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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Silverado formation*
  • Modifications:
    • Named
    • Biostratigraphic dating
  • Dominant lithology:
    • Conglomerate
    • Sandstone
    • Clay
    • Siltstone
  • AAPG geologic province:
    • Peninsular Ranges province
Publication:

Woodring, W.P., and Popenoe, W.P., 1945, Paleocene and Eocene stratigraphy of northwestern Santa Ana Mountains, Orange County, California: U.S. Geological Survey Oil and Gas Investigations Chart, OC-12, scale 1:1,800


Summary:

Named for Silverado Canyon. Type region designated as area northeast of Irvine Park [Black Star Canyon 7.5' quad], northwestern Santa Ana Mountains, Orange Co, CA. Extends southeastward as far as Tierra Colorado clay district. In type area and nearby, unit consists of lower nonmarine member and upper marine member. Includes Claymont clay bed about 65 to 140 ft above base and Serrano clay bed from about 275 ft above Claymont clay bed. Formation is composed of basal conglomerate, poorly sorted coarse-grained arkosic, micaceous gray sandstone and grit, and thin beds of reddish sandy clay and brown sandy siltstone and clay beds named above. Thickness ranges from about 700 to 1475 ft. Discordantly overlies different units of Late Cretaceous age on ridge forming divide between Sierra Canyon and Gypsum Creek and Coal Creek: Pleasants sandstone member and Schulz Ranch sandstone member (both of Williams formation) and Holz shale member of Ladd formation. [Unconformably] underlies Santiago formation or Sespe formation. Age is Paleocene based on brackish-water and marine fauna which are listed in text and stratigraphic sections.

Source: GNU records (USGS DDS-6; Menlo GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Silverado Formation
  • Modifications:
    • Biostratigraphic dating
  • AAPG geologic province:
    • Peninsular Ranges province
Publication:

Gaponoff, S.L., 1984, Palynology of the Silverado Formation (late Paleocene), Riverside and Orange Counties, California, IN Nichols, D.J., ed., Proceedings of the sixteenth annual meeting of the American Association of Stratigraphic Palynologists: Palynology, 16th annual meeting, American Association of Stratigraphic Palynologists, San Francisco, CA, October 25-29, 1983, v. 8, p. 71-106.


Summary:

Lower member of Silverado Formation is late Paleocene in age as indicated by presence of palynomorphs listed and described in report. Abundance of fungal and pteridophyte spores and angiosperm pollen indicate swampy or lowland bog depositional environment within paralic deltaic system. 24 outcrop samples were collected from unit in Aberbill, Riverside Co and Ranch Mission Viego, Orange Co, CA.

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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).