Late Quaternary water-level variations and vegetation history at Crooked Pond, southeastern Massachusetts

Sediment cores collected along a transect in Crooked Pond, southeastern Mas sachusetts, provide evidence of water-level changes between 15,000 cal yr B .P. and present. The extent of fine-grained, detrital, organic accumulation in the basin, inferred from sediment and pollen stratigraphies, varied ove r time and indicates low water levels between 11,200 and 8000 cal yr B.P. a nd from ca. 5300 to 3200 cal yr B.P. This history is consistent with the pa leohydrology records from nearby Makepeace Cedar Swamp and other sites from New England and eastern Canada and with temporal patterns of regional chan ges in effective soil moisture inferred from pollen data. The similarities among these records indicate that (1) regional conditions were drier than t oday when white pine (Pinus strobus) grew abundantly in southern New Englan d (11,200 to 9500 cal yr B.P.); (2) higher moisture levels existed between 8000 and 5500 cal yr B.P., possibly caused by increased meridonal circulati on as the influence of the Laurentide ice sheet waned; and (3) drier condit ions possibly contributed to the regional decline in hemlock (Tsuga) abunda nces at 5300 cal yr B.P. Although sea-level rise may have been an influence , moist climatic conditions during the late Holocene were the primary reaso n for a dramatic rise in water-table elevations. (C) 2001 University of Was hington.