Historical:Dykersburg Shale Member
Lithostratigraphy: Kewanee Group >>Carbondale Formation >>Dykersburg Shale Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Desmoinesian Series
Allostratigraphy: Absaroka Sequence
M. E. Hopkins and J. A. Simon
The Dykersburg Shale Member of the Carbondale Formation (Hopkins, 1968, p. 4) is named for Dykersburg (called Absher on some maps), Williamson County.
Dykersburg is near the type section which is in the highwall of an abandoned coal strip pit (SE SE NE 34, 9S-4E).
Extent and Thickness
The Dykersburg is confined to a belt 3-15 miles wide that extends southwestward from Wabash County to the outcrop in Saline County. The Dykersburg is as much as 100 feet thick in places.
Most of it is gray silty shale containing some sandstone, particularly one major channel sandstone that replaces the Harrisburg Coal along a narrow band. Where overlain by the Dykersburg Shale, the Harrisburg Coal is thicker, is commonly characterized by several shale splits, and contains much less sulfur (less pyrite) than in areas where it is overlain by black fissile shale or the St. David Limestone. The Dykersburg is also well developed in an adjacent area in western Indiana.
HOPKINS, M. E., 1968, Harrisburg (No. 5) Coal reserves of southeastern Illinois: Illinois State Geological Survey Circular 431, 25 p.
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