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 Qac
Unit name Mak Hill Glaiciation, abandoned channel deposits
Description Mak Hill Glaciation, abandoned channel deposits. Deposits in broad channels incised into ground moraine and originating from a lobe of the end moraine. Channel floor is usually flat where a modern stream is not present; where modern streams are present, they are clearly underfit. Channel range in width from about 200 to 4000 feet. Deposits within are mainly stratified gravel and sand containing lenses of silt; cut and fill structures are common. Top layer commonly silt that may have been carried into the channel from the loess mantle after abandonment
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