206 Tertiary. 



chain has been raised. There appears to be no doubt that these 

 horizontal strata are the ^ame ones which are tilted up in the 

 mountains, and that they belong to the Miocene Tertiary. At about 

 six miles from Santa Cruz are some singular examples of weathered 

 sandstone, which are known as the "Ruins" or the "Ruined City." 

 Here perpendicular tubes or chimneys of rock are found, from one to 

 three feet in diameter, the sandstone appearing to have been hardened 

 in concentric layers by the infiltration of ferruginous solutions, and 

 this hardened portion has withstood the action of the elements, while 

 the softer bands, and the interior columnar or cylindrical masses, have 

 weathered away, leaving a pile of rocks behind, which, by some ex- 

 ei'tion of the imagination, can be construed into a resemblance to a 

 ruined cit3% on a very small scale. 



The whole region traversed by the trail from Pescadero to Sears- 

 ville, as far as the metamorphic on the eastern edge of the range, is 

 bituminous shale, of Miocene age, with occasional beds of interstrati- 

 fied sandstone, of which the dip is irregular, but not high. 



Between Petaluma and the entrance of Tomales bay, patches of 

 Mioc^ie sandstone occur from 250 to 300 feet thick, resting uncon- 

 formably upon altered strata. The rocks are soft, yellow sandstone, 

 with large nodules of hard, blue calcareous sandstone, imbedded in 

 them. Between the highest points near the head of Tomales bay and 

 Puuta Keyes, there are minor ridges of Miocene sandstone, having a 

 low southwest dip. 



The sandstones of the ^anta Monica and Santa Susanna Ranges, 

 are, in large part, of Miocene age. The ridges bounding the San 

 Fernando valley on the southwest, are made up of light bituminous 

 slates, dipping generally to the east or north east ; they form rounded 

 hills, bearing the marks of extensive erosion. A higher range to the 

 west of these hills connects the two chains, and rises to a height of 

 3,000 feet above the sea, being made up of Miocene sandstones, highly 

 inclined and in some places metamorphosed. 



The chain of the Santa Inez Range rises to the north of Santa Bar- 

 bara, a conspicuous object to those approaching this place by water. As 

 far as known, it takes its origin at a point due north of Buenaventura, 

 and running a little north of west (N. 84 deg. W.) for a distance of over 

 60 miles, it meets the sea at Point Concepcion. The chain has its 

 greatest elevation apparently near Santa Barbara, where it is about 

 3,800 feet high. To the west of the Gaviota Pass it has an elevation 

 of about 2,500 feet. The main ridge is entiirely composed of Miocene 



