Historical:Howardton Limestone Member

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Handbook of Illinois Stratigraphy
Series Bulletin 95
Author H. B. Willman, Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, Jack A. Simon
Date 1975
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Lithostratigraphy: Hunton Limestone Megagroup >>Lingle Formation
Chronostratigraphy: Paleozoic Erathem >>Devonian System >>Middle Devonian Series
Allostratigraphy: Kaskaskia Sequence

Authors

Charles Collinson and Elwood Atherton

Name Origin

The Howardton Limestone Member of the Lingle Formation (North, 1969, p. 22-25) is named for Howardton, Jackson County, 2 miles east of the type section.

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.

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.

Stratigraphic Position

The Howardton Limestone Member of the Lingle Formation (North, 1969, p. 22-25) is the basal member of the Lingle Formation.

Description

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.

Fossils

The basal few feet of the Howardton is characterized by a small, button-shaped coral, Microcyclus.

References

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.

ISGS Codes

Stratigraphic Code Geo Unit Designation
6070
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