re) Cincinnati Society of Natural History. 
chain has been raised. There appears to be no doubt that these 
horizontal strata are the same 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- 
‘ertion of the imagination, can be construed into a resemblance to a 
ruined city, 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 
Mioceue 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 
Punta Keyes, there are minor ridges of Miocene sandstone, having a 
low southwest dip. ; 
The sandstones of the Santa 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 entirely composed of Miocene | 
