- Usage in publication:
-
- Cottage member
- Modifications:
-
- Overview
- AAPG geologic province:
-
- Illinois basin
Summary:
Deposits of Equality Formation in the study area probably correlate with the informal Woodfordian Texas City member (of Heinrich, 1982). Members were differentiated by Heinrich on the basis of stratigraphic position and composition. Heinrich determined that during the Altonian the Cottage member accumulated in a lake which reached a maximum elevation of about 350 ft. During the Woodfordian, elevation of the lake rose to 380 ft. Authors show the distribution of both members, but the contact between them is hypothetical. Contact between the Equality and the overlying Cahokia Formation in one boring is at an elevation of 387 ft, suggesting that Heinrich's estimate was low. Textural and mineralogic correlation with Heinrich's members could not be established.
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).