A geomorphic history based on topographic map evidence

The Tullock Creek-Sarpy Creek and Tullock Creek-Rosebud Creek drainage divide area is located in Montana, USA. Although detailed topographic maps of the Tullock Creek-Sarpy Creek and Tullock Creek-Rosebud Creek drainage divide area have been available for more than fifty years detailed map evidence has not previously been used to interpret the region’s geomorphic history. The interpretation provided here is based entirely on topographic map evidence. The Tullock Creek-Sarpy Creek and Tullock Creek-Rosebud Creek drainage divide area is interpreted to have been eroded during immense southeast-oriented flood events, the first of which flowed on a topographic surface at least as high as the highest points in the present-day drainage divide area. Flood erosion across the drainage divide ended when headward erosion of the deep Bighorn River valley captured all southeast-oriented flood flow.

Introduction:

• The purpose of this essay is to use topographic map interpretation methods to explore Montana Tullock Creek-Sarpy Creek and Tullock Creek-Rosebud Creek drainage divide area landform origins. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

• This essay is also exploring a paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and similar 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 Tullock Creek-Sarpy Creek and Tullock Creek-Rosebud Creek drainage divide area landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Tullock Creek-Sarpy Creek and Rosebud Creek drainage divide area location map

Figure 1: Tullock Creek-Sarpy Creek and Rosebud Creek 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 Tullock Creek-Sarpy Creek-Rosebud Creek drainage divide area location map and illustrates a region in Montana. The state of Wyoming is located south of Montana. The Yellowstone River flows from Billings in a northeast direction to Fallon, located near the figure 1 northeast corner. Rosebud Creek originates in the Wolf Mountains area of Montana (just north of the Wyoming state line) and flows north, northeast, and northwest to join the Yellowstone River at Rosebud, Montana. Sarpy Creek originates west of Bushby, Montana and flows north to join the Yellowstone River between Hysham and Sanders. Tullock Creek originates in the Rosebud Mountains area southwest of Busby and flows north-northwest to join the Yellowstone River at Bighorn (at almost the same location as the location where the Bighorn River joins the Yellowstone River). Figure 1 illustrates southeast and northwest-oriented Yellowstone River tributaries. The southeast and northwest-orientation of tributary valleys is evidence the northeast-oriented Yellowstone River valley eroded southwest across multiple southeast-oriented flood flow routes, such as might be found in a large-scale flood-formed anastomosing channel complex. Northwest-oriented tributary valleys were eroded by reversed flood flow on northwest ends of beheaded flood flow channels. Because channels were anastomosing (meaning they were interconnected) reversed flood flow on beheaded flood flow channels often captured yet to be beheaded southeast-oriented flood flow from flood flow channels further southwest. Such captures of yet to be beheaded flood flow helped erode significant northwest-oriented tributary valleys. Based on the northwest-southeast orientation of Yellowstone River tributary streams, landform evidence illustrated in this essay is interpreted in the context of an immense southeast-oriented flood flowing across the figure 1 map area and which was systematically captured and diverted further and further northeast by headward erosion of deep valleys eroded into a topographic surface at least as high as the figure 1 region highest elevations today. In the figure 1 map region headward erosion of the north-oriented Rosebud Creek valley first captured the southeast-oriented flood flow and diverted the flood waters to the northeast-oriented Yellowstone River valley and then headward erosion of the Sarpy Creek and Tullock Creek valleys (in that sequence) captured many of the southeast-oriented flood flow routes moving water to the newly eroded Rosebud Creek valley. Detailed maps below provide evidence supporting this interpretation. The Big Dry Creek-Yellowstone River drainage divide area essay and the Musselshell River-Yellowstone River drainage divide area essay describe regions north of the Sarpy Creek-Rosebud Creek drainage divide discussed here. The Sarpy Creek-Rosebud Creek drainage divide area essay describe a region located east of the Tullock Creek-Sarpy Creek drainage divide area discussed here.  Essays can be found under appropriate river names on the sidebar category list (in this case Yellowstone River).

