Abstract:

Introduction:

• The purpose of this essay is to use topographic map interpretation methods to explore Little Muddy River-White Earth River drainage divide area landform origins in northwest North 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 essay 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 Little Muddy River-White Earth River drainage divide area landform evidence 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.

Little Muddy River-White Earth River drainage divide area location map

Figure 1: Little Muddy River-White Earth 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 Little Muddy River-White Earth River drainage divide area location map. The Canada-United States border is shown. Saskatchewan is the Canadian province north of the international boundary. Montana is the state in the western third of figure 1 and North Dakota is located in the eastern two-thirds of the United States area. The northeast oriented South Saskatchewan River is located north of the figure 1 map area. The Missouri River flows east from Wolf Point across northeast Montana to North Dakota. Lake Sakakawea is a large reservoir flooding the Missouri River valley. The northeast oriented Yellowstone River joins the Missouri River near the Montana-North Dakota border. West of the northeast oriented Yellowstone River is the northeast- and north-oriented Redwater River, which joins the east-oriented Missouri River near Poplar, Montana. Southeast of the Yellowstone River is the unnamed (in figure 1) Little Missouri River, which flows north to the Theodore Roosevelt National Park (North Unit) area and then flows east to the Missouri River. The Little Muddy River originates south of Wildrose, North Dakota and flows west to near Zahl, North Dakota, where the Little Muddy River turns to flow south to join the Missouri River at  Williston, North Dakota. The White Earth River is located east of the Little Muddy River and as shown in figure 1 flows south through White Earth to the Missouri River. This essay uses greatly reduced topographic maps to illustrate how these two rivers are related to the Missouri Coteau and Missouri Escarpment, which are two prominent landforms not illustrated in figure 1, but which are shown in detailed topographic maps below. The Missouri Coteau briefly is a region of hummocky topography located between the Missouri River and the southeast-oriented Souris River to the northeast, and which extends diagonally across figure 1 from the northwest to the southeast. Missouri Coteau area drainage is often to local depressions or small lakes, although southwest areas of the Missouri Coteau region drain to the Missouri River. The Missouri Escarpment is a northeast-facing escarpment located immediately northeast of the Missouri Coteau and which drains to the Souris River. Essays describing regions near the Little Muddy River-White Earth River drainage divide area include the Big Muddy Creek-Little Muddy River drainage divide and the McKenzie County Cherry Creek region essays and are found under ND Missouri River on the sidebar category list.

• Detailed maps illustrated below provide evidence of a through valley extending north from the Little Muddy River elbow of capture (near Zahl, North Dakota) and which appears to have been blocked by subsequent glacial deposits. Prior to being blocked the through valley provided a northeast and north-oriented flood flow route from the present day Yellowstone River valley, northeast to Williston, and then north to the lowland region at the Missouri Escarpment base. That lowland at the Missouri Escarpment base in other essays is referred to as the Midcontinent Trench, which was eroded by an immense southeast and south-oriented glacial melt water river. The immense river will be named the Midcontinent River. The Missouri Escarpment will be interpreted to have been formed as the Midcontinent Trench’s southwest wall or the southwest wall of what at one time was the Midcontinent River’s ice-walled and bedrock-floored valley. What is important here is the south-oriented Little Muddy River valley segment is one component of a through valley linking the northeast-oriented Yellowstone River valley with the Midcontinent Trench located in northwest North Dakota. Also of importance is the through valley appears to have been blocked by glacial deposits, although the “glaciation” responsible for the blockage does not appear to have significantly eroded or otherwise altered the regional landscape. Before leaving figure 1 note the southeast-oriented Souris River and Des Lacs River (which is a Souris River tributary). While not at the Missouri Escarpment base in Divide County, North Dakota the southeast-oriented Souris River and/or southeast-oriented Souris River tributaries, such as the Des Lacs River, are located along the Missouri Escarpment base and have eroded valleys into the Midcontinent Trench floor.

