LATE PLEISTOCENE TO HOLOCENE CLIMATE VARIABILITY AS RECORDED IN THE SEDIMENT OF SILVER LAKE, OHIO

In order to provide greater spatial coverage of late Pleistocene to Holocene environmental change in the Midwest, a 13.5-m long sediment core was collected from Silver Lake in northeast OH. Age control is provided by radiocarbon dating and correlation to a dated kettle lake record from western OH. Lithologic descriptions and loss-on-ignition profiles allow the history of the lake to be divided into three periods. The first period spans 13.5 to 8.24 m core depth (~17,000-7,000 cal year BP) and is characterized by low organic content (average 13%), occurrences of silty layers and high dry bulk density. Within this period at Younger Dryas time, organic content is low (average 6%) and a silty sediment is present possibly reflecting increased terrigenous sediment input to the lake during cold conditions. Above the Younger Dryas interval, the organic content increases to 19%, likely reflecting a moderation of the climate at the onset of the Holocene. The second period spans 8.24 to 1.07 m core depth (~7,000-200 cal year BP), and is characterized by mud having no visible silty layers, and a pronounced increase in organic content (average 51%). Within this period there are 6 intervals of decreased organic content suggestive of millennial-scale variability in terrigenous input and/or lake productivity. The upper 1.07 m is the third period and is characterized by a pronounced decrease in organic content (average 19%) and a corresponding increase in dry bulk density. These sediment characteristics are interpreted as enhanced soil erosion resulting from Euro-American settlement and land clearance.