Information AboutPaleosol |
| CATEGORIES ABOUT PALEOSOL | |
| pedology | |
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More generally in Soil Science , paleosols are soils formed long periods ago that ''have no relationship in their chemical and physical characteristics to the present-day climate or vegetation''. Such soils form - apart from small scattered localities in outliers of ancient rocks - on extremely old contimental Cratons . Because of the changes in the Earth's climate over the last fifty million years, soils formed under Tropical Rainforest (or even Savanna ) have became exposed to increasingly Arid climates which cause former Oxisols , Ultisols or even Alfisols to dry out in such a manner that a very hard crust is formed. This process has occurred so extensively in most part of Australia as to restrict soil development - the former soil is effectively the parent material for a new soil, but it is so ''unweatherable'' that ''only a very poorly developed soil can exist'' in present dry climates, especially when they have become much drier during glacial periods in the Quaternary . In other parts of Australia, and in many parts of Africa , drying out of former soils has not been so severe. This has led to large areas of relict Podsols in quite dry climates in the far southern inland of Australia (where Temperate Rainforest was formerly dominant) and to the formation of Torrox Soils in Southern Africa . Here, present climates allow, effectively, the maintenance of the old soils under climates which they could not actually form if one were to start with the parent material on which they developed in the Mesozoic and Paleocene . Paleosols in this sense are always ''exceedingly infertile supplies. The fact that soil formation is ''simply not occurring'' makes ecologically sustainable management even more difficult. However, paleosols often contain the most exceptional Biodiversity due to the absence of competition (David Tilman; ''Resource Competition And Community Structure''; published 1982 by Princeton University Press). REFERENCES Retallack, G.J., 2001, ''Soils of the Past'', 2nd ed. New York, Blackwell Science. ISBN 0632053763 Kraus, M.J., 1999, ''Paleosols in clastic sedimentary rocks: their geologic applications'', Earth Science Review 47:41-70. SEE ALSO Pedogenesis Pedology (soil Study) |
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