Little Muddy River-White Earth River drainage divide area detailed location map

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

Figure 2 provides a more detailed map of the Little Muddy River-White Earth River drainage divide area. Burke, Divide, Mountrail, and Williams Counties are located in North Dakota. The north-south Montana-North Dakota state line is located near the figure 2 west edge. The west to east oriented Canada-United States boundary is located just north of the figure 2 north edge. The Missouri River is located along the figure 2 south edge. The Missouri River valley is today flooded by Lake Sakakawea, which is a large reservoir impounded behind Garrison Dam. The northeast-oriented Yellowstone River joins the Missouri River near the Montana-North Dakota state line just south of the figure 2 map area. From its confluence with the Yellowstone River the Missouri River flows northeast to Williston, North Dakota. The south-oriented Little Muddy River joins the Missouri River at Williston and is located in the south end of a large north-south through valley (now blocked by glacial deposits north of the Lake Zahl National Wildlife Refuge). The through valley links the northeast-oriented Yellowstone River and Missouri River valley segment (southwest of Williston) with the lowland or Midcontinent Trench at the Missouri Escarpment base near Crosby, North Dakota. Little Muddy River headwaters flow northwest and west in the region north and northwest of Ray, North Dakota and then enter the south-north oriented through valley just south of the Lake Zahl National Refuge. From the Lake Zahl National Refuge area the Little Muddy River flows south to join the Missouri River at Williston. White Earth Creek flows southwest to near Hamlet and then flows southeast to McGregor and Battleview and finally turns to join the south-oriented White Earth River, which flows almost straight south to White Earth and the Missouri River valley. The southwest oriented White Earth River headwaters joins White Earth Creek near the point where the White Earth River turns to flow straight south. This essay attempts to explain the origin of Little Muddy River and White Earth River valleys and their relationship to the present day Missouri River and Yellowstone River valleys as well as their relationship with the lowland located along the Missouri Escarpment base. Detailed maps below begin with a look at the Missouri Escarpment in Divide County, North Dakota and proceed south looking first at evidence of the through valley extending north from Williston now used by south-oriented Little Muddy River. Next reduced size topographic maps are used to follow the White Earth Creek and White Earth River valley southeast and south to the Missouri River valley. The essay concludes with a detailed look at a valley complex just west of where the White Earth River joins the Missouri River.

Missouri Escarpment and Missouri Coteau

Figure 3: Missouri Escarpment and Missouri Coteau. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 3 illustrates the Missouri Escarpment and the Missouri Coteau southeast of Crosby (in Divide County, North Dakota). Crosby is the town located in the figure 3 northwest corner. The red shading identifies stripped mine areas. The strip mine areas are located along the Missouri Escarpment base, with the Missouri Escarpment being the rise from the lowland north and east of the strip mine areas to the hummocky topography further to the south. The hummocky topography is located in the Missouri Coteau, which is located south and west of the Missouri Escarpment. The hummocky topography has the appearance of being covered by glacial deposits of the type associated with a stagnant ice sheet. Southwest of Crosby is a northeast indentation in the Missouri Escarpment (and Missouri Coteau), which is the north end of the large north and northeast-oriented through valley now drained further to the south by the south-oriented Little Muddy River (figure 4 below better illustrates the northeast end of the through valley). Other than that indentation (and several other indentations like it) the Missouri Escarpment and the Missouri Coteau can be traced in a southeast direction from east central Alberta across southwest Saskatchewan and northwest North Dakota to central North Dakota, where the Escarpment and Coteau become north-south oriented and can be traced southward to south central South Dakota. The Coteau is interpreted here to have been deposited by decaying remnants of the thick ice sheet that melted fast. That ice sheet was responsible for the immense floods this Missouri River drainage basin research project essay series describes.

• The thick ice sheet was located in a deep “hole” created by both ice sheet deep glacial erosion and crustal warping due to the ice sheet weight. Decaying ice sheet remnants responsible for deposition of the Missouri Coteau sediments probably represented roots of the thick ice sheet and probably were located at an elevation significantly below the elevation of the topographic surface upon which the ice sheet originally formed. Deep melt water flood erosion of Missouri River drainage basin upstream from northwest North Dakota probably removed most if not all of the preglacial topographic surface (perhaps over much of the continental United States). Immense melt water floods moved southeast along the ice sheet’s southwest margin until ice sheet melting permitted flood waters to flow east and northeast onto the melting ice sheet surface.

