LAKES CLARYVILLE AND BURLINGTON AND THE DEEP STAGE CHANNEL: A NEW LOOK AT PRE-WISCONSINAN GEOLOGY IN NORTHERN KENTUCKY USING BOREHOLES

Early Pleistocene glaciation in Northern KY (within a large loop of the Ohio River south of Cincinnati, OH) has not been studied extensively, due in part to lack of subsurface data. In Northern KY, pre-Wisconsinan glacial terranes are well preserved in the subsurface, and with them evidence of glacial/interglacial cycles extending back to early Pleistocene time. Future study of these cycles will be valuable in extending our understanding of glacial/interglacial and climate change cycles back in time from the Wisconsinan, and in connecting evidence preserved in the area to climatic events documented elsewhere.

Review of hundreds of deep geotechnical test boring logs and construction excavations made across the Northern KY area since the early 1960s is allowing characterization of pre-Wisconsinan strata preserved in the subsurface. Oriented sampling of key strata will allow measurement of remanent magnetism and possible correlation to independently-dated geomagnetic fluctuations and to each other. Consolidation testing of till samples will constrain maximum ice thicknesses.

This study focuses on three general areas in Northern KY shaped by pre-Wisconsinan glaciation. The first is a construction site located over the Old Licking River valley, which began to be filled with lacustrine clays when the north-flowing stream was blocked and formed Lake Claryville prior to arrival of the first Laurentide ice advance. The lacustrine deposits eventually accumulated to a thickness of 71.0 m. The second area is the Burlington, KY area, separated from the Old Licking River valley by a divide, where the existence of lacustrine clays was noted as early as 1919, but where the limits of proglacial Lake Burlington are being defined in detail for the first time. The presence of till beneath the clays suggests that Lake Burlington is the younger lake. The third area is a segment of the buried Deep Stage channel forming the western edge of the Northern KY area, in which the base of the lowest till is 12.2 m above the bedrock surface of the channel, and which may provide evidence that this segment of the Deep Stage channel was already present when the first ice advance arrived in the area. The subsurface stratigraphy encountered in extensive Deep Stage channel borings provides evidence of at least 5 pre-Wisconsinan ice advances into the Northern KY area.