Colluvium

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Colluvium is a general name for loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rainwash, sheetwash, slow continuous downslope creep, or a variable combination of these processes. Colluvium can be composed of often a heterogeneous range of sediments ranging from silt to rock fragments of various sizes. This term is also used to specifically refer to sediment deposited at the base of a hillslope by unconcentrated surface runoff or sheet erosion. Colluviation refers to the build up of colluvium at the base of a hillslope.[1][2]

Typically colluvium accumulates gently sloping aprons of fans either the base of or within gullies and hollows within hillslopes. These accumulations of colluvium can be several meters in thickness and often contain buried soils (paleosols), crude bedding, and cut and fill sequences. Thick accumulations of colluvium may preserve a rich record of longterm paleoclimatic change based on the paleosols and the remains of plants and animals, invertebrate and vertebrates that they often contain.[2] Thick accumulations of colluvium often contain well-preserved and sometimes deeply buried archaeological deposits as excavated at the Cherokee Sewer Site, Cherokee County, Iowa, and the Koster Site, Greene County, Illinois.[3][4]

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References[edit]

  1. ^ Jackson, JA, J Mehl, and K. Neuendorf (2005) Glossary of Geology American Geological Institute, Alexandria, Virginia. 800 pp. ISBN 0-922152-76-4
  2. ^ a b Goodie, AS (2003) Colluvium in A. S. Goodie, ed., pp. 173, Encyclopedia of Geomorphology Volume 1, A–I. Routledge, New York, New York. 1200 pp.
  3. ^ Anderson, D, and HA Semken (1980) The Cherokee Excavations: Holocene Ecology and Human Adaptations in Northwestern Iowa. Academic Press, New York.
  4. ^ Angel JR (1990) Koster site archaeology I: stratigraphy and landscape evolution. Research Series. vol. 8. Center for American Archeology, Kampsville, Illinois.

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