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 Qls
Unit name Landslide deposits
Description Consist of large angular blocks of bedrock and minor amounts of surficial material. Most slides appear to be stabilized by vegetation. Slides are most common in Jurassic sedimentary rocks and Tertiary volcanic rocks. Slides in the Jurassic sedimentary rocks along the Iniskin Peninsula involve millions of tons of rock and may be as much as 2 miles long. Landslide have a wide variety of ages; some are partially overridden by Pleistocene glacial deposits, whereas others happen as recently as the 1950's No landslides occurred as a result of the 1964 Great Alaska earthquake
Lithology Unconsolidated

Correlated geologic units

Label Qls
Description Landslide deposits
Geologic age Pleistocene to Holocene
Geologic setting Unconsolidated
Lithology Form Importance
Boulders < Coarse-detrital < Unconsolidated Landslide Major
Gravel < Coarse-detrital < Unconsolidated Landslide Major
Silt < Fine-detrital < Unconsolidated Landslide Minor
Clay < Fine-detrital < Unconsolidated Landslide Incidental