Directional analysis of surface artefact distributions: a case study from the Murghab Delta, Turkmenistan

This paper investigates directional influences in the distribution of Bronze Age surface pottery in the northern Murghab Delta, Turkmenistan. Drawing upon a continuous dataset of pottery sherd counts obtained by intensive field survey, it examines the degree to which we can make sense of the archaeological processes at work in a heavily obstructed and dynamic landscape. In so doing, it makes use of two analytical methods that have rarely been used in archaeology: a) geostatistical analysis using variograms to investigate directional spatial autocorrelation in recorded sherd counts; and b) angular wavelet analysis in evaluating directional influences in the sherd distributions for particular chronological periods. While some kinds of directional influence can be identified visually, a quantitative approach is particularly useful in deconstructing such patterns. In this particular dataset, distinct but related directional processes can be identified and measured: a) the impact of the complex system of watercourses in the delta on both settlement and post-depositional processes; and b) recovery bias in the observations made during survey.

► Exploration of anisotropy (directionality) in surface artefact distributions.
► Two methods: geostatistics/variography and angular wavelet analysis.
► Depositional/post-depositional processes behave differently in different directions.
► Watercourses influence anisotropy in surface scatter; sand dunes cause recovery bias.
► Important to consider directional influences in sampling methodologies.