50 GEOLOGY. 
composed of the debris of granite and similar rocks. Some included masses or boulders resemble 
sandstone. The trend is about north and south; dip westward 50°. These strata are soft and 
wear away rapidly where they are exposed. The outcrops of sandstone, near the two small 
ponds, were again observed with the same result as before—dip north at an angle of 40 or 50 
degrees. 
'T'he intrusive rock or dyke was found to extend towards the summit and at the base of the 
high granitic hills on the north side. Ridges of limestone, white and crystalline, were also 
found at the summit, and the trail passes between two of them. There is much debris of this 
limestone scattered about, and among it I found masses of a black ore, which attracts the needle 
strongly, and is probably ordinary magnetite or magnetic iron ore ; it, however, does not exhibit 
cleavage, or break like the ore. The outcrop of this ore was found on the top of the ridge, 
and is about three feet thick, trending nearly east and west; dip nearly vertical; limestone 
bounds it on each side. From this point the trail descends rapidly to a dry water-course, 
extending nearly north and south, or towards the small salt lake called Casteca Lake. 
Strata, probably Tertiary.—Passing along the dry channel towards the north, we found the 
hills on the left to consist of horizontal strata, exposed in many places, high up and inaccessible, 
by slides or ravines cut by the rain. These exposures revealed the presence of several colors 
in the strata—yellow, bluish, green, and other tints. "They seemed to be chiefly marls or clays; 
and very soft. A thickness of two or three hundred feet, at least, was visible. 
October 5.—Encamped last night at the ‘ bear camp,” (as we have called the camp where 
the inscription in memory of Peter Le Beck occurs,) and this morning left for the Tejon. Ad- 
ditional observations were made upon the geology along the trail, but no outcrops of sandstone, 
similar to that containing the fossils picked up at the entrance of the Cañada, could be found.’ 
1 Further observations on the geology of the Cañada de las Uvas will be found in Chapter XV. 
