|Cape Fear Formation, South Carolina Coastal Plain
Several studies characterize the confining unit above the Cape Fear Formation as a tight marine shale (Aucott and others, 1987; Aucott, 1988; Miller, 1990), and the shale interval is apparent in published cross-sections (Colquhoun and others, 1983; Aucott and others, 1987). However, there is no published map showing thickness of the Cape Fear confining unit. On the basis of evaluation of logs in published cross sections, we determined that the thickness of the confining unit is consistent across southeastern South Carolina and averages about 50 ft.
Aucott, W. R., Davis, M. E., and Speiran, G. K., 1987, Geohydrologic framework of the Coastal Plain aquifers of South Carolina: U.S. Geological Survey, Water-Resources Investigations Report 85-4271, 7 sheets.
Colquhoun, D. J., Woollen, L. D., Van Nienwenhuise, D. S., Padgett, G. G., Oldham, R. W., Boylan, D. C., Bishop, J. W., and Howell, P. D., 1983, Surface and subsurface stratigraphy, structure and aquifers of the South Carolina Coastal Plain: Columbia, SC, State of South Carolina, Office of the Governor, 78 p.
Miller, J. A., 1990, Ground water atlas of the United States—segment 6, Alabama, Florida, Georgia, and South Carolina: U.S. Geological Survey Hydrologic Investigations Atlas No. HA-730-G, 28 p.