Tullock Creek-Sarpy Creek and Rosebud Creek drainage divide area detailed location map

Figure 2: Tullock Creek-Sarpy Creek and Rosebud Creek drainage divide area detailed location map. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 2 illustrates a somewhat more detailed map of the Tullock Creek-Sarpy Creek and Tullock Creek-Rosebud Creek drainage divide area discussed here. Treasure, Big Horn and Rosebud Counties are located in Montana. The Tullock Creek-Sarpy Creek-Rosebud Creek drainage divide area discussed here is located in Treasure, Big Horn County and Rosebud Counties and is south of the Yellowstone River. Rosebud Creek flows north to Busby and then northeast from Busby in the Northern Cheyenne Indian Reservation (located in the figure 2 south center) before turning to flow north to the Yellowstone River at Rosebud. Sarpy Creek originates northwest of Busby and flows northwest and north into Treasure County and then north to the Yellowstone River between Hysham and Sanders. Tullock Creek originates southwest of Busby (and Sarpy Creek headwaters) and flows northwest and north-northwest to the Yellowstone River at Bighorn (which is also where the north-northeast oriented Bighorn River joins the Yellowstone River). Figure 2 shows many southeast-oriented Rosebud Creek tributaries, especially to the northeast-oriented Rosebud Creek valley segment. This southeast drainage alignment is evidence the northeast-oriented Rosebud Creek valley eroded southwest to capture southeast-oriented flood flow. The southeast-oriented tributary valleys were eroded by southeast-oriented flood flow moving into the newly eroded Rosebud Creek valley. Figure 2 also shows northwest-oriented Sarpy Creek and Tullock Creek headwaters and tributaries. The northwest-oriented valleys were eroded by reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow routes. Following headward erosion of the Rosebud Creek valley the Sarpy Creek valley eroded south to capture flood waters that were moving to the newly eroded Rosebud Creek valley and the northwest-oriented Sarpy Creek headwaters valleys were eroded by reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow channels. The Tullock Creek valley next eroded south to capture the southeast-oriented flood flow and the northwest-oriented Tullock Creek headwaters valleys were also eroded by reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow routes. Because flood waters move in and erode anastomosing (or interconnected) channels reversed flood flow on a beheaded flood flow route could capture flood flow from yet to be beheaded flood flow routes. Such captures of yet to be beheaded flood flow could enable the reversed flood flow routes to erode much deeper and larger northwest-oriented valleys than might otherwise be possible. Often evidence for such flow reversals and captures can be found on detailed topographic maps. Detailed maps below start with the Yellowstone River-Sarpy Creek drainage divide area east of Bighorn, Montana and then progress south along the Tullock Creek-Sarpy Creek drainage divide and conclude by looking at the Tullock Creek-Rosebud Creek drainage divide area near Busby.

Yellowstone River-Sarpy Creek drainage divide area

Figure 3: Yellowstone River-Sarpy Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 3 illustrates the Yellowstone River-Sarpy Creek drainage divide area at the north end of the Tullock Creek-Sarpy Creek drainage divide area. The Yellowstone River flows northeast from the figure 3 southwest corner to the figure 3 north center edge. Sarpy Creek flows north along the figure 3 east edge to the figure 3 northeast corner (and joins the Yellowstone River north of figure 3). Box Elder Creek flows northwest near the figure 3 south center edge and then north-northeast to Hysham in the figure 3 northeast quadrant. Note northwest-oriented Yellowstone River tributaries between Box Elder Creek and the Yellowstone River. These tributaries include Unknown Creek, Forty-six Creek, Forty-five Creek, and Forty-four Creek and they provide evidence the deep northeast-oriented Yellowstone River valley eroded headward across multiple southeast-oriented flood flow routes such as might be found in a southeast-oriented anastomosing channel complex. The northwest-oriented tributary valleys were eroded by reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow channels. Prior to being beheaded southeast-oriented flood flow on these routes had been flowing to what was then the newly eroded north-northeast oriented Box Elder Creek valley, which had eroded south-southwest from what was then the actively eroding deep Yellowstone River valley head to capture yet to be beheaded southeast-oriented flood flow. Through valleys link headwaters of the present day northwest-oriented Yellowstone River tributaries with the north-northeast oriented Box Elder Creek valley and provide evidence southeast-oriented flood flow once moved into the what was then the newly eroded north-northeast oriented Box Elder Creek valley. Headward erosion of the deep Yellowstone River valley head subsequently beheaded the southeast-oriented flood flow and resulted in flood flow reversals that eroded the northwest-oriented tributary valleys and also created the Yellowstone River-Box Elder Creek drainage divide. Note most Box Elder Creek tributaries from the east are northwest-oriented. These northwest-oriented tributaries provide evidence the Box Elder Creek valley eroded headward across multiple southeast-oriented flood flow routes. At least for a time flood flow was moving across the present day Box Elder Creek-Sarpy Creek drainage divide and was captured by northeast-oriented Sarpy Creek tributary valleys that eroded southwest in sequence from the newly eroded north-northwest oriented Sarpy Creek valley to capture the yet to beheaded southeast-oriented flood flow routes. This interpretation requires the southeast-oriented flood flow to have moving on a topographic surface at least as high as the highest figure 3 elevations today.

