CHAPTER VIII. 



SANTA LUCIA MOUNTAINS. 



Classification of thk range. — Peculiarity of the range in its axial rocks. — Absence of true granitic rock. — Glneral ele- 

 vation, INCREASED HEIGHT TOWARD THE SOUTH. — DIFFERENT LEVEL OF THE VALLEYS EAST AND WEST OF THIS RANGE — DUE TO THE 

 WIDTH OF THE SAN JOSE GRANITE. — SERPENTINE AND TRAP CONTAINING CALCITE. — TUFACEOUS DEPOSIT. — MeTAMORPHIC LIMESTONE. 



Nature op the changes which elevated this range. — San luis pass. — Volcanic rock occorrinh in. — CaSon of the sa>ita 

 MARIA. — Geological structure in — Disposition of the mountain chain in lesser ridges. — Age of the sedimentary beds. — 

 Are there paljeozoic beds in this range.' 



This range has been incidentally alluded to when noticing the coast ranges collectively under 

 division 2, group 3. It is the first of the ranges which are wholly of volcanic rock (as far as 

 examined) in passing from the east to the west. The Monte Diablo, the most eastern ridge, 

 merges into the Gavilan, which may be considered its reproduction further south. In that range, 

 trappean rock, trachyte, and scoriaceous lava, lie upon the east side of the granitic range, and 

 for 40 miles disturb the strata ; but the granite still predominates as the upheaving rock. So 

 with the next chain to the west, the Point Pinos or San Jose range. It is granitic where the 

 axis occurs, the serpentine and trap constituting an upheaving force on the east side, and forming 

 a distinct crested hill ; these volcanic rocks further south also disappear as a connected plutonic 

 vein, rising up here and there in partial dislocated localities. It is different, however, with this 

 range ; the granitic rock is wanting as an axial force, the whole upheaval appearing to be pro- 

 duced by trap, serpentine, and amygdaloidal felspathic rock, approaching trachyte in character. 

 This class of igneous rock produces uplifts in the northern part of the chain 2,500 to 3,000 

 feet ; toward the south a lofty mountain rises in this chain above T,000 feet high, the streams 

 flowing down from the snows and rains of this mountain contribute on its east side to form a 

 tributary of the Santa Maria in the extreme southern end of Cuyama valley. The geology of 

 this portion of the range not having been studied, owing to rapid transit over the district, 

 it cannot be affirmed that primary rock does not exist, but the sky outline of the range, and the 

 fact that the washed stones brought down by the stream into the Santa Maria valley are all of 

 volcanic origin, serpentine, trap and felspathic porphyry, a red, compact, argillitic rock, chal- 

 cedonic quartz, such as abounds further to the southwest in the Sierra Monica, are strong evidences 

 of its non-existence ; while in the localities where the hill range was passed through by the 

 survey, no trace of a granitic rock was observable ; trap and its accompanying serpentine were 

 the invariable plutonic rocks, sometimes axial, but more frequently elevating the strata to one 

 side, and appearing as a naked rock on the other ; this latter phenomenon presenting itself 

 where the elevation of the range was not at its greatest ; the general tilt was to the east, and 

 when it occurred as an axial rock t he eastern slope was the easiest, that of the west being steep 

 and above 45°. 



The valleys east of this range have a much higher level than those west. Santa Margarita 

 valley, San Jose valley, and that of the Santa Maria river, are several hundred feet higher than 



