CHARACTERIZING THE BURIED TEAYS VALLEY IN THE EASTERN MIDWEST, USA

Understanding the location and stratigraphy of the Teays River Valley system—the remnant of a major, extinct stream network mostly buried by Quaternary sediment—is important for refining glacial history and identifying potential aquifers. The goals of this ongoing Ohio-based, mapping-and-drilling project are to detail the subsurface contact between the consolidated Paleozoic bedrock surface and the overlying, unconsolidated Quaternary sediments and to provide new stratigraphic data for Teays Valley fill. In the Midwest, the unconformity between glacial sediment and bedrock is a fundamental boundary representing millions of years of erosion of an ancient land surface by pre-Pleistocene fluvial processes and multiple Pleistocene glaciations. Today, much of the regional bedrock topography (BT), and thus the Teays River Valley, is hidden beneath glacial materials with little to no expression on the present-day ground surface. To enhance the resolution of the Teays bedrock surface, multiple mapping projects utilized geophysical surveys (primarily passive seismic) and new borehole data (ranging from reviewing well records to drilling new test borings). Additionally, textural, geochemical, and geochronological analyses of two new rotary sonic boreholes drilled to bedrock directly within the Teays Valley provide new stratigraphic context to the region. The results of BT mapping projects further establish the gorge-like characteristic of the Teays Valley, especially in Ohio. The Teays exhibits a highly sinuous, incised, and meandering morphology south of the Bellefontaine Outlier in Ohio; but this sinuosity is not exhibited in much of the downstream, northwestern reaches of the Teays into Indiana, where it displays a more linear path. This linear path appears to parallel the orientation of buried Precambrian faults. These faults may have influenced the pre-Quaternary surface in northwestern Ohio by encouraging the development of a more rectangular, joint- or fault-controlled fluvial drainage network. This geomorphologic information, along with infill material characterization obtained from drilling projects in the Teays Valley, will be used in future studies to investigate preglacial and Quaternary history for Ohio and the Midwest region of the United States.