• Also, melt water on the ice sheet surface moved in immense rivers (or floods) to lower points at ice sheet margins. The immense supra-glacial rivers carved deep ice-walled and ice-floored valleys into the ice sheet surface, which in time became ice-walled and bedrock-floored valleys. The Midcontinent River, which eroded the southeast and south-oriented Midcontinent Trench became a major ice sheet drainage route and developed a large drainage basin on the ice sheet surface that included much of east central Alberta, southern and central Saskatchewan, northwest and central North Dakota, and central South Dakota. Headward erosion of the Midcontinent River ice-walled and bedrock-floored valley detached the decaying ice sheet’s southwest margin, which is here referred to as the Southwest Ice Sheet. In addition, as melting of the thick ice sheet lowered the decaying ice sheet surface, Midcontinent River tributary valleys eroded west and southwest to capture the immense southeast-oriented floods moving along the ice sheet’s southwest margin. These east and northeast-oriented valleys eroded deeper and deeper and probably migrated in terms of location as the thick ice sheet surface level was lowered by continued ice sheet melting and flood water “erosion”.

Northeast end of through valley across Missouri Coteau

Figure 4: Northeast end of through valley across Missouri Coteau. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 4 illustrates the northeast end of the northeast-oriented through valley cut across the Missouri Coteau seen in figure 3 and includes overlap areas with figure 3. South and southwest of the figure 4 map area the through valley is north oriented and is today partially filled with glacial moraine materials. Glaciation responsible for the valley fill definitely occurred after the valley was eroded and also, as seen in figure 4, did not destroy all evidence of the preexisting valley. In other words, the glaciation responsible for partially filling the valley was fundamentally different in nature than the glaciation responsible for creating the “thick ice sheet that melted fast”, which was responsible for the immense south-oriented melt water floods that were subsequently captured and diverted to flow northeast into space once occupied by the rapidly melting ice sheet. Landscape typical of the Missouri Coteau is located in the figure 4 southeast corner area and also in the figure 4 northwest and west center areas. At the time the northeast-oriented valley was being eroded the Missouri Coteau location was the southwest margin of the rapidly melting thick ice sheet. Headward erosion of the deep ice-walled and bedrock-floored Midcontinent River valley (or Midcontinent Trench) was detaching the ice sheet’s southwest margin from the main ice sheet further to the northeast. Also, headward erosion of ice-walled and bedrock-floored north and northeast-oriented valleys, such as the valley seen in figure 4, were separating segments of the detached ice sheet’s southwest margin. At that time the northeast-oriented valley was probably a deep and narrow ice-walled and bedrock-floored canyon. The canyon depth probably cannot be determined, but it probably was hundreds of meters deep. Also, valley walls probably were unstable and huge blocks of the decaying Southwest Ice Sheet probably periodically collapsed into the north-oriented canyon. Such collapses may have caused temporary blockages that may have ponded flood waters further to the south and southwest. Such ponding of flood waters at times may have temporarily caused flood waters to move southeast along the Southwest Ice Sheet’s southwest margin to locations of other breaches across the Southwest Ice Sheet, which was a northwest-southeast oriented ice wall, to the lower elevation Midcontinent Trench northeast of the Missouri Escarpment. Such southeast-oriented flood flow movements along the Southwest Ice Sheet’s southwest margin probably played a significant role in developing the present day Missouri River valley and also in the history of the Little Muddy River-White Earth River drainage divide area.

