South Fork Grand River-Moreau River drainage divide area landform origins, northwest South Dakota, USA

· Moreau River, SD Grand River, South Dakota
Authors

A geomorphic history based on topographic map evidence

Abstract

The South Fork Grand River-Moreau River drainage divide area is located in northwest South Dakota, USA. Although detailed topographic maps of the South Fork Grand River-Moreau 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 South Fork Grand River-Moreau River drainage divide area is interpreted to have been eroded during immense southeast-oriented flood events, the first of which flowed on a topographic surface at least as high as the highest points in the present-day drainage divide area. Flood erosion ended when headward erosion of the east and northeast-oriented South Fork Grand 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 South Fork Grand River-Moreau 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 essay 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 South Fork Grand River-Moreau River drainage divide area landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

South Fork Grand River-Moreau River drainage divide area location map

Figure 1: South Fork Grand River-Moreau 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.

The east-oriented South Fork Grand River drainage basin is located in northwest South Dakota and is immediately north of the east-oriented Moreau River drainage basin. Both the Grand River and the Moreau River flow today to the south-oriented Missouri River. North of the Grand River drainage basin is North Dakota’s east-oriented Cannonball River drainage basin and south of the Moreau River drainage basin is the east-oriented Belle Fourche-Cheyenne River drainage basin. West of these east-oriented drainage basins is the north-oriented Little Missouri River drainage basin. Other essays discuss the Little Missouri River-South Fork Grand River drainage divide area, the Little Missouri River-Moreau River drainage divide area, and the North Fork-South Fork Grand River drainage divide area and can be found under appropriate river names on the sidebar category list.  Evidence presented in those and other essays published on this website establishes a case for immense southeast-oriented floods that moved across the region and that were captured by headward erosion of deep east-oriented headcuts as the present-day drainage system valley complex eroded headward. This essay looks at evidence for the southeast-oriented floods (and also for capture of those floodwaters by headward erosion of an east-oriented valley system) along the South Fork Grand River-Moreau River drainage divide. Evidence presented here is not adequate to determine the flood water source, although the flood waters can be traced headward to a North American ice sheet location. Rapid melting of a large North American ice sheet would be a logical flood water source.

Detailed South Fork Grand River-Moreau River drainage divide location map

Figure 2: Detailed South Fork Grand River-Moreau River drainage divide location map. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 2 provides a more detailed South Fork Grand River-Moreau River drainage divide area location map. The Moreau River drainage basin is generally located south of the east to west oriented highway that serves as a north-south dividing line in figure 2 with the east and northeast-oriented South Fork Grand River drainage basin being primarily located to the north of that highway, although in the west of figure 2 northeast-oriented South Fork Grand River headwaters and some tributaries begin south of the highway. This essay illustrates and discusses South Fork Grand River-Moreau River drainage divide evidence beginning in the west and  proceeding east along the drainage divide. The discussion will begin with evidence in the East Short Pine Hills area, which is the green Custer National Forest area in southwest Harding County immediately south of the place-name labeled Lone Mountain. The essay next looks at evidence west of the Slim Buttes upland, which is the north-south (with a southeast extension) green Custer National Forest area in the figure 2 center. Continuing west, evidence will be illustrated in the Slim Buttes upland area where the southeast-oriented Rabbit Creek headwaters are located. The essay then illustrates and discusses evidence along the South Fork Grand River drainage divide east of Slim Buttes including in the Prairie City and Bison, South Dakota areas.

