USGS Visual Identifier
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Geologic Unit: Dillsboro

Dillsboro Formation (IN*)
Dillsboro Formation of Maquoketa Group (IN)

Ordovician, Late*
Richmondian, early*
Geologic Province:
Cincinnati arch*

Areal Extent:

Type Locality:
Type area: southwestern Dearborn Co. and east-central Ripley Co., in vicinity of Dillsboro, Dearborn Co., IN (Brown and Lineback, 1966).

Unit Name History:
Named (Brown and Lineback, 1966).
Assigned to Maquoketa Group (Gray, 1972).
Overview (Wahlman, 1992).
Age modified (Frey, 1995).

Note: If you need more information, please contact Nancy Stamm (
Asterisks (*) indicate usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" implies that a name has been abandoned or that it has fallen into disuse. Former usage and, if known, replacement name given in parentheses ().

Slashes (/) indicate unit name usage violates the 1983 North American Stratigraphic Code. This violation may be explained within brackets ([ ]).

U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
Database project personnel
Last modified: 15-Jan-2013