Little Muddy River-White Earth River drainage divide area south of Wildrose

Figure 5: Little Muddy River-White Earth River drainage divide area south of Wildrose. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 5 illustrates the Little Muddy River-White Earth River drainage divide south and west of the figure 3 map area. Note how the north half of figure 5 appears to be covered with more glacial moraine material than the southern half. Southwest and east-oriented White Earth Creek headwaters are located in the figure 5 northeast corner north of Big Meadow. The Little Muddy River originates in New Home Township (figure 5 center east) and flows southwest and northwest into Rainbow Township (figure 5 center). From Rainbow Township the Little Muddy River flows west, southwest into Ellisville Township, where it turns to flow northwest toward Appam (located in southern Blue Ridge Township in figure 5 northwest quadrant near west edge). South of Appam in what is locally referred to as Horseshoe Bend the Little Muddy River turns to flow southwest into the large north and northeast-oriented through valley located just west of the figure 5 map area and seen further north in figures 3 and 4 (the northeast-oriented valley southwest of Crosby). Once in the large through valley the Little Muddy River flows south and can be seen in the figure 5 southwest corner. The northwest-oriented Little Muddy River headwaters are aligned with headwaters of southeast-oriented Beaver Creek located in the figure 5 southeast corner area just west of Temple (the town located in the southeast corner area). Beaver Creek flows south-southeast to the east-oriented Missouri River valley and is illustrated in figure 7 below. The alignment of the northwest-oriented Little Muddy River headwaters with south-southeast oriented Beaver Creek provides evidence the northwest-oriented Little Muddy River headwaters valleys was eroded by northwest-oriented flood flow. The northwest-oriented flood flow was almost certainly beheaded by headward erosion of the Missouri River valley as it eroded west into the region.

• Between the figure 5 map area and the figures 3 and 4 map areas the north oriented through valley is partially filled with some type of glacial moraine material (the Big Muddy Creek-Little Muddy River drainage divide essay illustrates the partially filled through valley north of figure 5). Glacial moraines filling the through valley provide evidence of a minor glaciation during final stages of the thick ice sheet rapid melt down. That minor glaciation probably originated when the southeast and south-oriented Midcontinent River was dismembered as ice sheet melting opened up north oriented drainage routes to what is now Hudson Bay. When the immense south-oriented floods reversed direction to flow north Atlantic Ocean currents were changed causing a major cooling in the Northern Hemisphere. That climatic change probably caused flood waters to freeze on the former ice sheet floor at the same time as flood waters from the southwest continued to flow into the deep “hole” the thick ice sheet had once occupied. Freezing of flood waters produced a wet based thin ice sheet with remnants of what had been the decaying thick ice sheet embedded in it. This thin ice sheet was responsible for glacial moraine material now partially filling the north oriented through valley. Also the blockage of north and northeast oriented flood waters that occurred when the climate rapidly changed was responsible for southeast-oriented flood flow that moved to what was then the actively eroding Missouri River valley. The Missouri River valley eroded headward into the region south of figure 5 to drain final stages of the immense floods created by the thick ice sheet’s rapid melt down. Rapid freezing of flood waters in the north blocked flood movements onto the former ice sheet floor and flood waters were forced to flow along the former ice sheet southwest margin. As soon as headward erosion of Missouri River valley reached the north-oriented through valley flood waters in it drained south to the Missouri River valley to create the present day Little Muddy River drainage basin.

