South Fork Judith River-Musselshell River drainage divide area landform origins, Little Belt Mountains, Montana, USA

Authors

A geomorphic history based on topographic map evidence

Abstract:

The South Fork Judith River-Musselshell River drainage divide area discussed here is located in Little Belt Mountains, Montana, USA. Although detailed topographic maps of the South Fork Judith River-Musselshell River drainage divide area in the Little Belt Mountains 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 South Fork Judith River-Musselshell River drainage divide area in the Little Belt Mountains 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 South Fork Judith River-Musselshell River drainage divide in the Little Belt Mountains ended when headward erosion of the deep Missouri River valley and its tributary Judith River valley captured all 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 South Fork Judith River-Musselshell River drainage divide area landform origins in the Little Belt Mountains, Montana, USA. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions 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 the South Fork Judith River-Musselshell River drainage divide area landform evidence in the Little Belt Mountains will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

South Fork Judith River-Musselshell River drainage divide area in Little Belt Mountains location map

Figure 1: South Fork Judith River-Musselshell River drainage divide area in Little Belt Mountains 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 South Fork Judith River-Musselshell River drainage divide area location map and illustrates a region in Montana. The Missouri River flows northwest from Three Forks (located in the figure 1 southwest quadrant) to Wolf Creek and then northeast to Great Falls and Fort Benton (located along the figure 1 north edge). North of figure 1 the Missouri River turns to flow southeast back into the figure 1 map area and then flow east-northeast and southeast to Fort Peck Lake (the large reservoir located in the figure 1 northeast quadrant). The Judith River flows northeast from the Little Belt Mountains area through the Judith Basin and then north to join the east-oriented Missouri River in the figure 1 north center area. The Musselshell River flows south of the Little Belt Mountains area (figure 1 west center) to Martinsdale and then southeast to Harlowton, Ryegate, and Lavina. From Lavina the Musselshell River flows northeast to Roundup and Melstone where it turns to flow north to join the Missouri River at Fort Peck Lake. South of the southeast and northeast-oriented Musselshell River is the Yellowstone River, which in figure 1 flows through Billings and Custer. The South Fork Judith River-Musselshell River drainage divide area of concern in this essay is the drainage divide between the northeast-oriented South Fork Judith River and the Musselshell River, and is located at the southeastern end of the Little Belt Mountains (approximately where the word “Mountains” appears).

  • The Little Belt Mountains today are a high isolated mountain range, and the South Fork Judith River-Musselshell River drainage divide discussed in this essay is located in a mountainous region. This essay interprets drainage divide to have been eroded by an immense southeast-oriented flood. At the time flood erosion occurred the Little Belt Mountains did not stand high above the surrounding region and initially there was no Musselshell River valley to the south. And initially there was no Yellowstone River valley further to the south. The Little Belt Mountains at that time were not an obstacle to the southeast-oriented flood water movement perhaps because the Little Belt Mountains were buried in easily eroded sedimentary rock and/or ice. Another possibility is the Little Belt Mountains had not yet been uplifted and uplift occurred as flood waters eroded the region, although some combination of the two possibilities is probable. Regardless of why the Little Belt Mountains did not present an obstacle to flood water movement the Musselshell River valley eroded into the figure 1 map region to capture the southeast-oriented flood flow. The Musselshell River valley first eroded south to the Melstone area and then eroded southwest and west in the area south of the present day Big Snowy Mountains and then northwest into the region south of the Little Belt Mountains.
  • Southeast-oriented tributaries to the southeast, east, and northeast oriented Musselshell River valley provide evidence headward erosion of the Musselshell River valley captured southeast-oriented flow. At that time the Little Belt Mountains and the Big Snowy Mountains did not significantly interfere with flood water movements. However, as immense quantities of flood water moved to the newly eroded Musselshell River valley the Big Snowy Mountains and Little Belt Mountains emerged as a significant obstacles to flood flow, and southeast-oriented flood flow routes were progressively beheaded and reversed so as to flow north to the actively eroding Missouri River-Judith River valley head. Flood flow routes were beheaded and reversed as the northeast and north-oriented Judith River valley (and South Fork Judith River valley) eroded headward into the present day Little Belt Mountains. Other essays describe landform evidence in the nearby Big Snowy Mountains Judith River-Musselshell River drainage divide area and Fergus County Judith River-Musselshell River drainage divide area (north of the Big Snowy Mountains) and can be found under appropriate river names on the sidebar category list.