South Fork Grand-Moreau River drainage divide in East Short Pine Hills area

Figure 3: South Fork Grand River-Moreau River drainage divide in East Short Pine Hills areaUnited States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 3 illustrates the South Fork Grand River-Moreau River drainage divide west end where it is truncated by the north-oriented Little Missouri River drainage basin. The northeast-oriented South Fork Grand River  headwaters can be seen in the figure 3 northwest corner and northeast-oriented streams, including Clarks Fork Creek all flow to the South Fork Grand River. The southeast-oriented North Fork Moreau River can be seen in the figure 3 south center. In the figure 3 west center is a small area of a topographic surface drained to the northwest, or to the north-oriented Little Missouri River. The northeast-facing Jumpoff escarpment seen in figure 3 is the southern segment of a much more extensive Jumpoff escarpment that today partially encircles a large east-oriented escarpment-surrounded basin or abandoned headcut, which was eroded headward by southeast-oriented floodwaters prior to Little Missouri River valley headward erosion capture of those flood waters. The Little Missouri River-South Fork Grand River drainage divide essay provides additional illustrations and discussion of the Jumpoff escarpment-surrounded basin or abandoned headcut. Events shaping the landscape we see today began with southeast-oriented flood waters flowing across what is today the Jumpoff escarpment-surrounded basin into what is today the Moreau River drainage basin prior to being captured by east-oriented South Fork Grand River valley headward erosion and were eroding the deep Moreau River valley system (especially the North Fork Moreau River valley) northwest or headward into a topographic surface at least as high as the surface defined by the present day East Short Pine Hills upper surface. Headward erosion of the large and deep east-oriented South Fork Grand River valley (or Jumpoff escarpment-surrounded basin) next eroded west and was capturing southeast-oriented flood flow to the southeast-oriented Moreau River headwaters when the deep Little Missouri River valley eroded south into the region and captured the southeast-oriented floodwaters and diverted the water north. The present-day landscape features have remained largely unchanged since that capture event occurred.

South Fork Grand-Moreau River drainage divide west of Slim Buttes

Figure 4: South Fork Grand River-Moreau River drainage divide west of Slim Buttes. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 4 illustrates the area just east of the figure 3 map area and west of the Slim Buttes upland. Clarks Fork Creek can be seen flowing northeast across the figure 4 northwest corner. Southeast-oriented drainage routes in the figure 4 south half flow to the North Fork Moreau River which is located just south of the figure 4 map area. East and West Squaw Creeks join just north of the figure 4 map area and then join Clarks Fork Creek, which north of Slim Buttes joins the east-oriented South Fork Grand River. Southeast-oriented North Fork Moreau River tributaries are beheaded relics of southeast-oriented flood flow routes prior to their beheading by headward erosion of north and northeast oriented South Fork Grand River tributary valleys and the capture of all flood flow moving across the region by subsequent headward erosion of the north-oriented Little Missouri River valley. These valleys were eroded as large headcuts and were probably being eroded into a topographic surface at least as high as the present-day Slim Buttes upland upper surface, although evidence to support the claim must be seen by looking at how the Slim Buttes upland surface has been eroded. In other words, the large headcuts eroded headward along an ever-changing anastomosing complex of flood formed channels and with the exceptions of isolated buttes and uplands lowered the regional topographic surface from a level at least as high as the tops of the highest regional buttes and uplands we see today to the present day topographic surface. Note northwest-oriented tributaries to the northeast-oriented East Squaw, West Squaw, and Clarks Fork Creeks. These northwest-oriented tributaries are also relics of the southeast-oriented flood flow routes that once crossed the region. When those southeast-oriented flood flow routes were beheaded during capture events, flood waters already on the northwest ends of beheaded flood flow routes reversed flow direction to flow to the newly formed and deeper valleys that had captured the flood flow. These flow reversals produced the northwest-oriented tributaries we see today.

