USGS Visual Identifier
National Geologic Map Database logo GEOLEX database

Geologic Unit: Trap Falls

Trap Falls Formation*
Trap Falls Formation of Hartland Group

Ordovician, Early*
Ordovician, Middle*
Geologic Province:
New England province*

Areal Extent:

Type Locality:
East and west shores of Trap Falls Reservoir, north of Bridgeport, Long Hill quadrangle, Fairfield Co., southwest ern CT (Crowley, 1968).

Basal unnamed schist and granulite member, Shelton Member*, and Carringtons Pond Member*

Unit Name History:
Named (Crowley, 1968). Revised; Age modified (Rodgers, 1985). Revised (Sevigny and Hanson, 1993).

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