Age of the GaUfornia Coast Ranges. — Fairbanks. 27^ 
ing with the ocean by one or more sounds across the Coast ranges, — 
which is in general harmony with the foregoing It will be seen from 
the foregoing that up to the beginning of the Pleistocene, the area now 
occupied by the Great Valley was at no time the theatre of particularly 
heavy sedimentation or active subsidence. There is evidence that dur- 
ing the Cretaceous and Miocene the heaviest sediments and deepest 
depressions lay to the west of the present valley, and along the line now 
occupied by the Coast ranges." 
It seems also that a similar view lias recently been ex- 
pressed by Prof. Lawson*as the following quotation will show. 
"The granites of the southern and northern Coast ranges seem to be 
geologically continuous with those of the Sierra Nevada. The fact 
that the Sierras are separated from the Coast ranges by the valley of 
California is immaterial to the discussion, since the latter is clearly a 
delta-filled geo-syncline of late Tertiary or post-Tertiary origin." 
We will first take up a consideration of these statements 
^nd then proceed to show the evidence for the existence of a 
Coast range axis undergoing oscillations not only through 
the whole of the Cenozoic but also the greater part of the 
Mesozoic. 
An examination of the Great Valley reveals the fact that 
while the post-Jurassic sedimentary terranes along the foot 
of the Sierras are not greatly elevated or prominently exposed, 
there is found on the contrary on the eastern flanks of the 
Coast ranges a great thickness of sedimentary strata varying 
in age from the lower Cretaceous up through the Miocene. 
These have been greatly elevated and dip under the valle^^ at 
varying angles. Although there is only one spot (Marysville 
buttes) where any of them are exposed in the centre of the 
valley, yet all considerations lead us to believe that the great- 
er portion of the region which is now embraced within the 
Great Valley has been subject to continuous sedimentation 
from Cretaceous times down through the Miocene, and proba- 
bly at intervals through the Pliocene. The writer does not 
know of any reasons for doubting that this condition of things 
obtained in the Great Valley during the period mentioned. 
But what of the Coast Ranges? Were they non-existent prior 
to the Miocene as the authors quoted would have us believe, 
with an open sea bathing the base of the Sierra Nevadas, or 
nre there good evidences of a northwest and southeast land 
barrier through the Coast Range region which was probably 
♦American Geologist, vol. xv. p. 346. 
