Gley soils have grey and yellow patches where the soil is watterlogged, the oxygen supply is reduced, and anaerobic micro-organisms flourish by extracting oxygen from chemical compounds. This is most often the case when the sesquioxide of iron, ferric oxide is reduced to ferrous oxide by the removal of oxygen. This process gives a greenish-blue-grey colour to the soil. Gley soils are sticky and hard to work. For the heavy metal band see Soil (band) Soil is unconsolidated rock particle that lies on the surface of the earth, intermingled, perhaps, with organic matter from plant decay. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Anaerobic is a technical word which literally means without air. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... Iron(III) oxide - also known as ferric oxide, red iron oxide, synthetic maghemite, rouge,or rust - is one of several oxide compounds of iron, and is most notable for its ferromagnetic properties. ... Iron(II) oxide, also called ferrous oxide, is a black-colored powder with the chemical formula FeO. It consists of the element iron in the oxidation state of 2 bonded to oxygen. ...

They develop where drainage is poor and the water table (phreatic surface) is high. 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.