Anthropogenic Thermal Alteration of Marine Bivalves, Recrystallization, and Isotope Integrity

Summary

Archaeologists have given little direct attention to the taphonomic effects of cooking methods for marine invertebrates, particularly the effect on shell mineralogy. Various methods of heating and steaming shellfish directly in the shell are recorded as traditional for Northwest Coast peoples and the shell samples at the Tse-Whit-Zen Village site in Port Angeles, Washington State, contain many specimens that visually appear to be thermally altered. This type of heat exposure has been shown experimentally to cause aragonitic fish otoliths to convert to calcite and become depleted in 18O and 13C, and thus become unsuitable as a source of isotope ratios for paleoenvironmental reconstruction. Biogenic aragonite in marine molluscs is known to alter in the same way, but at lower than expected temperatures. I conducted controlled heating experiments of modern specimens of four taxa of molluscs common in the site assemblage (Clinocardium, Saxidomus, Leukoma, and Ostrea) to determine the conditions (temperature, time) at which isotopic integrity was lost.

SAA 2015 abstracts made available in tDAR courtesy of the Society for American Archaeology and Center for Digital Antiquity Collaborative Program to improve digital data in archaeology. If you are the author of this presentation you may upload your paper, poster, presentation, or associated data (up to 3 files/30MB) for free. Please visit http://www.tdar.org/SAA2015 for instructions and more information.

This Resource is Part of the Following Collections

• Society for American Archaeology 80th Annual Meeting, San Francisco, CA (2015)   •
• Preliminary Results from the Tse-whit-zen Project: Zooarchaeology and Geoarchaeology of a 2000 yr old Lower Elwha Klallam Village on the Strait of Juan de Fuca, Washington State

Keywords

Spatial Coverage