Historical:Solon 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 >>Cedar Valley Limestone >>Solon Member
Chronostratigraphy: Paleozoic Erathem >>Devonian System >>Middle Devonian Series
Allostratigraphy: Kaskaskia Sequence


Charles Collinson and Elwood Atherton

Name Origin

The Solon Member of the Cedar Valley Limestone (Norton, 1897, p. 148; Keyes, 1913, p. 205-206) is named for Solon, Johnson County, Iowa.

Type Section

No type section has been designated for the Solon Member.


The Solon is correlated with the upper Hamilton in New York (Collinson et al., 1967b).

Extent and Thickness

In Illinois the Solon Member has a maximum thickness of about 10 feet but is absent locally. It is 6-8 feet thick where exposed in quarries southeast of Milan and on the south side of Rock Island.

Stratigraphic Position

The Solon Member of the Cedar Valley Limestone is the basal member where the Hoing Member is not present.


The Solon Member is a fine- to medium-grained, grayish brown, very fossiliferous limestone with brecciated beds.


The Solon Member is characterized by an abundance of brachiopods, mainly Atrypa independensis, and corals, notably biostromes of Hexagonaria profunda (fig. D-6). Conodonts also are abundant.


COLLINSON, CHARLES, M. P. CARLSON, F. H. DORHEIM, and J. W. KOENIG, 1967b, Central Iowa Basin, in International symposium on the Devonian System: Alberta Society of Petroleum Geologists, v. 1, p. 963-971; Illinois State Geological Survey Reprint 1968-G.
KEYES, C. R., 1913, Late Devonic sequence of the Iowa region (synopsis): Iowa Academy of Science Proceedings, v. 20, p. 205-206.
NORTON, W. H., 1897, Artesian wells of Iowa: Iowa Geological Survey, v. 6, p. 113-428.

ISGS Codes

Stratigraphic Code Geo Unit Designation