A geomorphic history based on topographic map evidence

The Cannonball River drainage basin is located in southwest North Dakota, USA. Although detailed topographic maps of the Cannonball River basin have been available for more than fifty years detailed map evidence has not previously been used to interpret Cannonball River drainage basin geomorphic history. The interpretation provided here is based entirely on topographic map evidence. Based on map evidence the Cannonball River drainage basin is interpreted to have been eroded during immense flood events, the first of which flowed on a topographic surface at least as high as the highest points in the present-day Cannonball River drainage basin, and which stripped the Cannonball River drainage basin bedrock layers as deep broad headcuts, often several kilometers in width, eroded headward along routes of the present-day southeast-oriented Cannonball River segment and its various southeast-oriented tributaries. Flood erosion ended when headward erosion of the deep north-oriented Little Missouri River headcut 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 southwest North Dakota Cannonball River drainage basin landform origins. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

• This essay is also exploring a paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and similar essays is a thick North American ice sheet, comparable in thickness to the present day Antarctic ice sheet, occupied approximately the North American region usually recognized to have been glaciated and through its weight and erosive actions created a “deep” North American “hole”, through its weight and deep erosion (and perhaps deposition) along major south-oriented melt water flow routes caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

• If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain southwest North Dakota Cannonball River drainage basin landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Cannonball River drainage basin description

The Cannonball River drainage basin is located in southwest North Dakota, USA. The east-oriented Cannonball River drainage basin drains to the south-oriented Missouri River and is bounded on the north by the east-oriented Heart River drainage basin and on the south by Grand River drainage basin. The north-oriented Little Missouri River drainage is to the west. East-oriented Cannonball River headwaters begin on the rim of the deep Little Missouri River valley indicating Little Missouri River valley headward erosion beheaded flow to the Cannonball River drainage basin. For much of its course the Cannonball River is a southeast-oriented stream, although there is an elbow of capture and the Cannonball River becomes a northeast-oriented stream before joining the south-oriented Missouri River. This elbow of capture is evidence southeast-oriented flow was captured when a deeper northeast-oriented valley eroded to the southwest. The Cannonball River enters the Missouri River as a barbed tributary, which is evidence the deep Missouri River valley eroded north to capture Cannonball River flow. Cedar Creek is a major Cannonball River tributary to the south. Cedar Creek headwaters also appear to have been beheaded by headward erosion of the deep north-oriented Little Missouri River valley. After flowing in a southeast direction Cedar Creek becomes an east-oriented stream and then turns northeast to flow to the Cannonball River elbow of capture indicating the northeast-oriented valley that captured the southeast-oriented Cannonball River also eroded further southwest to capture Cedar Creek flow. Most other major Cannonball River tributaries are oriented in a southeast direction although several have pronounced elbows of capture where they turn to become northeast-oriented before flowing to the southeast-oriented Cannonball River (one such elbow of capture is visible in figure 1 on an unnamed Cedar Creek tributary, other such elbows will be shown on some of the detailed maps which follow).

Cannonball River and Cedar Creek headwaters area

Figure 2: Cannonball River and Cedar Creek headwaters area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

The Cannonball River and the north branch of its major tributary, Cedar Creek, originate along the east slope of the Chalky Buttes-White Butte upland, which represents North Dakota’s highest elevation. Headwaters for both streams have a northeast orientation. After flowing in a northeast direction headwaters for both streams turn to flow parallel to each other in a southeast direction. The Cannonball River headwaters then make an abrupt turn to the northeast and diverge from the North Cedar Creek route, which continues in a southeast direction. After flowing northeast for approximately 30 km the Cannonball River turns again and flows in a southeast direction parallel to the Cedar Creek route until the two streams join approximately 120 km downstream (see figure 1). This divergence of two major drainage routes and their downstream convergence is strong evidence the two drainage routes evolved as part of a large-scale anastomosing channel complex. The magnitude of this anastomosing channel complex is such that only an immense flood covering most or all of southwest North Dakota could have created it. Further, the origin of both drainage routes at the east wall of North Dakota’s highest butte area suggests the flood waters came from west of the butte area on a topographic surface at least as high as the present-day butte tops and the butte east face represents a remnant of a flood-eroded headcut face or wall. Both Chalky Buttes and White Butte contain thick fossiliferous deposits of coarse-grained alluvium derived from distant western sources. The alluvium age and origin has been debated, although it represents flood deposited fill in what had probably been a previously eroded flood-carved valley, and the map evidence indicates continuing or further flood erosion stripped all of the surrounding bedrock, leaving the previously deposited flood-transported alluvium as a high butte area.

