Gravel, sand, and silt; Quaternary; alluvium (IDQa;0)

State	Idaho
Name	Gravel, sand, and silt; Quaternary; alluvium
Geologic age	Quaternary
Original map label	Qa
Comments	includes stream alluvium and alluvial terraces (gravel, sand and silt), floodplain alluvium (sand, silt, clay and peat), and alluvial-fan deposits (including boulder to pebble gravel, sand and silt, and colluvium in uplands)
Primary rock type	alluvium
Secondary rock type	alluvial terrace
Other rock types	floodplain; alluvial fan; colluvium
Lithologic constituents	Major Unconsolidated > Coarse-detrital > Gravel (Alluvial)gravel in stream, terrace, and fan alluvium Minor Unconsolidated > Coarse-detrital > Sand (Alluvial)interstitial stream and proximal floodplain sand Incidental Unconsolidated > Fine-detrital (Colluvial)interstitial fines in colluvium
Map references	Bond, J.G., Kauffman, J.D., Miller, D.A., and Venkatakrishnan, Ramesh, 1978, Geologic map of Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, with contributions from U.S. Geological Survey, scale 1:500,000.
Unit references	Bond, J.G., Kauffman, J.D., Miller, D.A., and Venkatakrishnan, Ramesh, 1978, Geologic map of Idaho: Moscow, Idaho, Idaho Bureau of Mines and Geology, with contributions from U.S. Geological Survey, scale 1:500,000. Scott, W.E., 1982, Surficial geologic map of the eastern Snake River Plain and adjacent areas, 111o to 115o W., Idaho and Wyoming: U.S. Geological Survey Map I-1372, scale 1:250,000. [http://pubs.er.usgs.gov/publication/i1372] Bookstrom, A.A., Box, S.E., Jackson, B.L., Brandt, T.R., Derkey, P.D., and Munts, S.R., 1999, Digital map of surficial geology, wetlands, and deepwater habitats, Coeur d'Alene River valley, Idaho: U.S. Geological Survey Open-File Report OF 99-548, 121 p., 2 pl., 1:24,000 scale, 9 pl., 1:50,000 scale. [http://pubs.er.usgs.gov/publication/ofr99548]
Geographic coverage	Ada - Adams - Bannock - Bear Lake - Benewah - Bingham - Blaine - Boise - Bonner - Bonneville - Boundary - Butte - Camas - Canyon - Caribou - Cassia - Clark - Clearwater - Custer - Elmore - Franklin - Fremont - Gem - Gooding - Idaho - Jefferson - Jerome - Kootenai - Latah - Lemhi - Lewis - Lincoln - Madison - Minidoka - Nez Perce - Oneida - Owyhee - Payette - Power - Shoshone - Teton - Twin Falls - Valley - Washington