- Usage in publication:
-
- Huichica formation*
- Modifications:
-
- Original reference
- Dominant lithology:
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- Gravel
- Conglomerate
- Sand
- Clay
- AAPG geologic province:
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- Northern Coast Range province
Summary:
Pg. 16 (table 3), 98, pl. 11 (geol. map). Huichica formation. Terrace deposits composed of poorly stratified gravels, conglomerates, and clays; nonmarine. Basal deposits consist of reworked tuffs. Conglomerates, and poorly consolidated clayey sandstone; upper beds largely pebbly sandstone and conglomerate. Thickness 250 to 500 feet. Unconformably overlies tilted andesites and rhyolites. May be contemporaneous with Glen Ellen formation (new). Age is Pleistocene.
Named from Huichica Creek at head of San Pablo Bay in northern part of Mare Island quadrangle, Napa Co., northwestern CA. Exposed around margins of Napa and Sonoma Valleys.
Source: US geologic names lexicon (USGS Bull. 1200, p. 1832).
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 ([ ]).