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, scale 1:250,000.
Symbol be
Unit name Marine beach deposits
Description Moderately well sorted, locally stratified deposits of sand and gravel. Beach deposits on Bristol Bay coastline are chiefly sand derived from adjacent glacial deposits, whereas those along Shelikov Strait are chiefly sandy gravel or gravel derived from local bedrock. Beaches along Katmai and Dakavak Bays include abundant pumice from the 1912 Novaarupta eruption. Includes the more prominent beaches formed during late Pleistocene highstands of glacial Lake Naknek.
Lithology Unconsolidated

Correlated geologic units

Label Qb
Description Beach deposits
Geologic age Holocene
Geologic setting Unconsolidated
Lithology Form Importance
Sand < Coarse-detrital < Unconsolidated Beach Major
Gravel < Coarse-detrital < Unconsolidated Beach Indeterminate, major