Northeast-oriented Cannonball River headwaters

Figure 3: Northeast-oriented Cannonball River headwaters. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

From its origin east of the Chalky Buttes area the Cannonball River (North Fork Cannonball River in figure 3) flows in a northeast direction on an upland topographic surface east of the deep north oriented Little Missouri River valley. The northeast-oriented Cannonball River segment is joined by southeast-oriented tributaries from the northwest and by northwest-oriented tributaries from the southeast, although interesting exceptions exist. This aligned drainage pattern suggests the northeast-oriented Cannonball River valley eroded southwest across multiple southeast-oriented flood flow routes to capture a southeast-oriented flood moving in multiple anastomosing channels and water at the northwest ends of the beheaded southeast-oriented flood flow routes reversed direction to create the modern-day northwest-oriented tributaries. Many of the southeast-oriented Cannonball River tributaries begin at or near the Little Missouri River valley rim. Philbrick Creek is a major Cannonball River tributary and it was probably eroded west and southwest to capture flood waters moving to the newly formed northeast-oriented Cannonball River segment. The northwest-oriented Little Missouri River tributary valley rim north of Amidon has a classic abandoned headcut shape and appears to have been fed by large volumes of reversed flow flood water moving to the northwest from the Cannonball River and North Cedar Creek headwaters area (see figure 2) and also moving north from west of Chalky Buttes. An interesting Cannonball River tributary meanders between the west-to-east oriented highway segment and northwest-oriented Little Missouri River tributary valley north of Amidon. This tributary was formed when north and northwest-oriented reversed flow floodwaters responsible for eroding the northwest-oriented headcut were captured by northeast-oriented Cannonball River valley headward erosion.

Philbrick Creek and Adobe Wall Creek

Figure 4: Philbrick Creek and Adobe Wall Creek. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Philbrick Creek and its major tributary Adobe Wall Creek begin at the deep north-oriented Little Missouri River valley rim as northeast-oriented streams and turn to flow east and then southeast to join the northeast-oriented Cannonball River where it turns to become a southeast-oriented stream. A northwest-to-southeast aligned drainage pattern is present on the upland topographic surface east of the deep Little Missouri River valley escarpment rim and is evidence the upland topographic surface was eroded by southeast-oriented flood waters. Those flood waters were captured in sequence by headward erosion of the northeast-oriented Cannonball River, headward erosion of the South and North Forks of Bull Creek (a Heart River tributary), and headward erosion of the deep north-oriented Little Missouri River valley. Third Creek, a Little Missouri River tributary, has eroded a west and south-oriented valley into the north-oriented Little Missouri River valley wall. That west and south-oriented Third Creek valley was eroded by reversed flow on east-oriented flood flow routes that were beheaded when the deep Little Missouri River valley was rapidly eroded southward. The size of the Third Creek valley provides a rough estimate of the immense volume of reversed flood flow that moved west and south into the newly eroded deep Little Missouri River valley. The northeast-oriented Philbrick Creek valley adjacent to the Third Creek valley rim was eroded as a shallow headcut when continued headward erosion of the shallow southeast-oriented Philbrick Creek valley captured and reversed the west-oriented flood waters that had previously been reversed to flow back into the newly eroded deep Little Missouri River valley.

