84 Tlie Ahterican Geologist. February, isfti 
western slope of the Sierra Nevadas, and 1 have not yet seen any 
granite which I believe could lie correctly termed Archaean. It 
seems to have been squeezed into rocks varying in age from 
the Jurassic to Palseozoic inclusive. The time of intrusion ex- 
cept in some minor instances seems to have been as before stated, 
at the close of the Jurassic. It is possible that there are areas 
of older granites in eastern California, but 1 do not know that 
the presence of any extensive formation has been positively 
recognized. 
The Metamorphic series in the Coast ranges contains a great 
variety of intrusives of all ages, from the late Tertiary lavas to 
the most ancient and highh* altered ones whose original charac- 
ter has often been completely lost, and a part of which probably 
antedate the great upheaval. 
As great as is the time gap l)etween the periods of sedimenta- 
tion represented by the pre-Cretaceous series and the Miocene 
which rests upon it, yet in places they are with difficulty distin- 
guished from each other. Particularly is this so in San Luis 
Obispo county. The older series however everywhere show the 
effects of intense crushing. 
A vast amount of detail yet remains to be worked out in the 
Coast range geolog}', Ijut I believe the facts alreadj' known war- 
rant us in assuming as a basis of future work that the axes of 
the Coast range are structurally closel}' related to the Sierras, and 
were first raised during the post-Jurassic upheaval, which at 
least if it did not originate the Sierra axis gave it its present 
magnitude and approximate elcA'atiou. It thus appears that dur- 
ing Pahvozoic and early Mesozoic times the region occupied by 
these two important ranges was beneath the sea, receiving sedi- 
ments probabh' from an eastern continental area, and save for 
disturbances which thus far have Ijeen recognized onl}' locally, 
the sedimentation was continuous: and that if as old formations 
are not in the future recognized in the Coast ranges as have 
already been found in the Sierras, it is l)ecause of the less vio- 
lence of the post-Jurassic upheaval in the former region, and the 
consequent non exposure of the deeper seated sedimentary 
strata. 
