TERTIARY AND RECENT DEPOSITS—ERRATICS. 
207 
Tertiary and Post-tertiary deposits .—The white and chalk-like hanks or cliffs, which were 
observed in approaching the Tejon Depot Camp from the northward, are probably of the same 
age and lithological characters as the Miocene formation at Ocoya Creek. These hills flank the 
most western ridge of the granitic rocks, and slope down gradually to the level of the Tulares. 
They were not seen in section, and no observations upon their lithological characters can be 
presented. They are represented on the section. It is probable, however, that a continuation 
of these deposits underlies the whole of the detrital materials of the slope, and the alluvial and 
lacustrine clay of the Tulares ; and finally reappears on the opposite side of the valley to form 
the foot-hills of the Coast Mountains. 
The mountains north of the Depot Camp are more or less covered, up to an elevation of 1,000 to 
2,000 feet, with sedimentary materials, which, in all probability, are Tertiary, overlaid by more 
recent deposits of drift or detritus. The surface is covered with transported fragments and 
boulders of various rocks, most of them porphyritic and not in place in the vicinity. One 
boulder over five feet in diameter was observed. The washing away of a large part of these 
deposits, and the erosion of ravines by running water during rains, has supplied a large 
quantity of loose earth and sand to he spread out over the adjoining slopes of the Tejon and 
Tulares. 
The Tertiary deposits do not appear to extend as far east as the entrance to Tejon Eavine or 
Tejon Pass. In the Pass, however, there is an extensive accumulation of sedimentary materials 
of comparatively modern age. They are probably wholly formed of drift, or the rounded and 
water-worn debris of the adjoining mountains. This deposit occupies the bottom of the valley 
of the Pass nearly to the summit, and, as has been already stated, the creek has cut its channel 
upon the south side along the junction of the deposit with the granite. In travelling through 
the Pass, therefore, the granitic rocks are found on one side and rounded hills or steep banks of 
this drift deposit on the other. The many small tributaries to Tejon Creek, from the high 
ravines in the mountain on the north side, cut directly across the accumulation and form good 
sections, but they are generally so much overgrown with grass, and obscured by soil, that the 
lithological characters can hardly be determined. These sections show, however, that the 
deposit is at least over 100 feet thick ; and it probably is in some places over 500 feet, and may 
be underlaid by Tertiary strata. The general form of the valley of the Pass, and the relative 
positions of the drift, are shown in the annexed section from north to south, a few miles beyond 
the entrance. 
The materials composing this deposit are chiefly earth, sand, and gravel; and a large pro¬ 
portion of coarse drift of boulders and cobble stones, from six inches to four feet in diameter; 
masses of the latter size being rare. These are rudely stratified, as may be seen in some of the 
banks. The surface is generally undulating, and shaded by groves of oak. The transverse 
