Modeling soil-geomorphic associations and Archaic stratigraphic sequences in the lower Ohio River valley

Abstract

Adequate sampling of buried occupations in large river valleys requires an understanding of both the structure of valley fills at different scales and the properties of the archaeological record. Broad tracts of Holocene alluvium representing compound bank-side and point bars are present in the lower Ohio River valley. A substantial record of Archaic sites also exists, although certain hunter–gatherer sites from the late Wisconsin/early Holocene and middle Holocene are poorly represented, primarily because of their low archaeological visibility, especially in buried contexts. This study uses an extensive geological and archaeological base-line data set from the Caesars Archaeological Project to model soil-geomorphic relationships and Archaic stratigraphic sequences in alluvial units to better define the sampling parameters of these poorly known periods. Soil weathering properties, as reflected in soil order, are a proposed indicator of alluvium age. Radiocarbon ages from other sites in the lower Ohio River valley, which provide a test of this proposition, are found to be correlated with the order of soil series (Alfisol, Mollisol, Entisol/Inceptisol) mapped on landforms of different age. Early and late Holocene alluvium are differentially distributed in the region, a factor that may account for a better documented Early Archaic record below the Falls of the Ohio.