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The fauna of the so-called Dakota formation of northern central Colorado and its equivalent in southeastern Wyoming

Professional Paper 131-H
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https://doi.org/10.3133/pp131H

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Abstract

This paper describes a small fauna from beds in northern central Colorado that have long been designated the Dakota formation, often with doubt that all the beds so named were really equivalent to the typical Dakota sandstone of eastern Nebraska. The upper part of the equivalent beds in southeastern Wyoming was referred by some writers to the Benton Shale and the lower part of the Cloverly formation. This so-called Dakota formation of northern central Colorado and its equivalent in southeastern Wyoming consist of cherty conglomerate, brown quartzose sandstone, and dark shale. The conglomerate is usually at the base of the series and at many localities is overlain by a single shale unit and that in turn by a sandstone. At other localities, however, there are several alternations of sandstone and shale above the basal conglomeratic layer. The fossil described in this paper, except one specimen, were obtained from the shales of the middle part of the formation. The single specimen, an ammonite, came from the uppermost sandstone.

Suggested Citation

Reeside, J.B., 1923, The fauna of the so-called Dakota formation of northern central Colorado and its equivalent in southeastern Wyoming: U.S. Geological Survey Professional Paper 131, 9 p., https://doi.org/10.3133/pp131H.

ISSN: 2330-7102 (online)

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title The fauna of the so-called Dakota formation of northern central Colorado and its equivalent in southeastern Wyoming
Series title Professional Paper
Series number 131
Chapter H
DOI 10.3133/pp131H
Year Published 1923
Language English
Description 9 p.
First page 199
Last page 207
Country United States
State Colorado;Wyoming
Additional publication details