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 Waythomas, C.F., 1995, Surficial geologic map of northern Adak Island, Alaska: U.S. Geological Survey Open-File Report 95-128, Plate 1, scale 1: 50,000.
Symbol Qbb
Unit name Boulder beaches
Description Moderately sorted, rounded to well-rounded boulder and cobble gravel on high energy beaches. Common in the Clam Lagoon and Andrew Bay area where deposits are found on uplifted wave-cut terraces. Porous and permeable, but not water bearing.
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