M.A. Theses: Brian Pegg, 1999

The Taphonomic History of the Vertebrate Faunal Assemblage from British Camp, San Juan Islands, Washington

This study is an analysis of the taphonomic history of the faunal assemblage from the British Camp shell midden site on San Juan Island, Washington, and assesses the role of groundwater diagenesis in the post-depositional alteration of the vertebrate faunal assemblage. The sediments (shell and soils) in the lower portion of this site may have undergone diagenetic alteration due to the effects of groundwater, which has been shown by previous research to have the potential to remove molecules from shell and soil constituents at this site.

&nbspIn order to determine whether the faunal assemblage has been diagenetically altered, the distributions of element density, fragmentation, survivability and identifiability from groundwater-saturated and dry contexts were examined. The results show that faunal material from groundwater-saturated deposits has undergone significantly more post-depositional attrition than material from dry deposits. Faunal material from groundwater-saturated deposits is more fragmentary, composed of a larger portion of unidentifiable material, and is made up of denser elements, which consistently survive attritional processes better than elements of lower densities. A working hypothesis of alteration of bone specimens by groundwater leaching provides the best fit for data derived from this study, although it is beset by equifinality problems. It appears that leaching has altered the compositional structure of the assemblage, leading to biases against less durable elements and taxa. Simple taphonomic methods have been shown to be suitable to identify the influence of post-depositional attrition.