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Alluvium
Alluvium
(from the Latin
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.[1][2] Alluvium
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.[3]

Contents

1 Definitions 2 Age 3 Ores 4 See also 5 References 6 External links

Definitions[edit] 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.[3] Age[edit] Most alluvium is geologically Quaternary
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".[3] Alluvium of Pliocene
Pliocene
age occurs, for example, in parts of Idaho.[4] Alluvium
Alluvium
of late Miocene
Miocene
age occurs, for example, in the valley of the San Joaquin River, California.[5] Ores[edit] Alluvium
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.[3] See also[edit]

Alluvial fan Alluvial plain Alluvion Bay mud Braided stream Colluvium Desert pavement Diluvium Eluvium Fluvial Hydraulic action Illuvium

References[edit]

^ 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
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
River
Basin ( USGS
USGS
Professional Paper 1197) (PDF). Washington D.C.: USGS. p. 13. 

External links[edit]

Wikimedia Commons has media related to Alluvium.

 Chisholm, Hugh, ed. (1911). "Alluvium". Encyclopædia Britannica (11th ed.). Cambridge Unive

.