Clay, silt, sand, gravel, or similar unconsolidated detrital earthen material deposited during relatively recent geologic time by a stream or other body of running water. Alluvium usually contains rounded particles and usually collects in the channels and floodplains of creeks, streams, rivers, and lakes.
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Glossary
Alluvium
Amphibole
A group of generally dark hydrous silicate minerals including common rock-forming varieties, such as hornblende and actinolite.
Amphibolite
A type of dark metamorphic rock consisting mainly of amphibole and plagioclase feldspar with little or no quartz.
Arkose
A type of feldspar-rich sandstone commonly derived from rapid disintegration of granitic rocks.
Asbestos
A commercial term applied to a group of silicate minerals that readily separate into thin, strong fibers that are flexible, heat-resistant, and chemically inert; also, a mineral of the asbestos group, principally chrysotile, anthophyllite, and crocidolite.
Ashlar
Prepared stone work of any type of stone.