636 OREGON AND NORTHERN CALIFORNIA. 
mile, granite boulders were intermingled. A mile beyond, granite be- 
came the prevailing rock, and at the centre of the granite region, lofty 
pinnacles and needle peaks peered above the forests around to a height 
of three thousand feet. From granites and syenites we next passed 
successively to hornblende rocks, talcose and prasoid rocks, with 
protogine and some serpentine. ‘The rocks of the talcose series con- 
stitute the greater part of the ridges about the head waters of the 
Sacramento, to the emergence of the stream from the mountains. 
The protogine in the talcose region was met with about fifteen miles 
before reaching the Sacramento plains. 'Talcose rocks and slates were 
again met with near San Francisco. 
In this route we three times passed from talcose, through horn- 
blendic regions, to granite, or its next akin, syenite ; and as many times 
returned again nearly in the same order to compact talgose or prasoid 
rocks. 
The great preponderance of talcose rocks and others related having 
a prasoid character, is another fact of interest; it is but part of a still 
more general fact,—the great preponderance of this part of the Plu- 
tonic series over the globe. Although we have not specific facts and 
localities, we have sufficient evidence, from specimens examined, that 
it is abundant in New Caledonia to the north of Oregon. The serpen- 
tine, soapstone, and the material carved into pipes by the Northwest 
Indians, appear to come from this formation. The greenstone, usually 
called jade, used for ornaments, and also in making hatchets, probably 
has a similar origin. 
The relation of serpentine to other rocks of the series is also placed 
beyond doubt by the facts observed. 
Structure—Dip.—The hornblendic and talcose rocks have been 
described as rarely schistose ; and when this structure is apparent, 
it is seldom retained long enough to show the direction of the 
layers. The cleavages of the talcose argillite in the Shasty Moun- 
tains were often vertical, with numerous windings and contortions; 
and they varied from perpendicularity to a dip of sixty degrees. 
I traversed these rocks in a single direction only, and was of necessity 
obliged to keep with the party; and but few facts on this subject were 
therefore collected. 
The structure of the jaspery rock of San Francisco, is worthy of 
description. The green, red and yellow varieties occur in the same 
vicinity. They form a series of layers, averaging two inches in thick- 
ness, and varying from half an inch to four inches. The layers are 
