This overview essay provides highlights from more detailed essays using topographic map evidence to illustrate and interpret Black Hills landform origins. Detailed essays can be found under Black Hills region on this website’s sidebar category list. The Black Hills are highland region located in western South Dakota and northeast Wyoming and rise 1000 meters or more above the surrounding plains. The Black Hills upland is drained by tributary streams to the Cheyenne River and its major tributary, the Belle Fourche River. Both the Cheyenne River and Belle Fourche River originate west of the Black Hills in northeast Wyoming. The Cheyenne River flows in a northeast and southeast direction to reach the Black Hills southwest flank and then flows in a southeast direction to the Black Hills south end. From the Black Hills south end the Cheyenne River flows in a northeast direction to join the southeast oriented Missouri River. The Belle Fourche River flows in a northeast direction to the Black Hills north end and then turns to flow in a southeast and east direction to join the northeast-oriented Cheyenne River east of the Black Hills. Detailed essays describing all major present day Black Hills drainage divides provide evidence an abandoned southeast-oriented anastomosing channel complex crosses what is today the Black Hills upland region. Evidence for this abandoned anastomosing channel complex includes through valleys eroded into the Black Hills upland surface which today link north-oriented Belle Fourche River tributary valleys with south, southeast, and east-oriented Cheyenne River tributary valleys. This abandoned anastomosing channel complex provides evidence of an immense southeast-oriented flood prior to Black Hills uplift and/or prior to deep erosion of regions surrounding the Black Hills. These through valleys and a northwest-southeast orientation of many Cheyenne and Belle Fourche River tributaries suggests headward erosion of a deep Cheyenne River valley around the Black Hills south end and subsequent headward erosion of a deep Belle Fourche River valley around the Black Hills north end systematically captured a massive southeast-oriented flood which had been flowing across the Black Hills region and diverted the flood waters to the northeast. Flood waters were derived from a rapidly melting thick North American ice sheet, which had been located in a deep “hole” formed in the North American continent surface by deep glacial erosion and/or crustal warping caused by the ice weight. Emergence of the Black Hills upland occurred as flood waters were eroding the region and was the result of either deep flood water erosion of surrounding regions and/or of crustal uplift.

Figure 1: Black Hills location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Western South Dakota and northeastern Wyoming Black Hills drainage history

The Black Hills can be considered to be a Rocky Mountain outlier located in western South Dakota and northeast Wyoming and rise more than 1000 meters above the surrounding plains. The entire Black Hills uplift region is included in the Cheyenne River drainage basin. The Cheyenne River originates south and west of the Black Hills and flows in a northeast, southeast, and northeast direction to the Black Hills southwest margin and then flows in a southeast direction to the Black Hills south end. From the Black Hills south end the Cheyenne River flows in a northeast direction to eventually join the southeast oriented Missouri River (east of the figure 1 map area). The Belle Fourche River is a major Cheyenne River tributary, which also originates west and south of the Black Hills and which flows in a northeast direction past Devils Tower and Hulett, Wyoming to the Black Hills north end and then abruptly turns to flow in a southeast and east direction to join the Cheyenne River east of the Black Hills. Detailed essays found under Black Hill region on the sidebar category list use topographic map evidence to interpret the drainage history of drainage divides in the Black Hills upland region. All streams in the Black Hills upland region are tributary to either the northeast and southeast oriented Belle Fourche River, which flows around the Black Hills north end, or to the southeast and northeast oriented Cheyenne River, which flows around the Black Hills south end. The fact all Black Hills drainage systems are included in the same northeast-oriented Cheyenne River drainage basin is significant and suggests all Black Hills streams and drainage divide areas have a common origin.

