Metamorphic Rocks.— Fairbanks. 155 
Sierra Nevadas) to the metamorphic rocks of the Coast Ranges of 
uncertain age, but suspected to be older than Neocomian. 
To facilitate a thorough understanding of the subject it is 
necessary to quote briefly from the published views of the earlier 
workers in California geology, what has been understood by the 
term ‘‘Coast Ranges,’ and the difficulty in drawing a line be- 
tween these ranges and the Sierra Nevadas. Prof. Whitney says: 
‘We consider all those chains or ranges of mountains to belong 
to the Coast Range, which have been uplifted since the deposition 
of the Cretaceous formation; those, on the other hand, which 
were elevated before the epoch of the Cretaceous are conceived as 
belonging to the Sierra Nevada.”* Prof. Whitney's views in 
Auriferous Gravels, published a number of years after the termi- 
nation of the old Geological Survey, only make more emphatic his 
earlier declarations. He says: ‘‘The most striking fact with re- 
gard to the Coast Ranges is, that this very extensive group of 
mountain chains is of comparatively very recent geological age. 
It is made up of Cretaceous and Tertiary strata with no rocks 
older than these showing themselves in any portion of the com- 
plicated series of elevations which are properly included under 
the above designation.”’+ Again we find the following: ‘‘North 
of parallel thirty-nine, as far as the Klamath river, there is much 
monotony in the structure of the Coast Ranges. The rocks are 
almost exclusively Cretaceous and often very much metamor- 
phosed; jasper, serpentine, and even mica slate occurring in large 
quantities, and _in the most irregular manner.’ { To show the 
impossibility of drawing the line between the Sierras and Coast 
Ranges on structural grounds, the following will answer: +The 
lower part of the Trinity and Klamath rivers seems to form the 
boundary between the Coast Ranges proper and that portion of 
the coast mountains which appear to belong lithologically to the 
Sierras. * * ‘To an observer on any one of these peaks (gran- 
ite mountains in western Shasta county), and commanding a wide 
view over the region, there seems to be no physical break between 
the Coast Ranges and the Sierra. Scotts, the Klamath and 
Siskiyou ranges of mountains seem to represent the summit con- 
tinuation of the Sierra proper, and the Trinity mountains run into 
these from the south and from the Coast Ranges proper, without 
*Geological Survey of Cal. Vol. I, p. 167. 
tAuriferous Gravels, p. 16. {Auriferous Gravels, p. 25. 
