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 Berg, H.C., 1973, Geology of Gravina Island: U.S. Geological Survey Bulletin 1373, 41 p., 1 plate, scale 1:63,360.
Symbol Qt
Unit name Glacial-marine deposits
Description Stratified glacial till, gravel and blue clay containing Quaternary marine fossils, half a mile northwest of Dall Bay: deposit is about 8 feet thick and lies about 80 feet above sea level. A deposit at 200-300 feet above sea level west of Blank Inlet may also be a marine terrace deposit.
Lithology Unconsolidated

Correlated geologic units

Label Qm
Description Glacial deposits, undivided, of Holocene and/or Pleistocene age
Geologic age Pleistocene to Holocene
Geologic setting Unconsolidated
Lithology Form Importance
Gravel < Coarse-detrital < Unconsolidated Glacial Major
Sand < Coarse-detrital < Unconsolidated Glacial Major
Silt < Fine-detrital < Unconsolidated Glacial Indeterminate, major
Boulders < Coarse-detrital < Unconsolidated Glacial Minor