Stratification

Stratification is the building up of layers of deposits, and can have several variations of meaning.

• In archaeology, especially in the course of excavation, stratification is of major interest and significance. Where archaeological finds are below the surface of the ground (as is most commonly the case), the identification of the context of each find is vital to enable the archaeologist to draw conclusions about the site and the nature and date of its occupation. In most cases, "features" can be identified, and these relate to the laying down of soil and other material over a period. For example, the contents of a ditch will constitute a separate feature, or context, from the layer into which the ditch was cut. It is the archaeologist's role to attempt to discover what layers exist and how they came to be created. (See: E. C. Harris, Principles of Archaeological Stratigraphy, 2 nd Edition. Academic Press, London and San Diego 1989)

• See stratified sampling for the use of stratification in survey sampling. The term "stratified sampling" is also refers a method of variance reduction in Monte Carlo methods.

• Stratification (botany).

• In anthropology, stratification refers to the "layering" of people in a society into different classes, each with their own function. Sociology has a closely related usage, focusing more on the structure of inequality than on function.

• Stratification (mathematics): In logic, stratification is a layering of predicate symbols to guarantee unique interpretations and to avoid paradoxical definitions like Russell's paradox. There is a separate meaning as applied to manifolds, and singularity theory, of a decomposition into pieces with specified relationships on fitting together.

• In music stratification is a layering of musical texture or the independent operating of more than one parameter simultaneously.