Figure 2; Belle Fourche River-Cheyenne River drainage divide area west of the Black Hills. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 2 illustrates Belle Fourche River and Cheyenne River routes and tributaries west of the Black Hills in northeast Wyoming. Weston County is a Wyoming county. Campbell County is located west of Weston County. Niobrara County is located south of Weston County. The north to south oriented Wyoming-South Dakota state line is located along the Weston County east border and is near the figure 2 east edge. Green areas on figure 2 are National Forest lands, which generally are located in the Black Hills upland region. The Belle Fourche River flows in a northeast direction from the figure 2 west center edge in Campbell County to the figure 2 north center edge just east of the Campbell County east border. The Cheyenne River flows in a northeast direction into southern Weston County and then turns to flow in a southeast direction into northern Niobrara County. In northern Niobrara County the Cheyenne River turns again to flow in a northeast and east direction to the Black Hills upland southwest margin (near the Wyoming-South Dakota state line in the figure 2 southeast corner area) and then flows in a southeast direction to the figure 2 south edge (near the southeast corner). Note how Belle Fourche River tributaries from the northwest are generally oriented in a southeast direction and from the southeast are generally oriented in a northwest direction. Also note how Cheyenne River tributaries from the northwest are generally oriented in a southeast direction. This southeast and northwest orientation of Belle Fourche River and Cheyenne River tributaries provides evidence the Cheyenne River valley eroded headward to capture multiple southeast-oriented flood flow channels, such as might be found in a southeast-oriented anastomosing channel complex, and then Belle Fourche River valley headward erosion captured the same southeast-oriented flood flow channels. The northwest-oriented Belle Fourche River tributary valleys were eroded by reversals of flood flow on northwest ends of beheaded flood flow channels. Because flood flow channels were beheaded one channel at a time and because the flood flow channels were anastomosing (interconnected) reversed flood flow on a newly beheaded flood flow channel could capture flood flow from channels further to the southwest. Such captures of flood water from the southwest helped erode the northwest-oriented valleys. Essays found under Powder River, Little Missouri River, Belle Fourche River and Cheyenne River on the sidebar category list provide additional evidence for southeast-oriented flood flow in the region west of the Black Hills, including through valleys linking northwest-oriented Belle Fourche River tributary valleys with southeast-oriented Cheyenne River tributary valleys and topographic maps illustrating more detailed evidence of Belle Fourche and Cheyenne River tributary orientations. .

Figure 3 illustrates the Belle Fourche River route and tributary orientations north of the Black Hills upland region. Lawrence, Butte, and Meade are South Dakota counties and Crook County (west of Meade County) is located in the Wyoming northeast corner (Weston County is located south of Crook County). Again green areas are National Forest lands and are generally located in Black Hills upland regions, which extend into northeast Wyoming. The north to south oriented Wyoming-South Dakota state line is located between Crook County and Lawrence County. The Belle Fourche River flows in a northeast direction in the figure 3 northwest corner almost to the figure 3 north edge and then turns abruptly to flow in a southeast direction across the Butte County southwest corner and then to the figure 3 east edge (south half). The northeast oriented river located in the figure 3 northwest corner directly northwest of the Belle Fourche River is the Little Missouri River, which continues to flow in a northeast and north direction into west-central North Dakota before turning to flow in an east direction to join the southeast oriented Missouri River. Note how the Belle Fourche River flows in a northeast direction along the Black Hills northwest flank and then flows in a southeast direction along the Black Hills northeast flank. Also note how most Belle Fourche River tributaries from the north and west are oriented in a southeast direction. This southeast orientation of a significant Belle Fourche River segment and many Belle Fourche River tributaries provides further evidence of an immense southeast-oriented flood, which completely surrounded the Black Hills upland region. The southeast-oriented Belle Fourche River tributaries are relics of the southeast-oriented anastomosing flood flow channels captured by headward erosion of the deep northeast, southeast and east-oriented Belle Fourche River valley as it eroded headward along the Black Hills northeast flank and then along the Black Hills northwest flank. Headward erosion of the northeast and north oriented Little Missouri River valley beheaded flood flow channels supplying flood waters to the newly eroded northeast and southeast-oriented Belle Fourche River valley. Essays found under Little Missouri River on the sidebar category list illustrate topographic map evidence showing how Little Missouri River valley headward erosion captured the southeast-oriented flood flow. West of the Little Missouri River (and west of the figures 2 and 3 map areas) is the north and northeast-oriented Powder River and essays found under Powder River on the sidebar category list describe how headward erosion of the Powder River valley beheaded flood flow channels to the newly eroded Little Missouri River valley and to the newly eroded Belle Fourche River valley.

