A geomorphic history based on topographic map evidence

The Missouri River-James River drainage divide area in Sully, Hyde, Hand, and Hughes Counties is located in central South Dakota. The region is bounded on the west by the south and southeast oriented Missouri River and on the east by the south-oriented James River. The James River flows on the floor of the broad south-oriented escarpment-bounded James River lowland. The lowland west boundary is the east-facing Missouri Escarpment and west of the Missouri Escarpment is the Missouri Coteau, a region of thick glacial deposits. West of the Missouri Coteau is the Missouri River valley.

The James River lowland is interpreted here to be what remains of an immense south-oriented ice-walled and bedrock-floored valley sliced into the surface of a rapidly melting thick North American ice sheet. The Missouri Coteau is interpreted here to be where the ice-walled and bedrock-floored valley’s west ice wall once stood. Valleys cut across the Missouri Escarpment and Missouri Coteau are interpreted to have been eroded when northeast-oriented ice-walled and bedrock-floored valleys eroded headward (southwest) from the lower elevation James River lowland floor to capture southeast-oriented ice marginal melt water floods and to divert those melt water floods into the deep “hole” the decaying ice sheet had once occupied.

Preface:

• The purpose of this essay is to use topographic map interpretation methods to explore Missouri River-James River drainage divide area landform origins in Sully, Hyde, Hand, and Hughes Counties, South Dakota, USA. 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 and/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 new geomorphology 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 other Missouri River drainage basin landform origins research project essays is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet 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 Missouri River-James River drainage divide area landform evidence in Sully, Hyde, Hand, and Hughes Counties, South Dakota will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm. This essay is included in the Missouri River drainage basin landform origins research project essay collection.

Missouri River-James River drainage divide area location map

Figure 1: Missouri River-James 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 location map for the Missouri River-James River drainage divide area. Figure 1 illustrates a large area in central South Dakota. The Missouri River is the large south and southeast oriented river located in the figure 1 west half, with Lake Oahe flooding the Missouri River valley north of Oahe Dam (near Pierre, South Dakota). Major Missouri River tributaries from the west (from north to south) are the Grand River, Moreau River, Cheyenne River, Bad River, and White River. Note how the Grand River, Moreau River, and Cheyenne River, after flowing east or northeast, turn to flow in a southeast direction just before joining the Missouri River. Also note the northeast-oriented Bad River joins the south-oriented Missouri River as a barbed tributary, and the Cheyenne and Moreau Rivers could also be considered barbed tributaries. The James River flows south in the figure 1 east half and flows from the figure 1 north edge (north of Aberdeen, South Dakota) to Columbia, Ashton, Huron, Mitchell, and the figure 1 south edge. The Sully, Hyde, Hand, and Hughes County area studied in this essay is located south of highway 212 which passes through Gettysburg, Faulkton, and Redfield and north of highway 34, extending from Big Thompson to Wessington Springs. Between the Missouri River and the James River is the Missouri Coteau region, which is an upland region covered by thick glacial deposits, and bounded on the east by the east-facing Missouri Escarpment. The James River flows south on the floor of a broad south-oriented escarpment-bounded lowland, where the east-facing Missouri Escarpment  is the lowland’s western boundary. The eastern boundary is the west-facing Prairie Coteau escarpment, which is illustrated and described in the James River-Big Sioux River drainage divide area south of Redfield and Watertown and north of Huron and Brookings essay (found under either James River or Big Sioux River on sidebar category list). Of special interest in this essay are large valleys crossing the Missouri Coteau area and indented into the Missouri Escarpment. One such valley is in the Faulkton area and a much larger valley is located along the route of highway 14 between Blunt, Highmore, and Miller, South Dakota. The south-oriented James River lowland is interpreted here to the floor of what was an immense south-oriented ice-walled and bedrock-floored valley sliced into the surface of a rapidly melting thick ice sheet. The Missouri Escarpment is what remains of that valley’s west wall. The valleys crossing the Missouri Coteau area and indented into the Missouri Escarpment are interpreted here to have been eroded by southeast-oriented ice marginal melt water floods, captured by headward erosion of the northeast-oriented Bad River and Cheyenne River valleys and diverted northeast and east to the lower elevation James River lowland floor.