Northwest-oriented Little Muddy River valley

Figure 6: Northwest-oriented Little Muddy River valley. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 6 illustrates the northwest-oriented Little Muddy River valley segments seen in the reduced size figure 5 map above. The Little Muddy River originates as south-oriented stream in the figure 6 northeast quadrant and after entering a northwest-oriented lowland turns to flow northwest (with some jogs) to the figure 6 northwest corner area. From the figure 6 map area the Little Muddy River flows west to enter the south end of the north and northeast-oriented valley seen in figures 3 and 4, and then to flow south in that large valley (as seen in figures 5 and 7) to the east-oriented Missouri River valley. Note the broad northwest-oriented lowland or valley in which the northwest-oriented Little Muddy River valley segment is located. Figure 7 below illustrates the region southeast of that northwest-oriented valley and the deep east-oriented Missouri River valley located there. Flood waters responsible for the broad northwest-oriented lowland or valley did not come from the deep east-oriented Missouri River. Probably the flood waters came north along the north oriented Little Missouri River valley alignment and were moving northwest to the deep north and northeast-oriented valley across the Southwest Ice Sheet seen and described in figure 4 above. Headward erosion of the deep east-oriented Missouri River valley captured those flood waters and beheaded the northwest-oriented flood flow across the figure 6 map area. However, before headward erosion of the deep Missouri River valley reached the Williston, North Dakota area, ponding of flood waters by temporary (and later by permanent) blockages of the north and northeast-oriented valley across the detached Southwest Ice Sheet may have caused water to temporarily flood the broad northwest-oriented Little Muddy River lowland or valley, with water spilling across drainage divides in whatever direction the water could move. The region was probably drained of such ponded flood water when headward erosion of the deep Missouri River valley reached the Williston area and intersected the north and northeast-oriented valley. When the divide between the north and northeast-oriented valley was breached by Missouri River valley headward erosion all ponded flood waters in the present day Little Muddy River drainage basin could drain south through the south end of the north and northeast-oriented through valley. That final drainage created the present day Little Muddy River drainage basin.

Little Muddy River-Missouri River drainage divide area near Ray

Figure 7: Little Muddy River-Missouri River drainage divide area near Ray. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 7 illustrates the Little Muddy River-Missouri River drainage divide area south of the figure 5 map area and includes overlap areas with figure 5. Temple is the small town (really a ghost town) located in the figure 7 northeast corner. Ray, North Dakota is the larger town located southwest of Temple where the northeast oriented railroad crosses the west-east oriented red highway. Williston, North Dakota is the city located in the figure 7 southwest corner. The northeast and east-oriented Missouri River can be seen in the figure 7 southeast corner. The arcuate flat area north of the flooded Missouri River valley in the figure 7 southeast corner area is Hofflund Flats. South-southeast oriented Beaver Creek flows to the east end of Hofflund Flats and originates west of Temple. As seen in figure 5 above the Beaver Creek headwaters are aligned with the northwest-oriented Little Muddy River headwaters. Little Muddy River is located in the large valley along the figure 7 west edge area and the Little Muddy River here is flowing south to join the Missouri River just south of Williston. The East Fork of the Little Muddy River originates as a northwest-oriented stream in the figure 7 center north area and then turns to flow southwest to the south-oriented Little Muddy River in the figure 7 northwest quadrant. Spring Brook is the southwest-oriented Little Muddy River tributary flowing to join the Little Muddy River in the figure 7 southwest corner. Spring Brook headwaters are also northwest-oriented and originate almost at the edge of the deep Missouri River valley. Figure 7 evidence is consistent with the interpretation provided for figure 5 evidence. North-oriented flood water from southwest of the thick ice sheet southwest margin moving north onto the former ice sheet floor became ponded and was forced to flow southeast across the upland surface to what was then the actively eroding Missouri River valley. When headward erosion of the Missouri River valley reached the large north-oriented valley at Williston the ponded flood waters were able to drain east in the newly eroded Missouri River valley. The southwest-oriented Spring Brook and East Fork valleys were eroded headward by flood waters draining from the upland surface to the rapidly draining now south-oriented Little Muddy River valley. Headward erosion of the southwest-oriented Spring Brook and East Fork valleys beheaded the former southeast-oriented flood flow routes to the newly eroded Missouri River valley. Flood waters on the northwest ends of those beheaded flood flow routes reversed flow direction to flow northwest to the newly southwest-oriented valleys.