Figure 4: Cheyenne River route and tributary orientations south and east of the Black Hills. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 4 illustrates the Cheyenne River route and tributary orientations south and east of the Black Hills. Pennington, Custer, Fall River, and Shannon are South Dakota counties and the north to south oriented Wyoming-South Dakota state line is located near the figure 4 west edge. Green areas again are National Forest lands and are generally located in Black Hills upland regions, which in Pennington and Custer Counties can be 1000 meters or higher than the plains to the south and east. The red area in Custer County is Custer State Park in the north and Wind Cave National Park in the south, both of which are located in the Black Hills upland area. The red area in the figure 4 east half is Badlands National Park. The orange area in Shannon County is the Pine Ridge Indian Reservation. Note how the Cheyenne River flows into the Fall River County northwest corner and then flows in a southeast direction along the Black Hills southwest margin and at the Black Hills south end turns to flow in a northeast direction to the Fall River County northeast corner and then to the figure 4 north edge (near northeast corner). The White River is the northeast-oriented river in Shannon County flowing to the figure 4 east edge (near the Shannon County north border). Note how Cheyenne River tributaries from the northwest are generally oriented in a southeast direction and from the southeast are generally oriented in a northwest direction. Also note how White River tributaries have the same southeast and northwest orientations. Further, note how southeast-oriented Cheyenne River tributaries originate in the Black Hills upland region. The tributary orientations provide evidence the White River valley eroded headward across multiple southeast-oriented flood flow channels such as might be found in a southeast-oriented anastomosing channel complex. The Cheyenne River tributary orientation provide evidence the Cheyenne River valley eroded headward across the same southeast-oriented anastomosing channel complex and beheaded flood flow routes to the newly eroded White River valley. The fact the southeast-oriented Cheyenne River tributaries originate in the Black Hills upland region provides evidence the southeast-oriented flood was flowing across the Black Hills upland region. If so, at that time the Black Hills upland region did not stand high above the surrounding region as it does today. The Black Hills upland region may have emerged as flood waters deeply eroded the surrounding region, which means the Cheyenne River and Belle Fourche River valleys were eroded as deep valleys into easily eroded material surrounding the Black Hills erosion resistant core materials. Or, it is possible the Black Hills upland region was uplifted as flood waters flowed across the region and/or it is possible there was a combination of deep erosion and of Black Hills uplift as flood waters flowed across the region.

Figure 5: Belle Fourche River and Cheyenne River routes and tributary orientations east and north of the Black Hills upland region. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 5 completes our circle around the Black Hills upland region and illustrates the Cheyenne River and Belle Fourche River routes and tributary orientations in the region east and north of the Black Hills upland region. Meade and Pennington Counties are the two South Dakota counties shown. Green areas in the figure 5 southwest quadrant are National Forest lands located in the Black Hills upland region. The orange area in the figure 5 northeast corner is Cheyenne River Indian Reservation land and the red area along the figure 5 south edge is the Badlands National Park northern region. The Cheyenne River flows in a north-northeast direction from the figure 5 south center edge and then forms the Meade County-Pennington County border before flowing in a northeast direction to the figure 5 east edge (north half). East of the figure 5 map area the Cheyenne River flows in a northeast direction to join the southeast-oriented Missouri River. The Belle Fourche River flows in a southeast direction from the figure 5 northwest corner area to the figure 5 center area and then turns to flow in an east and east-northeast direction to join the Cheyenne River in the figure 5 east center area. Note how almost all Belle Fourche River tributaries from the north are oriented in a southeast direction, providing evidence headward erosion of the Belle Fourche River valley captured multiple southeast-oriented flood flow channels such as might be found in a southeast-oriented anastomosing channel complex. Also note how Cheyenne River tributaries from the south and east are generally oriented in a northwest direction, providing evidence Cheyenne River valley headward erosion beheaded multiple southeast-oriented flood flow channels and flood waters on northwest ends of the beheaded flood flow channels reversed flow direction to erode northwest-oriented Cheyenne River tributary valleys. Figures 2-5 have provided evidence for immense southeast-oriented floods which flowed around the present day Black Hills upland also which flowed across the Black Hills upland region. Because the Black Hills upland region today stands 1000 meters or higher than the surrounding regions and Black Hills peaks rise even higher readers may be skeptical about any interpretation of this evidence which requires a large flood to flow across the Black Hills upland region. The Black Hills landform origins detailed essays provide  topographic map evidence of Black Hills upland drainage divide evidence which can only be explained in the context of southeast-oriented floods which flowed across the present day Black Hills upland region, including across what are today some of the highest Black Hills regions. Figures 6, 7, and 8 of this overview essay illustrate examples of that evidence.

