Functional analysis of settlement areas: prospection over a defended enclosure of iron age date at The Bowsings, Guiting Power, Gloucestershire, UK

Abstract

A small, well-preserved, trapezoidal, ditched enclosure of mid to later Iron Age date at The Bowsings (Guiting Power, Gloucestershire, UK), closely defined in plan by magnetometer and resistivity survey, supplemented by extensive excavation, can be further divided into areas of differing usage by mapping levels of magnetic susceptibility (MS) and inorganic phosphate in basal topsoil over the site. A clear impression of the enclosure, with internal areas for habitation and pit-based storage, persists as a pattern of MS enhancement in the topsoil, and such survival may be of interest in the detection and analysis of highly eroded sites elsewhere. Although the habitation area showed well as an area of MS enhancement, its relative transparency to gradiometry provided another example of a larger class of such features, and stresses the importance of supplementing gradiometry with MS survey to provide more adequate assessment of sites. Use of MS survey as a method of prospection is discussed, especially in relation to adequacy of resolution. Application to MS survey of a newly developed, ground-insertable microprobe is briefly introduced as a means of increasing productivity of such surveys.

Geophysical Observations at Archaeological Sites: Estimating Informational Content

“…Clearly a combination of at least two independent geophysical methods is necessary for the first three gradations ( H , M and L ): gradation U implies no application of the method set (on a scale or not at all) in the area under investigation (Table ). Interestingly, practically the same gradation was applied by Marshall () for a subdivision of archaeological sites using magnetic anomaly gradations.…”

Sampling Design and Inferential Bias in Archaeological Soil Chemistry

“…In other words, variation is often discontinuous, periodic, or stochastic, but rarely homoscedastic. As such, soil surveys in archaeology have had to rely on systematic sampling strategies, often referred to as point lattice matrixes or grid (or mesh) sampling (e.g., Entwistle et al 2000;Marshall 2001). In this article I use the term "lattice" (i.e., regularly spaced array of points in Euclidean space) to refer to these sample designs.…”

“…Understanding soil properties can be done most efficiently by taking a random sample of soils from throughout the study area, which can be treated as the entire sample frame or else subdivided into sampling separate strata from which a consistent number of samples can be collected. There is no good rule of thumb for the number of units to obtain for the pilot study sample, but it seems reasonable, based on what is known about intra-pedon variability of soil properties (Entwistle et al 2007;Marshall 2001), that at least one sample per 5 m 2 should be collected for small-scale spaces and 20 m 2 for larger sample universes. By using a pilot study to understand variation in soil properties across the study area, it can be determined if the sample density should be increased because of poor soil conditions or a high degree of variability in soil properties over small distances.…”