Missouri River-James River drainage divide area detailed location map

Figure 2: Missouri River-James River drainage divide area detailed location map. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a somewhat more detailed location map for the Missouri River-James River drainage divide area discussed here. Potter, Faulk, Sully, Hyde, Hand, Spink, Hughes, Beadle, Lyman, and Jerauld are South Dakota counties and the county boundaries are indicated. This essay deals primarily with Missouri River-James River drainage divide area in Sully, Hyde, Hand, and Hughes Counties, although an area in southern Faulk County is also included. The Missouri River is located in the figure 2 west half and flows from the figure 2 north edge to the figure 2 south center edge. the James River is located in Spink and Beadle Counties near the figure 2 east edge and also flows from the figure 2 north edge to the figure 2 south edge. The red shaded area in the figure 2 northwest corner is the Cheyenne Indian Reservation. The red shaded area north of the Missouri River in the figure 2 south center is the Crow Creek Indian Reservation, while the red shaded south of the Missouri River is the Lower Brule Indian Reservation. The essay begins in western Sully County where the south-oriented Missouri River flows northwest before turning to flow southeast. The northeast-oriented Cheyenne River joins the Missouri River on the south side of that loop. Next Figure 4 shows the Missouri River valley near Pierre, South Dakota and illustrates where the Bad River joins the Missouri River as a barbed tributary. Continuing southeast along the Missouri River valley figure 5 is a map of the region where Medicine Knoll Creek enters the Missouri River in Hughes County. Medicine Knoll Creek originates in northern Hyde County and flows in a southwest direction across eastern Sully County to Blunt and Canning in Hughes County. Figure 6 shows the Medicine Knoll Creek valley upstream from Blunt. Figure 7 illustrates a Missouri Coteau remnant area and the north-facing escarpment along which the west-oriented South Fork Medicine Knoll Creek flows. Figure 8 illustrates the Missouri Escarpment and Missouri Coteau south of Faulkton (in Faulk County). Figure 9 illustrates the Missouri Escarpment and Missouri Coteau south of Miller (in Hand County). Figure 10 illustrates the large east-oriented through valley located between the Missouri Coteau upland surface segments seen in figures 7, 8 and 9. The through valley is drained to the west by Medicine Knoll Creek and its South Fork, while further east it is drained by Wolf Creek tributaries, with Wolf Creek flowing in an east and  northeast direction to join the south-oriented James River near Redfield (see figures 1 and 2).

Missouri River valley near Cheyenne River mouth

Figure 3: Missouri River valley near Cheyenne River mouth. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 illustrates the Missouri River valley near the northeast oriented Cheyenne River mouth. The Missouri River flows from the figure 3 north edge to the figure 3 south edge, although it does not flow along a direct route. It first flows from the north edge in a south-southeast direction and then turns to flow in a southwest direction before turning again to flow in a northwest direction. Then the Missouri River makes a complete U-turn to flow southeast and then south to the figure 3 south edge. The Missouri River valley in the figure 3 map area is flooded by Lake Oahe, which is a large reservoir impounded behind Oahe Dam (see figure 4 below). The flooded northeast and east oriented Cheyenne River valley enters the Missouri River valley in the figure 3 west center edge area on the south side of the Missouri River U-turn. The southwest-oriented stream in the figure 3 southeast quadrant is Okobojo Creek, which flows to the Missouri River. Many questions can be asked about figure 3 landform origins, but perhaps the most obvious is why does the Missouri River flow northwest and then make a U-turn to flow southeast? Note the Missouri River and Cheyenne River tributary valleys from the northwest. These valleys are all oriented in a northwest-southeast direction, which is the same orientation as the northwest- and southeast-oriented Missouri River valley segments. Also note Missouri River tributaries from the southeast. These are northwest-oriented tributaries, although they are much shorter than the tributaries from the northwest. These barbed northwest-oriented tributaries along with the southeast-oriented tributaries from the northwest are evidence the Missouri River valley eroded headward to capture an immense southeast-oriented flood moving across the figure 3 map area. Further evidence for the southeast-oriented flood can be seen along the Missouri River-Okobojo Creek drainage divide where multiple northwest-southeast oriented through valleys link the two southwest-oriented valleys. Figure 3 evidence suggests the southeast-oriented flood flow was moving in a large-scale southeast-oriented anastomosing channel complex, which was captured by headward erosion of the Okobojo Creek valley and then captured by headward erosion of the much deeper Missouri River valley. Northwest-oriented valley segments, including the Missouri River valley northwest-oriented valley segment, were initiated by reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow channels. In the case of the Missouri River valley it eroded headward (to the southeast) along a reversed flood flow channel before turning to erode headward in a northeast direction to capture flood waters from additional southeast-oriented flood flow channels.

