Historical:Hall Limestone Member
Lithostratigraphy: McLeansboro Group >>Modesto Formation >>Hall Limestone Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Missourian Series
Allostratigraphy: Absaroka Sequence
Authors
M. E. Hopkins and J. A. Simon
Name Origin
The Hall Limestone Member of the Modesto Formation (Willman, in Cooper, 1946, p. 12) is named for Hall Township, Bureau County.
Type Section
The type section consists of exposures in a ravine west of the coal mine refuse pile in the western part of the town of Spring Valley (NW SW 33, 16N-11E) (Wanless, 1956, p. 12).
Correlation
The Hall is correlated with the Macoupin Limestone of southern and eastern Illinois.
Extent and Thickness
The Hall is recognized only in northern Illinois.
Stratigraphic Position
In the type section it lies about 45 feet below the La Salle Limestone Member.
Description
At the type section, it consists of a 3-foot ledge of fine-grained, green, gray, and red limestone containing numerous brachiopods, crinoid columnals, and bryozoans. It is underlain by a persistent black shale.
References
COOPER, C. L., 1946, Pennsylvanian ostracodes of Illinois: Illinois State Geological Survey Bulletin 70, 177 p. WANLESS, H. R., 1956, Classification of the Pennsylvanian rocks of Illinois as of 1956: Illinois State Geological Survey Circular 217, 14 p.
ISGS Codes
Stratigraphic Code | Geo Unit Designation |
---|---|