Alluvium (from the
Latin alluvius, from alluere, "to wash against") is
loose, unconsolidated (not cemented together into a solid rock) soil
or sediments, which has been eroded, reshaped by water in some form,
and redeposited in a non-marine setting.
Alluvium is typically
made up of a variety of materials, including fine particles of silt
and clay and larger particles of sand and gravel. When this loose
alluvial material is deposited or cemented into a lithological unit,
or lithified, it is called an alluvial deposit.
4 See also
6 External links
The term "alluvium" is not typically used in situations where the
formation of the sediment can clearly be attributed to another
geologic process that is well described. This includes (but is not
limited to): lake sediments (lacustrine), river sediments (fluvial),
or glacially-derived sediments (glacial till). Sediments that are
formed or deposited in a perennial stream or river are typically not
referred to as alluvial.
Most alluvium is geologically
Quaternary in age, and is often referred
to as "cover" because these sediments obscure the underlying bedrock.
Most sedimentary material that fills a basin ("basin fill") that is
not lithified is typically lumped together as "alluvial". Alluvium
Pliocene age occurs, for example, in parts of Idaho.
Miocene age occurs, for example, in the valley of the San Joaquin
Alluvium can contain valuable ores such as gold and platinum and a
wide variety of gemstones. Such a concentration of valuable ores is
termed a placer deposit.
^ Glossary of Geological Terms. Geotech.org. Retrieved on 2012-02-12.
^ Geology Dictionary – Alluvial, Aquiclude, Arkose. Geology.Com.
Retrieved on 2012-02-12.
^ a b c d Chisholm, 1911
^ Ames, Dan (1998), "Formation of the Soils" (PDF),
Soil Survey of
Jerome County and Part of Twin Falls County, Idaho, Natural Resources
Conservation Service, USDA, p. 238
^ Huber, N. King (1981). Amount and Timing of Late Cenozoic Uplift and
Tilt of the Central Sierra Nevada, California—Evidence from the
Upper San Joaquin
River Basin (
USGS Professional Paper 1197) (PDF).
Washington D.C.: USGS. p. 13.
Wikimedia Commons has media related to Alluvium.
Chisholm, Hugh, ed. (1911). "Alluvium". Encyclopædia Britannica
(11th ed.). Cambridge Unive