Missouri River valley north of Pierre, South Dakota

Figure 4: Missouri River valley north of Pierre, South Dakota. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates the Missouri River valley south of the figure 3 map area and includes overlap areas with figure 3. The Missouri River flows south, east, southwest, and east from the figure 4 northwest corner to Oahe Dam in the figure 4 south center and then flows south to Pierre, South Dakota (located along the figure 4 south center edge). Southwest-oriented Okobojo Creek flows from the figure 4 north center edge to join the Missouri River in the figure 4 northwest quadrant. Medicine Knoll Creek can just barely be seen in the figure 4 southeast corner (see figure 5 below). Evidence for southeast-oriented flood flow dominates the region south and west of the Missouri River in the figure 4 southwest quadrant. This evidence can best be understood by looking at figure 4a below, which illustrates the northeast-oriented Bad River valley located southwest of Pierre. Note in figure 4a how the northeast-oriented Bad River valley has been eroded headward across multiple southeast-oriented flood flow channels, with present day southeast-oriented tributary valleys being eroded headward from the northeast-oriented Bad River valley along southeast-oriented flood flow routes and northwest-oriented Bad River tributary valleys being eroded by reversals of flood flow on the northwest ends of the beheaded flood flow routes. Evidence for southeast-oriented flood flow can also be seen northeast of the Missouri River in figure 4. However, in figure 4 the regions further to the northeast show evidence of a broad northeast-southwest oriented valley extending from the Warnes Slough area (in the figure 4 northeast quadrant) toward the southwest-oriented Missouri River valley segment. While additional map areas need to be seen this valley suggests there may have been a northeast-oriented flood flow route across the figure 4 map area prior to Missouri River valley headward erosion. That northeast-oriented flood flow route may have been responsible for initiating the northeast-oriented Bad River valley, which was greatly deepened when the much deeper Missouri River valley eroded northwest and north to behead and capture the northeast-oriented flood flow route. Figures 6, 9 and 10 below illustrate where flood waters in the northeast-oriented valley would have gone. As will be seen in figures below this figure 4 map area at the time flood waters were flowing across the map region was near the west and southwest margin of a rapidly melting ice sheet. The ice sheet had been located in a deep “hole” and as the ice sheet melted northeast-oriented valleys eroded headward from the “hole” to capture southeast-oriented ice marginal melt water floods and to divert flood water into the “hole”, which had once been filled by the rapidly melting ice sheet. Figures 3 and 4a provide evidence southeast-oriented floods were captured and diverted northeast and east onto the former ice sheet floor.

Figure 4a: Bad River valley southwest of Pierre, South Dakota. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Medicine Knoll Creek at the Missouri River valley

Figure 5: Medicine Knoll Creek at the Missouri River valley. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates where Medicine Knoll Creek flows to the Missouri River and is located southeast of figure 4 and includes an overlap area with figure 4. Lake Sharpe in the figure 5 southwest quadrant is located in the flooded Missouri River valley and is the reservoir impounded behind Big Bend Dam (see figure 1). Medicine Knoll Creek is the stream flowing from Canning (near the figure 5 north edge) to join the Missouri River near Rosseau in the figure 5 southwest quadrant. An unnamed barbed southwest-oriented tributary flows to the Missouri River south of the figure 5 map area near De Grey (in the figure 5 southeast quadrant). Note the north-south streamlined erosional residual located in the figure 5 center area. A close look at that erosional residual reveals northwest-southeast oriented valleys eroded across the streamlined hill. A northwest-oriented stream is shown flowing from one of those valleys. Figure 5a below provides a more detailed map of the northwest-southeast oriented through valleys. The northwest-southeast oriented through valleys provide evidence of southeast-oriented flood flow across the figure 5 map area prior to headward erosion of the Missouri River valley and the Medicine Knoll Creek valley. Headward erosion of the deep Missouri River valley  enabled the unnamed southwest-oriented tributary valley at De Grey to erode headward to capture south and southeast oriented flood flow (note southeast-oriented tributaries to that valley). As the Missouri River valley eroded headward it next enabled the Medicine Knoll Creek valley to erode headward to capture the southeast-oriented flood flow and in doing so the Medicine Knoll Creek valley beheaded southeast-oriented flood flow routes across the streamlined erosional residual. Northwest-oriented valleys were eroded by reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow channels. Elevation of the erosional residual top provides evidence that flood waters deeply eroded the region surrounding the erosional residual and that prior to Missouri River valley headward erosion the entire region was at least as high as the erosional residual top (if not higher). Figures below provide evidence regional elevations were once much higher.

