A geomorphic history based on topographic map evidence

The Little Missouri River-South Fork Grand River drainage divide area is located in northwest South Dakota, USA. Although detailed topographic maps of the Little Missouri-South Fork Grand 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. Based on the topographic map evidence the Little Missouri-South Fork Grand River drainage divide area is interpreted to have been eroded during immense 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 north and northeast-oriented Little Missouri River valley captured the 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 Little Missouri River-South Fork Grand 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 Little Missouri River-South Fork Grand River drainage divide area landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Little Missouri-South Fork Grand River drainage divide location

Figure 1: South Fork Grand River and Little Missouri-South Fork Grand River drainage divide location map (select and click on maps to enlarge). United States Geological Survey map digitally presented using National Geographic Society TOPO software.

The east-oriented South Fork Grand River drainage basin is located in Harding and Perkins Counties of northwest South Dakota. Immediately to the west is north-oriented Little Missouri River drainage. To the north is the North Fork Grand River drainage basin and to the south is the Moreau River drainage basin. The North and South Forks Grand River join at Shadehill Reservoir to form the east-oriented Grand River, which flows to the south-oriented Missouri River (not shown in figure 1). Major South Fork Grand River tributaries from the north are southeast-oriented. Tributaries from the south vary with northeast-oriented tributaries prevailing in the west and northwest-oriented tributaries further east. The Little Missouri-South Fork Grand River drainage divide is also the Little Missouri River-Missouri River drainage divide and as such is an asymmetric drainage divide. The Little Missouri River flows north in what we will discover is a shallow valley very close to the its drainage divide with the South Fork Grand River. The asymmetric drainage divide and northwest-southeast orientation of tributaries observable in figure 1 provides strong evidence the Little Missouri River valley was eroded headward across a series of southeast-oriented flood flow channels, beheading flood flow that had been moving to the South Fork Grand River drainage basin. Also the evidence suggests the Little Missouri River valley eroded headward across a southeast-oriented anastomosing channel complex that eroded the entire Figure 1 map region. Evidence of the asymmetric divide and the northwest-southeast drainage alignment is easily visible in figure 1, although evidence on the detailed maps is even more impressive. Note on figure 1 how some South Fork Grand River tributaries begin at almost the same place where some North Fork Grand River tributaries begin. This evidence suggests the South and North Fork Grand River drainage system evolved when immense deep headcuts eroded headward as part of an east-oriented (and further east northeast-east-oriented) anastomosing channel complex that was capturing flood flow that had been eroding a higher-level complex of southeast-oriented anastomosing channels. This essay will proceed south along the Little Missouri-South Fork Grand River drainage divide beginning in the north and proceeding south.

Little Missouri River-Bull Creek drainage divide

Figure 2: Little Missouri River-Bull Creek drainage divide. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Bull Creek is a major southeast-oriented South Fork Grand River tributary beginning at the Little Missouri River-South Fork Grand River drainage divide and also the North Fork Grand River drainage divide near Table Mountain. The Little Missouri River-North Fork Grand River drainage divide essay (found under either Little Missouri River or SD Grand River on sidebar category list) describes the Little Missouri River-North Fork Grand River drainage divide and also North Fork-South Fork drainage divide evidence in the Table Mountain area. Figure 2 illustrates the very narrow strip that serves as the eastern Little Missouri River drainage area, where Little Missouri River tributaries generally have a northwest orientation. These northwest-oriented Little Missouri River tributaries are linked by shallow through valleys with the southeast-oriented Bull Creek tributaries. This evidence suggests the Bull Creek drainage basin eroded headward to capture flood flow moving on multiple southeast-oriented flow routes until the Little Missouri River valley eroded headward to systematically behead the southeast-oriented flow and to create the present-day Little Missouri River-Bull Creek drainage divide. The map evidence also suggests that prior to its capture by the Little Missouri River the route now occupied by northwest-oriented Arnett Creek tributaries and southeast-oriented Bull Creek was a major southeast-oriented flood flow route. The northwest-oriented Little Missouri River tributary valleys were eroded by reversals of flood flow that occurred after southeast-oriented flood flow had been captured further up flood by headward erosion of the north-oriented Little Missouri River valley headcut.

Devils Half Acre area

Figure 3: Detail map of the Devils Half Acre area (see figures 2 and 4 for location). United States Geological Survey map digitally presented using National Geographic Society TOPO software.

