HOLOCENE ENVIRONMENTAL-CHANGES IN THE WHITEFISH DUNES AREA, DOOR PENINSULA, NORTHERN LAKE MICHIGAN BASIN, USA

A two meter sediment core taken from an inter-dune pond in Whitefish D unes State Park, Door Peninsula, Wisconsin, provides a record of paleo environmental changes in the area from approximately 3600 RCYBP to 510 0 RCYBP. The hydrology of the Whitefish Dunes pond is now apparently d ependent on ground water recharge from local precipitation that infilt rates into the dunes and from Clark Lake, making it very sensitive to low magnitude, short term climate fluctuations. Changes in lithology, molluscan species diversity, oxygen isotopes from gastropod shells, an d sediment organic content permit division of the core into several in tervals representing different environmental regimes. The basal sedime nts are older than 5130 RCYBP and resemble those of the Liberty Grove Member of the Pleistocene Horicon Formation. The oldest Holocene sedim ents recorded in the core are an organic rich layer dated at 5130 RCYB P, which accumulated in a depression on the surface of a sand bar Cont inued rise in the local water table during the Nipissing Transgression produced paludal conditions in the area, which were followed by the o nset of lacustrine conditions. During this interval, the area supporte d a diverse molluscan fauna. Minor, short term climate fluctuations ar e reflected in sediment and oxygen isotope changes which are absent fr om the record in deep water cores from Lake Michigan. This phase in th e history of the area ended with the eutrophication of the pond and th e development of dunes. Information from Whitefish Dunes pond and othe r onshore sites within the Lake Michigan basin are an important source of data for reconstructing the history of water levels and climate ch anges for this area of the Great Lakes drainage.