Geological Society of America

Session 4: Floods, Landslides, and Fluvial Systems

Tuesday, 19 May 2020
8:00 AM - 11:10 AM

LANDSLIDES IN THE RED RIVER VALLEY, MINNESOTA

Program: Virtual Meeting
Time: 8:45 AM – 9:05 AM

Authors

Stephanie Day Presenting Author
Fargo, ND
Micheal Sullivan
North Dakota State University, Fargo, ND
Charles Idell Nixon
North Dakota State University, Fargo, ND
Carrie Jennings
The Freshwater Society, St PAul, MN
Karen B. Gran
University of Minnesota - Duluth, Duluth, ND
Stephen DeLong
U.S. Geological Survey, Moffett Field, CA
Whitney M. DeLong
University of Minnesota, Minneapolis, ND
Megan Ostrand
North Dakota State University, Fargo, ND
Samuel D. Marolt
North Dakota State University, Fargo, ND
Victoria Elizabeth Halvorson
Department of Geosciences, Fargo, ND

Abstract

Despite its low relief, the Red River Valley in Minnesota does experience mass wasting, including landslides. Thousands of slides, primarily along rivers or lake shores, have been identified using airborne lidar data, and a subset of these have been field-verified. The size and failure mechanism of these slides changes throughout the valley in response to west-to-east changes in the surficial geology. Along the western edge of Minnesota, near the axis of the valley, the sediment is dominated by offshore glacial Lake Agassiz deposits of clay and silt which fail slowly as shallow slides, often as a result of changes to the vegetation or overburden. Moving a few tens of kilometers east into the near-shore Lake Agassiz environment, deposits are dominated by interbedded lacustrine and fluvial sands. Rivers in this area are deeply incised and form steep bluffs that can lead to large rotational failures. Farthest to the east towards the edge of the Red River valley watershed, rivers are less incised with lower river banks, but small rotational failures still occur in glacially dominated sediments. This inventory of Red River Valley landslides is a component of a greater Minnesota landslide mapping effort and highlights the need for understanding the variety of factors that contribute to landslide hazards in the state.

Geological Society of America Abstracts with Programs. Vol. 52, No. 5

doi: 10.1130/abs/2020NC-348211

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