Figure 5a: Streamlined erosional residual southeast of Canning, South Dakota. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Medicine Knoll Creek valley northeast of Blunt, South Dakota

Figure 6: Medicine Knoll Creek valley northeast of Blunt, South Dakota. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the Medicine Knoll Creek valley northeast of Blunt, South Dakota and is located northeast of the figure 4 map area and the northeast of figure 4 corner overlaps with the figure 6 southwest corner. Okobojo Creek is the southwest oriented stream in the figure 6 northwest corner. Onida is the town located in the figure 6 northwest quadrant and southeast of Okobojo Creek. Medicine Knoll Creek flows from the figure 6 northeast corner in a southwest, south, and southwest direction to the figure 6 south edge. Blunt is the town located near where Medicine Knoll Creek crosses the figure 6 south edge. The South Fork Medicine Knoll Creek flows west from the figure 6 southeast corner near the figure 6 south edge to join Medicine Knoll Creek near Blunt. Note how southwest oriented Medicine Knoll Creek and west-oriented South Fork Medicine Knoll Creek are draining a broad southwest and west oriented valley. Note the gradual slope from Onida to the Medicine Knoll Creek valley. Onida is approximately 30 meters higher than the erosion surface into which the Medicine Knoll Creek valley at Blunt has been eroded. Note also how this slope continues in a southwest to northeast-oriented direction diagonally across the figure 6 map area. Figure 6a below illustrates the region immediately south of the west-oriented South Fork Medicine Creek valley. In figure 6a Blunt is located near the west center edge. The South Fork Medicine Knoll Creek flows west through Harrold Township to join southwest and south oriented Medicine Knoll Creek  near Blunt. South of the South Fork Medicine Knoll Creek (in the figure 6a southeast quadrant) is a slope leading up to an upland surface in the figure 6a southeast corner. Note the presence of several small lakes on that upland surface. The upland surface is a Missouri Coteau remnant, which the broad Medicine Knoll Creek valley has separated from Missouri Coteau segments further to the north. The Missouri Coteau upland surface is a region covered with thick glacial deposits and is characterized by many small interior drainage basins. Figures 7, 8, and 9 illustrate additional Missouri Coteau regions and how the Medicine Knoll Creek drainage basin is related to those segments.

Figure 6a: Missouri Coteau upland surface south of South Fork Medicine Knoll Creek. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Missouri Coteau south of South Fork Medicine Knoll Creek

Figure 7: Missouri Coteau south of South Fork Medicine Knoll Creek. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Missouri Coteau south of the South Fork Medicine Knoll Creek and is located east of the figure 6a map area. Highmore is the town located near the figure 7 north center edge. The South Fork Medicine Knoll Creek originates in the figure 7 northeast quadrant and flows in a west-northwest direction to the figure 7 west edge (northwest corner area). South of the South Fork Medicine Knoll Creek is a north-facing slope leading up to the Missouri Coteau upland surface located in the figure 7 south half. Elevations at higher points on the Missouri Coteau upland surface are approximately 100 meters higher than elevations in the figure 7 northeast corner. Note how west-oriented South Fork Medicine Knoll Creek originates on the north-oriented slope leading into a deeper east oriented valley. More of that deeper east oriented valley, which is so large the reduced sized topographic maps at this scale cannot show it, is illustrated in figures 9 and 10 below. Figure 8 below shows a Missouri Coteau area north of this large east oriented valley and also evidence of another east-oriented through valley cut across the Missouri Coteau area. What are these large east-oriented through valleys and how did they form? To understand the valleys first think of a thick North American ice sheet located in a deep “hole”. The ice sheet was probably comparable in thickness to the present day Antarctic Ice Sheet and probably had “roots” that extended 1000-2000 meters below the topographic surface upon which the ice sheet had formed. The deep “hole” in which the ice sheet was located had been formed by crustal warping caused by the ice sheet weight and also by deep glacial erosion of the underlying bedrock. The Canadian Shield area is where glacial erosion was greatest, and this area in central South Dakota was on the southwest “hole” margin. At the peak of its development the ice sheet probably stood 2000 or more meters higher than the surface upon which it had formed. When the ice sheet started melting faster than new ice was being formed for a long time melt water floods flowed off the ice sheet surface and then southeast along the ice sheet margin until flood waters found routes south to the Gulf of Mexico. In time ice sheet melting progressed to the point that areas on the ice sheet surface were being lower in elevation than ice margin areas where southeast-oriented ice marginal melt water flows were moving. Generally the lower elevation ice sheet surface areas developed first along the ice sheet’s southern margin, such as this region in South Dakota. The lower elevation ice surface elevations developed as immense south-oriented ice-walled and bedrock-floored valleys were sliced into the decaying ice sheet surface. One such south-oriented ice-walled and bedrock-floored valley was located where the south-oriented James River lowland in South Dakota is located today. The east-facing Missouri Escarpment and the west-facing Prairie Coteau escarpment are what remain of the valley’s ice walls. The Missouri Coteau and Prairie Coteau upland surfaces are where the ice walls melted and deposited whatever debris they contained. Because the James River lowland ice-walled and bedrock-floored valley’s floor was significantly lower in elevation than area west and southwest of the ice margin, east- and northeast-oriented ice-walled and bedrock-floored valleys eroded headward to capture southeast-oriented ice marginal melt water floods. The large east-oriented valley seen here in figure 7 was one of those valleys and probably eroded west and southwest along the present day Bad and Cheyenne River alignments.

