SURFICIAL GEOLOGIC MAPPING OF THE UNION SPRINGS QUADRANGLE, NEW YORK: AN EXAMPLE OF THE UNBEKNOWNST SOCIETAL NEED FOR 3D GEOLOGIC MAPPING

The Union Springs Quadrangle located in the southern half of Cayuga County on the eastern shores of Cayuga Lake is representative of many communities in the Finger Lakes in central New York. Although, rural in nature with agriculture as a dominant land use activity the small communities such as Union Springs have not been spared by a legacy of industrial activity in the region. In response to groundwater contamination geologic models were developed that largely ignore the glaciated landscape produced by the Ontario Lobe of the Laurentide Ice Sheet.

As part of an ongoing geologic mapping project to investigate the natural history of the county the New York Geological Survey has compiled detailed lithologic data from outcrops and exploration cores, geophysical data and lidar terrain models to provide the requisite data to construct a comprehensive 3D geologic framework. The detailed mapping reveals the discovery of a buried bedrock valley system more than 5 km in length located on the upland between adjacent Finger Lake troughs.

The combined stratigraphic analysis from extensive exposures within Great Gully an east-west oriented tributary to Cayuga Lake and continuous sonic and wireline cores demonstrate laterally continuous glacial and non-glacial sequences more than 77 meters in thickness. These deposits include paleosols, subtill organic rich sands and multiple diamictons interpreted as till deposits. In addition many of the buried till sequences and associated deposits are overconsolidated and display various heterogenties, such as jointing and large scale deformation. 

The recovery of pollen from buried peats, plant macrofossils and logs from in situ stratum provide a remarkable context for paleoenvironmental reconstructions. Through the extensive application of radiocarbon and optically stimulated luminescence dating a time-stratigraphic model has been developed in conjunction with the geologic framework and indicates deposits in the quadrangle span Marine Isotope Stages (MIS) 1-6 and thus provides one of the most comprehensive records of Late Pleistocene glacial events in the Finger Lakes Region and New York. The completed mapping provides a context to illustrate both the complexity of glacial geology and the need for such detail to guide societal decisions when addressing natural resources.