Howardton Limestone Member
Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.
Charles Collinson and Elwood Atherton
The Howardton Limestone Member of the Lingle Formation (North, 1969, p. 22-25).
Named for Howardton, Jackson County, 2 miles east of the type section.
The type section of the Howardton Limestone Member is located in a quarry in the Backbone ridge north of Grand Tower (NE NE SE 23, 10S-4W), where it is 33 feet thick.
The Howardton Limestone Member of the Lingle Formation (North, 1969, p. 22-25) is the basal member of the Lingle Formation.
Extent and thickness
The Howardton extends throughout much of the area of the Lingle, but it is overlapped by the Tripp Member in the northern part. It is as much as 110 feet thick in southeastern Illinois and generally thins northward and westward.
The Howardton is gray, fine-grained, slightly silty, argillaceous limestone, most of which has thin, shaly partings. The base of the Howardton is the original Grand Tower-Lingle contact of Savage (1920). The top of the Howardton is charaterized by a thin intraformational microbreccia with light-colored limestone fragments in a dark matrix.
Well log characteristics
The basal few feet of the Howardton is characterized by a small, button-shaped coral, Microcyclus.
Age and correlation
Environments of deposition
NORTH, W. G., 1969, Middle Devonian strata of southern Illinois: Illinois State Geological Survey Circular 441, 45 p.
SAVAGE, T. E., 1920, Devonian formations of Illinois: American Journal of Science, v. 49, p. 169-182.
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