Late-glacial environmental changes south of the Wisconsinan terminal moraine in the eastern United States

Palynological analyses of two sediment cores, one 2.4 m long from northern Delaware, dated about 16,300 to 14,700 C-14 yr B,P,, and one 1.8 m long fro m New Jersey just south of the Wisconsinan terminal moraine and dated about 13,600 to 12,500 C-14 yr B,P,, give the first detailed evidence of vegetat ion in this area during these periods. The overall assemblages are similar to each other, with Picea and Pinus dominating the arboreal pollen and Poac eae and Cyperaceae the herbaceous flora. Nonarboreal pollen contributes abo ut 30-50% of the total, indicating a very open vegetation or a mix of fores t patches and open areas. Especially in Delaware, there is a diversity of o ther herbaceous pollen, including members of the Asteraceae, Fabaceae, and Ranunculaceae, The assemblages do not resemble current North American tundr a or boreal forest assemblages; rather, they resemble assemblages character istic of tundra on recently exposed land surfaces north of the Wisconsinan terminal moraine. The persistence of the assemblages for 1500-2000 years in late-glacial time suggests stable and cold climate during this time of gla cier retreat. (C) 2000 University of Washington.