Missouri Coteau remnant southwest of Faulkton, South Dakota

Figure 8: Missouri Coteau remnant southwest of Faulkton, South Dakota. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the north wall of the large east oriented valley, another Missouri Coteau remnant, and another east oriented valley carved into the Missouri Coteau upland surface. There is no overlap with previous figures, although there is overlap with figure 10 below. Faulkton is the town located in the figure 8 north center area and Fauklkton is located in Faulk County. The west-to-east oriented Faulk County southern boundary is located in the northern section of the figure 8 south half. Hyde County is located near the figure 8 west edge, although most of the area south of the Faulk County line is located in Hand County. The figure 8 east half is located in the James River lowland area. The south-oriented James River is located east of the figure 8 map area and is not seen. The east facing escarpment south of Faulkton is the Missouri Escarpment and is what remains of the immense south-oriented James River lowland ice-walled and bedrock-floored valley’s west wall. The south-southeast facing escarpment in the figure 8 southwest quadrant is the north wall of the east-oriented valley seen in figures 6 and 7. The north-oriented escarpment in the figure 8 west center area is the south wall of another east-oriented valley leading to the James River lowland. The lake covered upland surface bounded by these escarpments is a Missouri Coteau upland surface remnant. As already described the south-oriented James River lowland originated as an immense south-oriented ice-walled and bedrock-floored valley sliced into the surface of a rapidly melting thick ice sheet. The east-oriented valleys on either side of the Missouri Coteau upland surface originated as east- and northeast-oriented ice-walled and bedrock-floored valleys which eroded headward to capture southeast-oriented ice marginal melt water floods and to divert the water northeast and east onto the lower elevation James River lowland floor. The Missouri Coteau upland surface remnant is where a detached ice sheet remnant was located between the ice-walled and bedrock-floored valleys. That ice sheet remnant subsequently melted and deposited whatever debris it contained. Melt water floods removed some, but not all, of the ice sheet contained debris from the floors and walls of the ice-walled and bedrock-floored valleys, although flood water deposition occurred on the valley floors as well. Figure 8 evidence suggests the James River lowland floor was lowered by south-oriented flood waters following erosion (and probably abandonment of the east-oriented valleys). If so, floods continued to move south in the James River lowland ice-walled and bedrock-floored valley after headward erosion of the Missouri River valley.

