Unit symbol: | Qs |
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Age range | Quaternary (1.806 to 0 Ma) |
Lithology: | Unconsolidated |
Group name: | Unconsolidated and poorly consolidated surficial deposits |
Source map | Patton, W.W., Jr., Wilson, F.H., and Taylor, T.A., 2011, Geologic map of Saint Lawrence Island, Alaska: U.S. Geological Survey Scientific Investigations Map SIM-3146, pamphlet, 13 p., 1 sheet, scale 1:250,000, and database. |
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Symbol | Qs |
Unit name | Beach, bar, and alluvial deposits |
Description | Unit composed of gravel and sand eroded from the underlying bedrock platform and silt and sand alluvium eroded from upland areas. Location and physiographic expression-Unit includes active beach and bar deposits along the present shoreline and former beach and bar deposits that mantle a broad wave-cut bedrock platform , which stands less than 30 meters above sea level in the eastern and central part of the island. The formerly active beaches and bars are locally discernible in aerial photographs by their physiographic expression beneath a thin cover of peat and tundra vegetation. Alluvial deposits occur along small streams, mainly in the western part of the island |
Lithology | Unconsolidated |
Label | Qs |
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Description | Surficial deposits, undifferentiated |
Geologic age | Pleistocene to Holocene |
Geologic setting | Unconsolidated |
Lithology | Form | Importance |
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Gravel < Coarse-detrital < Unconsolidated | Bed | Indeterminate, major |
Sand < Coarse-detrital < Unconsolidated | Bed | Indeterminate, major |
Clay < Fine-detrital < Unconsolidated | Bed | Indeterminate, major |
Silt < Fine-detrital < Unconsolidated | Bed | Indeterminate, major |
Peat < Unconsolidated | Bed | Indeterminate, major |