North end of Tullock Creek drainage basin

Figure 4: North end of Tullock Creek drainage basin. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 4 illustrates the north end of the Tullock Creek drainage basin. The northeast-oriented Yellowstone River is located in figure 4 northwest corner. The north-northeast oriented Bighorn River flows from the figure 4 southwest corner to join the Yellowstone River just west of Bighorn, Montana. Northwest-oriented Tullock Creek flows from the figure 4 south center edge to also join the Yellowstone River at Bighorn. Northwest-oriented Unknown Creek is located in the figure 4 north center area. Other Yellowstone River tributaries from the southeast are northwest-oriented and include Tullock Creek (also Bighorn River tributaries from east are northwest-oriented). These northwest-oriented Yellowstone River (and Bighorn River) tributaries provide evidence the Yellowstone River valley (and Bighorn River valley) eroded headward across multiple southeast-oriented flood flow routes such as might be found in a southeast-oriented anastomosing channel complex. The northwest-oriented tributary valleys, including the northwest-oriented Tullock Creek valley, were eroded by reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow routes. Most Tullock Creek tributaries from the east are southwest-oriented and from the west northeast-oriented. The northwest-oriented Tullock Creek valley alignment was originally established as a significant southeast-oriented flood flow channel. Following beheading of southeast-oriented flood flow on the Tullock Creek alignment northeast-oriented Tullock Creek tributary valleys eroded southwest to capture yet to be beheaded southeast-oriented flood flow further to the southwest. Shallow through valleys link the northeast-oriented Tullock Creek tributary valleys with northwest-oriented Bighorn River tributary valleys and provide evidence southeast-oriented flood flow once moved southeast from the present day Bighorn River drainage basin into the northeast-oriented Tullock Creek tributary valleys. Through valleys also link the southwest-oriented Tullock Creek tributary valleys with headwaters of northwest-oriented Yellowstone River tributary valleys. The Tullock Creek southwest-oriented  tributary valleys may have been initiated before flood flow on the Tullock Creek alignment was reversed and for a time may have served as routes yet to be beheaded southeast-oriented flood flow on the Tullock Creek alignment used to move to newly beheaded and reversed flood flow further to the northeast.

Tullock Creek-Sarpy Creek drainage divide area near Whiskey Butte

Figure 5: Tullock Creek-Sarpy Creek drainage divide area near Whiskey Butte. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 5 illustrates the Tullock Creek-Sarpy Creek drainage divide area south and east of the figure 4 map area and includes overlap areas with figure 4. Tullock Creek flows north and north-northwest near the figure 5 west edge. Sarpy Creek flows north in the figure 5 east half. Other than in the figure 5 northwest corner where Tullock Creek is northwest-oriented Tullock Creek tributaries from the east are northwest-oriented, which is typical for north and northeast-oriented valleys that eroded headward across southeast-oriented flood flow. The northwest-oriented tributary valleys were eroded by reversals of flood flow on the northwest ends of beheaded flood flow routes. Sarpy Creek tributaries from the west vary in orientation, with some east-oriented and some northeast-oriented. Sarpy Creek tributaries from the east are northwest-oriented. Through valleys cross the Tullock Creek-Sarpy Creek drainage divide and provide evidence multiple channels of flood water flowed east from the present day north- and northwest-oriented Tullock Creek drainage basin to the present day north-oriented Sarpy Creek drainage basin. The deep Yellowstone River valley eroded headward from the east to the west and the deep north-oriented Sarpy Creek valley would have eroded south before headward erosion of the Yellowstone River valley beheaded southeast-oriented flood flow on the northwest-oriented Tullock Creek alignment. Flood flow across the Tullock Creek-Sarpy Creek drainage divide here ceased when headward erosion of the deep Yellowstone River valley beheaded southeast-oriented flood flow on the Tullock Creek alignment, which caused a reversal of flood flow that eroded the northwest-oriented Tullock Creek valley segment and enabled the north-oriented Tullock Creek valley segment to erode south to capture yet to be beheaded southeast-oriented flood flow routes further to the south.

