Elwood Atherton, Charles Collinson, and Jerry A. Lineback
The Gasperian Stage (Swann, 1963, p. 21-22, 67), the oldest stage of the Chesterian Series, is derived from the Gasper Limestone of Kentucky (Butts, 1917), which is named for the Gasper River, northwest of Bowling Green, Kentucky.
Extent and Thickness
In the Anna district of southwestern Illinois, sandstone of the Cypress alone constitutes about half of the Gasperian Stage. In the fluorspar district, where the Gasperian Stage is about 300 feet thick, about 200 feet is sandstone.
The Gasperian includes rocks from the base of the Sketlerville Member of the Renault Limestone to the top of the Beech Creek Limestone (fig. M-25). The upper part of the Cedar Bluff Group is included in the Gasperian, but the lower part is Valmeyeran and the group was described under Valmeyeran.
Sandstone predominates in the Gasperian Stage.
Marine fossils occur in limestones and shales of the Paint Creek Group and the Renault Limestone. The bryozoan Cystodictya labiosa Zone and the crinoid Talarocrinus Range Zone are the most definitive faunal zones of the Gasperian Stage, although the Talarocrinus Zone does not include the Beech Creek Limestone.
BUTTS, CHARLES, 1917, Descriptions and correlations of the Mississippian formations of western Kentucky, Part I of Mississippian formations of western Kentucky: Kentucky Geological Survey, v. 1, 119 p.
SWANN, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.
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