Paleohydraulics of pleistocene drainage development of the Souris, Des Lacs, and Moose Mountain spillways, Saskatchewan and North Dakota
Recent recognition of the rapid draining of numerous glacial lakes, including some in the Northern Plains, has revealed 'a need for further research concerning this process. Geomorphic interpretation of the Souris, Des Lacs, and Moose Mountain Valleys, and the gravel deposits in them, has resul...
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UND Scholarly Commons
1984
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| Online Access: | https://commons.und.edu/theses/182 https://commons.und.edu/context/theses/article/1181/viewcontent/Lord__Mark_L.__MS_Thesis_1984.pdf |
| Summary: | Recent recognition of the rapid draining of numerous glacial lakes, including some in the Northern Plains, has revealed 'a need for further research concerning this process. Geomorphic interpretation of the Souris, Des Lacs, and Moose Mountain Valleys, and the gravel deposits in them, has resulted in the recognition of five phases in the development of the drainageways. Textural analyses and paleohydraulic methods were applied to the sediments associated with each phase to distinguish and characterize the discharges. Four of the five phases of development involved short-lived, high velocity (>4 m/s) discharges resulting from the rapid draining of glacial lakes; the other phase (2) involved deposition by glacial meltwater. Phase 1 discharges (3 x 104 m3/s) initiated the development of the Des Lacs Valley; the source probably was a supraglacial lake in the vicinity of Bowbells, North Dakota. Deposits of generally unstructured sandy gravel occur relatively high on the valley walls and are confined to the lower Des Lacs and Souris spillways. Phase 2 discharges (2.1 x 103 m3/s) deposited outwash sediment, consisting of cross-bedded gravelly sand, in the Moose Mountain and lower Souris Valley. Glacial meltwater from the Moose Mountains, which commenced when the ice sheet divided around the Moose Mountains, was the source of these flows. Phase 3 and 4 discharges (1.9 x 104 m3/s) probably each resulted from the rapid draining of Glacial Lake Arcola. Phase 3 was an erosional stage that incised the Moose Mountain and lower Souris Valley and induced landslides along the valley walls. Deposition of unstructured pebble gravel throughout much of the lower Souris spillway occurred during phase 4. The deposits commonly are inset into the valley walls, indicating that they were later truncated by erosion. The upper Souris Valley was developed and the lower Souris and Des Lacs spillways were enlarged during the cataclysmic discharges of phase 5 (2.0 x 105 m3 /s) from Glacial Lake Regina. Huge bars of unstructured pebbly cobble ... |
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