Stepping on shells: an experimental archaeological soil micromorphology study of trampling on a modern shell midden at Swifterkamp

In this paper we report the study of shell midden taphonomy using archaeological soil micromorphology on an experimentally constructed shell midden. Using common cockle shells, and two different cooking techniques (boiling and roasting), we study the changes occurring in the shells, and in the soil below the shells. Our aim is to provide a clearer picture of trampling and various cooking techniques on prehistoric shell middens. Examples from Northern European contexts are provided as a comparison to our experimental analysis. We find that discolouration of the shell matrix occurs also at boiling temperatures. Differentiation between boiling and roasting can be done by studying the cracking of the shells. The temperature difference between boiling and roasting however does not lead to important differences in breakage resulting from trampling. Most importantly, our study highlights the need to incorporate the transformation of deposited shells into the formation processes of a shell midden accumulation.