Sedimentation rates in a Long Island marsh determined by ²¹⁰Pb dating1

Mean rates of vertical accretion of from 0.47 to 0.63 cm yr −1 have been determined for the past century from two widely separated sites at Flax Pond, a Spartina alterniflora marsh on the north shore of Long Island. Sediments were dated from 210 Pb activity. The rates are equivalent to deposition of 325 to 436 g of dry organic matter m −2 yr −1 or about 146 to 196 g of carbon m −2 yr −1 Although the two sites differed in salt peat thickness, the basal layer of the peat was deposited about 100 years ago at both.