South Fork Judith River-Musselshell River drainage divide area in Little Belt Mountains detailed location map

Figure 2: South Fork Judith River-Musselshell River drainage divide area in Little Belt Mountains 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 South Fork Judith River-Musselshell River drainage divide area discussed in this essay. Judith Basin, Wheatland, and Meagher Counties are located in Montana. The South Fork Judith River flows northeast (along the northeast-oriented highway) from the figure 2 west center near the Meagher County-Judith Basin County line. The Lost and Middle Forks of the Judith River join the South Fork at the National Forest boundary and the Judith River flows northeast from there to Utica and Hobson. The North Fork Musselshell River flows southeast through Checkerboard (located in the figure 2 southwest quadrant) to join the northeast-oriented South Fork Musselshell River a short distance northeast of Martinsdale and then flow southeast and east as the Musselshell River to Harlowton. From Harlowton the Musselshell River flows in a southeast direction to the figure 2 south edge. The Big Snowy Mountains are located in the figure 2 east center area and the Big Snowy Mountains Judith River-Musselshell River drainage divide area evidence was discussed in the essay for that drainage divide area. The Little Belt Mountains are located within the large National Forest area located in the figure 2 northwest quadrant and extending east to the figure 2 center area. The Judith River-Musselshell drainage divide serves as the county line and can be easily identified on figure 2. This essay addresses the drainage divide east of the north and northeast-oriented highway extending from the Checkerboard area to Utica and west of the highway going north from Harlowton to Judith Gap and Sipple. That north-oriented highway makes use of a large north-south oriented through valley, between the Little Belt Mountains to the west and the Big Snowy Mountains to the east, linking the north-oriented Judith River drainage basin with the east-oriented Musselshell River drainage basin.

  • Note southeast oriented streams flowing from the Little Belt Mountains to the southeast oriented Musselshell River. These southeast-oriented Musselshell River tributaries provide evidence multiple southeast-oriented flood flow routes once did cross the Little Belt Mountains. As previously mentioned, when flood waters moved across the present day Little Belt Mountains drainage divide to the newly eroded Musselshell River valley, the Little Belt Mountains were not an obstacle to flood flow movement. Evidence presented in this essay and in essays describing adjacent drainage divide areas suggests the Little Belt Mountains emerged as a significant obstacle while flood waters were eroding the figure 2 map area. Evidence in detailed maps below further suggests flood waters originally flowed on a topographic surface at least as high as the highest Little Belt Mountains elevations today. Flood waters of concern in this essay originally flowed to what was then a newly eroded and deep northeast-oriented Yellowstone River valley. Headward erosion of the deep southeast- oriented Musselshell River valley at some point captured the southeast-oriented flood flow routes and diverted the flood waters east, northeast, and north. As flood waters flowed across the figure 2 map area the Little Belt Mountains emerged as a major obstacle, which enabled the northeast-oriented Judith River valley to erode headward into the figure 2 map area and to capture and to divert the flood waters northeast. Emergence of the Little Belt Mountains as a mountain range occurred as flood waters deeply eroded the region.

