northwest-oriented Blacktail Creek. Yet to be beheaded flood flow on the present day Blacktail Creek alignment was captured by headward erosion of the north and northwest-oriented Beaver Creek valley and diverted north and northwest to what was then the actively eroding deep northeast-oriented Belle Fourche River valley head. West of Ellsbury Divide is north-oriented Hersey Creek, which flows to northwest-oriented Blacktail Creek. Note how a southwest-northeast oriented through valley just southeast of Sherrard Hill links the Hersey Creek valley with the northwest-oriented Lytle Creek valley to the southwest. Reversed flood flow on the Blacktail Creek alignment captured yet to be beheaded flood flow on the Lytle Creek alignment and the captured flood water was diverted northeast, north and then northwest on the Blacktail Creek route to what was then the actively eroding deep northeast-oriented Belle Fourche River valley head.

Belle Fourche River-Redwater River drainage divide area west of Sundance, Wyoming

Figure 7: Belle Fourche River-Redwater River drainage divide area west of Sundance, Wyoming. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 7 illustrates the region south of the figure 6 map area and includes overlap areas with figure 6 and has been reduced to show a larger area. Northwest-oriented Miller Creek flows to join the north oriented Belle Fourche River near Carlile Junction in the figure 7 northwest corner. Northwest-oriented Inyan Kara Creek joins the Belle Fourche River in the figure 7 west center edge area and northwest-oriented Arch Creek flows to the Belle Fourche River in the figure 7 southwest corner. Northwest-oriented Lytle Creek headwaters are located just north of the word “BLACK” in the figure 7 east center and east-oriented headwaters of north oriented Beaver Creek are located just east of the Lytle Creek headwaters, with through valleys linking the two drainage basins. Yet to be beheaded southeast-oriented flow on the Lytle Creek alignment was captured by headward erosion of the north and northwest-oriented Beaver Creek valley with the captured flood waters diverted north and northwest to what was then the actively eroding deep northeast-oriented Belle Fourche River valley head. Through valleys also link southwest-oriented Miller Creek tributary valleys with the northwest-oriented Lytle Creek valley, suggesting reversed flow on what is today the northwest-oriented Lytle Creek route captured yet to be beheaded flood flow on the Miller Creek alignment. However, the Miller Creek valley appears to have also been used by flood waters moving east to the Sundance area and then northeast along the northeast-oriented Sundance Creek valley route to the southeast-oriented Belle Fourche River. After headward erosion of the deep northeast-oriented Belle Fourche River beheaded southeast-oriented flood flow on the Miller Creek route the flow reversal captured yet to be beheaded flood flow on the Inyan Kara Creek route and that captured flood water was moving north using what are today the routes of south-oriented Inyan Kara tributaries (flowing to the figure 7 south edge), with increasing amounts of the captured flood waters moving northeast to erode the large northeast-oriented Sundance Creek valley. When Belle Fourche River valley headward erosion beheaded southeast-oriented flood flow on the Inyan Kara Creek alignment there was a major reversal of flood flow in the Sundance, Wyoming area, which created south-oriented Inyan Kara Creek tributaries from what had been north-oriented flood flow routes to the northeast-oriented Sundance Creek valley.

Inyan Kara Creek-Redwater River drainage divide at Sundance, Wyoming

Figure 8 illustrates the region south of the figure 7 map area and includes overlap areas with figure 7. Northwest-oriented Inyan Kara Creek is located in the figure 8 southwest corner. Northeast-oriented Sundance Creek originates near Sundance, Wyoming and flows through Sundance to the figure 8 northeast corner and then northeast to join the northeast-oriented Redwater River. Note how Beaver Creek originates as a northwest-oriented stream in the Black Flats area (figure 8 southeast corner) and then turns west and south to join northwest-oriented Inyan Kara Creek, which flows to the northeast-oriented southeast-oriented Belle Fourche River, which flows to the northeast-oriented Cheyenne River, etc. Southeast of the Black Flats area (and southeast of the figure 8 map area) are headwaters of Inyan Kara Creek, which like Beaver Creek flow northwest, east, and then south before turning northwest to join the Belle Fourche River. The Inyan Kara Creek headwaters are linked with headwaters of a north-oriented Redwater River tributary valley (north-northeast-oriented Cold Springs Creek). Reversed flow on what is today the northwest-oriented Inyan Kara Creek valley alignment resulted in a massive reversal of flood flow in the Sundance region. Prior to that reversal the flood waters had been moving southeast into the region and then northeast along the Sundance Creek and Inyan Kara Creek-Cold Springs Creek routes to the southeast-oriented Belle Fourche River. I have left out many drainage history complications recorded by landform evidence in this Sundance region. For example, the south-oriented Benton Creek valley eroded headward to capture southeast-oriented flood flow to the Black Flats area. That southeast-oriented flood flow may have been moving on what is today the northwest-oriented Inyan Kara Creek valley, then north on what is today the south-oriented Houston Creek valley, then east on what is today the west-oriented Houston Creek route, and then southeast to the Black Flats area and beyond to flow southeast on what is today a northwest-oriented Inyan Kara Creek valley segment and then north-northeast on a Cold Springs Creek-Sand Creek-Redwater River route to the southeast-oriented Belle Fourche River. Almost certainly this complicated southeast-oriented flood flow route was just one of many in what must have been an ever-changing and evolving southeast-oriented anastomosing channel complex.

