On any archaeological site, the highest phosphate levels are generally associated with midden locations. Kitchen garbage, especially bone, is one of the greatest contributors to soil phosphate content. Locating midden areas through phosphate analysis has been one of the main uses of the technique in archaeology (Eidt and Wood 1974: 44). Middens associated with settlement and other areas of human activity are both clearly identifiable in phosphate patterning as relatively large foci of increased phosphate content. The only other areas that exhibit equal or greater phosphate levels are cess/manure pits, outhouses and some animal pens.
Midden patterning was verified by Wells (2004) on the floor surface of a Classic Period Mayan plaza in Honduras. Phosphate patterning showed the highest level located in the plaza’s northeastern corner, which upon excavation corresponded to a large midden. The excavated midden and food production/consumption and storage areas were all clearly distinguishable in the phosphate patterning.
Pattern Maps and Interpretations
Midden patterning adjacent to Dungurrough conjoined hut structure
Patterning characteristic of the presence of a midden was located on the promontory fort of Dungurrough, Achill Island (Figure 6). An area of high phosphate content (Levels 4-5) is located directly along the southern edge of the visible foundation of a conjoined hut feature. This concentration is likely a result of the deposition of organic material associated with use of the huts, which is representative of a midden. The small size and only mid- to high-level phosphate readings indicate that the structure was not the site of constant habitation. The relatively low concentrations surrounding the huts indicate that this structure was not part of a grouping of structures that could have indicated a larger settlement, but is a solitary structure.