- Usage in publication:
-
- Washington Formation*
- Modifications:
-
- Revised
- Age modified
Summary:
In southwestern PA only, Washington Formation of Dunkard Group is of Early Permian age. As revised in this area, divided into three unnamed members (lower limestone member, middle member, and upper limestone member) and includes sequence of beds, 160 to 180 ft thick, between base of Washington coal bed and top of upper limestone member. This sequence represents upper part of Washington Formation as previously used in this area. Middle member consists of several impure sandstone beds, a unit of highly impure limestone beds near its middle, several lenticular thin limestone beds, and three impure coal and carbonaceous shale beds. Washington coal bed at base is stratigraphically highest persistent thick coal in Eastern U.S.
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 ([ ]).