Missouri Coteau remnant southwest of Miller, South Dakota

Figure 9: Missouri Coteau remnant southwest of Miller, South Dakota. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Missouri Coteau remnant southwest of Miller, South Dakota and south of the figure 8 map area. Note the north-south Hyde County-Hand County boundary in the figure 9 west half. Highmore is the town located near the figure 9 west center edge and the figure 9 southwest quadrant shows in less detail some of the same area seen in figure 7 above. Miller is the town located in the figure 9 east center. Ree Heights is the town located between Miller and Highmore. Southwest of Miller and occupying much the figure 9 southwest quadrant is a Missouri Coteau upland surface remnant. Note how this Missouri Coteau remnant is bounded on the north by a north-facing escarpment and on the east by an east-facing escarpment. The east-facing escarpment is the Missouri Escarpment, which is the James River lowland western boundary. The north-facing escarpment is the south wall of the east-oriented valley, the north wall of which was seen in the figure 8 southwest quadrant. West-oriented South Fork Medicine Knoll Creek flows along the north facing escarpment base to the figure 9 west edge (just south of Highmore). Between the valley’s north facing south wall and the south-facing north wall there is a large east-oriented valley, in which there is no evidence of Missouri Coteau type landscape. Figure 10 below illustrates the large valley located between the south and north-facing walls. As previously described the south-oriented James River lowland originated as an ice-walled and bedrock-floored valley sliced by south-oriented melt water floods into a rapidly melting ice sheet surface. The east-oriented valley originated as a large east-oriented ice-walled and bedrock-floored valley sliced into the ice sheet’s southwest margin by ice marginal floods flowing from the higher elevation ice sheet margin areas to lower elevations on the former ice sheet floor. The Missouri Coteau upland surface remnant is where a detached ice sheet remnant remained after headward erosion of the large ice-walled and bedrock-floored valleys. The ice sheet remnant subsequently melted and deposited whatever debris it contained. Melt water floods removed much of the ice sheet contained debris from the adjacent valley areas, although probably some flood deposited debris can be found. Figure 9 evidence suggests the valley may have been eroded by northeast-oriented flood flow, although further east the James River lowland appears to have been eroded by south-oriented flood flow. The east-oriented valley was eroded prior to headward erosion of the deep Missouri River valley and it is possible that prior to that time flood waters flowed north in the James River lowland to reach the newly reversed flow in the what is today the Red River valley. The Red River valley along the North Dakota-Minnesota border originated as a large south-oriented ice-walled and bedrock-floored valley and was reversed to flow north when it was beheaded by east-oriented flood flow routes to the Great Lakes area. Another explanation for present day northeast-oriented drainage from this valley area flowing to the south-oriented James River is a large south-oriented melt water flood in the James River lowland ice-walled and bedrock-floored valley spilled to the southwest when headward erosion of deep Missouri River valley beheaded and reversed the northeast-and east-oriented flood flow in this valley. The southwest-oriented drainage was then reversed by headward erosion of a deeper James River valley.

Medicine Knoll Creek-Wolf Creek drainage divide area

Figure 10: Medicine Knoll Creek-Wolf Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 illustrates the Medicine Knoll Creek-Wolf Creek drainage divide area located north of the figure 9 map area and south of the figure 8 map area and includes overlap areas with both figures 8 and 9. The Hyde County-Hand County border is marked along the figure 10 south center edge. Medicine Knoll Creek originates in the figure 10 north center and flows southwest, south, and southwest to the figure 10 southwest corner. The South Fork Medicine Knoll Creek is located just south of the figure 10 south edge and flows west from the Hyde County-Hand County border area to join Medicine Knoll Creek southwest of the figure 10 map area. East of the west and southwest oriented Medicine Knoll Creek drainage basin is a large east-oriented valley, which is a shallow V-shaped abandoned headcut eroded by east-oriented flood water flowing from southwest of the ice sheet southwest margin into the James River lowland. Today this broad valley is a through valley linking the Missouri River drainage basin to the west with the James River drainage basin to the east. The through valley provides evidence that large volumes of water once flowed northeast and east in this valley from areas west and southwest of the present day Missouri River valley to the lower elevation James River lowland floor. Evidence seen in earlier figures demonstrated northeast-oriented valleys southwest of where the ice sheet southwest margin was located captured southeast-oriented flood waters and diverted the flood flow in a northeast and east direction through this valley. Headward erosion of the deep Missouri River valley then beheaded and captured the northeast-oriented flood flow. Northeast and east oriented flood waters on the beheaded flood flow route then reversed flow direction to flow west and southwest to the newly eroded and deeper Missouri River valley. This reversed flood flow was responsible for creating the present day southwest-oriented Medicine Knoll Creek drainage route and also the west-oriented South Fork Medicine Knoll Creek drainage route. Flood waters further east in the valley continued to move east and eroded the shallow V-shaped headcut seen today. Areas within the V-shaped headcut enclosure do not appear to have a well-integrated drainage pattern in figure 10, although they are part of the northeast-oriented Wolf Creek drainage basin, which drains to the southeast-oriented James River near Redfield (see figure 2).

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.