Historical:Grindstaff Sandstone Member
Lithostratigraphy: McCormick Group >>Abbott Formation >>Grindstaff Sandstone Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Atokan Series
Allostratigraphy: Absaroka Sequence
M. E. Hopkins and J. A. Simon
The Grindstaff Sandstone Member of the Abbott Formation (Butts, 1925, p. 44) is named for Grindstaff Hollow in Gallatin County.
Outcrops along Grindstaff Hollow (NE cor. 28, 10S-8E) are the type section.
The Grindstaff Sandstone is correlated with the Babylon Sandstone of western Illinois.
Extent and Thickness
The Grindstaff varies considerably in thickness up to 60 feet.
The Grindstaff is similar in appearance and characteristics to the other two sandstones of the Abbott Formation in southern Illinois. It is best developed east of the Du Quoin Monocline. The Grindstaff is generally fine or medium grained, most of it is slightly micaceous. It sometimes contains quartz granules and pebbles in the western part of the southern Illinois outcrop belt but generally fewer than occur in the underlying Caseyville sandstones. The sandstone is thickest and coarsest where it was deposited in local distributary or fluvial channels. It grades laterally into and overlies gray, silty or sandy shale. In a few places a very impure, sandy, clastic limestone or calcareous sandstone, formerly called the Boskydell Marine Zone or Boskydell Sandstone, is found at or near the position of the Grindstaff Sandstone in southwestern Illinois.
BUTTS, CHARLES, 1925, Geology and mineral resources of the Equality-Shawneetown area: Illinois State Geological Survey Bulletin 47, 76 p.
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