Glossary Terms

A column of soil extending through all its horizons and into the parent material and large enough to be used to characterise the soil condition at a particular place.

The smallest volume that can be called "a soil.'' A pedon is three dimensional and large enough to permit study of all horizons. Its area ranges from about 1 to 10 m2, depending on the variability of the soil.

The solid or unconsolidated mineral material in or on which soil forms.

A surface horizon, or a subsurface horizon occurring at any depth if it has been buried, that consists of poorly aerated organic material. It is usually undecomposed or partially decomposed organic matter (litter such as leaves, needles, twigs, moss, and lichens) (WRB, 2006). Often referred as the histic horizon (from Greek histos, tissue).

One of the layers that form in the soil profile as a result of soil-forming processes. A horizon can appear as a defined visible layer.

Albic horizon, which is an eluvial horizon with evidences of losing soil components; it is usually a light-coloured subsurface horizon from which clay and free iron and aluminium have been removed to the extent that the colour of the horizon is determined by the colour of the sand and silt particles rather than by coatings [...]

Horizontal soil layers characterized by a combination of attributes that reflect widespread, common results of the processes of soil formation (Bridges, 1997) or indicates specific conditions of soil formation (WRB, 2006).

Mineral horizon or layer, excluding indurated bedrock, that is little affected by soil-forming processes and does not have the properties typical of the overlying horizon. The material of a C horizon may be either like or unlike that in which the solum formed. If the material is known to differ from that in the solum, [...]

The solid rock that underlies the soil and other unconsolidated material or that is exposed at the surface.