Historical:Hombergian Stage

Lithostratigraphy: Pope Megagroup
Chronostratigraphy: Paleozoic Erathem >>Mississippian Subsystem >>Chesterian Series >>Hombergian Stage
Allostratigraphy: Kaskaskia Sequence

Authors

Elwood Atherton, Charles Collinson, and Jerry A. Lineback

Name Origin

The Hombergian Stage (Swann, 1963, p. 22, 70), the middle stage of the Chesterian Series, derived from the Homberg Group (J. M. Weller, 1939), is named for Homberg, Pope County.

Description

The Hombergian Stage includes strata from the top of the Beech Creek up to the top of the Glen Dean (fig. M-25). The limestones in this stage are typically light brownish gray, light gray, or buff to gray and many of them and their associated shales are abundantly fossiliferous. Red shales in the upper part of the Fraileys and the lower part of the Hardinsburg are extensive marker beds.

Fig. M-25 -- Columnar section of the Chesterian Series (after Swan, 1963), showing biozones (after Collinson et al., 1971). In the columnar section, the blank areas are shale.

Fossils

The bryozoan Prismopora serrulata and the crinoid Pterotocrinus (fig. M-4) are typical Hombergian fossils.

Fig. M-4 -- Typical Mississippian fossils.

References

SWANN, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.
WELLER, J. M., 1939, Mississippian System: Kansas Geological Society Guidebook, 13th Annual Field Conference, southwestern Illinois and southeastern Missouri, p. 131-137.

ISGS Codes

Stratigraphic Code	Geo Unit Designation
4250	--