The Devils Half Acre area is located along the Little Missouri River-South Fork Grand River drainage divide. Note how the drainage divide is the rim of an escarpment separating the Little Missouri River drainage basin on the upper and smoother topographic surface shown in the west half of figure 3 from the South Bull Creek drainage basin on the rougher lower topographic surface shown in the east half of figure 3. South Bull Creek drains the area east of the drainage divide to Bull Creek and the South Fork Grand River and headwaters of northwest-oriented Middle Creek tributaries drain the area west of the divide to the north-oriented Little Missouri River. Figure 3 shows how the South Bull Creek drainage basin eroded headward along southeast-oriented flood flow to create what is today an abandoned headcut or escarpment-surrounded basin. Note how flood erosion has streamlined many of the smaller hills in a northwest-southeast direction. These streamlined residuals are further evidence for an immense southeast-oriented flood. Also note the through valleys linking the two drainage basins.

Kimble Creek area showing aligned drainage

Figure 4: Kimble Creek area showing aligned drainage. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

One remarkable landform feature observable along this stretch of the Little Missouri River-South Fork Grand River drainage divide is the northwest-southeast alignment of Little Missouri River and South Fork Grand River tributaries. Note how most Little Missouri River tributaries flow southeast to reach a north-oriented river. The exception in the northwest corner of figure 4 is Shaw Creek, which flows northeast to enter the north-oriented Little Missouri River. However, visible Shaw Creek tributaries flow southeast to enter northeast-oriented Shaw Creek. Little Missouri River tributaries from the west are all northwest-oriented and are linked by through valleys with southeast-oriented South Fork Grand River tributaries. This northwest-southeast oriented drainage alignment is evidence of southeast-oriented flood flow that flowed across the entire figure 4 region prior to headward erosion of the shallow north-oriented Little Missouri River valley. The northwest-oriented Little Missouri River tributaries, such as Kimble Creek, were formed by reversals of flood flow on beheaded southeast-oriented flood flow routes. These reversals of flood flow were responsible for eroding the present-day northwest-oriented tributary valleys. Note the shallow north-south through valley connecting the headwaters of Middle Creek, Kimble Creek, and Dry House Creek (and extending further north and south). This north-south through valley was eroded as a north-oriented flood flow route when first (in the described sequence) Middle Creek was beheaded and flow reversed to go northwest to the deeper and newly eroded north-oriented Little Missouri River valley, the reversed flow route captured flood flow that was still moving southeast along the Kimble Creek and Dry House Creek routes. As headward erosion of the Little Missouri River valley continued south it next beheaded southeast flow on the Kimble Creek route, and subsequently  reversal of flow on that route captured flood flow still moving southeast along the Dry House Creek route.

North End of the Jumpoff escarpment

Figure 5: North end of the Jumpoff escarpment. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Perhaps the most remarkable landform feature along the Little Missouri River-South Fork Grand River drainage divide is a large escarpment-surrounded basin known as the Jumpoff escarpment. The Jumpoff escarpment rim is today the Little Missouri-South Fork Grand River drainage divide. The Jumpoff escarpment-surrounded basin is just one of many such large flood-eroded escarpment-surrounded basins that can be observed throughout the Great Plains and Rocky Mountain regions. The Jumpoff escarpment-surrounded basin was formed as a giant headcut eroded headward along immense flood that was responsible for stripping away bedrock layers to produce the western South Fork Grand River drainage basin landscape. Erosion of this giant headcut or escarpment-surrounded basin ceased when headward erosion of the Little Missouri River valley captured the flood waters and diverted the floodwaters to the north. Note how the southeast-oriented South Fork Grand River tributaries are flowing across a basin floor that is lower in elevation than the elevation of the Little Missouri River valley to the west. Also note the northwest orientation of the Little Missouri River tributaries and how indentations in the Jumpoff escarpment rim are through valleys connecting the Little Missouri River and the South Fork Grand River drainage basins. Before moving further south let us briefly look at a detailed map of the Brush Creek headwaters to see further evidence of the southeast-oriented flood.

