Estimating Core Number in Assemblages: Core Movement and Mobility During the Holocene of the Fayum, Egypt Rebecca S. Phillipps 1 & Simon J. Holdaway 1 Published online: 7 May 2015 # Springer Science+Business Media New York 2015 Abstract 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. Keywords Stone artifacts . Mobility . Cortex ratio . Egypt Introduction Mobility studies have a long history in archeology, and change in human mobility is often considered in association with shifts in subsistence practices, particularly transi- tions to food production, general human-environment inter-relationships, and social structure (e.g., Binford 1978; Boyd 2006; Close 2000; Edwards 1989; Holdaway et al. 2010; Kelly 1992; Rafferty 1985). The transition to food production during the mid- J Archaeol Method Theory (2016) 23:520–540 DOI 10.1007/s10816-015-9250-2 * Rebecca S. Phillipps rphi025@aucklanduni.ac.nz 1 Anthropology in the School of Social Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand