Pedology

thumb|300px|Marshlands are often noted within wetlands, as seen here in the [[New Jersey Meadowlands at Lyndhurst, New Jersey, U.S.]] thumb|upright=1.35|right|Marsh in shallow water on a lakeshore

Permafrost () is soil or underwater sediment which continuously remains below for two years or more; the oldest permafrost has been continuously frozen for around 700,000 years. Whilst the shallowest permafrost has a vertical extent of below a meter (3 ft), the deepest is greater than . Similarly, the area of individual permafrost zones may be limited to narrow mountain summits or extend across vast Arctic regions. The ground beneath glaciers and ice sheets is not usually defined as permafrost, so on land, permafrost is generally located beneath a so-called active layer of soil which free

thumb|A freshwater swamp in Florida, [[United States]]

thumb|upright=1.35|A natural arch produced by erosion of differentially weathered rock in Jebel Kharaz ([[Jordan)]]

thumb|Loess in Vicksburg, Mississippi, United States

thumb|upright|Traditional laterite temple in Kerala thumb|upright|alt=This monument is constructed of laterite brickstones. It commemorates Buchanan who first described laterite at this site.|Monument of laterite brickstones at Angadipuram, [[Kerala, India, which commemorates where laterite was first described and discussed by Buchanan-Hamilton in 1807]]

Chernozem ( ), also called black soil, black earth, dark earth, regur soil or black cotton soil, is a black-colored soil containing a high percentage of humus (4% to 16%) and high percentages of phosphorus and ammonia compounds. Chernozem is very fertile and can produce high agricultural yields with its high moisture-storage capacity. However, prolonged agricultural use of chernozems still require replenishment with fertilizers because they easily can get depleted of nutrients through continuous decrease in humus content. Chernozems are a Reference Soil Group of the World Reference Base for So

Podzols, also known as podosols, spodosols, or espodossolos, are the typical soils of coniferous or boreal forests and also the typical soils of eucalypt forests and heathlands in southern Australia. In Western Europe, podzols develop on heathland, which is often a construct of human interference through grazing and burning. In some British moorlands with podzolic soils, cambisols are preserved under Bronze Age barrows.

300px|thumb|Soil Profile on Chalk at Seven Sisters Country Park, England

right|thumb|Cross-section illustrating the soil layer, showing the topsoil (A); [[regolith (B); and saprolite, a less-weathered regolith (C).]] The pedosphere () is the outermost layer of the Earth's crust that is composed of soil and subject to soil formation and erosion processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. The pedosphere is the "stratum corneum" of the Earth's surface and only develops when there is a dynamic interaction between the atmosphere (air in and above the soil), biosphere (living organisms and associated organic matters),

processes due to wind activity

soil forming processes

soil layer whose physical characteristics differ from the layers above and beneath

soil type

limestone-derived soil type of the Mediterranean region

thumb|Solonchak ground thumbnail|280px|Devil's Golf Course, Death Valley National Park, United States Solonchak (Russian and Ukrainian: Солончак) is a Reference Soil Group of the World Reference Base for Soil Resources (WRB). It is a pale or grey soil type found in arid to subhumid poorly-drained conditions. The word is Russian for "salt marsh", which is in turn from the Russian sol (соль) "salt".

property of a soil defined by the exact grain size distribution of its finer-grained anorganic matter

systematic categorization of soils

diameter of individual grains of sediment, or of lithified particles in clastic rocks

thumb|A variety of mire types in Carbajal Valley, Argentina thumb|right|Avaste Nature Reserve|Avaste Fen, one of the largest fens in Estonia thumb|right|A valley mire creates a level ground surface in otherwise dramatic topography. Upper Bigo Bog, Rwenzori Mountains, [[Uganda.]] A peatland is a type of wetland whose soils consist of organic matter from decaying plants, forming layers of peat. Peatlands arise because of incomplete decomposition of organic matter, usually litter from vegetation, due to water-logging and subsequent anoxia. Peatlands are unusual landforms that derive mostly from b

thumb|304x304px|Distribution of Gleysols A gleysol or gley soil is a hydric soil that unless drained is saturated with groundwater for long enough to develop a characteristic colour pattern. The pattern is essentially made up of reddish, brownish, or yellowish colours at surfaces of soil particles and/or in the upper soil horizons mixed with greyish/blueish colours inside the peds and/or deeper in the soil. Gleysols are also known as Gleyzems, meadow soils, Aqu-suborders of Entisols, Inceptisols and Mollisols (USDA soil taxonomy), or as groundwater soils and hydro-morphic soils.

right|thumb|300px|Solonetz profile Solonetz (, ) is a Reference Soil Group of the World Reference Base for Soil Resources (WRB). They have, within the upper 100 cm of the soil profile, a so-called "natric horizon" ("natrium" is the Latin term for sodium). A subsurface horizon (subsoil), higher in clay content than the upper horizon, has more than 15% exchangeable sodium. The name is based on the Russian соль (sol, meaning salt). The Ukrainian folk word "solontsi" means salty soil. In Ukraine, many villages are called Solontsi.

alt=Walrus |thumb|upright=1.5 |Sediment on the left tusk of a walrus. Walrus bioturbations in Arctic benthic sediments have large-scale ecosystem effects.

Ultisol, commonly known as red clay soil, is one of twelve soil orders in the United States Department of Agriculture soil taxonomy. The word "Ultisol" is derived from "ultimate", because Ultisols were seen as the ultimate product of continuous weathering of minerals in a humid, temperate climate without new soil formation via glaciation. They are defined as mineral soils which contain no calcareous (calcium carbonate containing) material anywhere within the soil, have less than 10% weatherable minerals in the extreme top layer of soil, and have less than 35% base saturation throughout the soi

thumb|upright=1.6|Alfisols of the world thumb|upright=1.6|One of the environments in which Alfisols can develop is the Temperate deciduous forest

taxonomic unit

In soil science, agriculture and gardening, hardpan or soil pan is a dense layer of soil, usually found below the uppermost topsoil layer. There are different types of hardpan, all sharing the general characteristic of being a distinct soil layer that is largely impervious to water. Some hardpans are formed by deposits in the soil that fuse and bind the soil particles. These deposits can range from dissolved silica to matrices formed from iron oxides and calcium carbonate. Others are man-made, such as hardpan formed by compaction from repeated plowing, particularly with moldboard plows, or by

international standard taxonomic soil classification system endorsed by the International Union of Soil Sciences

thumb|Rendzina soil (Castelltallat) thumb|Rendzina soil on the Maastrichtian Chalk in Kozubów Landscape Park, Poland Rendzina (or rendsina) is a soil type recognized in various soil classification systems, including those of Britain and Germany as well as some obsolete systems. They are humus-rich shallow soils that are usually formed from carbonate- or occasionally sulfate-rich parent material. Rendzina soils are often found in karst and mountainous regions.

thumb|upright=1.2|Fossil skeletal parts from extinct Belemnitida|belemnite cephalopods of the [[Jurassic – these contain mineralized calcite and aragonite.]]

thumb|right|upright=1.35|Paleosols sequence, Tuscany, Italy thumb|Etched section of paleosol from the Atlantic, San Salvador Island, Bahamas, indicating the top of the [[Pleistocene Grotto Beach Formation (limestone)]]

right|upright=1.35|300px|thumb|Caliche Petrified wood|fossil forest on [[San Miguel Island, California]]

upright=1.6|thumb|Vertisols of the world thumb|A more detailed map of the global distribution of Vertisols

classification of soil types

Illuvium is material displaced across a soil profile, from one layer to another one, by the action of rainwater. The removal of material from a soil layer is called eluviation. The transport of the material may be either mechanical or chemical. The process of deposition of illuvium is termed illuviation. It is a water-assisted transport in a basically vertical direction, as compared to alluviation, the horizontal running water transfer. The resulting deposits are called illuvial deposits. Cutans are a type of illuvial deposit.

thumb|Muskeg in Tongass National Forest

upright=1.6|thumb|Mollisols of the world upright=1.6|thumb|Mollisols are generally associated with the steppe biome

Andosols are soils found in volcanic areas formed in volcanic tephra. In some cases Andosols can also be found outside active volcanic areas. Andosols cover an estimated 1–2% of Earth's ice-free land surface. Andosols are a Reference Soil Group of the World Reference Base for Soil Resources (WRB). They are closely related to other types of soils such as Vitrosols, Vitrandosols, Vitrons and Pumice Soils that are used in different soil classification systems. The name comes from Japanese ( 'dark') and ( 'soil'), synonymous with (). In the USDA soil taxonomy (ST), many Andosols belong to the orde

underlying geological material in which soil horizons form

thumb|Cut-away section of soil, showing movement of soil layers due to cryoturbation. In gelisols (permafrost soils), cryoturbation (frost churning) refers to the mixing of materials from various horizons of the soil down to the bedrock due to freezing and thawing.

thumb|upright=1.6|Oxisols of the world thumb|upright=1.6|Oxisols are generally associated with the equatorial forest biome

thumb|Leptosol in Abergele (woreda)|Agbe (Ethiopia) A Leptosol in the World Reference Base for Soil Resources (WRB) is a very shallow soil over continuous rock or a deeper soil that is extremely rich in coarse fragments (gravelly and/or stony). Leptosols cover approximately 1.7 billion hectares of the Earth's surface. They are found from the tropics to the cold polar regions and from sea level to the highest peaks. Leptosols are particularly widespread in mountain areas, notably in Asia, South America, northern Canada and Alaska; and in the Saharan and Arabian deserts. Elsewhere, Leptosols can

thumb|Calcaric Cambisol (Humic) profile in Des'a forest in Ethiopia A Cambisol in the World Reference Base for Soil Resources (WRB) is a soil in the beginning of soil formation. The horizon differentiation is weak. This is evident from weak, mostly brownish discolouration and/or structure formation in the soil profile. thumb|400px|right|Distribution of Cambisols Cambisols are developed in medium and fine-textured materials derived from a wide range of rocks, mostly in alluvial, colluvial and aeolian deposits.

