In soil science, paleosols (spelt palaeosols in Great Britain and Australia) can have two meanings. The first, used in continents where present-day soils are very young due to glaciation, is simply that of a former soil preserved underneath sedimentary bedrock such as alluvium. Such artefacts can be more accurately referred to as soil fossils. Soil science deals with soil as a natural resource on the surface of the earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils per se; and these properties in relation to the use and management of soils. ... Glaciation, often called an ice age, is a geological phenomenon in which massive ice sheets form in the Arctic and Antarctic and advance toward the equator. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... This article is about the type of rock. ... Alluvium is soil land deposited by a river or other running water. ... For other uses of the term, see Fossil (disambiguation) Fossils are the mineralized remains of animals or plants or other artifacts such as footprints. ...

More generally, 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. A craton is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. ... The tropics are the geographic region of the Earth centered on the equator and limited in latitude by the two tropics: the Tropic of Cancer in the north and the Tropic of Capricorn in the southern hemisphere. ... Rainforest on Fatu-Hiva, Marquesas Islands A rainforest is a forested biome with high annual rainfall due to the Intertropical convergence zone. ... Savanna is a grassland dotted with trees, and occurs in several types of biomes. ... A dune in the Egyptian desert In geography, a desert is a landscape form or region that receives little precipitation. ... Ultisols are an order in USA soil taxonomy. ... Alfisols are a soil order in USA soil taxonomy. ... The Quaternary Period is the geologic time period from the end of the Pliocene Epoch roughly 1. ...

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. A satellite composite image of Africa Africa is the worlds second-largest continent in both area and population, after Asia. ... Podsol (also spelled Podzol) is the typical soil of Boreal forests. ... Categories: Africa geography stubs | Southern Africa ... The Mesozoic is one of three geologic eras of Phanerozoic eon. ... The Paleocene epoch (65-56 MYA) (early dawn of the recent) is the first geologic epoch of the Palaeogene period in the modern Cenozoic era. ...

Paleosols in this sense are always exceedingly infertile soils, containing available phosphorus levels orders of magnitude lower than in temperate regions with younger soils. Ecological studies have shown that this has forced highly specialised evolution amongst Australian flora (Tim F. Flannery, The Future Eaters: An Ecological History of the Australian Lands and People; published 1994 by George Braziller) to obtain minimal nutrient 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 Princton University Press). For the heavy metal band see Soil (band) Soil is the layer of minerals and organic matter, in thickness from centimetres to a metre or more, on the land surface. ... This article is about the chemical element. ... Nutrients and the body A nutrient is any element or compound necessary for or contributing to an organisms metabolism, growth, or other functioning. ... Biodiversity or biological diversity is the diversity of and in living nature. ...

See also

Pedogenesis
Pedology (soil study)

Pedogenesis or soil evolution (formation) is the process by which soil is created. ... Pedology, (from the Greek pedon = soil), is the study of soils and soil formation. ...