Historical:Tripp Limestone Member
Charles Collinson and Elwood Atherton
The Tripp Limestone Member of the Lingle Formation (North, 1969, p. 25-28) overlies the Howardton Limestone Member and is named for Tripp School, 200 yards northwest of the type section.
The type section of the Tripp Limestone Member is an outcrop on the south side of Kratzinger Hollow, 1 mile northwest of Jonesboro, Union County (N 1/2 NE NW 23, 12S-2W).
Extent and Thickness
The upper 17 feet of the member is exposed at the type section and 22-foot thicknesses are found in near-by wells. The Tripp is widespread and reaches 80 feet thick in south-central Illinois, although it is absent in southeastern Illinois (fig. D-15).
The Tripp Member contains limestone, dolomite, chert, siltstone, and shale. It is largely cherty, argillaceous, silty limestone, but beds of shale are abundant near its base and top. About half of the member is dolomite on the margin of the Sparta Shelf. Glauconite, quartz sand, oolite, and beds of phosphate pellets are locally abundant in the northern and western parts of the member.
Crinoids, brachiopods, and corals are abundant in some Tripp Member beds.
NORTH, W. G., 1969, Middle Devonian strata of southern Illinois: Illinois State Geological Survey Circular 441, 45 p.
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