Figure 6: Topographic map illustrating through valleys on Black Hills upland surface linking northwest oriented East Spearfish Creek (flowing to north-oriented Spearfish Creek and then to Belle Fourche River north of Black Hills) with southeast-oriented North Fork Rapid Creek and northeast-oriented Elk Creek (flowing to northeast-oriented Cheyenne River east of Black Hills). United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 6 illustrates anastomosing through valleys eroded across the high Black Hills upland surface. The northwest-oriented stream flowing to the figure 6 northwest corner is East Spearfish Creek, which north and west of figure 6 flows to north-oriented Spearfish Creek, which joins the southeast-oriented Belle Fourche River north of the Black Hills. The north-oriented stream north of Dumont is Whitewood Creek, which is another Belle Fourche River tributary. The northeast-oriented stream flowing to the figure 6 east edge (north half) is Elk Creek, which east of figure 6 turns to flow in a southeast and east direction to eventually join the northeast-oriented Cheyenne River east of the Black Hills. The southeast-oriented stream originating near Dumont in the figure 6 southeast quadrant and flowing to the figure 6 south edge (east half) is the North Fork Rapid Creek, which south of the figure 6 map area joins east-oriented Rapid Creek, which flows to the northeast-oriented Cheyenne River east of the Black Hills. The figure 6 map contour interval is 20 feet and the through valley linking the northwest-oriented East Spearfish Creek valley with the southeast-oriented North Fork Rapid Creek valley has an elevation of between 6140 and 6160 feet. A hill immediately to the north rises to more than 6400 feet and a hill to the south rises to more than 6500 feet. In other words the through valley is at least 240 feet deep and may have been even deeper when eroded. Further, the through valley is interesting because a through valley now drained to the northwest by Keough Draw parallels the northwest-oriented East Spearfish Creek through valley. In addition to this northwest-southeast oriented through valley a north-south oriented through valley links the north-oriented Whitewood Creek valley with the southeast-oriented North Fork Rapid Creek valley. The elevation of this through valley floor is hard to read on figure 6, but appears to be slightly higher than 6200 feet. Hills on either side of the through valley rise to elevations greater than 6400 feet. Still another through valley is located in the northwest corner of section 9 (in the figure 6 southeast quadrant) and links the southeast-oriented North Fork Rapid Creek valley with the northeast-oriented Elk Creek valley. The floor of this through valley has an elevation of between 6140 and 6160 feet and hills on either side rise to elevations greater than 6400 feet. These through valleys are water eroded features and only make sense in the context of a flood eroded anastomosing channel complex eroded into the Black Hills upland surface.