South Fork Grand-Moreau River drainage divide in Reva Gap area

Figure 5: South Fork Grand-Moreau River drainage divide in Reva Gap area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Continuing east along the South Fork Grand River-Moreau River drainage divide we next come to the Slim Buttes area. Southeast-oriented drainage east of the Slim Buttes upland flows to southeast-oriented Rabbit Creek, which flows to the east oriented Moreau River. Northwest and west-oriented drainage west of the Slim Buttes upland flows to the east and northeast-oriented South Fork Grand River, which flows east just north of the Slim Buttes upland and the figure 5 map area. North and northeast-oriented drainage along the figure 5 north center and northeast edge flows to the east-oriented South Fork Grand River. Reva Gap is the prominent wind gap or through valley eroded across the Slim Buttes upland and is located where the east-west highway crosses the Slim Buttes upland mass. Note the presence of several other northwest to southeast oriented through valleys in the Reva Gap area. Also note how northwest-oriented South Fork Grand River tributaries and southeast-oriented Rabbit Creek-Moreau River tributaries originate at those through valleys. Then note how southeast oriented Gap Creek has southeast-oriented tributaries originating at the north end of the Slim Buttes upland. All of this evidence indicates the southeast-oriented flood waters responsible for eroding this region originally flowed on a topographic surface at least as high as the present-day highest elevations in the Slim Buttes upland. Flood waters moving southeast across this region first eroded a large southeast-oriented Rabbit Creek valley northwest from what was then probably the newly eroded east-oriented Moreau River valley. Apparently the Slim Buttes upland mass is composed of more resistant rock than the bedrock material that surrounded it so the Rabbit Creek valley headward erosion was partially halted when it reached the Slim Buttes bedrock mass. However, the southeast-oriented flood flow was able to erode several deep northwest-southeast oriented valleys in the Reva Gap area before it was beheaded by headward erosion of the deep and  large South Fork Grand River valley, which was eroding west just to the north of the Slim Buttes upland bedrock mass. Because the large and deep South Fork Grand River valley did not encounter the resistant Slim Buttes bedrock mass, it was able to erode west and southwest faster than the somewhat shallower Rabbit Creek valley was able to erode northwest. As a result the deeper South Fork Grand River valley was able to behead and capture southeast-oriented flood flow routes responsible for eroding the southeast-oriented Rabbit Creek valley system northwest. Flood flow on the northwest ends of the beheaded southeast-oriented flood flow routes reversed direction and captured yet to be beheaded southeast-oriented flood flow moving into the region and in the process eroded northwest, north, and northeast-oriented valleys west of the Slim Buttes upland, which accounts for the lower topographic surface west of Slim Buttes than east of Slim Buttes. All southeast-oriented flood flow to the South Fork Grand River ceased when the Little Missouri River valley eroded south and captured and diverted the flood waters to the north.

South Fork Grand-Moreau River drainage divide east of Slim Buttes

Figure 6: South Fork Grand-Moreau River drainage divide east of Slim Buttes. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 6 illustrates the South Fork Grand River drainage divide east of the figure 5 map area and overlaps the figure 5 map area. Southeast-oriented drainage in the figure 6 southwest quadrant flows to southeast-oriented Rabbit Creek and the east-oriented Moreau River. The east-oriented South Fork Grand River can be seen flowing across the figure 6 north edge. White Hill Creek can be seen in the north center of figure 6 flowing northeast and then northwest to reach the South Fork Grand River. The topographic surface present in the figure 6 southeast quadrant is drained by headwaters of the southeast-oriented Thunder Butte Creek, which flows to the east-oriented Moreau River. Note how the southeast-oriented Rabbit Creek tributary channels are interconnected by dry valleys suggesting they were once part of a southeast-oriented anastomosing channel complex. This evidence suggests the southeast-oriented Rabbit Creek valley eroded northwest not as a single deep valley, but as a series of valleys associated with an anastomosing complex of channels. Note also the dry valley, or through valley, connecting  southeast-oriented Rabbit Creek tributary valleys with east-oriented Thunder Butte Creek headwaters. This evidence suggests headward erosion of the Rabbit Creek valleys beheaded southeast-oriented flood flow going to what is now the Thunder Butte Creek route (probably the anastomosing channel complex once included both the Thunder Butte Creek and Rabbit Creek drainage basins and subsequently deeper erosion in the western Rabbit Creek drainage basin beheaded flow to the Thunder Butte Creek drainage basin). Further, note White Hill Creek and the northeast-oriented tributary valley to South Fork Grand River and the multiple southeast-oriented and northwest-oriented tributaries to that valley in the northeast figure 6 quadrant. The southeast-oriented and northwest-oriented tributaries and valley segments are relics of  southeast-oriented flood flow routes that once crossed the region and that were beheaded when the deep South Fork Grand River valley eroded west into the region. Flood flow on the northwest ends of beheaded southeast-oriented flood flow routes reversed flow direction to flow into the newly carved South Fork Grand River valley. Reversed flow on northwest-oriented tributaries was augmented by capture of southeast-oriented flood flow on yet to be beheaded southeast-oriented flood flow routes further west. The northeast-oriented through valley connecting the southeast-oriented Rabbit Creek tributary valleys with Thunder Butte Creek headwaters was used by southeast-oriented flood flow captured by reversed flow further east. Headward erosion of the deep South Fork Grand River valley subsequently captured all southeast-oriented flood flow and the figure 6 landscape has changed little since.

