Geological Notes on the sierra Nevada. — Turner. 247 
turbed and little metamorphosed. The facts; too, thai serpentine is in- 
trusive in the Knoxville beds, and that some of the granite of the Sierra 
is later than some of the serpentine of thai range, mighl be used as an 
argument thai the absence of intrusive granite in the Knoxville beds 
merely shows that no granite intrusions have occurred in the Coast 
ranges as late as the post-Mariposa granite of the Sierra Nevada. 
Against the hypothesis of Mr. Becker and Dr. White, just discussed, 
is the opinion of Prof. Hyatt that the fauna of the Mariposa beds is not 
identical specifically with that of the Knoxville series. The proof of 
there having been a continuous sedimentation in the northern Coast 
ranges of California from the Knoxville epoch to the Chico, inclusive, 
that has lately been broughl forward by Messrs. Diller* and Stantonf , re- 
sulting in establishing the Shasta-Chico series, also does not favor this 
hypothesis, since, as before noted, the Chico is conspicuously uncon- 
formable on the Mariposa slates at Folsom. 
The proof of the intrusion of serpentine into the Knoxville beds is. 
however, unquestionable, and if the large areas of serpentine in the 
central Coast ranges are also post-Knoxville in age, it seems almost cer- 
tain that a disturbance of the Knoxville beds must have occurred at the 
time of the extrusion of the basic igneous rock from which the serpen- 
t ine is derived. 
J'ost-Mc iriposa upheaval. As was shown many years ago by 
Prof. Whitney, the Sierra Nevada was upheaved as a great 
mountain range after the Mariposa beds were deposited. Evi- 
dence has already been presented under "Mariposa forma- 
tion," showing that granitic rocks were intruded into the 
slates of the Mariposa formation at the time of this upheaval. 
It is indeed possible that much of the granite of the range 
dates from this upheaval. 
Post-Tertiary elevation. During Cretaceous and Tertiary 
time, the Jurassic Sierra Nevada had been reduced to an ap- 
proximate peneplain. In the late Tertiary a large part of the 
western slope was covered with volcanic materials, extensive 
areas of which still remain, preserving underneath them the 
Tertiary peneplain, the drainage system of which is repre- 
sented by the Neocene auriferous river gravels. 
About the close of the Tertiary the range was elevated and 
the streams, with added force of gravity, cut new and deep 
canons in the hard eroded base of the Jurassic range in a sur- 
prisingly short time. This elevation of the range was not 
accompanied by the folding of the strata, but the formation 
of a series of normal faults appears to date from this time. 
*Bull. (Jriil. Soc. Am., vol. I. pp. 205-224. 
Ilbid., pp. 245-256. 
