Bristow Sandstone Member


Tobinsport Formation,

Mississippian System

Type section and history of name: The Bristow Sandstone Member was named for Bristow in west-central Perry County, Ind. The name was originally applied in a formational sense (Malott, 1925, p. 111-112) but was later suppressed in favor of the term Palestine Sandstone from the standard Chesterian section (Malott, 1931, p. 222). Malott's restricted usage as a single bed of sandstone, however, was at variance with standard usage, which includes much shale in the formation. (Compare Malott, Esarey, and Bieberman, 1948, with Willman and others, 1975, p. 161.) Because of this variance and apparently insoluble boundary problems associated with the broader unit, Gray (1978, p. 12) recommended a return to Malott's original concept of the Bristow for outcrop usage and specified a section near Bristow, earlier described by Malott (1925, p. 126), as the type section. Indiana Geological Survey drill hole 132, near Oriole in Perry County (Gray, 1978, appendix 2), is here designated as a principal reference section.

Description: At Bristow the Bristow Sandstone Member reaches its maximum known thickness of 15 feet (5 m) (Malott, 1925, p. 126). More commonly it is 2 to 12 feet (0.6 to 4 m) thick. It is 25 to 50 feet (8 to 15 m) above the base of the Tobinsport Formation and about 210 feet (64 m) above the top of the Glen Dean Limestone (Gray, 1978, p. 12). In most places the member is a single ledge that ranges from fine-grained ripple-bedded quartzose sandstone to thinly interstratified sandstone, siltstone, and shale. It forms a widely recognizable unit in Perry County, although it is absent from some areas and is not known outside that county.

Correlation: The Bristow Sandstone Member falls within the limits of the Palestine Sandstone of the standard Chesterian section, but the internal stratigraphy of the Palestine is complex (Swann, 1963, p. 39-40 Willman and others, 1975, p. 161), and there is at present no way to determine the position of the Bristow member within that formation. The term Bristow has not been applied in the subsurface.

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