Beech Creek Limestone


Stephensport Group,

Mississippian System

Type section and description: The Beech Creek Limestone was named by Malott (1919, p. 11-15) for exposures along Beech Creek in Greene County, Ind. Malott later (19b2, p. 73-78) designated a type section at Rays Cave in sec. 13, T. 7 N. R. 4 W. The formation is typically a gray skeletal to biomicritic limestone 8 to 33 feet (2 to 10 m) thick (Perry and Smith, 1958, pl. 1). The lower third of the formation is characteristically somewhat darker than the upper two-thirds. This lithologic contrast is thought to represent a transgressive-regressive depositional couple (Kissing, 1967, p. 168-169). Typical fossils include large crinoid columnals as much as 25 mm in diameter and a variety of brachiopods. (See Malott, 1952, p. 15.)

The Beech Creek is recognized at the surface from Owen County southward to the Ohio River; in the subsurface, where it has sometimes been called the Barlow Lime, it is recognized from Clay County southwestward. It is the most widely recognized marker in the Chesterian Series, and in only a few places can this unit be demonstrated to be absent from its expected stratigraphic position. The Beech Creek conformably overlies the Elwren Formation and is overlain conformably by the Big Clifty Formation or disconformably by the Mansfield Formation (Morrowan).

Correlation: The Beech Creek Limestone was considered by Malott (1931, p. 222 1952, p. 15) to be equivalent to the upper part of the Paint Creek Formation in Illinois. The stated basis for this assignment was paleontologic affinity, but a prominent and widespread sandstone bed above each of these formations was also considered to be significant. Subsurface information, however, has demonstrated physical continuity of the Beech Creek Limestone with the lower part of the Golconda Group in southwestern Illinois (Swann and Atherton, 1948), and the name Beech Creek has now been accepted into the standard Chesterian section (Rexroad and Jarrell, 1961, p. 2014; Swann, 1963, p. 35-36; Willman and others, 1975, p. 155-156).

The Beech Creek Limestone contains the first appearance of the brachiopod Coelidium explanatum (McChesney) and also several species of the blastoid genus Pentremites that exhibit depressed ambulacra (P. cervinius Hall, P. elegans Lyon, P. tulipaformis Hambach). An upper sandy bed of the Beech Creek, recognized at several sites in Indiana by Kissling (1967), contains the distinctive wing plates of the crinoid Pterotocrinus capitalis (Lyon), which on the southwest side of the Illinois Basin is restricted to the Fraileys Shale. The Beech Creek corresponds to rocks within North American foraminiferal Zone 16s of Mamet and Skipp (1971) and within Zone V3cs of the type Visean sequence in Belgium. On the basis of contained conodonts, the Beech Creek is assigned to the Gnathodus bilineatus-Cavusgnathus altus Assemblage Zone of North American usage (Collinson, Rexroad, and Thompson, 1971).

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