Detailed map of Brush Creek headwaters area

Figure 6: Detailed map of the Brush Creek headwaters area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Brush Creek headwaters begin in a smaller escarpment-surrounded basin (or abandoned headcut) which has been eroded into the larger Jumpoff escarpment-surrounded basin (or abandoned headcut). What is today the Brush Creek escarpment-surrounded basin was probably eroded deeper into the larger Jumpoff escarpment-surrounded because it was eroded headward along a route of more intense southeast-oriented flood flow. Note the northwest-southeast oriented streamlined erosional residuals and the locations of the through valleys crossing the Jumpoff escarpment and connecting the present-day Little Missouri River and South Fork Grand River drainage basins. The fact there is a streamlined hill (or erosional remnant) immediately upstream from the head of the Brush Creek escarpment-surrounded basin and the through valleys connecting the Little Missouri River and South Fork Grand River drainage basins are not at the head of the Brush Creek escarpment-surrounded provides evidence of the amount of flood erosion that occurred following Little Missouri River capture of southeast-oriented flood flow moving along the modern-day Gallup Creek route (see figures 4 and 5). Following that capture flood waters along that route reversed direction to flow northwest to the newly eroded Little Missouri River valley. For a time southeast-oriented flood waters that had not yet been captured may have continued to flow east into the smaller escarpment-surrounded basin by use of the through valley seem in the west center of figure 6 and some of that water may have captured to move north and northwest by reversed flow moving on the Gallup Creek routes that carved the through valley just north of the word Jumpoff in figure 6. This process of systematic capture and flow reversal was probably responsible for systematically eroding other west and northwest-oriented through valleys across the Jumpoff rim.

The Jumpoff central basin

Figure 7: The Jumpoff central basin. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Jumpoff escarpment surrounded basin central basin and its relationship to the Brush Creek escarpment-surrounded basin segment shown in figures 5 and 6. Note how north of the Jumpoff central basin South Fork Grand River tributaries are flowing in a southeast direction and how tributaries from the southern half of the Jumpoff escarpment-surrounded basin are flowing in a northeast direction. The reason for this drainage pattern is because the southwest-northeast oriented Jumpoff escarpment may have been formed as the face of an immense headcut that was eroding northwest along a southeast-oriented flood route and the northwest-southeast oriented Jumpoff escarpment may have been eroded southwest as southeast-oriented floodwaters spilled northeast into the broad valley being formed as the southwest-northeast oriented Jumpoff headcut face eroded northwest. Active erosion of the Jumpoff escarpment ceased when headward erosion of the Little Missouri River valley beheaded and captured the southeast-oriented flood flow.

Detailed map of Pine Springs Creek headwaters area

Figure 8: Detailed map of Pine Springs Creek headwaters area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

The Pine Springs Creek headwaters area illustrates the same landform features observed in the Brush Creek headwaters area. A southeast-oriented Pine Springs Creek tributary begins in a small escarpment-surrounded basin eroded into the face of the larger Jumpoff escarpment-surrounded basin. This smaller basin was probably eroded by more intense southeast-oriented flood flow along that route. Also present are streamlined hills or erosional residuals and through valleys linking the Little Missouri River drainage basin with the South Fork Grand River drainage basin. The north-oriented through valley in the north center of figure 8 probably was used by southeast-oriented floodwaters still entering the southern half of the Jumpoff escarpment-surrounded that was being captured by a reversal of flow on the Antelope Creek route (see figure 7) after headward erosion of the north-oriented Little Missouri River valley headcut face beheaded and captured southeast-oriented flow on that route. Apparently the Little Missouri River valley headcut face eroded south rapidly enough that the reversed flow, while significant for a short period of time, did reach far enough east and did not continue long enough for the Little Missouri River to capture much of an eastern drainage basin.

The Jumpoff escarpment south end

Figure 9: The Jumpoff south section. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the southeast-northwest Jumpoff escarpment face at the south end of the Jumpoff escarpment. The upland in the southwest corner of figure 9 is the West Short Pine Hills (figure 11 shows the East Short Pine Hills and its relationship to the Jumpoff escarpment). The Little Missouri River flows in a northeast direction through Camp Crook in the northwest corner of figure 9. Note northwest-oriented Valley Creek that flows to the Little Missouri at Camp Crook and how it parallels the southeast-northwest oriented Jumpoff escarpment segment. When headward erosion of the north-oriented Little Missouri River valley headcut face had beheaded and captured southeast-oriented flood flow responsible for eroding the southwest-northeast orient Jumpoff escarpment face, floodwater moving on more southerly routes had not yet been beheaded and captured. For a short time the northernmost of those remaining southeast flood flow routes was through the Camp Crook area and southeast along the Valley Creek-Brush Creek route to the North Fork Moreau River (figure 11). Floodwaters from this continuing southeast-oriented flow route eroded a northwest-southeast oriented valley and some floodwaters spilled northeast over the southwest wall of the Jumpoff escarpment surrounded basin. This northeast-oriented spillage of southeast-oriented flood flow continued briefly until the Little Missouri River valley headcut face eroded south to behead and capture southeast-oriented flood flow on the Valley Creek-Brush Creek-North Fork Moreau River route. Once beheaded there was a reversal of flow on the northwest end of the Antelope Creek-Brush Creek-North Fork Moreau River flow route, with flood waters in the Valley Creek valley segment and the valley occupied by its tributary Brush Creek flowing northwest to create the Little Missouri River-North Fork Moreau River drainage divide.

