UNIFORM UPLIFTING FORCES TERTIARY BEDS. 25 



south. In the entire State there is no chain of mountains which runs east and west ; but while 

 the Sierra Nevada, in its southern portion, runs almost north and souths the chains of the Coast 

 Eange, 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 Kanges 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. Volcanic rocks pursue a course unusually constant in 

 direction for hundreds of miles, and their mineral character difi"ers 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 deej) 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 time, has preserved a constancy and equality which latitudes 

 more polar than 40° never possessed. 

 . 4U 



