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 Detterman, R.L., and Reed, B.L., 1973, Surficial deposits of the Iliamna quadrangle, Alaska: U.S. Geological Survey Bulletin 1368-A, 64 p., 1 plate, scale 1:250,000.
Symbol Qso
Unit name Solifluction deposits
Description Solifluction lobes are conspicuous features in northwestern part of quadrangle. Deposits are most common where regolith contains a considerable amount of fine material, such as loess-mantled hills and drift of the Mak Hill Glaciation. Transported material undergoes a minor amount of sorting and crude polygonal ground is formed. Fine materials are concentrated in the center and coarse fragments around the outside
Lithology Unconsolidated

Correlated geologic units

Label Qsf
Description Solifluction deposits
Geologic age Holocene
Geologic setting Unconsolidated
Lithology Form Importance
Sand < Coarse-detrital < Unconsolidated Solifluction Major
Silt < Fine-detrital < Unconsolidated Solifluction Major
Gravel < Coarse-detrital < Unconsolidated Solifluction Minor
Peat < Unconsolidated Solifluction Minor