A Gley (Russian: глей) is a wetland soil (hydric soil) that, unless drained, is saturated with groundwater for long enough periods to develop a characteristic gleyic colour pattern. This pattern is essentially made up of reddish, brownish or yellowish colours at surfaces of soil particles (peds) 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 and meadow soils (Russia), Aqu-suborders of Entisols, Inceptisols and Mollisols (USDA soil taxonomy), or as groundwater soils and hydro-morphic soils.

Gleysols occur on wide range of unconsolidated materials, mainly fluvial, marine and lacustrine sediments of Pleistocene or Holocene age, with basic to acidic mineralogy. They are found in depression areas and low landscape positions with shallow groundwater.

Wetness is the main limitation of virgin Gleysols; these are covered with natural swamp vegetation and lie idle or are used for extensive grazing. Artificially drained Gleysols are used for arable cropping, dairy farming and horticulture. Gleysols in the tropics and subtropics are widely planted to rice.

Gleysols occupy an estimated 720 million hectares worldwide. They are azonal soils and occur in nearly all climates. The largest extent of Gleysols is in northern Russia, Siberia, Canada, Alaska, China and Bangladesh. An estimated 200 million hectares of Gleysols are found in the tropics, mainly in the Amazon region, equatorial Africa and the coastal swamps of Southeast Asia.

A stagnohumic gley soil in a forest plantation in mid-Wales, U.K. The organic-rich topsoil is over a grey and orange mottled subsoil developed in glacial till ("boulder clay")

They exhibit a greenish-blue-grey soil color due to anoxic wetland conditions. On exposure, as the iron in the soil oxidizes colors are transformed to a mottled pattern of reddish, yellow or orange patches. During soil formation (gleying), the oxygen supply in the soil profile is restricted due to soil moisture at saturation. Anaerobic micro-organisms support cellular respiration by using alternatives to free oxygen as electron acceptors to support cellular respiration. Where Anaerobic organisms reduce ferric oxide to ferrous oxide, the reduced mineral compounds produce the gley soil typical color. Green rust, a layered double hydroxide (LDH) of Fe(II) and Fe(III) can be found as the mineral fougerite in gley soils.

Gley soils may be sticky and hard to work, especially where the gleying is caused by surface water, held up on a slowly permeable layer. However, some ground-water gley soils have permeable lower horizons, including some sands, for example in hollows within sand dune systems, known as slacks, and in some alluvial situations.

Groundwater gley soils develop where drainage is poor because the water table (phreatic surface) is high, whilst Surface-water gleying occurs when precipitation inputs at the surface do not drain freely through the ground. A reducing environment exists in the saturated layers, which become mottled greyish-blue or brown because of the content of ferrous iron and organic matter. The presence of reddish or orange mottles indicates localised re-oxidation of ferrous salts in the soil matrix, and is often associated with root channels, animal burrows or cracking of the soil material during dry spells.

In the World Reference Base for Soil Resources (WRB), soils with redox processes due to ascending groundwater belong to the Reference Soil Group Gleysols. Soils with redox processes due to stagnant water are Stagnosols and Planosols.

Distribution of Gleysols

See also



  • IUSS Working Group WRB: World Reference Base for Soil Resources 2014, Update 2015. World Soil Resources Reports 106, FAO, Rome 2015. ISBN 978-92-5-108369-7. (PDF 2,3 MB).
  1. Trolard F., Bourrié G., Abdelmoula M., Refait P. and Feder F. 2007: Fougerite, a new mineral of the pyroaurite-iowaite group: description and crystal structure. Clays and Clay Minerals, vol. 55, no. 3, p. 323-334; doi:10.1346/CCMN.2007.0550308.
  2. Génin J.-M. R., Aïssa R., Géhin A., Abdelmoula M., Benali O., Ernstsen V., Ona-Nguema G., Upadhyay Ch. and Ruby Ch. 2005: Fougerite and FeII-III hydroxycarbonate green rust; ordering, deprotonation and/or cation substitution; structure of hydrotalcite-like compounds and mythic ferrosic hydroxide Fe(OH)2+x. Solid State Sciences, vol. 7., no. 5, p. 545-572. doi:10.1016/j.solidstatesciences.2005.02.001.
Canadian system of soil classification

The Canadian System of Soil Classification is more closely related to the American system than any other, but they differ in several ways. The Canadian system is designed to cover only Canadian soils. The Canadian system dispenses with the sub-order hierarchical level. Solonetzic and Gleysolic soils are differentiated at the order level.

Index of soil-related articles

This is an index of articles relating to soil.

Polish Soil Classification

The Polish Soil Classification (Polish: Systematyka gleb Polski) is a soil classification system used to describe, classify and organize the knowledge about soils in Poland.

Rio Cajari Extractive Reserve

The Rio Cajari Extractive Reserve (Portuguese: Reserva Extrativista do Rio Cajari) is an extractive reserve in the state of Amapá, Brazil.

It protects a region of dense rainforest, cerrado fields and flooded riparian zones that is rich in biodiversity. Formerly it was used for rubber extraction, and later efforts were made to develop a pulp industry. Extraction of timber for sale is now prohibited. The residents, who are poorly educated and suffer poor health, engage in subsistence hunting, fishing and farming, and extract forest products such as Brazil nuts, açaí palm fruit and heart of palm.

Rio Curiaú Environmental Protection Area

The Rio Curiaú Environmental Protection Area (Portuguese: Área de Proteção Ambiental do Rio Curiaú) is an environmental protection area in the state of Amapá, Brazil. It attempts to protect the environment of a region of forest and flooded fields close to the state capital, Macapá, and also to preserve the values and culture of the traditional population, which is of African descent. It is threatened by urban expansion.

Saint-Lazare, Quebec

Saint-Lazare, also known as Saint-Lazare-de-Vaudreuil, is an off-island suburb of Montreal, in southwestern Quebec, Canada in the Regional County Municipality of Vaudreuil-Soulanges.

The city of Saint-Lazare has experienced rapid growth since 1990, fueled predominantly by the arrival of young, middle-class families. New residents flocked to the area seeking a more relaxed lifestyle than that of the island of Montreal, as well as larger homes and property for less money than on the island of Montreal.

World Reference Base for Soil Resources

The World Reference Base for Soil Resources (WRB) is an international soil classification system for naming soils and creating legends for soil maps. The currently valid version is the Update 2015 of the third edition 2014. It is edited by a working group of the International Union of Soil Sciences (IUSS).

Île Perrot

Île Perrot (French pronunciation: ​[il pɛʁo]) is an island west of the island of Montreal in the Canadian province of Quebec. Part of the Hochelaga Archipelago, the island lies between Lake Saint-Louis and Lac des Deux-Montagnes. The island was granted by the Intendant Talon of New France to its founder François-Marie Perrot then Governor of Montreal on 28 October 1672.

Nearly 38,000 people live in one of Île Perrot's four municipalities:



Terrasse Vaudreuil

L'Île-PerrotÎle Perrot holds the only working windmill in Quebec, dating from the time Île-Perrot was a seigneury in the French colony of New France. The windmill and associated miller's house were designated a National Historic Site of Canada in 1969, and a Historic Monument under provincial heritage legislation in 1977. In the windmill's honour, what now constitutes the commercial artery of the island was named boulevard Don-Quichotte.

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.