Otis Member

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Lithostratigraphy: Hunton Limestone Megagroup >>Wapsipinicon Limestone >>Otis 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 Otis Member of the Wapsipinicon Limestone (Norton, 1894, p. 22-24).


Named for the railway junction called Otis, east of Cedar Rapids, Linn County, Iowa.

Other names


Type section

Type location

The Otis Member is 26 feet thick where exposed in its type section in a quarry at Cleveland, Henry County (S1/2 31, 18N-2E).

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

The Otis Member of the Wapsipinicon Limestone overlies the Coggan Member (or Silurian dolomite where the Coggan is absent).

Extent and thickness


The Otis Member is fine-grained to lithographic, light gray to brown limestone with a few lenses of chert. In the region where it thins out on the flanks of the Sangamon Arch, lenses of quartz sandstone as much as 5 feet thick occur at the base.




Well log characteristics


Age and correlation

Environments of deposition

Economic importance



NORTON, W. H., 1894, Notes on the lower strata of the Devonian Series in eastern Iowa: Iowa Academy of Science Proceedings 1, part 4, p. 22-24.

ISGS Codes

Stratigraphic Code Geo Unit Designation