Micro-charcoal abundances in stream sediments from Buckeye Creek Cave, West Virginia, USA

Abstract

We compare micro-charcoal abundances in laminated cave-stream sediments to the presences of Native Americans and later settlers in the same watershed. Samples were obtained from a core taken from a 2.5 m high point bar located 1 km inside of Buckeye Creek Cave, West Virginia. Thirty-three subsamples were treated with hydrogen peroxide to bleach or whiten non-charcoal organic matter. In the absence of opaque mineral grains, this technique creates a large visual contrast between dark charcoal grains and other substances. The subsamples were photographed using a microscope-mounted camera, and pixels darker than 99/255 (grayscale) were used to calculate charcoal concentrations. The record spans the last 6,000 years, and four of the five highest charcoal concentrations are from the last 2,000 years. The highest concentration is from AD 1093, and the second-highest concentration is from the nineteenth century. Post-Colonial settlers began making extensive use of the watershed sometime in the eighteenth century and may, therefore, be responsible for the second-highest charcoal concentration. However, archaeologists independently concluded that Native Americans made peak use of the watershed between AD 1000 and 1200, which coincides with the highest charcoal concentration in the record. Native Americans are known to have extensively used fire, so there is good circumstantial evidence tying high concentrations in the last 2,000 years to human activities. Our method is suitable for use elsewhere, and we present a detailed statistical analysis of our data as a guide toward interpreting charcoal concentrations in karst and non-karst deposits.