Cannonball River-Philbrick Creek confluence

Figure 5: Cannonball River-Philbrick Creek confluence. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates where the northeast-oriented Cannonball River joins southeast-oriented Philbrick Creek and the combined flow continues as the southeast-oriented Cannonball River. The northeast corner of figure 5 shows southeast-oriented headwaters of northeast-oriented Antelope Creek, which flows to the Heart River. Multiple northeast-oriented through valleys crossing the Heart River-Cannonball River drainage divide suggest the Cannonball River turn from a northeast-orientation to a southeast-orientation is an elbow of capture where a southeast-oriented Cannonball River valley eroded headward to capture southeast-oriented flood water that was also being captured by an anastomosing complex of northeast-oriented Heart River tributary channels. A close look at the southeast-oriented Cannonball River valley reveals numerous dry valleys surrounding erosional residuals, which suggests the southeast-oriented Cannonball River valley also eroded northwestward as an anastomosing channel complex. In other words, the figure 5 Cannonball River elbow of capture evidence suggests a northeast-oriented anastomosing channel complex was captured by headward erosion of a southeast-oriented anastomosing channel complex. Such a capture could only take place during an immense flood and probably required an enormous surge of southeast-oriented flood water. Another measure of the volume of flood waters involved can be obtained from elevations of regional hills and buttes. Flood water channels are cut between these erosional residuals suggesting flood waters initially moved on a topographic surface at least as high as the tops of the present-day hills and buttes and were responsible for eroding the landscape we see today.

Thirtymile Creek headwaters region

Figure 6: Thirtymile Creek headwaters region. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Thirtymile Creek is the unnamed Cannonball River tributary in figure 1 originating near Lefor (between the Heart River and Cannonball River) and flowing southeast to join the southeast-oriented Cannonball River near Bentley. Figure 6 illustrates the Thirtymile Creek headwaters region. Note the multiple southeast-oriented headwaters streams and dry valleys. The multiple northwest-oriented streams in the figure 6 northwest corner flow to the northeast-oriented Antelope Creek, which in turn flows to the Heart River. This evidence suggests southeast-oriented flood waters moving to the southeast-oriented Thirtymile Creek-Cannonball River headcut were beheaded by headward erosion of the Heart River-Antelope Creek headcut. Northwest-oriented tributaries were formed as reversals of flood flow on northwest ends of beheaded southeast-oriented flood flow routes. North-oriented Heart River tributaries observable east of Lefor had eroded south to capture the southeast-oriented flood waters, but did not progress further because Antelope Creek valley headward erosion beheaded the southeast-oriented flood flow. Evidence visible in figure 6 demonstrates Heart River tributaries captured southeast-oriented flood waters moving to the Cannonball River. Note how south of Lefor an anastomosing channel complex has been carved in and around the cluster of present-day buttes. Anastomosing channel complexes are evidence of immense floods. The deep channels carved between the buttes are evidence the flood waters initially flowed on a topographic surface at least as high as the present-day butte tops and carved the topographic surface we see today. The amount of erosion required to reduce the regional topography so the present-day buttes could become erosional residuals provides a rough estimate of the magnitude of the flood involved.

Cannonball River valley anastomosing channel complex

Figure 7: Cannonball River valley anastomosing channel complex. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Both upstream and downstream from New England (ND) the Cannonball River valley is paralleled by an anastomosing complex of southeast-oriented through valleys. Figure 7 illustrates an area immediately upstream from New England. Northwest to southeast oriented through valleys link the northeast-oriented Cannonball River tributaries. Note how this combination of valleys has created numerous erosional residuals, several of which are streamlined in a northwest to southeast direction. Each of the valleys was carved by water erosion and the parallel southeast-oriented valleys can only be explained by having water initially flowing in all of the southeast-oriented valleys at the same time and headward erosion of the northeast-oriented valleys requires water spilling out of southeast-oriented valleys to flow northeast to other southeast-oriented valleys. As some valleys were eroded deeper they captured flow from less deep valleys leaving those less deep valleys as dry valleys. Eventually the present-day southeast-oriented Cannonball River valley captured flow from all of the parallel valleys. Similar through valley mazes surround erosional residuals throughout the Cannonball River drainage basin. Generally there is a northwest to southeast valley orientation, although northeast-oriented valleys are also present. Evidence suggests present-day stream valleys systematically captured flood flow from the less deep flow routes. The landscape we see today was carved by final flood flow events before the flood flow was beheaded and diverted to flow elsewhere.