Luvisols are a group of soils, comprising one of the 32 Reference Soil Groups in the international system of soil classification, the World Reference Base for Soil Resources (WRB). They are widespread, especially in temperate climates, and are generally fertile. Luvisols are widely used for agriculture.

Aridisols (or desert soils) are a soil order in USDA soil taxonomy. Aridisols (from the Latin aridus, for "dry", and solum) form in an arid or semi-arid climate. Aridisols dominate the deserts and xeric shrublands, which occupy about one-third of the Earth's land surface. Aridisols have a very low concentration of organic matter, reflecting the paucity of vegetative production on these dry soils. Water deficiency is the central defining characteristic of Aridisols. Also required is sufficient age to exhibit subsoil weathering and development. Limited leaching in aridisols often results in one

thumb|upright=1.6|Histosols of the world

upright=1.6|thumb|Andisols of the world upright=1.6|thumb|Many Andisols develop in the immediate vicinity of volcanoes

Latosols, also known as tropical red earth, are soils found under tropical rainforests which have a relatively high content of iron and aluminium oxides. They are typically classified as oxisols (USDA soil taxonomy) or ferralsols (World Reference Base for Soil Resources). Latosols are tropical soils, but not all soils in the tropics are latosolic. Latosols are red or yellowish-red in colour throughout and they do not have distinct horizons like a podsol. The red colour comes from the iron oxides in the soil. They are deep soils, often extending deep whereas podsols are deep.

thumb|upright=1.6|Entisols of the world upright=1.6|thumb|Entisols of stabilized sand dunes often fall into the Psamment soil suborder. thumb|upright=1.6|Much of the fertile agricultural soils of the Nile valley in Egypt are Entisols developed on alluvial materials (soil suborders Fluvent and Aquent)

thumb|Fluvisol profile along Soil in Kilte Awula'ilo|Agula'e River, [[Ethiopia]] thumb|right|400px|Distribution of Fluvisols A fluvisol in the World Reference Base for Soil Resources (WRB) is a genetically young soil in alluvial deposits . Apart from river sediments, they also occur in lacustrine and marine deposits. Fluvisols correlate with fluvents and fluvaquents of the USDA soil taxonomy. The good natural fertility of most fluvisols and their attractive dwelling sites on river levees and higher parts in marine landscapes were recognized in prehistoric times.

thumb|right|250px|alt=This is a diagram and related photograph of soil layers from bedrock to soil.|A represents soil; B represents [[laterite, a regolith; C represents saprolite, a less-weathered regolith; beneath C is bedrock.]]

An Acrisol is a Reference Soil Group of the World Reference Base for Soil Resources (WRB). It has a clay-rich subsoil. It is associated with humid, tropical climates, such as those found in Brazil, and often supports forested areas. In the USDA soil taxonomy, Acrisols correspond to the Humult, Udult, and Ustult suborders of the Ultisols and also to Oxisols with a kandic horizon and to some Alfisols. Acrisol's low fertility and toxic amounts of aluminium pose limitations to its agricultural use, favouring in many places its use for silviculture, low-intensity pasture, and protected areas. Crops

sylvan ecosystem type

branch of soil science dedicated to the technical description of soil and soil profiles containing multiple horizons

map showing diversity of soil types and/or properties

Imogolite is an aluminium silicate clay mineral with the chemical formula . It occurs in soils formed from volcanic ash and was first described in 1962 for an occurrence in Uemura, Kumamoto prefecture, Kyushu Region, Japan. Its name originates from the Japanese word , which refers to the brownish yellow soil derived from volcanic ash. It occurs together with allophane, quartz, cristobalite, gibbsite, vermiculite and limonite.

thumb|upright=1.6|Inceptisols of the world thumb|upright=1.6|Some soils in urban environments fall into the Inceptisol order (soil suborder Anthrepts|Anthrept)

Yedoma () is an organic-rich (about 2% carbon by mass) Pleistocene-age permafrost with ice content of 50–90% by volume. Yedoma are abundant in the cold regions of eastern Siberia, such as northern Yakutia, as well as in Alaska and the Yukon. ==Characteristics== thumb|Alas landscape in Megino-Kangalassky District, Yakutia The landscape of yedoma areas is of glacier plains and hills with shallow depressions known as alas. Yedoma usually form in lowlands or stretches of land with rolling hills where ice wedge polygonal networks are present, in stable relief features with accumulation zones of poo

An anthrosol (or anthropogenic soil) in the World Reference Base for Soil Resources (WRB) is a type of soil that has been formed or heavily modified due to long-term human activity, such as from irrigation, addition of organic waste or wet-field cultivation used to create paddy fields. alt=a soil profile of terra preta|thumb|400x400px|A soil profile of terra preta, an anthrosol found in the Amazon Basin. Such soils can be formed from any parent soil, and are commonly found in areas where agriculture has been practiced for centuries. Anthrosols can be found worldwide, though they tend to have d

thumb|upright=1.6|Gelisols of the world thumb|upright=1.6|Tundra#arctic|Arctic Tundras are the typical environment for the formation of gelisols thumb|upright=1.6|Other gelisols are observed in Tundra#alpine|Alpine Tundras