GEOLOGICAL HISTORY AND ARCHAEOLOGICAL POTENTIAL OF BUTLERS BLUFF, SOUTHEASTERN SHORE OF CHESAPEAKE BAY, VA

Butlers Bluff is a 2-km-long, 15-18-m-high, wave-cut bluff along Chesapeake Bay of the southern Delmarva peninsula in Virginia. The basal 7-8 m of the bluff are bedded sand deposited in Sangamon-age, near-shore bars. These are overlain by 1-2 m of silty sand that includes two paleosols: an ephemeral lower and a well-developed upper. Thick dune sand caps the paleosol and extends to the surface. Stumps, submerged in 1-2 m of water and rooted in peat, mark the offshore extension of an erosional channel at the north end of the bluff. Additionally, a drowned channel of the Susquehanna River occurs about 1 km offshore. Our study evaluated the potential for Paleoindian or Early Archaic occupations in the upper paleosol under the dune. The geological history of Butlers Bluff is based on field observations, soil analyses and C-14 ages. Charcoal dated to 33,090 +/- 320 BP (Beta-156796) in the lower paleosol and to 1180 +/- 40 BP (Beta-157935) in the upper. These ages, along with soil analyses, indicate that mid-Wisconsinan loess buried the lower paleosol after 33,000 BP. The upper paleosol developed in this loess and formed the surface for ca. 30,000 years until it was buried by a dune about 1200 BP, near the end of the Holocene marine transgression. A similar age (880 +/- 40 BP; Beta-156797) for a spruce cone from the submerged peat shows that Chesapeake Bay did not reach its modern level until after about 1000 BP. Butlers Bluff is a late Holocene feature formed by shoreline erosion and has receded 500-1000 m during the Holocene. Based on regional geological history, bluff recession began about 5000 BP when rising sea-level started to flood the Susquehanna valley. Although the upper paleosol from Butlers Bluff spans the Paleoindian and Archaic periods, occupations of that age more likely occurred along the early Holocene bluff that once existed nearer the drowned Susquehanna channel. Such occupations would have been destroyed as the bluff eroded after 5000 BP. Moreover, any successive late Holocene occupations likely also followed the receding shoreline and they too were eroded along with it.