- Usage in publication:
-
- Gragg Member*
- Modifications:
-
- Adopted
- AAPG geologic province:
-
- California Coast Ranges province
Summary:
Gragg Member of Pismo Formation of Hall (1973a) is adopted. Shown on geologic map of Morro Bay South and Port San Luis 7.5' quads, San Luis Obispo Co, CA. Contains LYROPECTEN CERROSENSIS (Gabb). Age is late Pliocene.
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Gragg Member
- Modifications:
-
- Named
- Dominant lithology:
-
- Sandstone
- Siltstone
- Conglomerate
- AAPG geologic province:
-
- California Coast Ranges province
Summary:
Named after Gragg Canyon as 3rd from lowermost of 5 members of Pismo Formation. Name formerly spelled "Gregg" in earlier report (Hall and Surdan, 1967). Type section is in Gragg Canyon [T32S R12E, Pismo Beach 7.5' quad] San Luis Obispo Co, CA. Consists of white to light-gray, medium-grained, well-sorted, poorly indurated sandstone that weathers to darker gray. Locally contains diatomaceous siltstone and conglomerate beds. Is 480 feet thick. Unconformably overlies Miguelito Member; concordantly underlies Belleview Member (both new and of Pismo Formation). Age is late Pliocene.
Source: GNU records (USGS DDS-6; Menlo 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 ([ ]).