Document Type

Thesis

Abstract

Middens located on the Atlantic Coastal Plain hold extensive information about the interplay between prehistorical communities of Native Americans and the ecology of the Chesapeake Bay and its tributaries. However, it is often difficult to source the shells found in middens to their location of origin. Here I explore the feasibility of accurately sourcing modern oyster shells by matching the geochemical signature of major Virginia rivers to the geochemistry of oyster shells. | analyzed dissolved strontium (Sr) and barium (Ba) concentrations in river samples and in oyster shells from the James, York, Rappahannock, and Potomac Rivers. Strontium and barium concentrations in both water and shell were correlated to salinity, watershed area, and lithology in order to understand the controls of these ions. The results found that Sr/Ba values in water are mirrored in oyster shell and Ba concentrations in both water and shell display a statistically significant correlation with salinity. The data also shows that barium in oyster shell is a more reliable indicator of ambient ion concentrations than strontium. The York River consistently displayed lower barium concentrations in both water and shells, with shell concentrations ranging between 5.1 to 6.5 parts per million, while shells collected from other rivers ranged in barium concentrations between 9.5 to 21.5 ppm, indicating that the York River can be distinguished from neighboring rivers. Because there are many factors controlling water chemistry of large river systems, it is difficult to isolate any one influence of ionic concentrations; however, the results of our data indicate that salinity and lithology do influence water and shell geochemistry, while watershed area has a less observable influence.

Date Awarded

2014

Department

Geology

Advisor 1

Rowan Lockwood

Advisor 2

James M. Kaste

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