Judith River-Musselshell River drainage divide area at Judith Gap

Figure 3: Judith River-Musselshell River drainage divide area at Judith Gap. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 illustrates the Judith River-Musselshell River drainage divide area at Judith Gap, which is located at the Little Belt Mountains east end. Judith Gap is a large north-south through valley linking the north-oriented Judith River drainage basin with the east-oriented Musselshell River drainage basin. Judith Gap is bounded on the east by the Big Snowy Mountains, located in the figure 3 northeast corner, and on the west by the Little Belt Mountains, located in the figure 3 west center area. In the figure 3 west half the Judith Basin County-Wheatland County line is located along the Judith River-Musselshell River drainage divide, with Judith Basin County being located in the north-oriented Judith River drainage basin and Wheatland County being located in the east-oriented Musselshell River drainage basin. South-oriented streams flowing to the figure 3 south edge are Musselshell River tributaries. Ross Fork Creek is the major figure 3 Judith River tributary and begins as a south-oriented stream in the western Big Snowy Mountains (figure 3 northeast area) and flows south-southeast before making a U-turn to flow north-northwest through Judith Gap and eventually to reach the northeast-oriented Judith River. All other figure 3 streams in Judith Basin County and Fergus County (except along the figure 3 east edge) are Ross Fork Creek tributaries. Note the southeast-orientation of Musselshell River tributaries flowing from the Little Belt Mountains in the figure 3 west half.

  • Figure 3 drainage history began at a time when the Little Belt Mountains and Big Snowy Mountains did not stand high above the surrounding region as they do now. Either they were buried in easily eroded sediments and/or ice and/or they had not yet been uplifted. In either case an immense southeast-oriented flood moved across the figure 3 map region, probably to what was then a newly eroded Yellowstone River valley to the south of the figure 3 map area. The Fish Creek-Big Coulee Creek and Painted Robe Creek-Yellowstone River drainage divide area essays describe flood erosion of the region between the present day Musselshell River and the Yellowstone River located south of this figure 3 map area (Fish Creek is a Musselshell River tributary). As flood waters flowed across the figure 3 map area the Big Snowy and Little Belt Mountains began to emerge, and being composed of erosion resistant bedrock they began to alter flood flow directions. The south-oriented flood flow was able to erode a deep valley headward through the Judith Gap area north into the present day Judith Basin region. At some point the east-oriented Musselshell River valley eroded headward to the south of figure 3 and captured the south-oriented flood flow. Soon thereafter headward erosion of the northeast-oriented Judith River valley north of the figure 3 map area beheaded the south-oriented flood flow route moving flood waters south through Judith Gap. Flood waters on the north end of the beheaded flood flow reversed flow direction to flow north-northwest and to erode the north-northwest-oriented Ross Fork Creek valley. The newly reversed flood flow captured several south-oriented streams from the western Big Snowy Mountains (these had been south-oriented flood flow routes a short time before), which accounts for the south-oriented Ross Fork Creek headwaters. The reversal of flood flow also created the present day Judith River-Musselshell River drainage divide.

Antelope Creek-Hopley Creek drainage divide area in eastern Little Belt Mountains

Figure 4: Antelope Creek-Hopley Creek drainage divide area in eastern Little Belt Mountains. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates the Antelope Creek-Hopley Creek drainage divide in the eastern Little Belt Mountains. The figure 4 map area is located west of the figure 3 map area and includes overlap areas with figure 3. The Judith River-Wheatland County line is defined by the Judith River-Musselshell River drainage divide. The major Judith River tributary in figure 4 is Antelope Creek, which flows northeast and north in the figure 4 northwest quadrant. North of the figure 4 map area Antelope Creek flows north and north-northeast to join the northeast oriented Judith River. Southeast of the drainage divide are headwaters of Musselshell River tributaries. These Musselshell River tributaries are almost all southeast-oriented. The multiple southeast-oriented tributary valleys eroded into the Little Belt Mountains suggest the region was eroded by multiple channels of southeast-oriented flood flow, which were beheaded by headward erosion of the Antelope Creek valley and other northeast and north-oriented Judith River tributaries (located east of north-oriented Antelope Creek). The southeast-oriented flood waters came from a source area northwest of figure 4 and must have flowed on a topographic surface at least as high as the highest figure 4 elevations today. At that time the Little Belt Mountains did not stand high above the surrounding region as they do today. It is possible the Little Belt Mountains were buried in easily eroded sediment and/or ice, and/or it is possible the Little Belt Mountains were uplifted as flood waters eroded the region. In either case, the Little Belt Mountains emerged as flood waters eroded the region. At first flood waters eroded the Little Belt Mountains southeast-facing slope and began to erode southeast-oriented valleys into that southeast-facing slope. Next headward erosion of north- and northeast-oriented Judith River tributaries began to capture flood waters moving to the actively southeast-oriented valleys. These captures occurred in sequence from the northeast to southwest. Headward erosion of the Antelope Creek valley beheaded all remaining southeast-oriented flood flow routes across the figure 4 drainage divide. Subsequently headward erosion of Judith River tributary valleys north and west of the figure 4 map area captured all southeast-oriented flood flow to the newly eroded Antelope Creek valley.

