Date of Award

5-2004

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Ecology and Environmental Sciences

Advisor

George L. Jacobson

Second Committee Member

Ann Dieffenbacher-Krall

Third Committee Member

Les C. Cwyner

Abstract

Evidence from studies conducted in the Northeast Region, comprised of the northeastern United States and the Maritime Provinces of Canada, indicate that, following deglaciation, a period of warming was punctuated by one or more minor cold events before the drastic cooling of the Younger Dryas chronozone (10,800-10,000 14C BP). One such cold event, the Killamey Oscillation (11,200-10,900 14C BP), is well known from Atlantic Canada, but evidence for it in Maine is tentative. Loss-on-ignition data and paleotemperature reconstructions based on chironomid analysis are used here to construct late-glacial climate profiles for Pennington Pond and Whited Lake, both in Aroostook County, Maine. The data from this study, and from other published results, are used to present a more comprehensive understanding of the late-glacial period in Maine and the Northeast Region. Sediment cores from Pennington Pond and Whited Lake were sampled and processed for chironomid head capsules, percent organic content, and AMS 14C dates. A weighted-averaging transfer function based on chironomid assemblages in a modern data set was used to reconstruct mean July surface-water temperatures for each sample. Pennington Pond and, to a lesser extent, Whited Lake exhibit late-glacial climate profiles that closely resemble those recorded from other study sites in the region, and the AMS 14C dates for Pennington Pond and Whited Lake indicate that the cold events of the late glacial period occurred synchronously throughout the region. The loss-on-ignition data at Pennington Pond indicate a reduction in sediment organic content associated with the Killarney Oscillation, but the chironomid data are inconclusive. No evidence for the Killarney Oscillation was detected at Whited Lake. The consistent presence of littoral chironomid taxa and sporadic appearance of cold-adapted types between ~11,400 to 11,000 AMS 14C years BP may be indicative of a cooler, but dry, period. Limnological factors may be overriding climate signals during this part of the late-glacial period.

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