- Usage in publication:
-
- North Ridge formation
- Modifications:
-
- Named
- Dominant lithology:
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- Volcaniclastics
- AAPG geologic province:
-
- Sierra Nevada province
Summary:
Type locality designated as Hinchman Ridge and Ravine, north ridge of Mount Jura, Plumas Co, CA. Also referred to as North Ridge agglomerate and North Ridge argillite[!]. Consists of crudely stratified, pyroclastic agglomerate of medium grain and basic composition. Color is dark gray, speckled white. Thickness is 200 ft. Fauna are very scarce. Overlies Hinchman Formation; underlies Forman [Foreman} Formation. Age is early Late Jurassic based on proplanulitan, CATACEPHALITES?
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- North Ridge Agglomerate*
- Modifications:
-
- Adopted
- AAPG geologic province:
-
- Sierra Nevada province
Summary:
North Ridge Agglomerate of Crickmay (1933) herein adopted. Correlation chart describes unit as breccia and tuff, 200 ft thick. Overlies Hinchman Sandstone and underlies Foreman Formation. Age is Middle Jurassic (Callovian) based on ammonites.
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 ([ ]).