Age of Some California Coast Range Lower Tertiary Marine Red Beds: ABSTRACT

Abstract

Microfossils, including benthonic and planktonic foraminifera as well as coccolithophorids and related nannoplankton, are abundant in the marine red beds of the California Coast Ranges. These have usually been assigned a middle Eocene age. Comparative studies of the foraminifera and nannoplankton in these red beds have revealed two of these microfossil assemblages (from San Miguel Island, Santa Barbara, and the Oakland hills) to be of Campanian, Upper Cretaceous age; two others (from the lower red bed, type Anite Shale End_Page 359------------------------------ and the lower Lodo, Media Aqua Creek) are known to be of Paleocene age. However, the bulk of both the foraminiferal and nannoplanktonic assemblages collected from several geographically distinct areas throughout the Coast Ranges represent the Penutian (West Coast lower Eocene) and/or Ulatisian (West Coast middle Eocene) Stages. Moreover, the foraminiferal faunal change which characterizes the Penutian-Ulatisian boundary, as well as the nannoplanktonic faunal change found to correlate widely with this foraminiferal change on the West Coast, occur within or close to the Poppin Shale of the Santa Barbara Coast and several of its Coast Range correlatives. End_of_Article - Last_Page 360------------