Tullock Creek-Sarpy Creek drainage divide area near Pleasant Creek

Figure 6: Tullock Creek-Sarpy Creek drainage divide area near Pleasant Creek. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 6 illustrates the Tullock Creek-Sarpy Creek drainage divide area south of the figure 5 map area and includes overlap areas with figure 5. North-oriented Tullock Creek is located in the figure 6 west half and north-northwest oriented Sarpy Creek is located in the figure 6 east half. Tullock Creek tributaries from the east are northwest-oriented with the exception of Plum Creek, which flows west-southwest. However, Plum Creek headwaters are northwest-oriented. Tullock Creek tributaries from the west appear to be east-oriented. Sarpy Creek tributaries from the west are northeast-oriented, with the exception of Spring Creek (located near the figure 6 south edge), which flows east-southeast. Sarpy Creek tributaries from the east include southwest-oriented Dawes Coulee and Horse Creek and the northwest-oriented East Fork of Sarpy Creek. Pleasant Creek is a northeast-oriented Sarpy Creek tributary originating in the Red Hills (figure 6 south center). Headwaters of northeast-oriented Pleasant Creek are linked by a shallow through valley across a Red Hills ridge with headwaters of east-southeast oriented Spring Creek. This evidence suggests headward erosion of the northeast-oriented Pleasant Creek valley beheaded southeast-oriented flood flow moving to the east-southeast oriented Spring Creek valley. Further, the evidence suggests the southeast-oriented flood flow was moving on a topographic surface at least as high as the highest Red Hills elevations today. The southeast-oriented flood flow was probably moving on the alignment of present day northwest-oriented Cottonwood Creek, which flows to north-oriented Tullock Creek. Southeast-oriented flood flow on the Cottonwood Creek-Spring Creek alignment was moving to a newly eroded and deep northeast-oriented Rosebud Creek valley located southeast of the figure 6 map area. Headward erosion of the Sarpy Creek-Pleasant Creek valley to capture that southeast-oriented flood flow occurred after headward erosion of the deep north-oriented Sarpy Creek valley had captured the southeast-oriented flood and the Spring Creek valley had eroded west-northwest to Red Hills area. Subsequently headward erosion of the north-oriented Tullock Creek valley captured the southeast-oriented flood flow and flood waters on the northwest end of the beheaded flood flow reversed flow direction to erode the northwest-oriented Cottonwood Creek valley. Note how Cottonwood Creek headwaters are north-northeast oriented and are linked to headwaters of northwest-oriented valleys draining to north-oriented Tullock Creek. The north-northeast oriented valley eroded south-southwest to capture yet to be beheaded southeast-oriented flood flow moving south of what was then the actively eroding north-oriented Tullock Creek valley head. The northeast-oriented Pleasant Creek valley (and other northeast-oriented Sarpy Creek tributary valleys) was eroded by yet to be beheaded southeast-oriented flood flow being captured by reversed flood flow on the Sarpy Creek alignment.