Detailed map of Antelope Creek-Hopley Creek drainage divide area

Figure 5: Detailed map of Antelope Creek-Hopley Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 provides detailed map of the Antelope Creek-Hopley Creek drainage divide area seen in less detail in figure 4 above. Antelope Creek flows east from the figure 5 west edge and then north to the figure 5 north edge in the figure 5 northwest quadrant. South and southeast-oriented East Fork Hopley Creek begins in the figure 5 northeast quadrant and flows to the figure 5 east center edge. The West Fork Hopley Creek flows southeast in the figure 5 southwest quadrant. In the figure 5 center area a south-oriented West-Fork Hopley Creek tributary valley is linked by a through valley with a north and northwest-oriented Antelope Creek tributary valley. This through valley is just one example of many such through valleys (many not as deep as this one) located along Little Belt Mountains drainage divide. A much shallower valley can be located along the drainage divide just west of the words “District” near the figure 5 west center edge. The through valleys were eroded by running water and provide evidence water once moved from the Judith River drainage basin to the Musselshell River drainage basin. The presence of multiple through valleys, which can be confirmed by studying detailed maps of the drainage divide area, provides evidence of anastomosing channels of flood flow, that once moved water across the entire eastern Little Belt Mountains region. The East and West Fork Hopley Creek valleys and their tributary valleys eroded headward into the figure 5 map region to capture the southeast oriented flood flow. The east and north oriented Antelope Creek valley then eroded headward into the figure 5 map area to capture flood waters moving to what were then the actively eroding East and West Forks Hopley Creek valleys. Flood waters on the north and northwest ends of beheaded flood flow routes reversed flow direction to flow north and northwest to the newly eroded Antelope Creek valley. The north and northwest-oriented Antelope Creek tributary valley was eroded by such reversed flood flow. Because the Antelope Creek valley eroded headward from the north to south and then from east to west, southeast-oriented flow routes were beheaded one at a time. Also, because antastomosing flood flow channels are interconnected reversed flood flow on a newly beheaded flood flow route could capture yet to be beheaded flood flow from adjacent flood flow routes. The capture of such yet to be beheaded flood water provided the water necessary to erode significant north and northwest-oriented reversed flow valleys. The beheading and reversal of the southeast-oriented flood flow routes also created the present day Judith River-Musselshell River drainage divide.

