Natural is becoming a blurred term in archaeology due to an increased understanding by researchers of natural processes. In addition, through the development of
geoarchaeology, scholars believe the
natural landscape has a bearing on interpretation of subsequent human activity on any given site. As geoarchaeology continues to influence the interpretation of processes that occur within the archaeological record, the term "natural" has become less useful. 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, rudimentary human or
prehistoric activity may go unrecorded, as opposed to an equivalent horizon on a rural site for which the study team's agenda is to look for prehistoric evidence. Chemical and soil process over time often obscure and cause decomposition of cultural materials, and thus a human-occupied layer may look natural. Additionally, early prehistoric tools were manufactured from natural materials, such as bone, stone and fiber; they do not stand out as clearly as metal, glass and plastic. The effect of decompositional processes is that the older an archaeological deposit is, the more it will appear similar to the underlying geology. For some archaeologists, a basic rule of thumb is "the greater the contrast a
context has with the natural, the younger it is." Similarly, United States prehistoric archaeologists often rely on significantly diminished counts of lithic flake
debitage to assess the excavation unit's trend toward natural stratigraphy. While a trend may be recognized, a stratum is not called natural or sterile, unless it is void of cultural materials. ==Notes==