A geomorphic history based on topographic map evidence

The Sheyenne River-James River drainage divide area discussed here is located in Wells, Benson, and Eddy Counties, North Dakota, USA. This drainage divide is the north-south continental divide, with water in the Sheyenne River eventually reaching Hudson Bay in the north and water in the James River eventually reaching the Gulf of Mexico in the south. Evidence in the drainage divide area makes a strong case the north-south continental divide was created when the eastern half of an immense south-oriented melt water flood was captured and diverted to flow north while the flood’s western half continued to flow south.

• The purpose of this essay is to use topographic map interpretation methods to explore Sheyenne River-James River drainage divide area landform origins in Wells, Benson, and Eddy Counties 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 essay 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 Sheyenne River-James River drainage divide area landform evidence in Wells, Benson, and Eddy Counties, North 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.

Sheyenne River-James River drainage divide area location map

Figure 1: Sheyenne 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 for the Sheyenne River-James River drainage divide area discussed in this essay. Figure 1 illustrates a region in eastern and central North Dakota, with Minnesota being the state located east of North Dakota along the figure 1 east edge. The north-oriented Red River forms the North Dakota-Minnesota boundary and Red River water eventually reaches Hudson Bay in northern Canada. The Missouri River is located in the figure 1 southwest quadrant and flows from Lake Sakakawea (a large reservoir along the figure 1 west edge) in a south-southeast direction to Bismarck and then to the figure 1 south edge. Missouri River water eventually reaches the Gulf of Mexico. The Sheyenne River originates southwest of Harvey (located in the southeast corner of the figure 1 northwest quadrant) and flows northeast to Harvey and continues to flow northeast before turning east to flow south of Devils Lake. The Sheyenne River then turns to flow south to Valley City and Fort Ransom (in the figure 1 southeast quadrant) and near Fort Ransom the Sheyenne River turns to flow northeast to join the north-oriented Red River near Fargo. Once in the Red River the water eventually reaches Hudson Bay. The James River originates south of Harvey and flows north and northeast before turning east and southeast to flow to New Rockford and Grace City. Near Grace City the James River turns to flow south to Jamestown and then southeast to Oakes and the figure 1 south edge. From the figure 1 south edge James River water eventually reaches the Missouri River, Mississippi River, and Gulf of Mexico. Another figure 1 river of interest is the Souris River located in the figure 1 northwest corner. The Souris River flows southeast to Minot and Velva and at Velva turns to flow northeast to Towner. Near Towner the Souris River turns again to flow northwest, making a complete U-turn, and Souris River water eventually reaches Hudson Bay. The Sheyenne River-James River drainage divide area illustrated and discussed in this essay is located upstream from Grace City on the James River and upstream from the Cooperstown area in the Sheyenne River drainage basin. A separate essay discusses the Sheyenne River-James River drainage divide area downstream (or south) of these points and can be found under James River on the sidebar category list. Probably one of the most remarkable features of the Sheyenne River-James River drainage divide area in the region illustrated and discussed in this essay is the Sheyenne River-James River drainage divide is the north-south continental divide. Water in the Sheyenne River flows north to Hudson Bay and water in the James River flows south to the Gulf of Mexico. How can two rivers, which parallel each other for considerable distance and which (as is seen below) flow in adjacent and interconnected valleys then diverge and flow to opposites sides of the North American continent? The answer to this question develops as this essay progresses, although before leaving figure 1 note the Sheyenne elbow capture (where the Sheyenne River turns from flowing south to flowing northeast) located in the figure 1 southeast quadrant and the Souris River elbow of capture (where the Souris River turns from flowing southeast to flowing northwest) located in the figure 1 northwest quadrant. These elbows of capture are important pieces of evidence located outside the Sheyenne River-Souris River drainage divide area discussed below.