Plum Creek elbow of capture

Figure 8: Plum Creek elbow of capture. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

One of the more interesting Cannonball River drainage basin elbows of capture is the Plum Creek elbow of capture where the northwest and north-oriented Plum Creek has been captured by the east oriented Cedar Creek. Note how a ridge separates the east oriented Cedar Creek valley from the extensive lowland where the northwest oriented Plum Creek headwaters are located. The northwest and north-oriented Plum Creek flows north in a north-oriented valley or water gap cut through that ridge. Other than northwest-oriented Plum Creek headwaters the southern lowland appears to be lacking the pronounced northwest to southeast drainage orientation found elsewhere in the Cannonball River drainage basin, but is drained to the east by east oriented Hay Creek (figure 8 southeast corner along highway). Beyond the map area the east-oriented Hay Creek turns to become a north-oriented stream and flows to Cedar Creek (see figure 9 for elbow of capture). The map evidence (figure 8) suggests the east-oriented Cedar Creek valley eroded west to behead a south and southeast-oriented flood flow route where water was captured by the east- and north-oriented Hay Creek headcut and diverted to east-oriented Cedar Creek. Northwest and north-oriented Plum Creek was formed when southeast-oriented flood flow on the northwest end of this beheaded flood flow route reversed direction to flow back after the deep Cedar Creek valley eroded headward and beheaded southeast flow. This evidence illustrates the magnitude of multiple channels used by flood waters that eroded the Cannonball River drainage basin. Flood waters in the Cedar Creek drainage basin were of sufficient volume they flowed south and southeast to erode the Plum Creek water gap and then return to the Cedar Creek via the Hay Creek route at the same time they spilled east to carve the east-oriented Cedar Creek valley.

Hay Creek elbow of capture

Figure 9: Hay Creek elbow of capture. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Southeast-oriented Hay Creek headwaters are shown in figure 8. Figure 9 shows Hay Creek further east where it has turned to be an east-northeast-oriented stream and then turns again to become a north oriented Cedar Creek tributary. Note the southeast-oriented and northwest oriented tributaries. As shown in figure 8 large volumes of flood water flowed south and southeast from what is today the western Cedar Creek drainage basin area along the present-day northwest and north oriented Plum Creek route. The north and northeast-oriented Hay Creek valley eroded south and southwest to capture at least some of that south and southeast-oriented flood water. In other words the Plum Creek-Hay Creek route was for a period of time moving water from what is today the western Cedar Creek drainage basin to the eastern Cedar Creek valley. At the same time flood water must also have been flowing east along the shorter present-day Cedar Creek valley route and that water eroded the deep Cedar Creek valley headward. Headward erosion of the deep Cedar Creek valley beheaded and captured flood waters moving on the longer Plum Creek-Hay Creek route. Flood waters already present at the northwest end of the Plum Creek-Hay Creek route reversed direction to flow northwest and north to the newly eroded deep Cedar Creek valley to create the present-day Plum Creek drainage basin. At the same time flood waters further along on the Plum Creek-Hay Creek route continued to flow east and then north to reach the eastern Cedar Creek valley. This Plum Creek-Hay Creek route is just one example of how flood waters created and then beheaded anastomosing channels.

