Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean: Vol. 5, Pt. 2

CHAPTER XV.
GEOLOGY OF THE TEJON PASS AND CAINADA DE LAS UVAS'SECTION
*~ ~ OF THE SIERRA NEVADA.
SIERRA NEVADA AT THE TEJON.-BOUNDARIES OF THE TEJON. —TEJON PASS AND CANADA DE LAS UVAS.-GEOLOGICAL MAP AND SECTIONS. SECTION OF THE SIERRA NEVADA AT THE TEJON.-ROCKS OF THE WESTERN RIDGE.-PLANES OF STRUCTURE OR LAMINATION.-GRANITIC
OUTCROPS IN THE PLAIN.-SECTION AT THE TEJON RAVINE.-WHITE LIMESTONE.-ROCKS AT THE ENTRANCE TO THE PASS.-DRIFT
DEPOSITS.-OAK TREES.-ROCK AT THE SUMMIT AND BEYOND.-QUARTZ ROCK.-WHITE CRYSTALLINE LIMESTONE AND QUARTZ ROCK. PROBABLE SEDIMENTARY ORIGIN.-PLICATIONS OR FOLDING OF THE STRATA.-PROBABLE CARSONIFEROUS AG'.-GENERAL TREND OF THE
ROCKS.-TERTIARY AND POST TERTIARY DEPOSITS.-DRIFT OF THE VALLEY OF THE PASS.-SECTION AT THE CANiADA DE LAS UVAS OBSERVATIONS ON THE SECTION; ITS DIRECTION.-SIMILARITY OF THE ROCKS TO THOSE OF THE TEJON.-WHIITE CRYSTALLINE LIMESTONE
IN RIDGES.-GRANITE NEAR CASTECA LAKE.-LIMESTONE WITH TRAP DYKES AND IRON ORE.-PROBABLE SYNCHRONISM OF THE LIMESTONE
WITH THAT OF THE TEJON.-VOLCANIC ROCKS AND SANDSTONE.-RELATIONS OF THE VALLEY OF THE PASS TO THE BERNARDINO SIERRA
AND THE SLOPE OF THE GREAT BASIN.
The Sierra Nevada at the southern part of the Tulare Valley ceases to be a range of snowy
heights, and is broken into a series of ridges, not exceeding six or seven thousand feet in elevation. These ridges do not conform in their direction to that of the Sierra Nevada a short distance
to the northward, or at the head waters of Posuncula River, neither do they exhibit any well
defined parallelism among themselves, but extend in different directions, generally inclining
southwesterly, turning more and more to the west as they succeed southward, until their direction becomes nearly transverse to the general direction of the Sierra Nevada, and they unite
with the mountain ranges lying west of the Tulares; commonly known as the prolongation of
the Coast Range or Coast Mountains. The angle which is thus formed by the intersection or
unison of the Sierra with the Coast Mountains is not abrupt nor well defined; the ridges being
arranged so that they form a great curve around the head of the Tulare Valley, and partly
enclose the large space known as the Tejon. On the northeastern side of this plain-like area,
a projecting ridge of granite forms a partial boundary on the north, and extending nearly
parallel with the main ridge, it shuts off a portion of the Tejon from the broad plains of the
Tulare Valley. The portion of the Tejon thus bounded is a nearly quadrangular space with
mountains on three sides, it being open only towards the southwest. It was in this part of the
Tejon that the Depot Camp was located.
The Tejon Pass extends from the eastern side of this part of the Tejon, by the valley of the
Tejon Creek, over the crest of the Sierra to the Great Basin on the eastern side. Its general or
average direction is N. 60~ W., S. 60~ E. The Cafiada d(le las Uvas is about twenty miles
further to the southwest, and may be said to turn the southern extremity of the Sierra Nevada.
The relative positions of these passes, and the direction of the mountains, may be seen by
reference to the small Geological Map prepared to accompany this chapter. The topography is
taken'from the General Map of the Survey, and is on the same scale. The portion of the country
represented includes the southern end of the Sierra Nevada, from Tah-ee-chay-pah Pass southwesterly to the Cainada de las Uvas; also, a portion of the Bernardino Sierra, from the Pass of
San Amedio to Williamson's Pass. On the western side of the Sierra Nevada, the slope of the
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