Portable x-ray fluorescence in sourcing prehistoric whelk shell artifacts

Abstract

Portable x-ray fluorescence spectrometry was used to chemically source Busycon shell items from three eastern Tennessee Mississippian period sites. Discriminant function analysis of portable x-ray fluorescence data from control shells from the Atlantic and Gulf coasts indicated variation in strontium levels in Busycon provides a statistically significant predictor of shells’ origins, correctly classifying 86.5% of controls to their coasts of origin. Application of the discriminant function to shell items from Mississippian sites in northeastern and southeastern Tennessee indicated significant differences by region in proportions of artifacts classified as deriving from Atlantic or Gulf coast shell. More than 60% of items from southeastern Tennessee exhibited strontium levels similar to Gulf coast control shells; less than 50% of northeastern Tennessee items were classified as deriving from the Gulf. Variation in ratios of Gulf- to Atlantic-sourced shell artifacts by region is consistent with past predictions that late prehistoric inhabitants of southeastern and northeastern Tennessee participated in different long-distance exchange networks.