Detailed map of South Fork Grand River headwaters

Figure 10: Detailed map of South Fork Grand River headwaters. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 is a detailed map of where the South Fork Grand River originates as a northeast-oriented stream at the base of the Jumpoff escarpment. Note the sharp contrast between landscape features on the topographic surface southwest of the Jumpoff and landscape features on the northeast of the Jumpoff escarpment.  Note especially the streamlined residuals or northwest-southeast oriented hills on the upper topographic surface southwest of the Jumpoff escarpment. These were streamlined by southeast-oriented flood flow moving to the North Fork Moreau River (observable in figure 11). Also note the southwest-oriented Valley Creek tributary beginning at the Jumpoff escarpment crest in the center of figure 10. That southwest-oriented tributary represents a reversal of flow on what had been a northeast-oriented flow route created when southeast-oriented flow to the North Fork Moreau spilled over the Jumpoff escarpment face. That spillage eroded the smaller escarpment-surrounded basin that forms an indentation into the northwest-southeast oriented Jumpoff escarpment segment. Apparently the spillage did not last long enough, or did not involve enough water, to carve a deeper valley. Erosion of the Jumpoff escarpment ceased when the Little Missouri River valley headcut eroded south of the Camp Crook area and the reversed flow floodwaters had drained from the region.

Little Missouri River-South Fork Grand River-North Fork Moreau River drainage divide

Figure 11. The Little Missouri River-South Fork Grand River-North Fork Moreau River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 11 illustrates the Little Missouri River-South Fork Grand River-North Fork Moreau River drainage divide area. The high area in the southwest corner of figure 11 is the West Short Pine Hills. The South Fork Grand River drainage is northeast of the Jumpoff escarpment and can be recognized by its northeast-oriented drainage. The North Fork Moreau River drainage basin is east of the East Short Pine Hills and south of a southeast extension of the Jumpoff escarpment and can be recognized by its southeast-oriented drainage. The Little Missouri River drainage basin is southwest of the Jumpoff escarpment and west of the East Short Pine Hills and can be recognized by its north and northwest-oriented drainage and smoother landscape texture. The north and northwest-oriented drainage in the Little Missouri River drainage basin area was formed by a reversal of flood flow when headward erosion of the north-oriented Little Missouri valley headcut beheaded and captured southeast-oriented flood flow that had been moving to the North Fork Moreau River. Some southeast-oriented flood flow moved southeast between the Jumpoff and the East Short Pine Hills and eroded the North Fork Moreau River and Chalk Butte Draw headcuts (better observed in figure 12). Erosion ceased and the Little Missouri River-North Fork Moreau River drainage divide was created when headward erosion of the Little Missouri River valley headcut beheaded and captured the southeast-oriented flood flow in the Camp Crook area. Prior to that time flood waters also moved south between the East Short Pine Hills and the West Short Pine Hills to a North Fork Moreau River tributary just south of the figure 11 map area. Erosion of that north-south valley between the East and West Short Pine Hills suggests flood erosion of the region began on a topographic surface at least as high as the tops of the present-day East and West Short Pine Hills.

Detailed map of the Little Missouri River-South Fork Grand River-North Fork Moreau River drainage divide

Figure 12: Detailed map of the Little Missouri River-South Fork Grand River-North Fork Moreau River drainage divide. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 12 provides a detailed map of Little Missouri River-South Fork Grand River-North Fork Moreau River drainage divide illustrated in the figure 11 map. The Buffalo Creek drainage basin (northeast corner) drains to the South Fork Grand River. The North Fork Moreau River drains the area between the East Short Pine Hills and the Jumpoff, while the Little Missouri River drainage is located on the upland surface in the northwest figure 12 area. Note how Buffalo Creek headwaters begin by flowing southeast and then turn northeast to flow to the South Fork Grand River. These seemingly insignificant elbows of capture provide evidence the Buffalo Creek valley headcut eroded southwest to capture southeast-oriented flood water moving to the North Fork Moreau River drainage basin. Note how headward erosion of the North Fork Moreau River drainage divide did not capture flood flow from the Buffalo Creek headcut basin, which was capturing flow to the North Fork Moreau River. Instead the North Fork Moreau headcut eroded headward just to the southwest of the Buffalo Creek headcut rim, leaving what is today the ridge labelled “The Jumpoff” in figure 12.

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 the detailed 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 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.