White Earth Creek headwaters area

Figure 8: White Earth Creek headwaters area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 8 illustrates the White Earth Creek headwaters area and includes overlap areas with the figure 5 northeast corner. Hamlet, North Dakota is the (ghost) town located near the figure 8 west center edge. White Earth Creek flows southwest from the figure 8 north center area and east of Hamlet turns to flow southeast through McGregor and Battleview to the figure 8 southeast corner area. Southeast of the figure 8 map area White Earth Creek joins the south-oriented White Earth River to flow south to the east and southeast oriented Missouri River. The figure 8 map area is located along the south margin of the Missouri Coteau area where glacial moraine type landscape is most prevalent. North of the figure 8 map area hummocky topography with no well-defined drainage prevails until the Missouri Escarpment slope is reached (see figures 3 and 5). The Missouri Escarpment slope drains to the southeast oriented Souris River (which further to the southeast makes a U-turn to flow northwest and north and eventually reach Hudson Bay). The Souris River is located on the Midcontinent Trench floor. The Missouri Coteau is here interpreted to be evidence of the detached Southwest Ice Sheet, which was detached from the decaying thick ice sheet by headward erosion of the southeast- and south-oriented Midcontinent River ice-walled and bedrock-floored valley (or Midcontinent Trench). Melt water floods moving along the ice sheet’s southwest margin were captured by deep ice-walled and bedrock-floored valleys that eroded west and southwest from the Midcontinent River. Figure 4 illustrated one such valley. Probably there were many other smaller breaches where flood waters from southwest of the Southwest Ice Sheet margin broke through to move to the much deeper Midcontinent Trench floor to the north and northeast. The southwest-oriented White Earth Creek headwaters valley may be located on the alignment of a northeast-oriented breach. Flood waters may have been moving northeast into the figure 8 map area and then northeast in a narrow ice-walled and ice-floored valley to the deep Midcontinent Trench located northeast of the detached Southwest Ice Sheet. Headward erosion of the deep Missouri River valley into the region southeast of figure 8 permitted the south-oriented White Earth River valley to erode north to capture the northeast-oriented flood flow and divert the flood waters southeast along the present day White Earth Creek alignment and then south in the deeper White Earth River valley.

White Earth River valley north of White Earth

Figure 9: White Earth River valley north of White Earth. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 9 illustrates the White Earth River valley north of the town of White Earth and includes overlap areas with figure 8. Hamlet is the (ghost) town located in the figure 9 northwest corner. The White Earth Creek headwaters flow southwest to near Hamlet and then turn to flow southeast through McGregor and Battleview to the figure 9 center north area where in the Sletten Lake area it turns to flow south in a deep valley to the figure 9 south edge. In the center north area White Earth Creek is joined by southwest-oriented White Earth River, which originated as a southeast-oriented stream flowing to Smishek Lake and then turning to flow southwest to the deep south-oriented White Earth River valley. Joining the southwest-oriented White Earth River is a northwest-oriented valley extending southeast through the Powers Lake area to Lunds Valley and to the southwest end of north-northeast oriented chain of Lakes in Lostwood National Wildlife Refuge. Up until very late in the decaying ice sheet history, and perhaps even after the Midcontinent River had been dismembered to flow north and freezing of flood waters was beginning to cause flood waters to accumulate along the decaying ice sheet’s southwest margin, flood waters from southwest of the ice sheet margin reached the figure 9 map area and flowed southeast until they could find weak spots in the decaying ice sheet’s (detached) southwest margin. The southwest-oriented White Earth Creek headwaters northeast of Hamlet, the southwest-oriented White Earth River valley in the Smishek Lake area, and the north-northeast oriented chain of lakes in the Lostwood Wildlife Refuge area are probably evidence of northeast and north-northeast oriented flood flow routes across the detached Southwest Ice Sheet ice wall to the Midcontinent Trench. Unlike the much larger Little Muddy River-Crosby through valley further to west these flood flow routes were probably narrow ice-walled and ice-floored valleys, although they may have been very deep. This northeast-oriented flood flow was either blocked by freezing of flood waters when rapid climate change caused by Midcontinent River dismemberment occurred or was just captured by headward erosion of the deep Missouri River valley to the south of the figure 9 map area. In either case the deep White Earth River valley eroded north from the newly eroded Missouri River valley to capture the flood flow moving northeast across the present day Missouri Coteau and to divert the flood waters south to what was then the actively eroding the Missouri River valley.

