U.S. Geological Survey Home AASG Logo USGS HOME CONTACT USGS SEARCH USGS
National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Chatsworth Formation
  • Modifications:
    • Named
    • Biostratigraphic dating
  • AAPG geologic province:
    • Los Angeles basin
    • Ventura basin
Publication:

Colburn, I.P., Saul, L.E.R., and Almgren, A.A., 1981, The Chatsworth Formation; a new formation name for the Upper Cretaceous strata of the Simi Hills, California, IN Link, M.H., Squires, R.L., and Colburn, I.P., eds., Simi Hills Cretaceous turbidites, southern California: Society of Economic Paleontologists and Mineralogists, Pacific Section, Field Trip Guidebook, October 10, 1981, p. 9-16.


Summary:

Chatsworth Formation is applied to beds in the Simi Hills previously referred to as the Chico Formation. Consists of four principal lithesomes composed of turbidite sandstone and interbedded hemipelagic mudstone described by Colburn (1973) as Descriptive Facies I, II, III, and IV. Deposition under shallow, littoral conditions is suggested by meager faunas. Base of the unit is not exposed; older beds unconformably underlie Miocene strata; younger beds concordantly or unconformably underlie the lower(?) Tertiary Simi Conglomerate. Thickness is more that 1830 m. Age is Late Cretaceous (middle Campanian to early Maastrichtian) based on mollusks. (B1565)

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 ([ ]).

Accessibility FOIA Privacy Policies and Notices

USA Gov U.S. Department of the Interior | U.S. Geological Survey
Supported by the National Cooperative Geologic Mapping Program
Page Contact Information: Personnel
Page Last Modified: Thu 28 Aug 2025 02:00:42 PM MDT