Experimental Micromorphology on Burnt Shells of Anomalocardia brasiliana (Gmelin 1791) (Bivalvia, Veneridae) and Its Potential for Identification of Combustion Features on Shell‐Matrix Sites

Abstract

The identification of in situ or reworked hearths in archaeological sediments is currently one of the main topics in archaeological micromorphology. In the case of shell‐matrix sites (shell mounds and middens), the clast‐supported matrix and high porosity can hamper the clear identification of combustion features. Previous experimental approaches were useful to identify in thin section the transformations induced by heating in mollusk shells, which are related to its mineralogy. Since different species of mollusks contain diverse mineralogy (aragonite, calcite, or both), it is expected that each species follows a specific thermal behavior, although similar general trends exist. In this short contribution, a set of valves of the mollusk Anomalocardia brasiliana (Gmelin 1791) (Bivalvia, Veneridae), the most important component of Brazilian shell mounds, was heated in a muffle furnace at temperatures from 200°C to 800°C. Thin sections were made and their description is presented for the identification of burnt shell of A. brasiliana. This information can help to infer the temperature of prehistoric fires and can assist in the identification of in situ versus reworked hearths in shell‐matrix sites.