Edit a page: Rapid Member

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Lithostratigraphy
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Primary source[edit | edit 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)[edit | edit source]

Charles Collinson and Elwood Atherton

Name[edit | edit source]

Original description[edit | edit source]

The Rapid Member of the Cedar Valley Limestone (Keyes, 1912, p. 149; 1913, p. 205-206).

Derivation[edit | edit source]

Named for a locality in Johnson County, Iowa, not specified by Keyes.

Other names[edit | edit source]

History/background[edit | edit source]

Type section[edit | edit source]

Type location[edit | edit source]

Type author(s)[edit | edit source]

Type status[edit | edit source]

Reference section[edit | edit source]

Reference location[edit | edit source]

Reference author(s)[edit | edit source]

Reference status[edit | edit source]

Stratigraphic relationships[edit | edit source]

The Rapid Member of the Cedar Valley Limestone overlies the Solon Member.

Extent and thickness[edit | edit source]

The Rapid is the most widespread and thickest member. It is as much as 60 feet thick in the Rock Island area, but it thins to the east and south. It forms the upper 53 feet of the quarry southeast of Milan.

Lithology[edit | edit source]

The Rapid Member consists of gray to buff, fine-grained, argillaceous, locally dolomitic limestone. Most of it is thick bedded, but the upper and lower parts are thin bedded and have shaly partings.

Core(s)[edit | edit source]

Photograph(s)[edit | edit source]

Contacts[edit | edit source]

Well log characteristics[edit | edit source]

Fossils[edit | edit source]

Some beds, especially near the top and bottom, are very fossiliferous. Brachiopods and corals are most common, particularly ''Atrypa'', ''Stropheodonta'', ''Chonetes'', ''Spirifer'', ''Schizophoria'', ''Pentamerella'', ''Hexagonaria'', ''Favosites'', and ''Heliophyllum'' (Edmund and Anderson, 1967) (fig. D-6). Conodonts indicate a late Middle Devonian age (Collinson et al., 1967b). <center> {| class="wikitable" style="text-align: center;" |- |<gallery caption="" widths=250px heights=250px perrow=4> Figure D-6.jpg|{{file:Figure D-6.jpg}} </gallery> |} </center>

Age and correlation[edit | edit source]

Environments of deposition[edit | edit source]

Economic importance[edit | edit source]

Remarks[edit | edit source]

Reference(s)[edit | edit source]

place a <pre><br></pre>at the end of a line to get a line return 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.<br> EDMUND, R. W., and R. C. ANDERSON, 1967, Mississippi River Arch: 31st Annual Tri-State Field Conference Guidebook, Augustana College, Rock Island, Illinois, 64 p.<br> KEYES, C. R., 1912, Some provincial and local phases of the general geologic section of Iowa: Iowa Academy of Science Proceedings, v. 19, p. 147-151.<br> KEYES, C. R., 1913, Late Devonic sequence of the Iowa region (synopsis): Iowa Academy of Science Proceedings, v. 20, p. 205-206.

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