White Earth River valley south of White Earth

Figure 10: White Earth River valley south of White Earth. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 10 illustrates the White Earth River valley south of the town of White Earth and south of the figure 9 map area. The flooded Missouri River valley is located in the figure 10 south edge area. The deep south-oriented White Earth River valley is located just east of the figure 10 center and drains to the east and southeast-oriented Missouri River in the figure 10 southeast quadrant. Note how the deep valley is composed of many incised meanders. This may be evidence the valley route was initiated as a narrow south-oriented ice-walled and bedrock-floored valley draining flood waters from the decaying Southwest Ice Sheet surface. The valley suggests significant volumes of water did move south in the valley to what was then the newly eroded Missouri River valley, which would be consistent with the interpretation the valley eroded headward to capture flood waters moving to narrow ice-walled and ice-floored (or bedrock-floored) north and northeast-oriented breaches across the detached Southwest Ice Sheet. Ray, North Dakota is the town located in the figure 10 northwest quadrant. Beaver Creek flows south-southeast from area east of Ray to the east edge of arcuate Hofflund Flats (immediately north of the Missouri River in the figure 10 southwest quadrant). As previously mentioned the south-southeast oriented Beaver Creek valley is aligned with northwest-oriented Little Muddy River headwaters. The Beaver Creek valley eroded headward from the deep Missouri River valley at the time headward erosion of the deep Missouri River valley reached the Hofflund Flats area, but before headward erosion of the deep Missouri River valley reached the Williston area (where it beheaded the north-oriented flood flow route now used by the south-oriented Little Muddy River). It is possible the north-oriented flood flow route had become blocked before it was beheaded. Note the east to west oriented through valley linking the south-oriented White Earth River valley with the Hofflund Flats lowland.

• Figure 10a below illustrates the Hofflund Flats area with less reduction than in figure 10 and also areas south of the Missouri River. The north-northeast oriented stream joining the east-oriented Missouri River opposite the west end of the Hofflund Flats area is Tobacco Garden Creek. Tobacco Garden Creek flows northeast to the figure 10a map area along the northeast end of the large northeast oriented through valley linking the present day deep north and north-northeast oriented Little Missouri River valley with the present day deep Missouri River valley (see Cherry Creek drainage basin essay). At its northeast end the northeast-oriented through valley narrows and deepens where present day Tobacco Garden Creek joins the deep east-oriented Missouri River valley (the Missouri River valley has been flooded by Garrison Dam to produce Lake Sakakawea so the full valley depth is not evident). Figure 10a shows where Tobacco Garden Creek flows into Lake Sakakawea and also the large incised Hofflund Flats meander immediately north of the Tobacco Garden Creek mouth. This evidence supports the previously stated hypothesis that prior to headward erosion of the deep east-oriented Missouri River valley flood waters from the present day Little Missouri River drainage basin may have moved north and northwest to the deep ice-walled and bedrock-floored Southwest Ice Sheet breach seen in figure 4 above (and also to other Southwest Ice Sheet breaches such as those identified in figures 8 and 9).

• The interpretation given in the Cherry Creek drainage basin essay is the large incised meander opposite the Tobacco Garden Creek mouth suggests a large north oriented flood was captured by a deep southeast-oriented Missouri River valley to create an elbow of capture and then a more direct east-oriented valley was eroded across the narrow drainage divide between the north and southeast-oriented channels. This interpretation was based on study of landform evidence south of the Missouri River valley. This interpretation suggests north-oriented flood water probably continued to supply flood water surges that flowed around the northern loop and eroded the northern semicircular Hofflund Flats valley around the present day Red Mike Hill. The north-oriented flood surges ended when the deep east-oriented Little Missouri River valley captured all northeast oriented flood flow to the Tobacco Garden Creek valley. Subsequent east-oriented Missouri River valley flood waters deeply eroded the east-oriented Missouri River valley south of Red Mike Hill, which resulted in the Hofflund Flats meander route being abandoned. Flood waters probably moved in several different directions in this region and further research probably will be able to significantly improve on my interpretation.

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.