556 H. W. FAIRBANKS 
JURASSIC PERIOD. 
Golden Gate series. — This series forms the base of the unal- 
tered sedimentary rocks in the central and southern Coast 
Ranges. The exact position of these rocks in the geologic scale 
remained a puzzle to geologists for many years, partly because 
of the scarcity of fossils, and partly because of the obscure strati- 
graphic relations. 
In former papers* the writer has advanced considerations for 
the belief in the pre-Cretaceous age of this series of rocks, and 
that it underlies the Knoxville unconformably. In later papers” 
the series was named and more definite proofs given of its rela- 
tion to the Knoxville. During the recent detailed study of the 
region about San Luis Obispo the question was conclusively set- 
tled in favor of the position maintained by the writer. Two 
lines of evidence aided in the determination. The first concerns 
the relation of the series to the Knoxville. Both of these groups 
of rocks are extensively developed in the region in question, 
each with its characteristic features. The Golden Gate series is 
most largely exposed along the southern slope of the Santa 
Lucia range, in the large valleys at its base, and on the northern 
slope of the San Luis range. A narrow strip also occurs on the 
northern side of the Santa Lucia range, exposed through fault- 
ing. The Knoxville beds begin as scattered outcrops on the 
southern slope of the Santa Lucia range east of the town of 
San Luis Obispo and extending northwest through the depres- 
sion in the range known as Cuesta Pass, expand to form many 
square miles of mountainous country through the heart of the 
range. At numerous points on the northern slope of the range, 
from the Eagle Ranch to the head of Morro Creek, were found 
patches of the basal Knoxville conglomerate, either resting upon 
the upturned Golden Gate series, or upturned itself and faulted 
down into the latter series. Specimens of Aucella were found 
in strata of sandstone and fine conglomerate within four feet of 
*Am. Geol., Vol. 1X, p. 153; Am. Geol., Vol. XI, p. 70; Bull. Geol. Soc. Am., 
Woll, Ws je /itc 
2Jour. GEOL., Vol. III, p. 415; Am. Geol., Vol. XVIII, p. 350. 
