CONSTITUTION OF THE STRATA 69 



panied with reddish jaspery sandstone and serpentine in veins, constituted the volcanic and 

 altered rocks of the upheave. 



These metamorphic rocks occupied the foot hills of the range which immediately overhung 

 camp, and presented cliff edges or forming bold escarjiments. These rise for several hundred 

 feet at such a steep angle that it is difficult to ascend them on foot without deviating consider- 

 ably ; they presented to the eye only a mass of brownish red and yellow sandstones, which, 

 when the ascent was gained, were found to dip south a few degrees east. The mountain here 

 was not a single chain, hut presented two crests through the depressions, in the further one of 

 which the ocean was descried. The second range also dipping similarly to the south and east, 

 they appeared to be repetitions of each other. In passing through the Gaviote pass a similar 

 duplicate stratum was observed. 



From the camp to the river Santa Inez the strata dipped in the opposite direction — that is, to 

 the N.W. — and thus sections were afforded on each side of the axis, whose course here was N. 76 

 W., (magnetic.) 



The sections on the valley side were : 



1st. A little above camp and close to the axis, although not observed in contact with it, a 

 greenish grit passing into conglomerate ; where the rock approaches a fine grain it becomes 

 calcareous, containing small grains of crystalline carbonate of lime. The exposed thickness of 

 this bed was 200 feet. 



2d. Brownish yellow sandstone, coarse grained, containing layers and seams of gypsum in 

 places, and decomposing irregidarly, so as to form cavities — fossiliferous. 



3d. Whitish yellow sandstones, with fossil casts injured, followed by brownish flagstones ; 

 thickness, 200 feet. 



4th. Sandstone grit, calcareous, and having flinty laminae and veins of calc spar ; this bed has 

 layers of ostrea and pecten in great numbers ; 160 feet thick. 



At this point the bed of the Santa Inez river is reached, on the opposite side of which were 

 observed the layers of the white fissile argillaceous rock already alluded to as found on the hill 

 dividing the valleys Inez and La Purissima. 



In figure 1 of plate 3 a section of the northern beds is given. 



The section on the south side of the range was afforded by passing down the Gaviote pass. 

 This is a cleft in the range carried down to the level of the surrounding land, and having a 

 small stream traversing it. It is much blocked up by masses of sandstone which have fallen 

 from the overhanging ledges of rock on either side. The mean width of the bottom of the pass 

 might be about 50 feet, divided between the stream and the wagon road ; it is in places only 

 30 feet ; the road necessarily very rugged and contested often by the brook. With a little 

 work, however, it might be made a good road, and appears to be the natural route to cross these 

 mountains from the southern counties to reach San Luis Obispo and the north. 



The pass occupies the position of a synclinal axis, the strata being bent downward on each side 

 to this point, where, being fissured and broken by the pressure of the uplifting axes on either 

 side, the debris has been removed by the usual actions of weather and running water. 



Plate 4, figure 1, gives a view of the pass looking south, and figure 2 represents the ideal 

 condition antecedent to the removal of the ruptured portion. 



In the pass the sandstones dip at angles varying from 25° to 40° in the direction S. 15° E. 

 Between tlie pass and the shore is an elevated plateau, or terrace, perfectly smooth, and with a 

 gentle slope to the ocean, above which it is raised at least 80 feet ; tlie strata on shore dipping 