Coon Creek, Goose Creek and Coal Bank Creek drainage basin region

Figure 10: Coon Creek, Goose Creek and Coal Bank Creek drainage basin region. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

The Cannonball River valley downstream from New England contains many parallel and anastomosing channels and streamlined erosional residuals suggesting an immense southeast-oriented flood eroded the region. For example note how Coon Creek flows north and northeast and then within Cannonball River valley turns east and joins the meandering but southeast-oriented Cannonball River as a barbed tributary by flowing northwest in what was once a southeast-oriented channel. Also note how northeast-oriented Goose Creek turns southeast to flow parallel to the Cannonball River in a southeast-oriented through valley before joining Coal Bank Creek. Coal Bank Creek after flowing northeast does not immediately enter the southeast-oriented Cannonball River, but instead flows in a southeast-oriented through valley paralleling the Cannonball River. Southeast-oriented Chanta Peta Creek (a Cedar Creek tributary) flows southwest of East Rainy Butte. Coal Bank Creek itself begins near the East Rainy Butte base and flows in a meandering east-southeast oriented direction before turning northeast to enter the Cannonball River valley. The northeast-oriented Coal Bank Creek, Goose Creek and Coon Creek valleys probably eroded headward from a deep southeast-oriented Cannonball River valley eroding northwest to capture flood water from northwest of East Rainy Butte. The height of East Rainy Butte suggests flood waters originally flowed on a topographic surface at least that high and subsequently lowered the surrounding landscape to what we see today. This East Rainy Butte evidence provides a hint of the enormity of the southeast-oriented flood involved.

Heart River-Chanta Peta Creek drainage divide

Figure 11: Heart River-Chanta Peta Creek drainage divide. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figures 10-13 illustrate the large through valley extending in a southeast direction from the Heart River elbow of capture to the Cannonball River and beyond. Southeast-oriented Chanta Peta Creek flows to the Cannonball River. The southeast-oriented through valley is of sufficient size and depth that it must have been eroded by a large amount of southeast-oriented water and is a segment of an extensive southeast-oriented through valley that also extends further northwest and southeast. Previous researchers have named the through valley the Killdeer-Flasher-Shields channel and have suggested it once served as an ice marginal diversion trench . Supporting this interpretation is evidence that abundant glacial erratics, but no fine-grained glacial drift, can be found north and east of the northwest to southeast oriented through valley while south and west of the through valley glacial erratics are rare. While an ice sheet margin may have been present and may have played a role in locating the through valley position, landscapes between the through valley and the present-day Missouri River valley are flood eroded. Further, if the through valley served as an ice marginal diversion channel as previously suggested, there is no reason why the present-day Missouri River valley should have formed. The through valley can better be explained in the context of a flood-eroded landscape.

Chanta Peta Creek-Dogtooth Creek drainage divide

Figure 12: Chanta Peta Creek-Dogtooth Creek drainage divide. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 12 illustrates the southeast extension of the large through valley shown in figure 11. Chanta Peta Creek (east) as seen in figure 12 is a Dogtooth Creek tributary and Dogtooth Creek flows to the northeast-oriented Cannonball River. South of Flasher the large valley splits with one branch going west of Rattlesnake Hill while the branch used by Chanta Peta Creek (east) goes east of Rattlesnake Hill (providing evidence that the valley was carved as part of an anastomosing channel complex). Today the western branch crosses the Chanta Peta Creek (east)-Louse Creek drainage divide and Louse Creek uses part of the western branch to flow southeast to the large east-oriented valley south of Rattlesnake Hill linking the two through valley branches. Louse Creek then flows east to the Chanta Peta Creek (east) southeast-oriented valley. Extending south from west to east-oriented Louse Creek valley is a continuation of the northwest to southeast-oriented through valley, which crosses the Louse Creek-Dogtooth Creek drainage divide. A Louse Creek tributary flows north-northwest in that through valley’s north end. The through valley continues south from Dogtooth Creek to the northeast-oriented Cannonball River valley and beyond, although Dogtooth Creek flows in an east-northeast direction to reach the northeast-oriented Cannonball River valley. The northwest to southeast-oriented through valley crosses at least five present-day drainage divides. These drainage divide crossing are not consistent with previous interpretations that this through valley originated as an ice-marginal diversion channel. If the through valley had been formed as an ice-marginal diversion channel the Missouri River should be flowing in it today. Since the Missouri River is located in another valley this northwest to southeast-oriented through valley must have been part of a massive anastomosing channel complex.

