SEDIMENTOLOGY AND HUMIFICATION INDEX OF PEAT DEPOSITS IN NEW YORK AND MAINE

The purpose of this study is to reconstruct a climate proxy record from peat deposits in the northeastern United States for part of the Holocene period. Fieldwork was completed at two sites: Greenfield Center, located in upstate New York, and Quoddy Head State Park, located in eastern coastal Maine. A GIS analysis of the topography and surficial geology is in progress for both sites in order to better understand the environmental and hydrological controls affecting the bogs. Three shallow cores were collected from the New York site using a Russian Peat Corer (BR-08-01 and BR-08-03) and a Universal Percussion Corer (BR-08-02). The three cores had an average depth of 30 cm and each contain a gradational contact between an upper peat layer and a lower silty clay layer. Each core was subsampled at continuous 2 cm intervals. A radiocarbon date on charcoal pieces from BR-08-03 revealed that 20 cm of peat represents 100 ± 40 years BP. A linear age model was created for BR-08-03, revealing that the core contains a record of approximately the past 200 years. Peat samples were also collected from a 280 cm outcrop of a raised coastal bog in Maine and sub-sampled using approximately 2 cm intervals. In the laboratory, sedimentology analyses, including water content, magnetic susceptibility, and loss-on-ignition (LOI), were measured on all samples. A decrease in LOI is interpreted as a period of lower productivity with cool conditions while an increase in LOI signifies higher productivity and a warmer climate. Preliminary laboratory results from the New York site show more fluctuations in percent organic carbon content throughout BR-08-03 while BR-08-01 and BR-08-02 demonstrate more stability. All three cores have the highest percent LOI in the upper peat unit and a decrease in LOI at approximately the same stratigraphic level near the base of each core. Fluctuations in magnetic susceptibility and water content are also visible in all three cores. The degree of humification, the extent to which the peat has decomposed, is used as a proxy for precipitation. Measurements of absorbance and percent light transmission are being performed on a Spectronic 20 Genesys at 540 nm. The degree of humification measurements are in progress for the samples from the coastal bog in Maine.