- Usage in publication:
-
- Kelseyville Formation*
- Modifications:
-
- Named
- Dominant lithology:
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- Sandstone
- Tuff
- AAPG geologic province:
-
- California Coast Ranges province
Summary:
Named for lacustrine and less abundant fluvial beds near Kelseyville, CA. Measured type section designated as exposures along Kelsey Creek and along ravine south of Kelseyville and west of HWY 29 in SE/4 NE/4 sec.27, NW/4 NW/4 sec.26, and SW/4 SW/4 sec.23, all in T13N R9W, Kelseyville 7.5' quad, Lake Co, CA. Shown on geologic sketch map. Formerly included in unrestricted Cache Formation by McNitt (1968). Crops out in southern half of Big Valley and surrounding hills. Consists mainly of sandstone interbedded with minor conglomerate and tuff. Includes marker bed, Kelsey Tuff Member (new). Is about 500 m thick. Overlies rocks of Franciscan assemblage and locally serpentinite and flows of Clear Lake volcanic field. Underlies Quaternary terrace deposits. Contains megafossil plants which indicate growth during glacial interval. Is mainly younger than 0.64 Ma based on age of unnamed pumiceous lapilli tuff exposed near base of formation. Age is Pleistocene.
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 ([ ]).