40,000 YEARS OF VEGETATION AND CLIMATE CHANGE FROM EMILY'S POND, GRAFTON PONDS NATURAL AREA PRESERVE, YORK COUNTY, VIRGINIA COASTAL PLAIN
BEACH, T. A., Virginia Department of Transportation, P.O. Box 3402, Colonial Heights, VA 23834, beachhouse@widomaker.com and ANDERSON, R. S., Center for Environmental Sciences and Education, Northern Arizona Univ, Flagstaff, AZ 86011

The Grafton Ponds Natural Area Preserve in York County, Virginia contains a paleoecological record that dates prior to 41,750 ± 730 years B.P. Analysis of pollen and plant macrofossils preserved in a sediment core collected from Emily's Pond (pond #105-7N) identified several major shifts in vegetation indicative of a changing climate. Age estimates of the major changes in vegetation were determined utilizing AMS radiocarbon dating of select macrofossils. Prior to 41,750 ± 730 years B.P. the deciduous taxa Quercus, Nyssa, Castanea, and Carya were present with Pinus and Picea indicating interstadial conditions. Wetland taxa indicate that the water in the pond during this time was clear and poorly buffered. Termination of that interstadial and establishment of colder stadial conditions after ca. 41,750 ± 730 years B.P. is evidenced by a sharp decline in the pollen of deciduous taxa and increased Picea and Pinus pollen at that time. Between 41,750 ± 730 years B.P. and 34,730 ± 280 years B.P., wetland taxa indicate that the water in the pond was deeper than during the earlier interstadial period. After 34,730 ± 280 years B.P. the wetland taxa were replaced by Sphagnum indicating decreased water levels and possibly more acidic water. Although unverified through radiometric dating by this study, elevated Alnus and Betula pollen percentages in this record appear to correlate with other paleoecological records that indicate an increase in moisture. That condition has been radiometrically dated by other studies ca. 14,000 years B.P.

Southeastern Section - 50th Annual Meeting (April 5-6, 2001)
Session No. 30
Atlantic Coastal Plain Geology: A Symposium in Honor of Gerald H. Johnson (Part A)
Sheraton Capital Center Hotel: Hannover Ballroom III
8:30 AM-11:40 AM, Friday, April 6, 2001
 

© Copyright 2001 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.