Sheyenne River-James River drainage divide area detailed location map

Figure 2: Sheyenne 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 map of the Sheyenne River-James River drainage divide area. Benson, Wells, Eddy, and Foster are North Dakota counties. West of Wells County is Sheridan County. South of Foster County is Stutsman County and west of Stutsman County is Kidder County. The red shaded area in Benson County is the Fort Totten Indian Reservation (now the Spirit Lake Reservation). The Sheyenne River originates in northeastern Sheridan County and flows southeast to the Wells County border where it turns to flow northeast through Harvey to southern Benson County, where it then meanders in an easterly direction (and serves as the Fort Totten Indian Reservation south border) until it reaches the figure 2 east edge. The James River originates south of Harvey in western Wells County and flows generally north to the highway northwest of Manfred and then turns to flow generally east to New Rockford. At New Rockford the James River turns to flow southeast to near Grace City, where it turns to flow south to the figure 2 south edge. Figure 2 does not show topography, but if it did the area of small lakes in northwest Stutsman County, Kidder County, southwest Wells County, and Sheridan County is a region of hummocky topography with numerous water filled depressions (at least during wet years) known as the Missouri Coteau. Immediately northeast of the Missouri Coteau is the northeast-facing Missouri Escarpment and east of the Missouri Escarpment the prevailing elevation is 100 or more meters lower than typical Missouri Coteau elevations. West and southwest of the Missouri Coteau is the Missouri River valley. The Missouri Coteau and Missouri Escarpment are recognizable topographic features that extend in a northwest-southeast direction from east central Alberta to southern South Dakota. The Missouri River marks the Missouri Coteau southwest and west boundary in North Dakota and South Dakota. Both the Sheyenne River and James River originate in the Missouri Coteau at the east end of what was at one time an east or northeast-oriented valley across the present day Missouri Coteau (see Missouri River-Sheyenne River drainage divide area essay found under ND Missouri River on the sidebar category list). Both rivers quickly emerge onto the lowland at the Missouri Escarpment base and flow north, northeast, and east before turning to flow south (more or less parallel to the Missouri Escarpment in southern North Dakota). As can be seen in figure 2 the two rivers are roughly parallel as they flow across Wells County and into Eddy and Foster Counties. East of figure 2 the Sheyenne River turns to flow south and the rivers continue to flow approximately parallel to each other until the Sheyenne River reaches southeast North Dakota (see figure 1). Again, what is remarkable about these two rivers is they flow to opposite margins of the North American continent. Water in the Sheyenne River eventually reaches Hudson Bay in northern Canada. Water in the James River eventually reaches the Gulf of Mexico.

Sheyenne River-James River drainage divide area south of Harvey

Figure 3: Sheyenne River-James River drainage divide area south of Harvey. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 3 uses reduced size maps to illustrate Sheyenne River and James River headwaters south of Harvey, North Dakota. Harvey is the town located near the figure 3 north center edge. Manfred is the smaller town located southeast of Harvey on the highway and railroad. The northwest-southeast oriented northeast-facing escarpment south of Harvey is a Missouri Escarpment segment. Hummocky topography at the Missouri Escarpment crest is the Missouri Coteau northeast margin. The Missouri Coteau extends west and southwest almost to the Missouri River valley (see figure 1). The Missouri Escarpment in the figure 3 map area has been interrupted by what appear to have been east and northeast-oriented valleys carved into the Missouri Escarpment slope and then later filled with what appear to be glacial moraine materials. One such valley cut into the Missouri Escarpment slope is located in the figure 3 west center area. The Sheyenne River today originates west of the figure 3 west edge and flows to northwest-southeast oriented Sheyenne Lake near that valley mouth and then flows southeast before turning north-northeast to flow to Harvey and the figure 3 north edge. Another valley cut into the Missouri Escarpment slope is located in the figure 3 southeast corner area and the James River flows north from that valley area to the red highway (between Harvey and Manfred) and then turns southeast to flow parallel to the highway to Manfred. At Manfred the James River turns to flow east to the figure 3 east edge. The relationship of the Sheyenne and James Rivers to these east and northeast-oriented valleys is important evidence, but first we need to know what the Missouri Escarpment is.

• The Missouri Escarpment was created as the southwest wall of an immense southeast and south-oriented ice-walled and bedrock-floored canyon during a thick North American ice sheet’s rapid melt down. When the thick ice sheet began to melt supra-glacial melt water rivers flowed across its surface to ice sheet margins. One such supra-glacial melt water river, which is here named the Midcontinent River, flowed southeast across present day North Dakota and then south in present day South Dakota. Initially the Midcontinent River carved an ice-walled and ice-floored valley into the tick ice sheet surface. As ice sheet melting progressed the Midcontinent River valley became deeper and deeper and probably eroded headward while also developing a network of tributary ice-walled and ice-floored valleys. As ice sheet melting progressed in time the ice-walled and ice-floored valleys sliced right through the thick ice sheet and became an ice-walled and bedrock-floored canyons. Probably the depth of these ice-walled and bedrock-floored canyons cannot be determined, however the southeast and south-oriented Midcontinent River ice-walled and bedrock-floored canyon (named here the Midcontinent Trench) did detach the thick ice sheet’s southwest margin. The Missouri Escarpment is the Midcontinent Trench’s southwest wall. The Missouri Coteau represents glacial moraines deposited as the thick ice sheet’s detached southwest margin (named here the Southwest Ice Sheet) eventually melted.