South Fork Judith River-Daisy Dean Creek drainage divide area

Figure 6: South Fork Judith River-Daisy Dean Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the South Fork Judith River-Daisy Dean Creek drainage divide area southwest of the figure 4 map area and includes overlap areas with figure 4. Northeast and north oriented Antelope Creek is located in the figure 6 northeast quadrant. The county line is marked by a dashed black line, which follows the present day Judith River-Musselshell River drainage divide. Judith Basin County is located north of the drainage divide. The dashed black line extending south from Mount High is the Meagher County-Wheatland County line, with Meagher County located in the figure 6 southwest quadrant and Wheatland County in the southeast quadrant. The South Fork Judith River flows east from the figure 6 west edge and then northeast to the figure 6 north center edge area. North of the figure 6 map area the South Fork Judith River flows north-northeast to join northeast oriented Lost Fork and Middle Fork and to create the northeast and north oriented Judith River. Deadhorse Creek is the northeast oriented South Fork Judith River tributary flowing the from the figure 6 west center edge. The East Fork Haymaker Creek begins south of Mount High and flows northeast and southeast to the figure 6 southeast corner. Note southeast-oriented Musselshell River tributaries, especially in the figure 6 southeast quadrant. Daisy Dean Creek also originates in the Mount High area and flows south-southwest between Daisy Peak and Daisy Notch to the figure 6 south edge. South of the figure 6 map area Daisy Dean Creek turns to flow southeast to the Musselshell River. Spring Creek originates northwest of Daisy Peak and flows southwest to the figure 6 southwest corner area. Southwest of the figure 6 map area Spring Creek turns to flow in a southeast direction to the Musselshell River. Note how through valleys, some well-defined and some rather subtle, link many of the different valleys, with some of the best through valleys linking southwest and northeast-oriented valleys. The figure 6 drainage history is complex and to some extent probably reflects underlying bedrock structures and characteristics. However, the southeast-oriented Musselshell River tributaries and north and northwest-oriented South Fork Judith River tributaries provide evidence the northeast-oriented South Fork Judith River valley eroded headward to capture multiple southeast-oriented flood flow routes. The through valleys also provide evidence of flood flow across present day drainage divides. Note how South Fork Judith River tributaries from the south are north or northwest-oriented and are well-developed in the area north of Daisy Peak. Also note how headwaters of those north- oriented South Fork Judith River tributaries are linked by a large through valley with headwaters of south-southwest oriented Daisy Dean Creek, northeast- and southeast-oriented East Fork Haymaker Creek, and southwest-oriented Spring Creek. Figure 7 below provides a more detailed map of that through valley area.

Detailed map of South Fork Judith River-Daisy Dean Creek drainage divide area

Figure 7: Detailed map of South Fork Judith River-Daisy Dean Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 provides a detailed map of the large through valley linking headwaters of north-oriented South Fork Judith River tributaries with headwaters of south-southwest oriented Daisy Dean Creek, northeast and southeast-oriented East Fork Haymaker Creek, and southwest-oriented Spring Creek, which was illustrated in less detail in figure 6 above. North-oriented Cabin Creek and Bluff Mountain Creek in the figure 7 northwest quadrant are the South Fork Judith River tributaries. Note how Bluff Mountain Creek is northwest-oriented and Cabin Creek headwaters are northwest-oriented. The northwest-orientations probably reflect reversals of flood flow on northwest ends of beheaded southeast-oriented flood flow routes. Southeast-oriented Morrisy Coulee in the figure 7 southeast quadrant also probably eroded headward along a southeast-oriented flood flow route. The southeast-oriented basin at the Morrisy Coulee head is probably an abandoned headcut, which had been eroding northwest along the Morrisy Coulee alignment. The East Fork Haymaker Creek originates in a northeast oriented valley in the figure 7 northeast quadrant, but then turns to flow southeast to the Musselshell River. The southeast-oriented valley also probably eroded headward along a southeast-oriented flood flow route, while the northeast oriented headwaters valley probably eroded southwest along a zone of bedrock weakness to capture southeast-oriented flood waters moving to what was then the actively eroding Morrisy Coulee headcut. At about the same time headward erosion of the south-southwest oriented Daisy Dean Creek headcut eroded into the region and captured southeast-oriented flood flow that had been moving to the newly eroded northeast and southeast oriented East Fork Haymaker Creek valley. The same situation occurred in the figure 7 southwest quadrant, where south-southeast oriented Muddy Creek originates between Muddy Mountain and Daisy Peak. South and southeast-oriented flood flow was beheaded by headward erosion of the southwest-oriented Spring Creek valley and by headward erosion of the southeast-oriented headwaters valley of Daisy Dean Creek. Next headward erosion of the deep northeast-oriented South Fork Judith River valley beheaded southeast-oriented flood flow routes moving flood waters across the figure 7 map area. Flood waters on the northwest ends of the beheaded flood flow routes reversed flow direction to erode the northwest-oriented Bluff Mountain Creek valley and the north-oriented Cabin Creek valley.

