- Usage in publication:
-
- Orchard Creek Shale
- Modifications:
-
- Age modified
- Revised
- Reference
- AAPG geologic province:
-
- Ozark uplift
Summary:
Ordovician (Cincinnatian) Orchard Creek Shale is assigned to Maquoketa Group. Type section was designated along Orchard Creek (now covered), 2 mi south of Thebes, sec. 21, T15S, R3W, Alexander Co., southern IL. Reference section is designated across Mississippi River from southern Cape Girardeau Co., on east bank of Mississippi River 1 mi north of Thebes, SE1/4SE1/4 sec. 5, T15S, R3W, Thebes 7.5-min quad, Alexander Co., southern IL (Thompson, 1991).Report includes stratigraphic columns, correlation and nomenclature charts, and type section maps.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
-
- Orchard Creek Shale*
- Modifications:
-
- Overview
- AAPG geologic province:
-
- Illinois basin
- Upper Mississippi embayment
Summary:
Orchard Creek Shale of Maquoketa Group is mapped undivided with Cape La Croix Shale and Thebes Sandstone, both of Maquoketa Group. Consists of blue-gray to olive-green shale interbedded with limestone beds in uppermost section, becoming noncalcareous and sandy down section. Although type section was described in along Orchard Creek in Thebes quad by Savage (1909), section is now covered by loess-derived colluvium.
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 ([ ]).