• But, there is more to the regional history that needs to be explained. The Midcontinent River, which flowed southeast and south in the Midcontinent Trench, was an immense melt water river flowing on the thick ice sheet’s floor. Crustal warping caused by the ice sheet weight and also deep glacial erosion created a deep “hole” in which the thick ice sheet was located, which meant the ice sheet had developed on a topographic surface much higher than any elevations present in North Dakota today. This Missouri River drainage basin research project essay series is developing a case that the topographic surface on which the thick ice sheet originally formed was at least as high as the highest level present day Rocky Mountain erosion surfaces, if not higher. Whatever elevation the ice sheet rim area was it was considerably higher than the Midcontinent Trench floor. The Midcontinent River was just one of several large melt water rivers draining the rapidly melting thick ice sheet interior. There were other immense melt water rivers that flowed to the ice sheet margins further to the northwest and west. Some of those immense melt water floods the moved southeast along the ice sheet margin and were captured by headward erosion of northeast and east-oriented tributary valleys from the deep southeast and south-oriented Midcontinent River. Probably the Sheyenne River and James River today originated in what remains of two of those northeast and east-oriented tributary valleys.

Sheyenne River-James River drainage divide area west of Manfred

Figure 4: Sheyenne River-James River drainage divide area west of Manfred. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 4 provides a less reduced size map of the Sheyenne River-James River drainage divide area west of Manfred, North Dakota seen in the reduced size map used for figure 3. The Sheyenne River flows southeast in the figure 4 southwest corner before turning north-northeast to flow to Harvey along the figure 4 north edge. Further east the James Rivers flows north and north-northeast to the red highway and railroad before turning southeast to flow to Manfred and the figure 4 east edge. A northeast-oriented James River tributary flows from the figure 4 south edge across the figure south center area. What makes this figure 4 map area interesting is evidence of several glacial features suggesting the Midcontinent Trench floor was glaciated subsequent to the final Midcontinent River melt water floods. In the figure 4 south half there are two linear ridges, a northwest-oriented ridge adjacent to a northwest-oriented James River segment and a north-northeast and north oriented ridge between the north-northeast oriented Sheyenne River and an unnamed northeast-oriented James River tributary. These two ridges appear to be eskers. Also, south of the red highway between Harvey and Manfred is Egg Lake and an adjacent hill. The hill may have originated when bedrock frozen solid with an otherwise wet based thin ice sheet was lifted from the present day Egg Lake basin and moved a short distance southeast. Other small lakes in the figure 4 map area might be kettles. One possibility for the origin of these kettles is as Midcontinent River flood flow waned large blocks of ice were stranded on the Midcontinent Trench floor. Flood flow then deposited sediments around the stranded ice blocks, but no longer was flood flow great enough to move the ice blocks. Melting of the ice blocks would have left the present day kettles or water filled depressions. However, the eskers and ice thrust bedrock slab require the present of some sort of wet based thin ice sheet covering the figure 4 map area. Such a wet based thin ice sheet could have developed if flood waters late during the Midcontinent River history froze on the Midcontinent Trench floor. Such an explanation is consistent with evidence the Missouri Escarpment and the east and northeast-oriented valleys eroded into it were not destroyed by subsequent glacial erosion. Freezing of flood waters on the Midcontinent Trench floor could produce a wet-based thin ice sheet, which also included frozen slabs of underlying water saturated bedrock. Further, climatic conditions leading to development of such a wet based thin ice sheet could also have incorporated the remnants of the decaying thick ice sheet, which in turn could explain why valleys across the Missouri Coteau have been at least partially filled with glacial moraine materials.

