A(fe of the California Coast, lianges. — Fairbanks. 271 
sample gave a particle of carbon much larger than a pin-head, one sam- 
ple gave two small specks, while the third dissolved without giving a 
trace of carbon. When treated with hydrochloric acid all samples, 
with the exception of one, dissolved without giving evidence of com- 
bined carbon: this one sample gave a very strong odor resembling that 
given off when dissolving steel in hydrochloric acid. 
About three grammes were used in making the- tests for the metals 
noted as "none " or " trace," or sufficient to be sure that the results 
given are very nearly correct. 
This supposed variation in composition is in keeping with 
the spotted appearance of the weathered convex surface of the 
specimen. 
THE AGE OF THE CALIFORNIA COAST RANGES. 
H, W. Fairbanks, Berkeley, Cal. 
In a recent paper devoted to a criticism of the theory of 
isostasy Mr. F. Leslie Ransome* treats of the subject as ex- 
emplified in the formation of the Great Valley of California. 
He reaches the conclusion that the principle of isostasy is 
insufficient to account for the formation of this valley and 
the Coast ranges bounding it on the west. 
It seems to the writer that the evidences given in the above 
paper in favor of the view taken are well supported by the 
facts, and he is in hearty accord with the main conclusions, 
but the discussion of the history of the Coast ranges as inti- 
mately related to this question could have been made much 
more effective, and have strengthened Mr. Ransome's position 
materially, if he had taken pains to acquaint himself more 
fully with the recent literature bearing on the geological his- 
tory of the Coast ranges. 
The writer agrees with Mr. Ransome that the history of 
these ranges is as yet very imperfectly known, but neverthe- 
less, a large mass of facts has been accumulated bearing upon 
it which are diametrically opposed to the assumption which 
he makes of a post-Miocene age. That the Coast ranges 
originated at the close of the Miocene is the opinion which 
was held by the older geologists, but since their time there 
has been a great increase in our knowledge of this field, and 
we now have good reasons for believing that the structure and 
history of the Coast ranges are not so simple, nor the date of 
♦Bull. Dept. Geol. Univ. Cal. vol. r, pp. 371-428. 
