YOU CAN SEE THE FOREST THROUGH THE TREES: LIDAR & GLACIAL LAND SYSTEMS, EXAMPLES FROM CAYUGA COUNTY, NEW YORK

Located in Central New York, Cayuga County extends from the northern Finger Lakes carved into Devonian age limestone and shale formations of the Appalachian Plateau northward to streamlined low relief topography of the Ontario Lowlands that intersect Lake Ontario. Drift thickness ranges from less than a meter to more 125 meters. Ice from the Ontario Lobe of the Laurentide Ice sheet established the present distribution of Late Wisconsin sediment – landform assemblages in the region.

LIDAR data for Cayuga County obtained as part of an ongoing three-dimensional geological mapping project for the Montezuma Wetlands Complex provides an unprecedented level of high resolution terrain data. Combined with subsurface data from geotechnical, exploration and well borings and detailed field mapping, the LIDAR terrain provides a suit of information for investigating the distribution of glacial landforms, regional stratigraphic relationships and to test and refine current models of deglacial chronology.

The southern half of the county is dominated by through valleys associated with the Finger Lake troughs, under printed on a subdued north-south streamlined landscape. The northern half of the county is dominated by an impressive drumlinized topography. Shoreline features and a region of beveled drumlins associated with phases of glacial Lake Iroquois are also unmistakable.

Previous models of deglaciation have identified three to four ice marginal positions. Whereas the LIDAR terrain data clearly displays at least eight ice marginal positions. Plainly visible in the northern half of the county are multiple eskers transecting drumlins at oblique angles. Eskers terminate at numerous small to medium sized fans that define the ice marginal positions. East-West meltwater channels, in excess of one kilometer in width truncate the north-south oriented drumlins signifying outflows of water originating from a westerly source.

Radiocarbon dates collected in the Montezuma Wetlands Complex provide control to establish a high resolution chronology for late glacial events. A ten meter thick varved lake clay recovered from 16 meters at depth should provide greater chronologic control. Combined with ice marginal positions identified by more definitive LIDAR data should provide an additional element of control to test present models.