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Open-File Report 2012–1218
Preliminary Physical Stratigraphy, Biostratigraphy, and Geophysical Data of the USGS South Dover Bridge Core, Talbot County, Maryland
By Wilma B. Alemán González, David S. Powars, Ellen L. Seefelt, Lucy E. Edwards, Jean M. Self-Trail, Colleen T. Durand, Arthur P. Schultz, and Peter P. McLaughlin
 Abstract
The South Dover Bridge (SDB) corehole was drilled in October 2007 in Talbot County, Maryland. The main purpose for drilling this corehole was to characterize the Upper Cretaceous and Paleogene lithostratigraphy and biostratigraphy of the aquifers and confining units of this region. The data obtained from this core also will be used as a guide to geologic mapping and to help interpret well data from the eastern part of the Washington East 1:100,000-scale map near the town of Easton, Md. Core drilling was conducted to a depth of 700 feet (ft). The Cretaceous section was not penetrated due to technical problems during drilling. This project was funded by the U.S. Geological Survey’s (USGS) Eastern Geology and Paleoclimate Science Center (EGPSC) as part of the Geology of the Atlantic Watersheds Project; this project was carried out in cooperation with the Maryland Geological Survey (MGS) through partnerships with the Aquifer Characterization Program of the USGS’s Maryland-Delaware-District of Columbia Water Science Center and the National Cooperative Geologic Mapping Program.
The SDB corehole was drilled by the USGS drilling crew in the northeastern corner of the Trappe 7.5-minute quadrangle, near the type locality of the Boston Cliffs member of the Choptank Formation. Geophysical logs (gamma ray, single point resistance, and 16-inch and 64-inch normal resistivity) were run to a depth of 527.5 ft; the total depth of 700.0 ft could not be reached because of the collapse of the lower part of the hole. Of the 700.0 ft drilled, 531.8 ft of core were recovered, representing a 76 percent core recovery. The elevation of the top of the corehole is approximately 12 ft above mean sea level; its coordinates are lat 38°44′49.34″N. and long 76°00′25.09″W. (38.74704N., 76.00697W. in decimal degrees).
A groundwater monitoring well was not installed at this site. The South Dover Bridge corehole was the first corehole that will be used to better understand the geology and hydrology of the Maryland Eastern Shore.
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First posted December 20, 2012
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Suggested citation:
Alemán González, W.B., Powars, D.S., Seefelt, E.L., Edwards, L.E., Self-Trail, J.M., Durand, C.T., Schultz, A.P., and McLaughlin, P.P., 2012, Preliminary physical stratigraphy, biostratigraphy, and geophysical data of the USGS South Dover Bridge Core, Talbot County, Maryland: U.S. Geological Survey Open-File Report 2012–1218, 16 p. plus appendixes.
Contents
Introduction
Physical Stratigraphy and Lithology
Acknowledgments
References Cited
Appendix A.South Dover Bridge Lithologic Log
Appendix B.South Dover Bridge Core-Run Log
Appendix C.South Dover Bridge Core Sampling Log
Appendix D.Photographs of Boxed Core From the South Dover Bridge Corehole
Appendix E. Calcareous Nannofossil Occurrences in the South Dover Bridge Corehole for the Late Paleocene to Middle Miocene
U.S. Department of the Interior |
U.S. Geological Survey