40,000 YEARS OF VEGETATION AND CLIMATE CHANGE FROM EMILY'S POND, GRAFTON PONDS NATURAL AREA PRESERVE, YORK COUNTY, VIRGINIA COASTAL PLAIN

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.