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Tree macrofossils dating from the middle to end (about 1000 years, ca. 12 600-11 600 cal years BP) of the Younger Dryas chronozone were found in an organic deposit on the southwest side of the Mohawk River, near its junction with the Hudson River in Cohoes, New York, USA. The fossils included substantial wood fragments, associated plant remains, and pollen, which indicate a forest of white spruce ( Picea glauca), balsam fir ( Abies balsamea), and tamarack ( Larix laricina). The presence of white, rather than black ( P. mariana) or red ( P. rubens) spruce in the Younger Dryas was probably due to a riparian-type environment, confirmed by its location and American beaver tooth marks on some of the wood fragments. The clusters of wood radiocarbon dates indicate periodic changes in erosion and deposition at the site. One possible but very short decline (temperature reversal?) may be indicated by tree-ring growth, but in general, the ring widths of the trees and their growth responses suggest variable but slowly improving conditions over time, possibly from warming temperatures, before the end of the Younger Dryas. [ABSTRACT FROM AUTHOR]