Model for sand hills development: Geometry, sediment supply and deposition, river systems and climatic implications
- UNL, Lincoln, NE (United States). Geology Dept.
- USD, Vermillion, SD (United States). Dept. of Earth Science
A model of sand hills development was formulated using processes occurring along the Dismal, Middle Loup and Platte rivers. A widespread alluvial fan blanketed by loess and sand dunes with interspersed lacustrine deposits is the product. The great arc of the sediment-supplying river indicates direction of wind transport. The key is a Platte-like river with flows near threshold capacity for transport of sediment from the river's source through the area during wetter climatic periods. During dryer periods stream channels fill with sediment pulses transported from mountain headwaters during snowmelt flood flows. The flood flows cause vertical reworking and sorting of the sediment. With waning flood flows many stream channels dry up leaving sediments vulnerable to wind erosion and transpore. With time stream channels become blocked by aggradation of sediment and dune formation diverting snowmelt floods to new paths in the forming dune field or around the margin of the new dune field. This process continues until increased flows with wetter comates are once again able to transport sediment through the area and erode a new river valley. Rivers rising in sand hills are groundwater fed, uniform in flow, and change only in response to climatic changes. They do not have the energy to rework the extensive gravel deposits of the Platte-like rivers and their net effect is to rework sediment above the coarser alluvium and transport the finer sediment out of the sand hills.
- OSTI ID:
- 5806228
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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