Figure 7: Topographic map illustrating through valleys on Black Hills upland surface linking north-oriented Spearfish Creek (flowing to Belle Fourche River north of the Black Hills) with east-oriented Rapid Creek (flowing to Cheyenne River east of the Black Hills). United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 7 provides an example of evidence suggesting anastomosing southeast-oriented flood flow channels were eroded into the Black Hills upland surface and illustrates the drainage divide between north-oriented Spearfish Creek, which flows to the Belle Fourche River north of the Black Hills, and southeast-oriented Rapid Creek, which flows to the Cheyenne River east of the Black Hills. Northwest-oriented Clayton Draw in the figure 7 northwest quadrant drains to north-oriented Spearfish Creek as do other north-oriented valleys in the figure 7 northwest quadrant. East-southeast and south-southeast oriented South Fork Rapid Creek can be seen in the figure 7 south center. East-oriented Tilson Creek in the figure 4 northeast quadrant is another Rapid Creek tributary. Note how Clayton Draw is linked by through valleys with both the south-southeast oriented South Fork Rapid Creek valley and the east-oriented Tilson Creek valley. The spot elevation at the Clayton Draw-South Fork Rapid Creek drainage divide on the through valley floor is 6604 feet and hills on either of the valley rise to elevations greater than 6740 feet (the map contour interval is 20 feet). In other words the through valley, which is a water eroded valley, is approximately 140 feet deep. Note another through valley just to the north in the northwest corner of section 28, which has a higher elevation, but is also a water eroded through valley. Also north of Besant Park along the figure 7 north edge another through valley links the south- and east-oriented Rapid Creek valley with the north-oriented Spearfish Creek valley. And the list of through valleys in the figure 7 map area could continue and by enlarging the map area more through valleys could be found. The through valleys provide evidence of multiple anastomosing flood flow channels eroded into the Black Hills upland surface by an immense southeast-oriented flood which flowed across what are now the high Black Hills. Flood waters were flowing in a southeast direction to what was then the actively eroding and deep northeast-oriented Cheyenne River valley, which at that time was eroding headward in the area east of the Black Hills. At that time the deep Belle Fourche River valley did not exist. Headward erosion of the deep Belle Fourche River valley and its north-oriented tributary valleys, such as the Spearfish Creek valley, captured southeast-oriented flood flow and diverted flood waters in a north direction to the newly eroded Belle Fourche River valley.

Figure 8: Through valleys in high Black Hills (linking northwest-oriented Cold Springs Creek with southeast-oriented Castle Creek) eroded across the Belle Fourche River-Cheyenne River drainage divide. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 8 provides still more evidence south and/or southeast-oriented flood waters crossed what is now the high Black Hills upland surface. The northwest and north-oriented streams in the figure 8 northern third are headwaters of northwest-oriented Cold Springs Creek, which flows to north-oriented Sand Creek, which in turn flows to the northeast and north-oriented Redwater River, which reaches the Belle Fourche River at Belle Fourche, South Dakota, which is located north of the Black Hills. South and southeast-oriented drainage in the figure 8 southeast quadrant are Castle Creek headwaters, which eventually reach east-oriented Rapid Creek, which flows to the northeast-oriented Cheyenne River east of the Black Hills. Northwest and southeast-oriented drainage in the figure 8 southwest quadrant represents headwaters of south oriented Redbird Creek and south oriented Stockade Beaver Creek, both of which flow in a south direction to join the southeast-oriented Cheyenne River south of the Black Hills. Note how these diverging drainage systems are linked by well-defined through valleys eroded into the Black Hills upland surface. The figure 8 contour interval is 20 feet and the floor of the through valley linking the northwest-oriented Cold Springs Creek valley with the southeast-oriented Castle Creek valley has an elevation of 6847 feet while hills on either side of the through valley rise to elevations greater than 7000 feet. In other words a 150-foot plus deep water eroded through valley links the present day Belle Fourche River drainage basin with the northeast-oriented Cheyenne River drainage basin. Study of the figure 8 map area reveals other similar through valleys linking the north-oriented Cold Spring Creek valleys with the south oriented Redbird Creek and Stockade Beaver Creek valleys. In other words, there is not just one through valley, but there are several through valleys such as might be found in a large-scale south-oriented flood formed anastomosing channel complex. These through valleys provide further evidence a south- and/or southeast-oriented flood crossed what is today a high Black Hills upland surface.

