Catastrophic failure of the Northern Great Plains: A unifying hypothesis

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5578862

Clausen, E N ^[1]

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1. Minot State Univ., ND (United States). Science Div.

The Northern Great Plains, at peak Laurentide glaciation, was a 1,600 km thick barrier between meltwater sources and the lower Missouri Valley. Meltwater and floodwaters flowed along the ice margin, moved between the Black Hills and Laurentide ice. Water was trapped between ice to the N and E and mountains to the W and S. The Pine Ridge Escarpment began as the S wall of a W-trending headcut while other headcuts eroded N, parallel to the ice margin. Sheetflow from the west and northwest stripped the easily-eroded surface between major headcuts. The Cheyenne Valley headcut then captured sheetflow from the eastern Powder River Basin, both N and S of the Black Hills. Sheetflow moving through the western Powder River Basin, however, continued to spill over the southern wall of the initial headcut, carving the upper White River Valley. These floodwaters filled the lower White River Valley, including the Scenic and Sage Creek Basins, and breached divides by spilling over into the newly formed Cheyenne Valley. Another W-trending headcut next initiated the upper Little Missouri Valley by diverting sheetflow from the northeastern Powder River Basin. The Little Missouri Valley was extended northward by diversion of flow to a fourth major headcut and then again by diversion to the Missouri Valley headcut. Sheetflow, moving SE into the Powder River Basin, was progressively captured and diverted as SW-trending headcuts formed the Yellowstone-Powder, Yellowstone-Tongue, and Yellowstone-Bighorn valleys. At the same time sheetflow was progressively captured and diverted by a northerly set of SW-trending headcuts which eroded the Redwater, Big Dry, and Musselshell valleys. Major spillways finally breached the 1,600 km thick barrier by cutting between the Highwood and Bearpaw Mountains and between Milk River Ridge and the Cypress Hills.

• OSTI ID: 5578862
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
DEVELOPED COUNTRIES
DISASTERS
DRAINAGE
EROSION
FLOODS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GLACIERS
MELTING
MONTANA
NORTH AMERICA
PHASE TRANSFORMATIONS
POWDER RIVER BASIN
RIVERS
STREAMS
SURFACE WATERS
USA
WATERSHEDS
WHITE RIVER
WYOMING