Phosphates and Archaeology
Phosphate analysis is used in archaeology as an indication of past human activity. This is based on the consistent generation of organic debris as a result of human agency. Phosphates are esters of elemental phosphorus, and are one of the main building blocks for all forms of organic matter. Phosphates are released and become fixed to the soil upon the decomposition of organic matter. Archaeological sites and features are located through the identification of areas with increased phosphate content. Certain activities associated with settlement and other anthropogenic occupations generate phosphate levels that are easily discernible from natural phosphate levels. The habitual use of specific archaeological features creates distinct and identifiable patterns that are globally and cross-culturally accurate (Matthews et al. 1997).
The applicability of assigning function to areas based on phosphate signatures has been tested through the comparison of several culturally and temporally distinctive archaeological and ethnographic sites by Middleton and Price (1996), Middleton (2004) and Wilson et al. (2005), among others. All tested house floor surfaces, including examples from Classical Period residences in Oaxaca, Mexico (AD 250 – 700) and Neolithic residences in Çatalhöyük, Turkey (7500 – 6500 BC) (Middleton 2004: 56), showed the same phosphate patterns. These specific patterns can be identified when phosphate levels are mapped across a site, and interpreted to create site-specific use-of-space models. This allows for the breakdown of an archaeological site into different zones of use based on the presence of distinct phosphate patterns. Studies that test the validity of phosphate analysis techniques, the consistency of resultant patterning, interpretation techniques and the presentation of phosphate data can be used to make phosphate testing more applicable to archaeology. In this article I will discuss how fast, accurate phosphate analysis results can be obtained and analyzed to best compliment archaeological research goals.