Drury Shale Member (abandoned)
Nelson, W.J., 2020, Pennsylvanian Subsystem in Illinois: Illinois State Geological Survey Bulletin (in press).
Edited and figures drafted by Jennifer M. Obrad.
Lamar (1925, p. 91–95) divided the Pottsville Formation into four newly named members in the Carbondale, Illinois, 15-minute quadrangle. In ascending order, these were the Wayside sandstone and shale, the Lick Creek sandstone, the Drury sandstone and shale, and the Makanda sandstone. Among the four, only the name Wayside is still in use.
The unit took its name from Drury Creek, a north-flowing tributary of the Big Muddy River in Union and Jackson Counties, southern Illinois.
With the rise of cyclic classification, the Drury became a formation in the Caseyville Group (Wanless 1939). However, Weller (1940) and Wanless (1956) showed it as the Drury shale member of the Battery Rock formation. Kosanke et al. (1960) formalized the unit as the Drury Shale Member of the Caseyville Formation (Figure 2-7).
Remapping the southeastern part of the Carbondale 15-minute quadrangle, Nelson and Weibel (1996, p. 21) determined that the Drury Member, as mapped by Lamar (1925), “is largely in the lower part of the Tradewater Formation, although in some areas the Drury includes uppermost Caseyville strata.” Lamar’s original usage of Drury therefore conflicted with later usage, which placed the Drury entirely within the Caseyville. Rather than redefining the Drury, Nelson and Weibel opted to leave the interval unnamed. Additional factors favoring abandonment include extreme lithologic variability of the Drury and inability to demarcate the member in areas where either the Pounds or Battery Rock Sandstones cannot be identified.
None was designated or described.
- Kosanke, R.M., J.A. Simon, H.R. Wanless, and H.B. Willman, 1960, Classification of the Pennsylvanian strata of Illinois: Illinois State Geological Survey, Report of Investigations 214, 84 p., 1 pl.
- Lamar, J.E., 1925, Geology and mineral resources of the Carbondale Quadrangle: Illinois State Geological Survey, Bulletin 48, 173 p., 3 pls.
- Nelson, W.J., and C.P. Weibel, 1996, Geology of the Lick Creek Quadrangle, Johnson, Union, and Williamson Counties, southern Illinois: Illinois State Geological Survey, Bulletin 103, 39 p., 1 pl.
- Wanless, H.R., 1939, Pennsylvanian correlations in the Eastern Interior and Appalachian coal fields: Geological Society of America, Special Paper 17, 130 p., 9 pls.
- Wanless, H.R., 1956, Classification of the Pennsylvanian rocks of Illinois as of 1956: Illinois State Geological Survey, Circular 217, 14 p.
- Weller, J.M., 1940, Geology and oil possibilities of extreme southern Illinois: Illinois State Geological Survey, Report of Investigations 71, 71 p.
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