Daisy Dean Creek-Nevada Creek-Morrisy Coulee drainage divide area

Figure 8: Daisy Dean Creek-Nevada Creek-Morrisy Coulee drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the Daisy Dean Creek-Nevada Creek-Morrisy Coulee drainage divide area located south and east of the figure 7 map area and includes overlap areas with figure 7. Daisy Dean Creek flows south-southwest in the figure 8 west half. Southwest of figure 8 Daisy Dean Creek turns to flow southeast to the Musselshell River. Morrisy Coulee drains from the figure 8 north center area southeast to the figure 8 southeast corner area. Morrisy Coulee continues in a southeast direction to join southeast oriented Haymaker Creek, which flows to the Musselshell River. Nevada Creek flows southeast, southwest and south from the figure 8 center area to the figure 8 south edge and then continues to flow south to join southeast oriented Daisy Dean Creek (see figure 9 below). Southeast-oriented headwaters of Morris Creek are located along the figure 8 south edge between Daisy Dean Creek and Nevada Creek. South of figure 8 Morris Creek flows south to join Daisy Dean Creek (see figure 9 below). Figure 8 illustrates several through valleys, the three most obvious of which are located between the south-southwest oriented Daisy Dean Creek valley and the 1.) southeast oriented headwaters of Morris Creek, 2.) the southeast-oriented West Fork Nevada Creek headwaters, and 3.) the southeast-oriented Nevada Creek headwaters. These through valleys provide evidence the south-southwest oriented Daisy Creek valley eroded headward to capture multiple southeast- (or east) oriented flood flow routes moving water to what was then the actively eroding Nevada Creek valley. These captures occurred in sequence from south to north. West-oriented Daisy Dean Creek tributary valleys were eroded by reversed flood flow on the west ends of the beheaded flood flow routes. Another, much more subtle through valley is located in the figure 8 north center. That through valley is Daisy Notch, which is located at a much higher elevation than the three previously mentioned through valleys. However, like the other three through valleys Daisy Notch is a water eroded feature and provides evidence of one route flood waters used when flowing to what was then the actively eroded Morrisy Coulee valley. The Daisy Notch through valley also provides evidence flood waters originally flowed on a topographic surface at least as high as the Daisy Notch floor, which means flood waters deeply eroded the figure 8 map area. A close look at figures 7 and 8 reveals several other subtle high level through valleys, providing evidence of earlier flood flow routes dismembered as present day valleys eroded headward into the figures 7 and 8 map regions.

