Solon Member

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

Primary source

Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.

Contributing author(s)

Charles Collinson and Elwood Atherton


Original description

The Solon Member of the Cedar Valley Limestone (Norton, 1897, p. 148; Keyes, 1913, p. 205-206).


Named for Solon, Johnson County, Iowa.

Other names


Type section

Type location

No type section has been designated for the Solon Member.

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

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

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.


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




Well log characteristics


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.

Age and correlation

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

Environments of deposition

Economic importance



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