Working with broken agents: Exploring computational 2D morphometrics for studying the (post)depositional history of potsherds

The study of size and shape of ceramic fragments is a common approach used for unraveling the depositional and post-depositional history of archaeological assemblages. Similar to sediment particles, the size and shape of a potsherd are altered under conditions of abrasion, breakage, or weathering, occurring during or after deposition, which can be the product of both human and non-human agents. Thus, the analysis of dimensional and morphological changes of fragments not only points towards specific (post)depositional processes, but can also shed light on the nature of human interaction with broken pottery. By coupling a traditional sedimentological framework for shape description and a computational approach to 2D morphometrics, in this paper we present a quick, reproducible and accurate method for studying the alteration of shape and size of potsherds. Three main shape descriptors, i.e. sphericity, roundness, and convexity, were tested on a combination of experimental and Early Neolithic potsherds in Northwest Romania from contexts where the conditions of fragment alteration were known or could be safely inferred. In addition, potsherds from an Early Neolithic pit discovered at Călineşti-Oaş-Dâmbul Sfintei Mării (Satu Mare County, Romania) were analysed for determining the pit infilling process and understanding the extent of the interaction between humans and broken pots. Results from morphometric tests show the reliability of the computational technique and shape descriptors for identifying different conditions of alteration of potsherds. The analysis of the Romanian assemblages provide insight into (post)depositional processes, showing downslope movement as the main mechanism behind the infilling of the pit at Călineşti-Oaş-Dâmbul Sfintei Mării. In addition, the potsherds possessed a high level of erosion and fragmentation, highlighting a long span of human interaction with broken materials at this site during Early Neolithic times.