Redwater River drainage basin northeast of Sundance, Wyoming

Figure 9 illustrates the region east of the figure 7 map area and northeast of the figure 8 map area and includes overlap areas with figure 7 and 8. Beaver Creek flows north in the figure 9 northwest corner to eventually reach the northeast oriented Belle Fourche River. Just east of north oriented Beaver Creek are northeast oriented headwaters of the Redwater River, which then turn east before turning northeast near Beulah, Wyoming to flow north of the figure 9 north center edge before turning southeast to flow to the figure 9 northeast corner, where the Redwater River turns northeast again. Sundance Creek flows northeast from Sundance, Wyoming to join the northeast oriented Redwater River in the figure 9 northeast corner near Beulah. Joining the Redwater River in the figure 9 northeast corner is northwest and north-northeast oriented Sand Creek, which flows to the northeast oriented Redwater River. Flowing to north-northeast oriented Sand Creek is north-northeast Cold Springs Creek, which flows in the deep valley labeled “Grand Canyon”.  Tributaries to the north-northeast oriented Grand Canyon-Sand Creek valley from the east are predominately northwest oriented. An interesting tributary from the west is northeast and east-oriented Red Canyon. Red Canyon headwaters are both northeast-oriented and northwest-oriented. Cold Spring Creek headwaters south of the figure 8 and 9 map areas are linked by through valleys to northwest-oriented Inyan Kara Creek headwaters, indicating the deep Grand Canyon here was eroded by southeast-oriented flood moving on the Inyan Kara valley route (partially illustrated in figure 8) and then north-northeast on the Cold Spring Creek-Sand Creek route to the northeast-oriented Redwater River, which flows to the southeast-oriented Belle Fourche River. Headward erosion of the deep northeast-oriented Belle Fourche River valley captured southeast -oriented flood flow moving to the southeast-oriented Inyan Kara Creek valley route. Prior to erosion of what must have been the deeply eroded southeast-oriented Inyan Kara Creek-Redwater River anastomosing channel complex southeast-oriented flood waters flowed on a topographic surface corresponding with the present day Bear Lodge Mountain elevations and flood waters moved directly across what are today the Bear Lodge Mountains. Headward erosion of deep valleys around the Bear Lodge Mountains and other resistant rock masses was responsible for producing present day landscape features.

Beaver Creek-Redwater River drainage divide in the Bear Lodge Mountains

Figure 10: Beaver Creek-Redwater River drainage divide in the Bear Lodge Mountains. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 10 illustrates the region north of the figure 9 map area and west and south of the figure 5 map area and the figure 5 southeast corner slightly overlaps the figure 10 northwest corner. North, northeast, and northwest-oriented Beaver Creek, flowing to the northeast-oriented Belle Fourche River, is located in figure 10 northwest corner. Beaver Creek tributaries from the east are northwest-oriented and are linked by a complicated pattern of shallow through valleys with southeast and east oriented North Redwater River headwaters. The highway along the figure 10 north edge makes use a through valley, which links the northwest-oriented Beaver Creek valley in the figure 10 northwest corner with the east-southeast oriented and northeast oriented South Fork of Hay Creek, which flows to the southeast-oriented Belle Fourche River. Similar shallow through valleys link northwest-oriented Little Beaver Creek with the southeast-oriented North and South Forks of North Redwater River and other northwest-oriented Beaver Creek tributaries with southeast-oriented North Redwater River headwaters to the south. Evidence illustrated in this essay describes a deep east-oriented valley system trying to erode west to capture southeast-oriented flood flow through what is now the northeast-oriented southeast-oriented Belle Fourche River drainage divide area. At that time flood waters were flowing on a topographic surface at least as high as the present day Bear Lodge Mountain highest elevations. Headward erosion of the deep east-oriented valleys on the east- and southeast-oriented Redwater Creek, Hay Creek and Oak Creek routes (further north) encountered the Bear Lodge resistant rock mass and erosion slowed significantly, while a deep southeast-oriented tributary valley to the north (the present day southeast-oriented Belle Fourche River valley) and a deep northeast-oriented to the south did not encounter resistant rock masses and were able erode headward rapidly. The deep northeast-oriented Belle Fourche River valley eroded southwest and south from the deep and successful southeast-oriented valley (the southeast-oriented Belle Fourche River valley)  and was able to behead southeast-oriented flood flow moving to what had been the successful northeast-oriented valley (the north oriented Inyan Kara Creek-northeast-oriented Sundance Creek route). While these deep valleys were being actively eroded the entire region was probably covered by an ever-changing anastomosing complex of flood flow channels. Flood flow across what is now the northeast-oriented southeast-oriented Belle Fourche River drainage divide area did not completely end probably until headward erosion of the deep northeast-oriented Little Missouri River valley and the deep north- and northeast-oriented Powder River valley further to west captured all southeast-oriented flood flow.

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.