THE CORRESPONDENCE BETWEEN RIVER SHOALS AND ARCHAIC SHELL MIDDEN SITES IN THE MIDDLE GREEN RIVER VALLEY OF KENTUCKY

In the middle Green River valley of west central Kentucky we are investigating Archaic shell midden sites (ca. 6000-3000 year B.P.) to understand geological conditions affecting local shoal formation, and using modern habitat preferences of identified mussel species found at each archaeological site to estimate prehistoric water depth, current velocity, and substrate composition. Freshwater mussels thrive in fast flowing rivers with a stable substrate of gravel, sand, and silt. Using a detailed map of the Green River made in 1829 by Army Engineers prior to impoundment and modern dredging, we compare the distribution of known site locations to mapped river shoals that presumably would have been prime mussel habitat. Our working hypothesis is that each mapped shoal should have a corresponding shell midden site and vice versa, but correspondence has been less than straightforward. The lower and middle Green River is incised into Pleistocene lake sediments, and the location of stable river shoals is primarily controlled by the river course flowing over buried bedrock islands and fault zones of the Rough Creek Graben. The Haynes, Carlston Annis, and DeWeese sites in the Big Bend of Butler County all appear to be related to bedrock sandstone islands. The Chiggerville site in Ohio County is clearly associated with the Browder Fault system. The Indian Knoll site in Ohio County, however, does not correspond to a historically mapped river shoal. Paleoenvironmental reconstruction of the river based on identified mussel species indicates a swiftly flowing, large to medium-sized river, with a gravel/gravel-sand substrate, and water depth between 0.9 and 1.5 m at the Haynes and Carlston Annis sites. The Indian Knoll site mussel assemblage indicates only slightly deeper water (0.9-2.4 m), but otherwise similar to the Butler County sites. Alternative explanations for the Indian Knoll site may be that (1) the 1829 river conditions do not reflect prehistoric conditions in all cases, (2) the shoal located at Indian Knoll was not geologically stable, for example, a moving point bar, or (3) shellfish were collected at a distance and transported to Indian Knoll.