CHIRONOMID EVIDENCE FOR LATE-GLACIAL CLIMATIC REVERSALS IN MAINE

Previously published pollen studies from Maine have not identified any late-glacial reversals despite evidence for them from adjacent areas. The distribution and abundance of midge flies are strongly correlated with summer surface-water temperatures. We analyzed fossils of larval midge flies from the sediments of two ponds (Trout and Tilley) from Maine. Each site reveals a major and a minor oscillation during which inferred summer surface-water temperatures fell by 7-13 degrees C and 2.1-2.6 degrees C, respectively. We tentatively correlate these events with the Younger Dryas cooling and Killarney Oscillation reported from adjacent Maritime Canada, where they have been AMS C-14-dated at 10,770-10,000 and 11,160-10,910 yr B.P., respectively. A third oscillation occurs at the northernmost site, Tilley Pond, and may represent the effects of a local ice advance in northern Maine. (C) 1995 University of Washington.