Cretaceous strata are believed to occur. Portions of the Ter- 
tiary are highly bituminous, and asphaltum is often met with. 
Gold occurs in small quantities, especially onthe San Antonio 
river, and there have long been traditions of silver mines in the 
interior. : 
A range of Tertiary hills, known as the San Antonio hills, 
branches from the main chain, and crosses the Salinas valley 
about 75 or 80 miles from its mouth. Above this, are great de- 
242 Whitney’s Geology of California. ’ 
with regularly arranged strata on the two sides, we have a 
like structure, suggesting a synclinal axis; but the position on 
the north side of the chain is not given. With respect to the re- 
gion east of this point we have no data. : 
outh of San Luis Obispo, there is a lower range of hills, 
having also the fan-structure, shown on the same section; while 
between these chains are more or less isolated hills of serpentine 
of which we know little as to the details of their structure. 
far as is known, they are composed almost entirely of Miocene 
and Pliocene strata, in places of immense thickness. There 18 
much metamorphic rock, but little if any eruptive. It is be 
lieved that Cretaceous strata occur on the north of the Santa 
Iiiez chain, but of this we have no proof. The strata are every" 
The Santa Iitez chain.—The Santa Ifiez chain be 
