Geology of California. — Turner. 319 
of the river belonging to the auriferous slate series, and those to 
the west to the Coast range series. 
Mr. Fairbanks also appears to recognize a difference in the two 
sets of rocks. On page 158 he writes: "The granite mass of 
the Trinity mountains terminates abruptly on the south, being 
cut off by a body of massive serpentine which forms the summit 
of Bully Choop, one of the highest peaks of the Coast range. 
Directly south of the serpentine along the crest of the range we 
encounter green talcose and granitic schists in which the silicifi- 
cation characteristic of the Coast range metamorphics is well 
developed. The schists are somewhat crumpled with the appear- 
ance of minute veins and bunches of quartz which follow the 
cleavage planes in an irregular manner. These rocks are pene- 
trated for several miles by porphyritic dikes, evidentl}- offshoots of 
the granite on the north. This is positive proof that their period 
of upheaval dates back to the extrusion of the granite." 
It is to be regretted that the author has not given the reader a 
more exact lithological description of these porphyritic dikes. The 
evidence above presented can hardly be regarded as "positive 
proof" of the relations of the Coast range metamorphics to the 
granite of the Trinit}' mountains. 
On page 160 occurs the following: "The line of contact be- 
tween the Cretaceous and the older rocks has been particularly 
favorable for the intrusion of the peridotitic rock from which the 
serpentine has been derived, and this together with the general' 
covering of the rocks with soil makes it hard to find good expo- 
sures. The best contact observed was on Elk creek in Colusa 
county ; here the soft black shales rest directly against the green 
silicified schists. A few hundred feet distant the shales have a 
dip of 40** to the east; as the contact is approached the}^ dip more 
and more, finally becoming somewhat broken and reversed, while 
for several feet adjoining the schists they are crushed to a clayey 
mass. The change to the vertical green schists is abrupt. To- 
wards the crest of the mountain, five miles away, they become 
more silicified. Black slates' and hornblende schists are also to 
be observed in places. The cla}'^ at the contact has been formed 
by an upward movement of the metamorphic ridge, a condition 
noticed at several points farther south, and which, to a certain 
degree, obscures the non-conformity. This is undoubtedly the 
reason for the apparent conformity between the Aucella-bearing 
