Calera limestone member of Cahil sandstone of Franciscan group. Gray, compact, foraminiferal limestone resembling lithographic limestone and containing lenses of chert. Occurs in lower part of Cahil sandstone, basal formation of Franciscan group. Thickness averages about 60 feet. Age is Jurassic(?).
Named from exposures in sea cliffs at lower end of Calera Valley, San Mateo Co., San Francisco region, western CA (p. 5).

Source: US geologic names lexicon (USGS Bull. 896, p. 316); GNC index card files (USGS-Menlo).

[Since †Cahil Sandstone of Lawson (1914) is herein abandoned, Calera Limestone Member is assigned to Franciscan Formation.] Foraminifers from Calera are considered to be early Late Cretaceous in age.
Type locality stated to be along Pacific Ocean shoreline, 9.5 mi south of San Francisco North quadrangle, [in Calera Valley adjacent to Rockaway quarry, Montara Mountain 7.5-min quadrangle, San Mateo Co., western CA].

Source: GNU records (USGS DDS-6; Menlo GNULEX); GNC index card files (USGS-Menlo).

[Now that Franciscan is no longer considered a formation (see Hamilton, 1978), Calera Limestone Member is raised in rank to Calera Limestone]. Age is Late Cretaceous on basis of its foraminifers and coccoliths.

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

Age of Calera Limestone is Early to Late Cretaceous (Aptian to Coniacian) on basis of foraminifers from samples from Pacifica and Permanente Quarries.

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