In search of sealed Palaeolithic and Mesolithic sites using core sampling: the impact of grid size, meshes and auger diameter on discovery probability

Since the 90s core sampling, particularly within Dutch and Belgian wetland research, has increasingly become important for detecting covered prehistoric hunter-gatherer sites, comprised mainly of scatters of lithic artifacts of variable size and find density. Several methodological studies (Tol et al., 2004; Verhagen et al., 2013) have tried to develop standard sampling protocols differentiating grid size, core diameter and sieving mesh width according to the expected site-types. These studies are all based on a statistical analysis of excavation data, using simulations. However, these theoretical models have never been fully tested against empirical data coming from augering projects. In this paper core sampling data from 11 cored sites, some of which were subsequently excavated, are used in view of developing a core sampling strategy which allows the detection of the broadest possible range of prehistoric sites. The study concludes that in most cases, augering within a 10 m grid with a 10 cm-12 cm core and sieving through 1 mm-2 mm meshes allows the detection of buried sites, eventually even small and low-density ones. In order to further increase the discovery chances a two-step gridding approach is recommended.