Historical:State Pond Member
Elwood Atherton, Charles Collinson, and Jerry A. Lineback
The State Pond Member of the Springville Shale (Collinson and Scott, 1958a, p. 5), at the base of the formation, is named for State Pond, an artificial lake a mile northwest of Jonesboro, Union County.
The type section of the State Pond Member is in the south bank of the stream, below the spillway of the dam (NW SE 14, 12S-2W), where the member is 14-15 inches thick.
The State Pond is a greenish gray, soft, glauconitic shale containing phosphate nodules.
The State Pond Member has yielded conodonts and ostracodes typical of the Fern Glen, Burlington, and Keokuk Limestones and probably is a deep-water equivalent of all three formations.
COLLINSON, CHARLES, and A. J. SCOTT, 1958a, Age of the Springville Shale (Mississippian) of southern Illinois: Illinois State Geological Survey Circular 254, 12 p.
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