574 H. W. FAIRBANKS 
not exactly known. It may have taken place before the deposi- 
tion of the Knoxville beds. 
With the beginning of the Cretaceous the Coast Range region 
sank and the thin bedded sandstones and dark shales of Knox- 
ville age were formed. They lie unconformably upon the 
upturned strata of the Golden Gate series and their basic intru- 
SiVes. 
At the close of the Knoxville a disturbance not heretofore 
recognized in the Coast Ranges took place and the great masses 
of diabase were formed which threw the beds of that age along 
the Santa Lucia into a synclinal form. Before the beginning of 
the Chico another important event took place. This was the 
welling up of vast bodies of peridotite, now altered to serpen- 
tine, which appear everywhere in the Coast Ranges in rocks older 
than the Chico. Dikes of serpentine penetrate the diabase just 
referred to and are therefore younger. It is then clear that the 
conglomerate at the base of the Chico and the nonconformity 
of this formation upon the Knoxville is due to a widespread 
disturbance resulting in an elevation of the region above the 
sea during a portion of the Middle Cretaceous. 
The Eocene is absent from this portion of the Coast Ranges 
and it is legitimate to infer that the region was above water dur- 
ing the whole period. 
Before the inauguration of the Neocene sinking commenced, 
and we find rocks of this period everywhere underlaid by a con- 
glomerate formed as the sea encroached upon the land. Shortly 
after the beginning of the deposition of the Monterey series 
violent volcanic disturbances are recorded as having taken place. 
Local flows of rhyolite occurred and ash of that composition in 
the form of glass was thrown out in vast quantities and distrib- 
uted over the sea for many miles. Following this the bituminous 
shales and limestones were formed. They consist almost wholly 
of organic material, the more or less blended and broken skele- 
tons of foraminifera, diatoms, and radiolaria. A very extended 
period of time must have been required for the deposition of 
5000 feet of these sediments which are believed to accumulate 