South Fork Grand-Moreau River drainage divide in Prairie City area

Figure 7: South Fork Grand-Moreau River drainage divide in Prairie City area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Proceeding east along the South Fork Grand River-Moreau River drainage divide figure 7 illustrates the area east of Prairie City (with some overlap of the figure 6 map area). A southeast oriented South Fork Grand River segment can be seen in the figure 7 northeast corner. South Branch Thunder Butte Creek headwaters begin in the Prairie City area. The South Branch Thunder Butte Creek flows in an easterly direction across the upland topographic surface in the figure 7 center before joining southeast oriented Thunder Butte Creek and flowing in southeast direction to reach the east oriented Moreau River (not shown in figure 7). The south-oriented slope south of the upland topographic surface, upon which the South Branch Thunder Butte Creek originates and flows, drains to the southeast oriented Rabbit Creek and east oriented Moreau River. Tributaries to the northeast-oriented South Fork Grand River tributary located in the figure 7 northwest quadrant have already been noted and discussed, however at least one of the South Fork Grand River tributaries on the northeast-facing valley wall in the northeast figure 7 quadrant merits attention. Snake Creek, which crosses the north to south oriented highway, has southeast, east, north, northwest, and northeast-oriented segments and also has southeast oriented tributaries. The southeast and northwest oriented segments are relics of southeast-oriented flood flow routes that flowed across the region when the deep South Fork Grand River valley eroded west. Flood erosion events recorded in the figure 7 landscape began with a deep and broad Thunder Butte Creek valley eroding northwest from the newly eroded Moreau River valley (into a topographic surface at least as high as the present day Slim Buttes highest elevations) along southeast-oriented flood flow routes responsible for eroding the upland topographic surface now drained by Thunder Butte Creek. At about the same time the large and deep Rabbit Creek valley eroded northwest from the newly eroded Moreau River valley along southeast-oriented flood flow routes further to the west (and that were flowing over what is today the Slim Buttes upland). The Rabbit Creek valley was able to erode slightly deeper than the Thunder Butte Creek valley, perhaps because headward erosion of the deep South Fork Grand River valley beheaded southeast-oriented flood flow to the Thunder Creek drainage basin first. In any case, headward erosion of the deep east and northeast-oriented South Fork Grand River valley captured all of southeast-oriented flood waters flowing across the figure 7 region and the Thunder Butte Creek and Rabbit Creek drainage basin landscapes have changed little since.

South Fork Grand-Moreau drainage divide in the Bison area

Figure 8: South Fork Grand-Moreau drainage divide in the Bison area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 8 completes the journey east along the South Fork Grand River-Moreau River drainage divide. The South Fork Grand River is located along the figure 8 north edge and northeast of figure 8 turns northeast to flow to its confluence with the southeast and east-oriented North Fork Grand River. Downstream from that confluence area the combined river is the east-oriented Grand River. A separate essay illustrates and discusses Grand River-Moreau River drainage divide area landforms downstream from this point. The southwest-oriented slope in the figure 8 southwest corner drains to southeast-oriented Rabbit Creek and the east-oriented Moreau River. Most of the upland topographic surface extending in a northwest to southeast direction across the figure 8 map area is drained by southeast-oriented Thunder Butte Creek, which also flows to the east-oriented Moreau River. The north-facing South Fork Grand River south valley wall is drained by multiple northwest and north-oriented tributaries. The northwest-oriented tributaries and northwest-oriented tributary valley segments are relics of southeast-oriented flood flow routes that were beheaded when the deep South Fork Grand River valley eroded southwest and west. Reversals of flow on the northwest ends of the beheaded flood flow routes augmented by flood flow from yet to be beheaded southeast-oriented flood flow routes further to the west were responsible for eroding northwest-oriented tributary valleys we see today. A good example of how reversed flow on a beheaded flood flow route captured flood flow from yet to be beheaded southeast-oriented flood flow routes can be seen along the figure 7 east edge. Northeast-oriented Hart Creek has several southeast-oriented tributaries and flows to the northwest-oriented Butcher Creek valley. Southeast-oriented flood flow along the Butcher Creek valley route was beheaded first and flood flow already on the northwest end of that flood flow route reversed direction to flow northwest into the newly eroded South Fork Grand River valley. The reversed flow captured southeast-oriented flood flow still moving on yet to be beheaded flood flow routes represented by southeast-oriented Hart Creek tributaries seen in figure 7. When those flood flow routes were beheaded, floodwaters already on the northwest ends of those flood flow routes also reversed direction and flowed northwest into the newly eroded valley and eroded the northwest-oriented tributary valleys, and the Hart Creek-Butcher Creek drainage system has changed little since.

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.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: