Jake Creek Sandstone 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.
Wanless (1957, p. 89) wrote, “The Jake Creek sandstone is herein named for exposures along the upper part of Jake Creek, in the NE¼ sec. 13, T 4 N, R 1 E, Vermont Quadrangle. It is only locally present but has a maximum thickness of about 18 feet [5.5 m].”
How the stream came to be named is unknown.
The type section consists of exposures along Jake Creek in the NE¼ of sec. 13, T 4 N, R 1 E, Fulton County, on the Ipava 7.5' sheet, where the Jake Creek Member is 19.5 ft (5.94 m) thick.
Wanless (1957, geologic section 38, p. 204).
In the type section, the Jake Creek sharply underlies the Oak Grove Member and grades downward to the Francis Creek Shale. The Mecca Quarry Shale is absent here and at other localities where Wanless observed the sandstone. On this basis, the type Jake Creek appears to be an upper, sandy facies of the Francis Creek. However, C.M. Wright (1963), a student of Harold Wanless, treated the Jake Creek as the clastic unit lying above the Oak Grove Limestone and below the Lowell [Survant] Coal. Wanless (1964, p. 600–601) considered the Jake Creek “sandstone” (his quotes) to be “a sand–shale complex from an easterly direction, on which the Lowell–Wheeler–Bevier coal swamp was supported, in part.” A year later, Wright (1965) did not even mention the Jake Creek Member in her dissertation, which covered the Liverpool cyclothem throughout the Illinois and Midcontinent Basins. She mapped the “sandstone below the Lowell and equivalent coals” without a formal name.
In summary, the original author of the Jake Creek Member offered conflicting definitions and then (through a student) quietly cast the unit aside half a century ago. Its relationships to enclosing units remain poorly defined. The Jake Creek Member is therefore regarded as abandoned.
- Wanless, H.R., 1957, Geology and mineral resources of the Beardstown, Glasford, Havana, and Vermont Quadrangles: Illinois State Geological Survey, Bulletin 82, 233 p.
- Wanless, H.R., 1964, Local and regional factors in Pennsylvanian cyclic sedimentation, in D.F. Merriam, ed., Symposium on cyclic sedimentation: Kansas Geological Survey, Bulletin 169, v. 2, p. 593–605.
- Wright, C.R., 1963, Environmental study of the Liverpool cyclothem of the Eastern Interior basin and the Forest City basin: Urbana, University of Illinois, M.S. thesis, 33 p.
- Wright, C.R., 1965, Environmental mapping of the beds of the Liverpool cyclothem in the Illinois Basin and equivalent strata of the northern mid-continent region: Urbana, University of Illinois, Ph.D. thesis, 100 p.
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