Tullock Creek-Sarpy Creek drainage divide area near Plum Creek

Figure 7: Tullock Creek-Sarpy Creek drainage divide area near Plum Creek. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 7 illustrates the Tullock Creek-Sarpy Creek drainage divide area south of the figure 6 map area and includes overlap areas with figure 6. North-oriented Tullock Creek is located in the figure 7 west half. Sarpy Creek flows northwest from the figure 7 southeast corner and then turns to flow north in the figure 7 east half. Headwaters of northeast-oriented Pleasant Creek in the Red Hills area are located in figure 7 north center. East-southeast oriented Spring Creek is located southeast of the Red Hills area. Tullock Creek tributaries from the east are either northwest-oriented or have northwest-oriented headwaters and/or tributaries. Sarpy Creek tributaries from the east are northwest-oriented and the northwest-oriented tributaries and northwest-oriented Sarpy Creek valley in the figure 7 southeast corner provide evidence the north-oriented Sarpy Creek valley eroded south to capture multiple southeast-oriented flood flow routes. The southeast-oriented flood flow was moving on a topographic surface at least as high as the Red Hills elevations today and the deep Sarpy Creek valley eroded into that surface. Flood waters on the northwest ends of the beheaded southeast-oriented flood flow routes then reversed flow direction to erode the northwest-oriented Sarpy Creek tributary valleys and the northwest-oriented Sarpy Creek valley. Subsequently the deep north-oriented Tullock Creek valley eroded south to capture the southeast-oriented flood flow. Tullock Creek valley headward erosion may have been accomplished by a reversal of flow in what was then a shallower south and southeast-oriented valley that had been eroding headward from the deep and newly eroded northeast-oriented Rosebud Creek valley located southeast of the figure 7 map area (see figures 9 and 10 below). Northwest-oriented Tullock Creek tributary valleys (and northwest-oriented Tullock Creek tributary headwaters valleys) were eroded by reversals of flood flow on the northwest ends of beheaded southeast-oriented flood flow routes.

Tullock Creek-East Fork Tullock Creek-Sarpy Creek drainage divide area

Figure 8: Tullock Creek-East Fork Tullock Creek-Sarpy Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 8 illustrates the Tullock Creek-East Fork Tullock and the East Fork Tullock Creek-Sarpy Creek drainage divide area south of the figure 7 map area and includes overlap areas with figure 7. Sarpy Creek originates near the boundary between the Crow Indian Reservation (west side) and the Northern Cheyenne Indian Reservation (east side) in the figure 8 southeast corner area and flows north-northwest and northwest to the figure 8 north edge. The East Fork Tullock Creek flows northwest from the figure 8 south edge (southeast corner area) to join Tullock Creek in the figure 8 northwest corner area. The Middle Fork Tullock Creek flows northwest from the figure 8 south center edge to join the northwest-oriented West Fork Tullock Creek in the figure 8 southwest quadrant and then flow north-northwest to join the East Fork Tullock in the figure 8 northwest corner. The northwest-oriented drainage routes predominating in figure 8 were eroded by reversals of multiple southeast-oriented flood flow routes moving flood waters to what was then the newly eroded northeast-oriented Rosebud Creek valley (see figures 9 and 10 below). The Rosebud Creek valley eroded south and southwest from what was then the actively eroding east and northeast-oriented Yellowstone River valley. At the time headward erosion of the deep Rosebud Creek valley reached the figures 9 and 10 region headward erosion of the deep Yellowstone River valley had not yet beheaded southeast-oriented flood flow moving across the figure 8 map area. As the deep Yellowstone River valley head eroded west and southwest it first beheaded flood flow in the Sarpy Creek drainage basin causing reversals of flood flow that eroded the northwest-oriented Sarpy Creek headwaters valley. Subsequently headward erosion of the deep Yellowstone River valley (and its tributary Bighorn River valley) beheaded southeast-oriented flood flow moving across the Tullock Creek drainage basin causing reversals of flood flow that in sequence eroded the northwest-oriented East Fork Tullock Creek valley, the Middle Fork Tullock Creek valley, and the West Fork Tullock Creek valley.

