St. Peter Sandstone, Illinois Basin (05)

Comments on Geologic Parameters

05 Percent Shale:

The St. Peter Sandstone is a mature quartz arenite that contains little or no silt and clay, except near its perimeter. Lamar (1928; his fig. 10) provided results of grain-size analysis for a number of St. Peter Sandstone samples in which the percent clay ranged from 0 to 5.8 with a mean of about 2.5 percent. Because clay is a minor constituent of the St. Peter Sandstone, we simply assign the percent shale to be 2.5 throughout the central Illinois Basin.

05 Reference:

Lamar, J. E., 1928, Geology and economic resources of the St. Peter Sandstone of Illinois: Illinois Geological Survey Bulletin No. 53, 175 p.