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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 Miller, M.L., and Bundtzen, T.K., 1994, Generalized geologic map of the Iditarod quadrangle, Alaska, showing potassium-argon, major-oxide, trace-element, fossil, paleocurrent, and archaeological sample localities: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219A, 48 p., 1 sheet, scale 1:250,000.
Symbol QTs
Unit name Surficial deposits
Description Unconsolidated fluvial, terrace, colluvial, glacial, and eolian deposits, usually covered by vegetation. Deposits range between 3 and 20 m thick and generally contain permafrost to some degree. Unit primarily Pleistocene to Holocene in age, however stream gravel terraces from other unglaciated areas elsewhere in Alaska have yielded Pliocene pollen and it is possible other terraces in the map area may also.
Lithology Unconsolidated

Correlated geologic units

Label Qs
Description Surficial deposits, undifferentiated
Geologic age Pleistocene to Holocene
Geologic setting Unconsolidated
Lithology Form Importance
Gravel < Coarse-detrital < Unconsolidated Bed Indeterminate, major
Sand < Coarse-detrital < Unconsolidated Bed Indeterminate, major
Clay < Fine-detrital < Unconsolidated Bed Indeterminate, major
Silt < Fine-detrital < Unconsolidated Bed Indeterminate, major
Peat < Unconsolidated Bed Indeterminate, major