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Results for podsol:

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podsol

SYNONYMS OR RELATED TERMS: podzol, podsol soil, podzol soil
CATEGORY: geology
DEFINITION: A soil type characteristic of coniferous woodland, heath, tundra or moorland -- leached, acid soils formed under conditions of very cold climate's forest vegetation cover. The fauna produce phenols which are washed into the horizons and disperse the clay/humus complexes. Minerals, humus, and nutrients are washed down the profile and become deposited as illuvial horizons of humus and iron oxides. The latter is often called the 'iron pan'. A bleached, sandy eluvial horizon is left at the top of the profile. Podsols develop naturally in areas of high annual rainfall, but most of the large areas of podsols in the uplands and lowland heaths of the British Isles were probably at least initiated by man's clearance of woodland during the present Interglacial.

sol lessivé

SYNONYMS OR RELATED TERMS: podzolic soil, podsolic, lessivé soil
CATEGORY: geology
DEFINITION: Soil usually forming in a broadleaf forest and characterized by moderate leaching, which produces an accumulation of clay and some iron that have been transported (eluviated) from another area by water. The humus formed produces a textural horizon that is less than 50 cm (20 inches) from the surface. Podzolic soils may have laterite in place of the humic horizon or along with it. Sols lessivés are often difficult to identify, but they are the dominant soil type of much of lowland Britain, where forest was cleared to make way for agriculture.

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pollen analysis

SYNONYMS OR RELATED TERMS: palynology
CATEGORY: technique
DEFINITION: The study of pollen grains in soil samples from an archaeological site which provides information on ancient human use of plants and plant resources. This technique, which is used in establishing relative chronologies as well as in environmental archaeology, was developed primarily as a technique for the relative dating of natural horizons. Pollen grains are produced in vast quantities by all plants, especially the wind-pollinated tree species. The outer skin (exine) of these grains is remarkably resistant to decay, and on wet ground or on a buried surface, it will be preserved, locked in the humus content. The pollen grains of trees, shrubs, grasses, and flowers are preserved in either anaerobic conditions or in acid soils. Samples can be taken from the deposits by means of a core or from individual layers at frequent intervals in a section face on an archaeological site. The pollen is extracted and then concentrated and stained and examined under a microscope. Pollen grains are identifiable by their shape, and the percentages of the different species present in each sample are recorded on a pollen diagram. A comparison of the pollen diagrams for different levels within a deposit allows the identification of changes in the percentages of species and thus changes in the environment. As a dating technique, pollen has been used to identify different zones of arboreal vegetation which often correspond to climatic changes. The technique is invaluable for disclosing the environment of early man's sites and can even, over and series of samples, reveal man's influence on his environment by, for example, forest clearance. The sediments most frequently investigated are peat and lake deposits, but the more acid soils, such as podsols, are also analyzed. Radiocarbon dates may be taken at intervals in the sequence, and it is possible to reconstruct the history of vegetation in the area around the site where the samples were taken. Palynology plays an important role in the investigation of ancient climates, particularly through studies of deposits formed during glacial and interglacial stages of the Pleistocene epoch.

soil profile

CATEGORY: feature; geology
DEFINITION: The vertical sequence of horizons in the soil which occur not as the result of stratification but as a result of weathering and other processes. The profile provides environmental or palaeoenvironmental information, such as information on vegetation and climate. The term also refers to a vertical section exposed in excavation or naturally that shows horizons and parent material. The soil profile is made up of some or all of the following: the A or humus horizon, the E or leached horizon, the B or (B) horizons or accumulation or chemical weathering, and the C horizon of parent material. Different soil profiles occur in different environmental regions, ranging from rendsinas, through brown earths, to podsols, gleys, and chernozems. The soil profile and the type of vegetation are interdependent, and man's activities have an effect on and are affected by both.