Comments on Geologic Parameters
05 Percent Shale:
A number of studies present cross sections of the Cape Fear interval that include geophysical logs (gamma ray, spontaneous potential) (Colquhoun and others, 1983; Aucott and others, 1987; Temples and Waddell, 1996). These logs are a source of semiquantitative estimates of percent shale in the Cape Fear interval. Brown and others (1979) provided actual percentages for the Cape Fear interval (their Unit E), but these estimates are from wells in Georgia. Gohn and others (1977) presented results of textural and mineralogical analysis of the Cape Fear Formation conducted on samples from a well near Charleston. Their analyses indicate that the Cape Fear interval is primarily silt and that shale composes between 20 and 40 percent of the unit. For the GIS, we combined the analysis of Gohn and others (1977; their fig. 3) and Brown and others (1979). These shale percentages generally agree with the estimates derived from the geophysical logs.
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.
Brown, P. M., Brown, D. L., Reid, M. S., and Lloyd, O. B., Jr., 1979, Evaluation of the geologic and hydrologic factors related to the water-storage potential of Mesozoic aquifers in the southern part of the Atlantic coastal plain, South Carolina and Georgia: U.S. Geological Survey, Professional Paper 1088, 37 p., 11 plates.
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.
Gohn, G. S., Higgins, B. B., Smith, C. C., and Owens, J. P., 1977, Lithostratigraphy of the deep corehole (Clubhouse Crossroads Corehole 1) near Charleston, South Carolina: U.S. Geological Survey, Professional Paper 1028E, p. 59–70.
Temples, T. J., and Waddell, M. G., 1996, Application of petroleum geophysical well logging and sampling techniques for evaluating aquifer characteristics: Ground Water, v. 34, p. 523–531.