CAJON PASS-SANDSTONE-GRANITE. 
87 
inclined. About one mile from the summit, the disturbance is very great, and the strata rise in 
a series of nearly vertical beds, forming precipitous ledges of bare sandstone, which have become 
fantastically worn and moulded by weathering. All the angles and edges of the beds are 
rounded off, and a series of hollows and cavities has been produced along the junction of the 
strata differing in hardness. Sufficient soil has accumulated in these cavities to support a growth 
of small vines and shrubs, that form belts of verdure on the barren bluffs. The appearance of 
some of these hills is well shown in the preceding sketch, taken from a point in the valley of 
the creek, which at that time was quite dry. 
At another point not far distant from that represented in the sketch, and much nearer the 
granite, the strata rise up in a succession of sharp pinnacles—produced by weathering—and are 
inclined away from the granite. The prevailing dip of the strata is about 45°, and they do not 
present any appearance of metamorphism by heat or great pressure. They have a modern look, 
and their barren and singular surfaces present a strange contrast with the green shrubs that 
cover the slope of the adjoining granite. This formation is unlike that which forms the bluff 
at the summit, being more even in texture, harder, and apparently uncomformable in stratifica¬ 
tion. The strata are, however, of a light color, and are not very firmly consolidated, but in many 
places are soft and friable, and have a light reddish or pink color, which may be caused by the 
large amount of pink feldspar that they contain. The beds seem chiefly composed of sand and 
angular gravel, derived from the attrition and wearing of granite and the allied rocks. Some 
of the beds are compact sandstone, very uniform in texture, and others are conglomerates, fre¬ 
quently containing large rounded boulders of granite and other rocks. It will be seen that, 
lithologically, they resemble the strata of the summit, and at first I was inclined to consider 
them as one formation, but the tilted strata are undoubtedly older than the recent or drift 
deposits of the slope, and underlie them ; but where the strata are not disturbed, it would be 
difficult to distinguish between the two. The sandstones vary but little in composition ; there 
are no shales or other strata that simulate the sandstones of the vicinity of San Francisco and 
Benicia ; their color and appearance are entirely different. I searched in vain for any fossils. 
I also looked for outcrops of intrusive volcanic rocks, to which the present highly tilted condi¬ 
tion of the strata could be referred, but was unsuccessful. 
The granite appears to have been disturbing rock, but no indications of a local intrusion were 
seen. The ridges were, however, examined only at their bases, it being impossible to carry 
the observations far beyond the trail. The whole bulk of the sandstone formation is insignifi¬ 
cant when compared with the adjoining granite ridges, which rise from one to three thousand 
feet above the outcrops of the strata. It is highly probable that this formation is Tertiary, and 
that it corresponds with the sandstone of Williamson’s Pass and the Pass of San Francisquito ; 
