The Online Handbook of Illinois Stratigraphy (ILStrat)
You do not have permission to edit this page, for the following reason:
For Help in formatting please see the Wiki Help
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.
H. B. Willman and T. C. Buschbach
The Mortimer Member of the Dunleith Formation (Templeton and Willman, 1963, p. 121).
Named for Mortimer Street in East Dubuque, Jo Daviess County, near the type section.
The type section of the Mortimer Member is part of the Dunleith Formation type section (in an exposure in the Mississippi River bluffs on the north side of East Dubuque (SE 19, 29N-2W))(fig. O-2B), where the Mortimer Member is 11.3 feet thick. <center> {| class="wikitable" style="text-align: center;" |- |<gallery caption="" widths=250px heights=250px perrow=4> Figure O-2B.jpg|{{file:Figure O-2B.jpg}} </gallery> |} </center>
The Mortimer Member of the Dunleith Formation overlies the Fairplay Member.
The Mortimer Member is commonly 10-13 feet thick.
The Mortimer Member consists of thick-bedded vuggy dolomite that contains bands of large white chert nodules. Its purity is between that of the pure Fairplay Member below and the argillaceous Rivoli above. It has a 2.2-foot argillaceous zone at the top in the type section, which thins to 5-6 inches in the Dixon and Rockford areas. It contains a few dense argillaceous beds. Thin lenses of bentonite occur along a prominent bedding plane at the top.
place a <pre><br></pre>at the end of a line to get a line return TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.
Save page Show preview Show changes Cancel