Unconsolidated surficial deposits, undivided

Unit symbol: Qs
Age range Quaternary (1.806 to 0 Ma)
Lithology: Unconsolidated
Group name: Unconsolidated and poorly consolidated surficial deposits
Unconsolidated, poorly to well-sorted, poorly to moderately well-stratified deposits; consist predominantly of alluvial, colluvial, marine, lacustrine, eolian, and swamp deposits. May include some glacial deposits. Also includes widespread glacial and periglacial deposits that consist of end, lateral, and ground moraine, outwash, rock glacier deposits, and other glacial and periglacial deposits as well as glacially scoured bedrock that may be covered with thin, glacially derived deposits. These glacial deposits are of Holocene and Pleistocene age and may include small areas of potentially latest Tertiary deposits. Map unit locally includes reworked volcanic debris as well as block and ash flows. On generalized map, shown as part of unit QTs

Source map information

Source map Riehle, J.R., and Detterman, R.L., 1993, Quaternary geologic map of the Mount Katmai quadrangle and adjacent parts of the Naknek and Afognak quadrangles, Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-2032, 1 sheet, scale 1:250,000.
Symbol st
Unit name Stream terrace deposits
Description Poorly to moderately well sorted and stratified deposits of sand, gravel, and boulders having flat surfaces above level of adjacent floodplain. Mapped only along King Salmon River and along unnamed north-flowing tributary of the Naknek River. Terrace deposits in mountain valleys are mapped as neoglacial outwash (no)
Lithology Unconsolidated

Correlated geologic units

Label Qt
Description Terrace deposits
Geologic age Pleistocene to Holocene
Geologic setting Unconsolidated
Lithology Form Importance
Gravel < Coarse-detrital < Unconsolidated Alluvial Major
Sand < Coarse-detrital < Unconsolidated Terrace, stream Major
Silt < Fine-detrital < Unconsolidated Terrace, stream Major
Boulders < Coarse-detrital < Unconsolidated Terrace, stream Indeterminate, major