Archaeological natural

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Natural in Archaeology is a term to denote a horizon in the stratigraphic record representing the point from which there is no anthropogenic activity on site and the archaeological record ends. Natural is often the underlying geological makeup of the site and is formed by geological processes. It is the goal of complete Excavation to remove the entirety of the archaeological record all the way to "Natural" thus leaving only the natural deposits of pre human activity on site. Development led practice has lead impact assessment which may stipulate excavation will cease at a certain depth because the nature of the development will not disturb remains below a certain level and thus may not reach natural or sterile.

[edit] Issues of definition

Natural can be a relative term. On urban sites where research interests may make a detailed examination of the earliest part of the record impractical, prehistoric or rudimentary human activity may go unrecorded compared to an equivalent horizon on a rural site with an agenda to look for prehistoric evidence. The visibility of features in natural is to some extent a function of chemical and soil process overtime, usually causing decomposition of cultural materials. Additionally, early prehistoric tools were manufactured from natural materials, such as bone, stone and fiber - and therefore do not stand out as clearly as metal, glass and plastic. The effect of these decompositional processes is that the older an archaeological deposit is, the more it will appear similar to the underlying geology. For some archaeologists, a very basic rule of thumb is "the greater the contrast an context has with the natural, the younger it is". Similarly, American prehistoric archaeologists often rely on significantly diminished counts of lithic flake debitage to assess the excavation unit's trend toward natural stratigraphy. However, while a trend may be recognized, the stratum is not called natural, or sterile, until it is actually void of cultural materials.

[edit] Geoarchaeology

Natural is becoming a blurred term in archaeology due to an increased understanding of natural processes and the development of Geoarchaeology in which the natural landscape is seen as having a bearing on interpretation of subsequent human activity on any given site. Geoarchaeology is also having an impact on interpreting processes which occur within the archaeological record and the term natural becomes less of a distinct horizon in the record.