Dogtooth Creek-Cannonball River-Porcupine Creek drainage divides

Figure 13: Dogtooth Creek-Cannonball River-Porcupine Creek drainage divides. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 13 continues to follow the large northwest to southeast oriented through valley further to the southeast (from figures 11 and 12). The through valley links the east-northeast oriented Dogtooth Creek valley with the northeast oriented Cannonball River valley and then links the Cannonball River valley with the northeast and then southeast-oriented Porcupine Creek valley. Note northwest to southeast-alignment of tributaries flowing to the major valleys. As already noted the through valley could not have served as a temporary ice-marginal diversion channel, because if it had today the Missouri River would be flowing in it. The through valley had to be eroded before the northeast-oriented Porcupine Creek, the northeast-oriented Cannonball River, the east-northeast-oriented Dogtooth Creek, the northeast-oriented Heart River, and the northeast-oriented Knife River valley headcuts eroded headward to systematically capture and divert southeast-oriented flow that carved the northwest to southeast oriented valley. Headward erosion of those northeast-oriented headcuts could only have occurred if a large southeast-oriented flood was captured and diverted to flow northeast. Today the Missouri River flows south so the south-oriented Missouri River headcut had to subsequently erode northward to capture the northeast-oriented flood water. These multiple captures occurring over a large region of easily eroded bedrock can only be explained by immense floods first moving in large-scale anastomosing channel complexes oriented in one way and then being captured by massive anastomosing channel complexes oriented in another direction.

Porcupine Creek drainage basin

Porcupine Creek has a unique drainage route. Porcupine Creek  (see figure 14) begins as a underfit stream flowing northwest in the large through valley extending northwest to the Cannonball River, Heart River and Knife River valleys. However, before reaching the northeast-oriented Cannonball River valley, Porcupine Creek turns northeast and then after some distance turns southeast, east and southeast to reach the Missouri River. Interestingly southeast of the northwest oriented Porcupine Creek headwaters, in the same large northwest to southeast-oriented through valley, are headwaters of the southeast-oriented Oak Creek, which follows the large through valley southeast to its confluence with the Missouri River (located near the where the Grand River joins the Missouri River). In other words, the northwest oriented Porcupine Creek headwaters represent a reversal of flow direction in the large northwest to southeast-oriented through valley. Further, a northeast-oriented tributary joining Porcupine Creek where it turns from flowing southeast to flowing east. An east oriented through valley links the northwest to southeast-oriented through valley between the Cannonball River and Porcupine Creek valleys with headwaters of that northeast-oriented Porcupine Creek tributary suggesting east and southeast-oriented water once moved along that route as well. The simplest way to explain this unusual Porcupine Creek route and the related through valleys is to think in terms of multiple flood-eroded southeast-oriented valleys as in a large-scale anastomosing channel complex that were captured systematically by headward erosion of deeper northeast-oriented flood-eroded headcuts, and then the northeast-oriented valleys were next captured by headward erosion still deeper south and southeast-oriented valleys.

