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 blik
Unit name Drift of Iliuk advance, Brooks Lake drift
Description Unsorted, unstratified till forming morphologically fresh to slightly modified arcuate end moraines and lateral moraines that are confined to mountain valleys. Locally includes stratified sand and gravel deposits. Clast shapes vary from subangular to round; clasts comprise lithologies restricted to local drainages.
Lithology Unconsolidated

Correlated geologic units

Label Qwr
Description Latest Wisconsin, Iliuk, Riley Creek, and other glaciations
Geologic age Late-Pleistocene
Geologic setting Unconsolidated
Lithology Form Importance
Gravel < Coarse-detrital < Unconsolidated Glacial Major
Boulders < Coarse-detrital < Unconsolidated Glacial Indeterminate, major
Sand < Coarse-detrital < Unconsolidated Glacial Indeterminate, major
Silt < Fine-detrital < Unconsolidated Glacial Indeterminate, major