Deadhorse Creek-Spring Creek drainage divide area

Figure 9: Deadhorse Creek-Spring Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Deadhorse Creek-Spring Creek drainage divide area west and south of the figure 6 map area and includes overlap areas with figure 6. Bair Reservoir in the figure 9 southwest corner is located in the southeast-oriented North Fork Musselshell River valley and is located just upstream from Checkerboard, Montana. Mount High is located in the figure 9 northeast corner. South of Mount High are headwaters of northeast and southeast-oriented East Fork Haymaker Creek and further south is Daisy Notch and headwaters of southeast-oriented Morrisy Coulee. West of Daisy Notch are Daisy Dean Creek headwaters. Daisy Dean Creek can be seen flowing south-southwest and then southeast from the Daisy Notch area. South-oriented Morris Creek and Nevada Creek join Daisy Dean Creek in the figure 9 southeast corner area. Deadhorse Creek flows northeast to join east-southeast and northeast oriented South Fork Judith River in the figure 9 north center area. Spring Creek flows southwest from the Muddy Mountain area to Cooks Flat and then turns to flow southeast to the Musselshell River. Basin Creek and Whitetail Creek are the two major southeast-oriented Spring Creek tributaries and provide evidence the southwest-oriented Spring Creek valley eroded headward to capture multiple southeast-oriented flood flow routes (a through valley north of Muddy Mountain provides evidence headward erosion of the Spring Creek valley also captured south-oriented flood flow on the Cabin Creek alignment, which was reversed when headward erosion of the northeast-oriented South Fork Judith River captured the southeast-oriented flood flow). Figure 10 below provides a detailed map of the Whitetail Creek-Basin Creek drainage divide area. Figure 9 provides evidence the Little Belt Mountains were not always high like they are today, but were uplifted at some point in geologic history. The uplift appears to have occurred as flood waters were rapidly eroding the figure 9 region. Why would a mountain range be uplifted while an immense southeast-oriented flood was rapidly eroding the adjacent region? While the source of the southeast-oriented flood waters described in this essay cannot be determined from evidence presented here, a logical flood water source would be rapid melting of a thick North American ice sheet located in a deep “hole” occupying approximately the North American location usually recognized to have been glaciated. The deep “hole” would have been created by deep glacial erosion and by crustal warping caused by ice sheet weight. Such a flood water source would not only explain the immense southeast-oriented floods this essay series describes, but would also explain why deep valleys were eroding headward to capture the southeast-oriented flood waters and diverting flood waters further and further northeast and north into space in the deep “hole” the rapidly melting thick ice sheet had once occupied. In addition, such a flood water source may explain uplift of mountains regions, such as the Little Belt Mountains, during an immense southeast-oriented flood. A thick North American ice sheet, in a deep “hole” created in part by the ice sheet’s weight, would probably cause crustal warping elsewhere on the continent, especially along ice sheet margins. Rapid erosion of significant amounts of overlying bedrock material might also trigger localized uplift.

Detailed map Whitetail Creek-Basin Creek drainage divide area

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

Figure 10 provides a detailed map of the Whitetail Creek-Basin Creek drainage divide area illustrated in less detail in figure 9 above. Northeast-oriented Deadhorse Creek is located in the figure 10 northwest quadrant. Whitetail Creek flows southeast and south from the figure 10 northwest corner area to the figure 10 south edge (west half). Southeast-oriented Basin Creek originates in the west half of the figure 10 southeast quadrant and flows to the figure 10 south edge. Basin Creek headwaters are located in a large south-oriented basin, from which Basin Creek probably obtains its name. The rim of that south-oriented basin is an abandoned headcut, which was abandoned when headward erosion of the northeast-oriented South Fork Judith River-Deadhorse Creek valley and the southeast-oriented Whitetail Creek valley captured southeast-oriented flood flow routes that had been moving southeast-oriented flood waters to what was then the actively eroding Basin Creek valley headcut. Note through valleys near Willow Flat linking the south-oriented Basin Creek headwaters with the headwaters of northeast-oriented Deadhorrse Creek. Those through valleys provide evidence headward erosion of the northeast-oriented Deadhorse Creek captured south-oriented flood waters moving to the actively eroding Basin Creek valley headcut. Headward erosion of the east-southeast oriented South Fork Judith River valley to the north of figure 10 then beheaded all south-oriented flood flow to the Deadhorse Creek valley (see figure 9 above). Note also the northwest-southeast oriented through valley near Bear Park linking Basin Creek headwaters with headwaters of a southwest-oriented Whitetail Creek tributary. Also note the northwest-southeast oriented through valley near the Hunters Camp linking that Bear Park through valley with the southeast-oriented Whitetail Creek valley to the northwest. Those through valleys provide evidence headward erosion of the Whitetail Creek valley (and its southwest-oriented tributary valley) captured southeast-oriented flood flow moving to the what was then the actively eroding southeast-oriented Basin Creek valley. Such captures are typical of captures occurring in anastomosing channel complexes, where one channel erodes deeper and captures flood flow moving to an adjacent channel. Numerous through valley such as those pointed out here provide evidence an immense flood flowed across the Little Belt Mountains in this region.

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.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: