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 Patton, W.W., Jr., and Moll-Stalcup, E.J., 2000, Geologic map of the Nulato quadrangle, west-central Alaska: U.S. Geological Survey Geologic Investigations Series I-2677, 41 p., 1 sheet, scale 1:250,000.
Symbol Qfo
Unit name Older flood-plain deposits
Description Chiefly light-gray and grayish-orange micaceous silt. Subordinate lenses of sand and peat, reworked eolian sand, and gravel. Deposits are at or near river level but youthful floodplain features such as oxbow lakes, meander scrolls, and abandoned channels are much modified or absent.
Lithology Unconsolidated

Correlated geologic units

Label Qac
Description Abandoned channel deposits
Geologic age Pleistocene
Geologic setting Unconsolidated
Lithology Form Importance
Sand < Coarse-detrital < Unconsolidated Alluvial Major
Silt < Fine-detrital < Unconsolidated Alluvial Indeterminate, major