Estimating core number in Assemblages: core movement and mobility during the Holocene of the Fayum, Egypt

The utility of the cortex ratio first developed by Dibble et al. (American Antiquity, 70(3), 545–560, 2005) and extended by Douglass et al. (American Antiquity, 73(3), 513–526, 2008) is examined in contexts where cores rather than flakes may be transported. The cortex ratio is used to demonstrate the movement of artifacts by quantifying missing surface area, typically where it is the flakes that were removed and the cores that were left behind. In such situations, the removal of flakes with small volumes will result in the removal of relatively large cortical surface areas resulting in a low cortex ratio. However, when it is the cores that were removed, assemblages will lose greater proportions of artifact volume relative to the loss of artifact surface area. Here, we propose methods to investigate the effects of high-volume artifact removal from archeological assemblages as a proxy for human movement in addition to the cortex ratio. We apply the methods to stone artifact assemblages from the Fayum, Egypt, where changes in mid-Holocene mobility are closely linked to food production.