Soil

Mineral or organic matter that is unconsolidated and on or near the land surface. A prerequisite for soil formation is the growth of vegetation. Gradual colonization, first by lichens and then by higher plants causes build-up of organic matter (humus) in the developing soil. Clay minerals form complexes with humus and act as reservoirs of nutrients. Water from rainfall, entering the top of a soil profile, drains down the soil, taking with it nutrients and sometimes parts of the clay/humus complexes. The type of vegetation, the fauna of small animals that lives in the soil, the type of parent material, the way in which the clay/humus complexes behave, the amount of rainfall and the quality of drainage all go to determine the type of soil that develops. Soil forms differentiated layers (soil horizons) with respect to the land surface. The study of soils is called pedology. Studies of the way soils have developed may allow a reconstruction of the environmental changes which have taken place. Several complicated soil classification systems exist.

Material which has been subject to soilforming processes. A prerequisite for soil formation is the growth of vegetation. Gradual colonization, first by lichens and then by higher plants causes a parallel build-up of organic matter — humus — in the developing soil. Weathering of the underlying parent material provides finely divided minerals. Clay minerals form complexes with humus. These complexes act as reservoirs of nutrients, essential to plant growth, which become adsorbed on to their surface. Water from rainfall, entering the top of a soil profile, drains down the soil, taking with it nutrients and sometimes parts of the clay/humus complexes. The type of vegetation, the fauna of small animals that lives in the soil, the type of parent material, the way in which the clay/ humus complexes behave, the amount of rainfall and the quality of drainage all go to determine the type of soil that develops. The study of soils is called pedology. In archaeology, pedology may be applied to soils in a particular region, or it may be used to investigate the buried soils which are found underneath ramparts and barrows. Studies of the way soils have developed may allow a reconstruction of the environmental changes which have taken place. There are many different soil types throughout the world, developing under different climatic regimes and floras, and on various parent materials. Several complicated soil classification systems exist. Amongst the main soil types which an archaeologist is likely to encounter in Europe are the brown earths (which include brown gleyed soils and primitive soils (including the ranker and rendzina).