Geologic Map of Alaska: Unconsolidated surficial deposits, undivided

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	Wilson, F.H., Detterman, R.L., and DuBois, G.D., 2015, Geologic framework of the Alaska Peninsula, southwest Alaska, and the Alaska Peninsula terrane: U.S. Geological Survey Bulletin 1969-B, scale 1:500,000, 2 plates, 34 p.
Symbol
Unit name	Surficial deposits
Description	Typically unconsolidated, poorly sorted to well sorted, poorly to moderately well-stratified sand, gravel, and silt. Includes alluvial, colluvial, glacial, marine, lacustrine, and eolian deposits, as well as locally reworked volcanic-ash and debris-flow deposits (unit not shown on map)
Lithology	Unconsolidated

Correlated geologic units

Label	Qs
Description	Surficial deposits, undifferentiated
Geologic age	Pleistocene to Holocene
Geologic setting	Unconsolidated

Lithology	Form	Importance
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