STRATIGRAPHY OF CALIFORNIA COAST RANGES. 433 
must be postulated a considerable period during the middle of 
the Cretaceous in which that region was elevated and undergoing 
erosion. 
The Chico-Tejon has a thickness of at least 20,000 feet in 
several places. We have no knowledge at present of a strati- 
graphic break in the series, but the direct superposition of the 
Miocene on the Chico in many localities lends some degree of 
probability to the view that a break exists. 
The Miocene exposed on the Arroyo Grande has a thickness 
of from 5000 to 8000 feet. The succession of strata from the 
top downward is as follows: (1) Bituminous slate, (2) Sand- 
stone carrying Ostrea ttan, (3) Bituminous slate and argillaceous 
sandstone. 
In the vicinity of the Eagle Ranch there is one of the most 
interesting associations of strata of different age to be found in 
the Coast Ranges. Four formations are present from all of 
which fossils were obtained: The Miocene, Chico, Knoxville 
and Golden Gate series, each being separated from the others by 
a nonconformity. Haroitp W. FAIRBANKS. 
BERKELEY, California. 