Cannonball River elbow of capture

Figure 14: Cannonball River elbow of capture. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Like the Heart and Knife Rivers the southeast-oriented Cannonball River makes an abrupt turn to flow northeast before joining the south-oriented Missouri River. Figure 14 shows the southeast-oriented Cannonball River joining the east and northeast-oriented Cedar Creek to flow in a northeast direction. Southeast-oriented and northwest-oriented tributaries flow to the northeast-oriented Cedar Creek-Cannonball River valley. This northwest to southeast drainage alignment is also present in the Porcupine Creek drainage basin located between the northeast-oriented Cedar Creek-Cannonball River and the south-oriented Missouri River and is evidence the same southeast-oriented floods that crossed the western Cannonball River drainage basin also crossed the eastern Cannonball River drainage basin. The northeast-oriented Cedar Creek-Cannonball River valley eroded southwest to systematically capture and behead multiple southeast-oriented flood flow routes. The deeper south-oriented Missouri River valley headcut subsequently eroded north to capture flow moving in the northeast-oriented Cannonball River valley. Evidence seen in figure 14, like evidence in the Heart, Knife, and other regional river drainage basins describes an immense southeast-oriented flood that was captured and diverted to flow northeast, and then for some reason was redirected to flow south again. The northeast-oriented headcuts that captured the southeast-oriented flood waters and diverted those flood waters to the northeast originated north and east of the Missouri Escarpment, suggesting the flood waters spilled over a stagnant ice barrier occupying the present-day Missouri Coteau region to reach what must have been an ice-free area north and east of the Missouri Escarpment and eroded deep valleys headward.

Summary

• The Cannonball River southeast-oriented headwaters originate at or near the rim of the deep north-oriented Little Missouri River valley. This evidence suggests the deep Little Missouri River valley headcut eroded south to capture and behead multiple southeast-oriented flood flow routes headed for the Cannonball River drainage basin. The multiple flow routes can best be explained by an anastomosing channel complex created by an immense flood event. Evidence throughout the Cannonball River drainage basin supports this flood interpretation. Included in such evidence is the presence of a northwest to southeast oriented drainage alignment, numerous barbed tributaries and elbows of capture, and mazes of through valleys, which can best by explained in the context of both large-scale and small-scale anastomosing channel complexes.

• The earliest flood event for which we have evidence occurred on a topographic surface at least as high as the tops of the present-day buttes. Several buttes, including White Butte, the highest point in North Dakota, are composed of coarse-grained alluvium, which includes rock types derived from Yellowstone River drainage basin source areas. This alluvium contains fossils and underlies other fossil containing rock layers and is usually considered to be Oligocene in age. However, the alluvium origin suggests transport over great distances by large volumes of water followed by rapid deposition. Such an origin is not consistent with usual Oligocene interpretations. It is quite possible, in fact probable, that the floods responsible for transporting the alluvium were also responsible for eroding deep valleys in which the alluvium was deposited and for subsequently stripping the surrounding landscape to produce the present-day Cannonball River drainage basin landscape where the alluvium deposits and other resistant rock materials remain as isolated erosional residuals, remnants of a previous topographic surface.

• Stripping of western Cannonball River drainage basin bedrock layers probably occurred as deep broad headcuts, several kilometers in width, eroded northwest along routes of the southeast-oriented Cannonball River and major southeast-oriented Cannonball River tributaries, including Thirtymile Creek, Chanta Peta Creek (west), North Cedar Creek and Cedar Creek. At the same time headward erosion of these broad southeast-oriented headcuts was stripping the landscape, deeper northeast-oriented headcuts eroded south and west from the Missouri Escarpment, sliced what may have been deep narrow ice-walled and bedrock floored valleys across stagnant ice occupying the present-day Missouri Coteau region, and eroded headward into southwest North Dakota to capture the southeast-oriented flood flow. Upsteam from elbows of captures the deep valleys then eroded northwest to deepen existing southeast-oriented flood flow routes. As water from parallel southeast-oriented flood routes spilled northeast into the deepened valleys, northeast-oriented tributary valleys eroded southwest and captured the parallel southeast-oriented flood flow. Headward erosion of the deep north-oriented Little Missouri River valley then captured the southeast-oriented flood flow, and the beheaded Cannonball River drainage basin 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.