UNIFORM UPLIFTING FORCES—TERTIARY BEDS. 
25 
south. In the entire State there is no chain of mountains which runs east and west; hut while 
the Sierra Nevada, in its southern portion, runs almost north and south., the chains of the Coast 
Range, in their south course, have an easterly trend of not less than 45°. On account of this 
deviation from the meridian course of the Sierra Nevada, the two mountain ranges appear to 
merge into each other about latitude 34° 30'. 
It may be remarked of the Coast Ranges that the granitic chains lie more in the meridian 
than the volcanic chains, and where a granitic axis and an intrusion of pyroxenic rock, or of 
serpentine, trap, and amygdaloid occurs, then the latter, having a greater trend to the southeast, 
cuts across the granitic ridge. Hence it is that most of the valleys are triangular in shape ; 
that they are of less size in the southern counties than in the north ; and that they all appa¬ 
rently converge in the northern part of Los Angeles county. The serpentine and amygdaloid 
prevail as axial rocks in San Luis Obispo and Los Angeles counties, and give the direction to 
the chains. 
The conditions of deposit of the various strata flanking the mountain ranges of California are 
remarkably uniform over large areas. Yolcanic rocks pursue a course unusually constant in 
direction for hundreds of miles, and their mineral character differs but little throughout. The 
subterranean forces to which the country between latitude 37° and 32° was subjected, were, if 
not powerful to produce lofty chains, at least sufficiently prolonged to extend over 500 miles 
from north to south, without much loss of energy. All of these phenomena taking place while, 
as yet, the whole was a deep sea bottom, whose shore, was several degrees to the east. 
All the observed sedimentary rocks were of the post cretaceous period, so that this portion of 
the United States, while it is one which has emerged most recently from below the level of the 
sea to a height several thousand feet above it, is also interesting from the thickness of the 
tertiary deposits, rivalling those of Mediterranean Europe, and exceeding anything of the kind 
on the Atlantic shores. Nor is it the mere thickness of the deposit—the time of deposition 
unusually prolonged, as it must have been, since it bears the mark of a quiet deposit every¬ 
where—which is alone interesting, but it is the variety and abundance of aquatic life which 
these beds have disclosed ; species and varieties in endless profusion tenanted these waters, from 
the molluscs of mammoth form, as the ostrea of the Panza and Santa Margarita valley, to the 
foraminifera, whose tiny shells require the aid of the lens to recognize them. 
The great distance apart at which these similar fossils are found indicate that the climate, 
and other conditions, as depth and temperature of the waters, must have been pretty much 
alike over the whole of the south of California; thus the polythalamous shells have been found 
at the town of Monterey, on the shore near Santa Barbara, and on the plains of Los Angeles, 
involving distances 300 miles apart. Considerations founded on the zoological characters of 
the molluscs of the Miocene period of Europe, have led to the belief that the temperature of 
that epoch approached very much to that of Spain and Italy at the present time, or a mean 
temperature about 66° Fahrenheit. As that temperature is almost the exact figure for a great 
portion of the area observed, it follows that there is little, if any, difference between the climate 
of the Miocene of Europe and the present period in those places ; and since the drift of California 
is local, and not general, and there are no traces on the surface of rocks exposed, of scratching 
or grooving, no moraines, no polished rocks, (roches moutonnees,) no traces of glacier action, 
perhaps it may be asserted with safety that the climate and temperature of this region, from 
the Miocene period to the present fiime, has preserved a constancy and equality which latitudes 
more polar than 40° never possessed. 
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