Sheyenne River-James River drainage divide area north of Manfred

Figure 5: Sheyenne River-James River drainage divide area north of Manfred. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 5 illustrates the Sheyenne River-James River drainage divide area north and east of Manfred and includes overlap areas with figure 4. The James River flows southeast to Manfred and then east and southeast along the figure 5 south edge area. The Sheyenne River is located in the figure 5 northwest quadrant and flows northeast, southeast, northeast, and north to the figure 5 north edge (west half). Big Slough is a northwest-oriented Sheyenne River tributary originating in a northwest-southeast oriented through valley near Heimdal. Southeast from Heimdal the through valley is drained by a southeast-oriented James River tributary (also named Big Slough), which is seen further to the southeast in figure 7. This northwest-southeast oriented through valley is remarkable because it crosses the present day north-south continental divide. As previously mentioned the present day Sheyenne River water eventually reaches Hudson Bay, while James River water eventually reaches the Gulf of Mexico. North of the northwest-southeast oriented Big Slough valley is evidence of glacial moraines. These moraines could have been deposited by thick ice sheet remnants and/or by the subsequent thin ice sheet described in figure 4, or perhaps by a combination of the two. Whatever their origin they appear to have influenced the Big Slough valley orientation, which is roughly parallel to the Missouri Escarpment orientation. It is possible the Big Slough valley orientation developed because it was located along the northeast margin of a southeast-oriented channel in what was an anastomosing complex of Midcontinent River channels. If so, the more northern channel in which the Sheyenne River now flows was able to erode a slightly deeper valley and was able to behead southeast-oriented flood flow in the southeast-oriented Midcontinent River channel now drained by the James River drainage system. If this interpretation is correct the north-south continental divide in Wells, Benson, and Eddy counties, North Dakota, developed during an immense flood event when one anastomosing flood flow channel beheaded another flood flow channel.

Sheyenne River-James River drainage divide area at Heimdal

Figure 6: Sheyenne River-James River drainage divide area at Heimdal. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 6 provides a more detailed map of the Sheyenne River-James River drainage divide area at Heimdal seen in less detail in figure 5 above. Big Slough drains northwest to the figure 6 west edge (Northwest quadrant) and then joins the northeast and north-oriented Sheyenne River (see figure 5) and the water eventually reaches Hudson Bay. Note how the northwest-oriented Big Slough drains the northwest end of a northwest-southeast oriented through valley. The northeast-oriented stream immediately south of Heimdal enters the northwest-southeast oriented through valley and then flows southeast in the through valley (it is also named Big Slough). The southeast-oriented Big Slough drains to the James River (see figure 7) and the water eventually reaches the Gulf of Mexico. Note the northwest-oriented tributary to the northeast-oriented stream south of Heimdal. The northwest-southeast-oriented through valley provides evidence water once flowed across what is today the north-south continental divide and also is a continuous channel linking the present day Sheyenne River valley with the present day James River valley. This evidence strongly suggests the northwest-southeast oriented through valley originated as one of several anastomosing channels during an immense southeast-oriented flood flow event. During that flood flow event the southeast-oriented flood waters at one time flowed to both the James River valley and the Sheyenne River valley, however headward erosion of the deeper Sheyenne River valley beheaded the southeast-oriented flood flow channels to the James River valley. Flood waters on the northwest ends of the beheaded flood flow channels reversed flow direction to flow northwest to the deeper Sheyenne River valley and created northwest-oriented Sheyenne River tributaries , such the northwest-oriented Big Slough in figure 6. The same process occurred when the northeast-oriented valley eroded headward south of Heimdal and beheaded southeast-oriented flood flow. Flood waters on the northwest ends of the beheaded flood flow routes reversed flow direction to flow northwest to the newly eroded northeast-oriented valley and in the process eroded the northwest-oriented tributary valley. Figure 6 evidence also suggests the presence of glacial features on the Midcontinent Trench floor.

Sheyenne River-James River drainage divide area north of Bremen

Figure 7: Sheyenne River-James River drainage divide area north of Bremen. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 7 illustrates the Sheyenne River-James River drainage divide area north and east of the figure 5 map area and includes overlap areas with figure 5. The Sheyenne River flows southeast and northeast in the figure 7 northeast quadrant. East-southeast oriented Big Slough flows near Hamberg (near figure 7 west edge) and then near Bremen before joining the northeast and southeast-oriented James River, which flows to the figure 7 southeast corner area. Note the anastomosing channel in the region where Big Slough joins the James River. These anastomosing channels represent just a small area of a much larger anastomosing channel complex, more of which is seen in figure 8 below. This anastomosing channel complex provides evidence an immense southeast-oriented flood on the Midcontinent Trench floor was moving to the present-day south-oriented James River valley, which drains eventually to the Gulf of Mexico. As seen in figures 4 and 5 headward erosion of the Sheyenne River valley beheaded southeast-oriented flood flow routes on the Midcontinent Trench floor, but did not behead a north-oriented flood flow route from what was probably one of two deep ice-walled and bedrock-floored valleys eroded across the Southwest Ice Sheet (see figure 3).

• Why was headward erosion of the Sheyenne River valley able to capture southeast oriented flood flow on the Midcontinent Trench floor and from the northern of the two ice-walled and bedrock-floored valleys eroded across the Southwest Ice Sheet, but not from the southern of the two valleys eroded across the Southwest Ice Sheet? To understand refer back to figure 1. The southeast and south-oriented Midcontinent River probably carved anastomosing ice-walled and ice-floored valleys into the thick ice sheet surface and the south-oriented Sheyenne River and James River valleys probably originated as two such anastomosing south-oriented ice-walled and bedrock-floored valleys. The two valleys were probably linked at various points, but were also probably separated by detached ice sheet remnants in other locations. In time the two valleys became anastomosing ice-walled and bedrock-floored canyons moving immense volumes of southeast and south oriented melt water. South-oriented flood flow in the eastern ice-walled and bedrock-floored valley was then captured when thick ice sheet melting opened up a flood flow routes that caused south-oriented flood flow in the present day Red River valley to reverse direction and flow north. Evidence that reversal of flood flow in the Red River valley captured south-oriented flood flow in the Sheyenne River valley is seen in southeast North Dakota where the Sheyenne River makes a U-turn to flow northeast to the north-oriented Red River.

• This capture of the eastern half of the immense southeast and south-oriented Midcontinent River permitted a slightly deeper Sheyenne River valley to erode north, west, and then southwest across the Midcontinent Trench floor and to begin to capture the immense Midcontinent River. However, as the deeper Sheyenne River valley was eroding headward, the Midcontinent River was captured further to the northwest. Evidence of that second Midcontient River capture (and diversion to the north) is seen where the present day southeast-oriented Souris River makes a U-turn to flow northwest and north. That capture beheaded the southeast-oriented Midcontinent River flood flow, but it did not affect the ice marginal flood waters that were flowing northeast and east through the ice-walled and bedrock-floored valleys carved into the Southwest Ice Sheet. Headward erosion of the deeper Sheyenne River valley was able to capture the flood flow moving through the northern valley seen in figure 3, but flood flow moving through the southern valley seen in figure 3 continued to move to the western (or James River valley) half of the former south-oriented anastomosing flood flow routes.

James River tributaries west of New Rockford

Figure 8: James River tributaries west of New Rockford. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 8 illustrates James River tributaries west of New Rockford and is located south of figure 7 (and includes overlap areas with figure 7). The James River flows east at the figure 8 west edge and then turns north and northeast before turning southeast to flow to New Rockford (the town located along the figure 8 east edge). Note how the Jame River elbow of capture area (where the James River turns from flowing east to flowing north) is the headwaters area for a southeast and east-oriented James River tributary. Also note how that southeast and east-oriented James River tributary valley is one channel in a much larger southeast-oriented anastomosing channel complex. In fact the northern two-thirds of the figure 8 map area provides excellent evidence of a southeast-oriented anastomosing channel complex, which suggests the entire Midcontinent Trench floor was being eroded by anastomosing flood flow channels just prior to the time flood flow across the region finally ceased. The northern James River elbow of capture (where the northeast-oriented James River turns to flow southeast) is where the northeast-oriented James River valley enters the southeast-oriented Big Slough valley seen in figures 5, 6, and 7 above. Evidence presented in figures 5 and 6 illustrated that headward erosion of Sheyenne River valley beheaded southeast-oriented flood flow in that Big Slough valley and the evidence presented in figure 8 illustrates the Big Slough valley eroded headward from the present day James River valley (or the western half of what was probably an immense south-oriented anastomosing channel complex. The anastomosing channel complex seen in figure 8 between the north and northeast-oriented James River valley (in the figure 8 northwest quadrant) and the figure 8 east edge was beheaded when the present day James River valley eroded southwest, south, and then west to behead the multiple southeast-oriented flood flow channels. At about the same time headward erosion of the Sheyenne River valley beheaded southeast-oriented flood flow in the Big Slough valley.

