Upper Sun River Drainage Basin Origin Determined by Topographic Map Interpretation Techniques: Lewis and Clark and Teton Counties, Montana, USA

Abstract

A new and fundamentally different regional geomorphology paradigm in which massive south-and southeast-oriented meltwater floods flowed across the entire Missouri River drainage basin is tested by interpreting detailed topographic maps of the Montana upper Sun River drainage basin region by trying to explain origins of previously unexplained or poorly explained erosional landforms located upstream from Sun River Canyon (which cuts across Montana's north-to-south oriented Sawtooth Range). Mountain passes, through valleys, and other drainage divide low points along what are today high mountain ridges, including the North American east-west continental divide, are interpreted to be evidence of drainage routes that once crossed the region. These drainage divide crossings suggest that prior to erosion of present-day upper Sun River drainage basin valleys, massive floods moved in south directions across what are today the north-oriented Middle and South Fork Flathead River drainage basins into today's upper Sun River drainage basin area and carved a complex of diverging and converging channels into what was probably a low relief surface now represented by the crests of the region's highest mountain ridges. Further, the map evidence shows how a diverging complex of south-and southeast-oriented upstream Sun River drainage basin flood flow channels changed flow direction to cross the Sawtooth Range in a northeast direction before converging on the Montana plains at a location downstream from Sun River Canyon. The observed upper Sun River drainage basin area topographic map evidence is consistent with the new geomorphology paradigm predictions, in which massive south-oriented meltwater floods flowing across the rising rim of a continental ice sheet created deep "hole" (created by deep ice sheet erosion and ice sheet weight How to cite this paper: Clausen, E.

Yellowstone Region Drainage History as Determined from the 1955 Ashton, Idaho, Montana, and Wyoming 1:250,000 Scale Topographic Map, USA

“…Another paper [25] interprets topographic map evidence to show that immense south-oriented floods eroded mountain passes now crossing continental divide segments surrounding the Boulder River drainage basin (located to the east of the Clark Fork River headwaters seen in Figure 1). And a third paper [26] interprets topographic map evidence to show that immense southoriented floods eroded mountain passes crossing continental divide segments surrounding the upper Sun River drainage basin (located in Figure 1 to the west of where the Missouri River turns from flowing in a northwest direction to flow in a northeast direction).…”

Use of Topographic Map Evidence to Test a Recently Proposed Regional Geomorphology Paradigm: Wind River-Sweetwater River Drainage Divide Area, Central Wyoming, USA

“…Several such papers demonstrate how topographic map evidence indicates north-oriented valleys eroded headward from a continental ice sheet location (where ice sheet melting was opening up space at the deep "hole's" southern end) to capture massive southeast-oriented ice-marginal floods [18] [19] [20]. Other papers describe topographic map evidence demonstrating how massive floods flowed across a rising Laramie Range [21] and a rising Black Hills uplift [22] and carved what is today a northern Montana east-west continental divide segment [23].…”

Use of Wyoming Southern Bighorn Mountains Topographic Map Evidence to Test a Recently Proposed Regional Geomorphology Paradigm: USA

“…As a bulge within the Missouri River drainage basin near, but not on the deep "hole's" southwest rim, the new paradigm requires southor southeast-oriented melt water floods to have flowed across what must have been a rising Bighorn Mountain range. Previously published new paradigm papers among other things demonstrate how detailed topographic map evidence suggests large south-and southeast-oriented floods flowed across a rising Wyoming-South Dakota Black Hills upland (Clausen, 2018b), a rising Wyoming Laramie Range (Clausen, 2018c), rising Montana Lewis and Clark and Sawtooth Ranges (Clausen, 2019), a rising Montana Boulder Batholith region (Clausen, 2017a), rising Montana Beaverhead, Centennial, Pioneer, and Anaconda Mountain ranges (Clausen 2017b) and the eastern Powder River Basin (Clausen, 2018d) and also demonstrate how the southeast Montana north-oriented Powder River valley eroded headward across massive southeast-oriented floods (Clausen, 2018e). The study reported here seeks to determine whether detailed topographic map evidence in the high elevation southern Bighorn Mountains region can be interpreted in similar ways.…”