Alluvium

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Alluvium and adjacent constituents
Alluvium deposits in the Gamtoos Valley in South Africa
An alluvial plain in Red Rock Canyon State Park (California)
subsistence farming
in the Amazon Basin along the river banks.

Alluvium (from

estuaries, lakes, or ponds, are not described as alluvium.[1]

Floodplain alluvium can be highly fertile, and supported some of the earliest human civilizations.[6]

Definitions

The present

alluvion (the French term for alluvium) as new land formed by deposition of sediments along rivers and seas.[8]

By the 19th century, the term had come to mean recent sediments deposited by rivers on top of older

fluvial origin.[8]

Alluvium and diluvium were grouped together as colluvium in the late 19th century. "Colluvium" is now generally understood to mean sediments produced by gravity-driven transport on steep slopes, while the definition of "alluvium" has switched back to an emphasis on sediments deposited by river action. There continues to be disagreement over what other sediment deposits should be included under the term "alluvium."[8]

Age

Most alluvium is 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".[9] Alluvium of Pliocene age occurs, for example, in parts of Idaho.[10] Alluvium of late Miocene age occurs, for example, in the valley of the San Joaquin River, California.[11]

See also

References

  1. ^ .
  2. ^ Glossary of Geological Terms. Geotech.org. Retrieved on 2012-02-12.
  3. ^ Geology Dictionary – Alluvial, Aquiclude, Arkose. Geology.Com. Retrieved on 2012-02-12.
  4. .
  5. .
  6. .
  7. ^ Allaby 2013, "alluvial".
  8. ^ .
  9. ^ Chisholm, Hugh, ed. (1911). "Alluvium" . Encyclopædia Britannica (11th ed.). Cambridge University Press.
  10. ^ Ames, Dan (1998), "Formation of the Soils" (PDF), Soil Survey of Jerome County and Part of Twin Falls County, Idaho, Natural Resources Conservation Service, United States Department of Agriculture, p. 238
  11. USGS
    . p. 13.

External links

  • Media related to Alluvium at Wikimedia Commons