Historical:Otis 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 >>Wapsipinicon Limestone >>Otis Member
Chronostratigraphy: Paleozoic Erathem >>Devonian System >>Middle Devonian Series
Allostratigraphy: Kaskaskia Sequence


Charles Collinson and Elwood Atherton

Name Origin

The Otis Member of the Wapsipinicon Limestone (Norton, 1894, p. 22-24), which overlies the Coggan Member (or Silurian dolomite where the Coggan is absent), is named for the railway junction called Otis, east of Cedar Rapids, Linn County, Iowa.

Type Section

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).


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.


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