Sarpy Creek and Tullock Creek-Rosebud Creek drainage divide area

Figure 9: Sarpy Creek and Tullock Creek-Rosebud Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 9 illustrates the Sarpy Creek-Rosebud Creek and the Tullock Creek-Rosebud Creek drainage divide area south of the figure 8 map area and includes overlap areas with figure 8. Northeast-oriented Rosebud Creek is located in the figure 9 southeast corner. Southeast and east-oriented drainage in the figure 9 east half is flowing to Rosebud Creek. North-oriented Sarpy Creek headwaters are located along the Crow Indian Reservation-Northern Cheyenne Indian Reservation boundary line in the figure 9 northeast quadrant. Northwest oriented drainage to the figure 9 northwest corner includes the Middle Fork and West Fork of Tullock Creek while northwest-oriented East Fork Tullock Creek flows to the figure 9 north center edge. Northeast-oriented drainage in the figure 9 southwest quadrant flows to northwest-oriented West Fork Tullock Creek and is linked by through valleys across a high drainage divide to west, and northwest-oriented tributaries to the northwest-oriented Little Bighorn River. Through valleys across the Sarpy Creek-Rosebud Creek and the Tullock Creek-Rosebud Creek drainage divides provide evidence flood waters once moved southeast to what was then the newly eroded and deep northeast-oriented Rosebud Creek valley. Figure 9 evidence suggests a deep northeast-oriented Rosebud Creek valley eroded headward into the figure 9 map region to capture southeast-oriented flood flow moving on a topographic surface at least as high as the highest figure 9 elevations today. Headward erosion of the deep Yellowstone River valley north of the figure 9 map area beheaded southeast-oriented flood flow causing a flow reversal in the northwest-oriented Sarpy Creek headwaters valley (seen in figure 8) and the north-oriented Sarpy Creek headwaters valley eroded south to capture yet to be beheaded southeast-oriented flood flow still moving further to the south. Soon thereafter headward erosion of the deep Yellowstone River valley beheaded southeast-oriented flood flow moving in the figure 9 Tullock Creek drainage basin causing a reversal of flood flow to erode the northwest-oriented East, Middle, and West Forks of Tullock Creek valleys and to create the Tullock Creek-Rosebud Creek drainage divide. The northeast-oriented West Fork Tullock Creek tributary valleys eroded southwest in sequence to capture yet to be beheaded flood flow moving southeast on the present day Little Bighorn River alignment.

Tullock Creek-Rosebud Creek drainage divide area

Figure 10: Tullock Creek-Rosebud Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 10 illustrates the Tullock Creek-Rosebud Creek drainage divide area south of the figure 9 map area and includes overlap areas with figure 9. North and northeast-oriented Rosebud Creek is located in the figure 10 southeast corner and east center areas. Northwest-oriented West Fork Tullock Creek flows to the figure 10 northwest corner area. Northwest-oriented Middle Fork Tullock Creek flows to the figure 10 north edge to the east of the West Fork. Northwest-oriented Reno Creek is located in the figure 10 southwest corner and flows to the northwest-oriented Little Bighorn River located west of the figure 10 map area. Figure 10 evidence tells the same story as figure 9 evidence. Southeast-oriented flood flow moving on a topographic surface at least as high as the highest figure 10 elevations today was captured by headward erosion of the deep northeast-oriented Rosebud Creek valley which eroded south and southwest from what was then the actively eroding east and northeast-oriented Yellowstone River valley head. Headward erosion of the deep Yellowstone River valley subsequently beheaded southeast-oriented flood flow across the figure 10 map area causing a flood flow reversal that eroded the northwest-oriented Tullock Creek headwaters valleys and created the Tullock Creek-Rosebud Creek drainage divide. North and northeast-oriented West Fork Tullock Creek tributaries eroded south and southwest in sequence to capture yet to be beheaded southeast-oriented flood flow on the present day northwest-oriented Little Bighorn River alignment (located southwest and west of figure 10). Headward erosion of the deep Bighorn River valley then beheaded those southeast-oriented flood flow routes and the reversed flood flow eroded the northwest-oriented Little Bighorn River valley and tributary valleys and also created the Little Bighorn River-Tullock Creek drainage divide. The source of the flood waters can not be determined from evidence presented here. However, the hundreds of Missouri River drainage basin landform origins research project essay published on this website when viewed collectively can be used to trace flood waters toward their source. A logical flood water source would be rapid melting of a thick North American ice sheet located in a deep “hole” in approximately the North America location usually recognized to have been glaciated. Such a flood water source would not only explain the immense southeast-oriented floods involved, but would also explain why deep valleys were eroding headward to capture southeast-oriented flood waters and divert the flood flow further and further to the northeast into space in the deep “hole” the rapidly melting thick ice sheet had once occupied.

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.