Sheyenne River-James River drainage divide area north of New Rockford

Figure 9: Sheyenne River-James River drainage divide area north of New Rockford. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 9 illustrates the Sheyenne River-James River drainage divide area north of New Rockford and east of figure 7 (and includes overlap areas with figure 7). New Rockford is located along the figure 9 south edge and Sheyenne, North Dakota is located just south of the Sheyenne River in the figure 9 north center. The southeast-oriented James River is located in the figure 9 southwest quadrant and east of New Rockford turns to flow southeast. The Sheyenne River flows east-northeast across the figure 9 northwest quadrant and is south-southeast oriented in the figure 9 northeast quadrant. Note how the Tiffany Flats area separates the southeast-oriented James River from the south-southeast oriented Sheyenne River and is today the north-south continental divide. The hilly area between the east-northeast oriented Sheyenne River and the southeast-oriented James River also serves as the north-south continental divide and is probably some type of glacial moraine. If so, the glacial moraine appears to pre-date the east-northeast oriented Sheyenne River valley, although it is possible (and probable) that the east-northeast oriented Sheyenne River eroded headward as an ice-walled and bedrock-floored valley across the ice sheet responsible for that moraine. That ice sheet may have been a thick ice sheet remnant, but it also could have been a thin ice sheet formed by the freezing of flood waters on the Midcontinent Trench floor. If the latter is correct then the hills may be ice thrust slabs of bedrock that had been frozen solid when flood waters on the Midcontinent Trench floor froze. Subsequent flood flow might have moved those wet based thin ice sheet masses and caused lifting of the frozen bedrock slabs. This figure 9 map area is south of the Devils Lake basin area, which may have served as a source area for the bedrock slabs moved to this figure 9 location. Whatever the source of the figure 9 hilly area it was there when the east-northeast oriented Sheyenne River valley eroded headward to capture southeast-oriented flood flow in the Midcontinent Trench further to the west and southwest as seen in figure 3.

Sheyenne River-James River drainage divide area at Tiffany Flats

Figure 10: Sheyenne River-James River drainage divide area at Tiffany Flats. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 10 illustrates the Sheyenne River-James River drainage divide area at Tiffany Flats located east and south of the figure 9 map area and includes overlap areas with figure 9. The James River flows east and south in the figure 10 southwest corner area. South of the figure 10 map area the James River turns to flow southeast and then turns to flow south (see figure 1). The Sheyenne River flows southeast and northeast in the figure 10 northeast quadrant. From the figure 10 map area the Sheyenne River after flowing northeast turns to flow east for a significant distance before turning to flow south (see figure 1). The Tiffany Flats area is the north-south continental divide and a close look at Tiffany Flats reveals several drainage routes, suggesting the continental divide can be defined even more specifically. Robinson Coulee is a named drainage route on Tiffany Flats and begins as a southeast-oriented stream and then makes a U-turn to flow northwest to join the Sheyenne River at its elbow of capture (where the southeast-oriented Sheyenne River turns to flow northeast). Note the southeast-oriented valley located immediately southeast of the northwest-oriented Robinson Coulee valley segment. That southeast-oriented valley continues southeast of the figure 10 map area and is linked to a south-oriented James River tributary. This evidence suggests the Sheyenne River valley upstream from the figure 10 Sheyenne River elbow of capture originally drained south to the James River and was subsequently captured by headward erosion of the Sheyenne River valley. Also, note the southeast-oriented stream in Columbia Township in the figure 10 southeast corner. From the figure 10 map area that stream turns to flow south to the south-oriented James River. That southeast-oriented stream is located on approximately the same alignment as the southeast-oriented Robinson Coulee headwaters, suggesting the southeast-oriented Robinson Coulee headwaters originally flowed southeast and south to the south-oriented James River valley. Note also how the southeast-oriented Robinson Coulee headwaters provide evidence southeast-oriented flood flow once moved across the hilly area seen in figure 9. The hilly area did not contain evidence of channels cut across it (except for the east-northeast-oriented Sheyenne River valley), which suggests the region may still have been ice-covered as southeast-oriented flood waters were moving across the figure 10 map area to the south-oriented James River valley. If so, this Tiffany Flats area may have been the north end of a south-oriented ice-walled and bedrock-floored tributary canyon or valley to the southeast-oriented Midcontinent Trench located to the southwest and west. Using that interpretation the slightly deeper Sheyenne River valley was able to erode an ice-walled and bedrock-floored valley west and southwest into the figure 10 map area to behead the southeast-oriented flood flow and to divert the water east, south, and then north to Hudson Bay.

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.