• Why would immense southeast-oriented floods be flowing across what is now the high Black Hills upland surface and how could those southeast-oriented flood waters flow across what are today high elevations? Black Hills region drainage history began with development of a North American ice sheet comparable in size to the present day Antarctic Ice Sheet, if not larger. The ice sheet was thick, probably several kilometers thick, and was located in a deep “hole”, which the ice sheet had formed by a combination of deep glacial erosion and crustal warping caused by the ice sheet weight. When at its maximum size the ice sheet stood high above the pre-glacial surface, but also had roots that extended well below the pre-glacial surface, which no longer exists. The Black Hills were probably located south and west of ice sheet’s southwest margin, although evidence for the ice sheet’s southwest margin has probably been removed by deep melt water flood erosion. The pre-glacial surface under the ice sheet was completely destroyed by deep glacial erosion and the pre-glacial surface adjacent to the ice sheet and elsewhere on the North American continent was deeply eroded by deep melt water flood erosion and was also probably significantly altered by crustal warping caused by the thick North American ice sheet presence.

• Events important to Black Hills drainage history began as the ice sheet was rapidly melting and had melted to the point that in the south it no longer stood high above the surrounding non-glaciated surface, which had probably already been significantly lowered by deep melt water erosion. Immense melt water floods were flowing in a southeast direction along the ice sheet’s southwest margin and were just beginning to deeply erode the region between the Black Hills and the ice sheet’s southwest margin, which at that time was located north and east of the Black Hills. At that time the Black Hills did not stand high above the ice sheet surface, or for that matter above the surface located between the Black Hills and the ice sheet southwest margin. Initially immense floods of melt water flowing from the rapidly melting ice sheet flowed in a southeast direction between what were then the emerging Rocky Mountains and ice sheet southwest margin and the Black Hills location was on the flood flow route. At first flood waters flowed across the present day Blacks Hills, but later as the Black Hills emerged, flood waters flowed around the Black Hills. Flood waters were probably derived from immense southeast and south-oriented supra-glacial melt water rivers which carved giant ice-walled and ice-floored (later bedrock-floored) canyons into the decaying ice sheet surface and which flowed to the ice sheet’s southwest margin in present day Alberta and then in a southeast direction along the decaying ice sheet’s southwest margin. The surface on which the southeast-oriented floods were initially moving was significantly higher than the ice sheet floor elevation and probably is longer preserved anywhere.

• How did the deep “hole” the ice sheet had been occupying open up so as to permit headward erosion of the deep northeast-oriented Cheyenne River valley? Remember, the ice sheet was thick and had deep roots. The ice sheet roots may have extended more than a kilometer below the pre-glacial surface on which the ice sheet had formed. The deep “hole” had probably been formed by a combination of deep glacial erosion of the pre-glacial surface underlying the ice sheet and of crustal warping caused by the weight of an ice sheet several kilometers thick. The crustal warping, which almost certainly did not occur instantaneously, probably also affected regions elsewhere on the continent and may have contributed to uplift of the Black Hills and other North American mountain ranges and high plateau areas as flood waters flowed across them. In other words, not only was the rapidly decaying ice sheet located in a deep “hole” that was opening up as the ice sheet melted, but delayed crustal warping caused by the ice weight was raising mountain ranges and high plateaus regions south and west of the ice sheet margin. The combination of these two events created a situation where the gigantic southeast-oriented melt water river flowing along the decaying ice sheet’s southwest margin was systematically captured by headward erosion of deep northeast-oriented valleys, which were eroding headward from the decaying ice sheet location. Headward erosion of the deep northeast-oriented Cheyenne River valley first captured southeast-oriented flood flow east and south of the Black Hills erosion resistant core materials and subsequently headward erosion of the deep Belle Fourche River captured the same southeast-oriented flood flow north and west of the Black Hills erosion resistant core materials.

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.