Quaternary Environmental Changes Inferred From Pollen Analysis of Ponds, Green Mountains, Vermont

Great changes have taken place in the Green Mountains of Vermont since the Wisconsin continental glacial ice sheet left. The Champlain Valley has undergone changes as Lake Vermont. and the Champlain Sea which was later replaced by Lake Champlain. Meanwhile, vegetation migrated northward following the retreating ice. Little pollen work has been done in Vermont. The only study with systematic radiocarbon dating was done by L.L McDowell in 1971. The purpose of my research is to use pollen analysis to explain the distribution pattern and first arrival time of different tree species in the Green Mountains, Vermont, enrich the local pollen research data, and attempt to figure out whether the Younger Dryas climatic oscillation occurred in North America. Pollen analysis is an effective way to interpret paleovegetation distribution and therefore infer changes in paleoclimate. Due to the extremely resistant characteristic of the pollen grain wall, pollen grain can be well preserved in lake. pond, bog, and peat sediments. The unique morphological characteristics of pollen grains make it easy to identify to species-level. By coring at the deepest portion of lakes or ponds, one can retrieve a complete pollen archive. I have collected three cores from Sterling Pond, and two cores from RiUerbush Pond. Before the cores were taken, I made detailed bathymetric maps to identify depocenters. In the lab, the cores have been subsampled at five to ten centimeters interval. Pollen has been extracted from forty two of fifty seven samples at Dr. Ray Spear's lab. Six AMS radiocarbon dates of sediments and macrofossils have come back from the Lawrence Livermore National Laboratory. The sediment from the deepest part of Sterling Pond yielded an age of 12,760+/-70 years BP. High resolution loss-on-ignition and macrofossil identification will be done in the coming lab work. Because Ritterpush Pond are almost 1,000 feel lower and further north than Sterling Pond, it, may help us understand the altitudinal and latitudinal migration pattern of vegetation