METAMORPHIC SANDSTONE AND LIMESTONE. 
205 
At a point near 212, quartz rock again makes its appearance in a bed about one hundred feet 
thick; then follows a fine-grained syenite two hundred feet thick ; and a second bed of quartz 
and one of limestone, (at 212,) in which there are numerous imperfectly formed crystals of a 
brown garnet. 
This is the last outcrop of limestone in the Pass, and is succeeded, five hundred feet eastward, 
by a fine mica and hornblende slate, with a trend hi. 37° E., dip S. E. about 45°. This rock 
is remarkably homogeneous, and its trend and dip is unusually distinct. It has planes of 
cleavage other than those in the direction of the beds, giving to the broken masses a sharp, 
angular outline, which, with the dark color, makes them resemble a trap or basaltic rock. 
This series of beds of granite, quartz rock, limestone, and hornblendic rock presents a slightly 
different appearance when examined at the outcrops along the wagon trail about three- 
quarters of a mile further north. There, the last described syenitic rock is more highly crys¬ 
talline, and contains transverse veins of white limestone and quartz several inches in width. 
These rocks are the last that are exposed in the natural section, and hardly rise above the 
surface of the broad slope of the Great Basin, which is composed of sedimentary accumulations 
of modern age. 
We have thus considered in succession all the outcrops of the rocks from the Tulare Plains 
to the summit of the mountains, and then downwards along the course of a creek on the east 
slope to the Great Basin. 
It is evident that the rocks east of the summit are chiefly metamorphosed sedimentary forma¬ 
tions, and it is probable that a great part of those on the western flank are also metamorphic. 
The predominance of the rocks, with the composing minerals arranged in parallel planes, is one 
of the most striking features of the section ; and west of the summit it becomes difficult, if not 
impossible, to distinguish between the metamorphic rocks and those which are decidedly erup¬ 
tive in their character. If the structural condition of the rock was regarded as conclusive 
evidence of its metamorphic character, we would be obliged to consider the whole series as 
metamorphosed. There is, however, little reason to doubt that the gray and compact granite, 
with its included lenticular masses of minerals, is eruptive. The beds of white limestone, with 
the adjoining beds of quartz rock, are exceedingly interesting. The limestone varies from a 
coarsely crystalline structure to a fine-grained, granular or sacharoidal marble. It is very white, 
and some of the beds contain disseminated crystals of graphite. The metamorphism is so com¬ 
plete that if the rock originally contained fossils, they are now completely destroyed. A part 
of the rock very closely resembles the coarsely crystalline white limestone of Sussex county, 
New Jersey. 
The quartz rock may be regarded as metamorphosed beds of sandstone. The color is light 
buff, or yellowish, and not unlike that of the Potsdam sandstone along Lake Champlain. 
Several of the specimens exhibit a sub-granular structure, and prove to be calcareous.—(See 
No. 4, Catalogue and descriptions.) The recurrence of similar beds at regular intervals along 
the section leaves little doubt that they were formerly continuous, and that they have been 
uplifted and thrown into flexures, or plicated. This is also shown by the dips or inclinations 
of the beds, those nearest the summit being nearly vertical, while those lower down the slope 
incline at a considerable angle from the vertical. The flexure has possibly taken place as 
indicated upon the section by a dotted line. If such a plication exists, the upper parts of $ie 
curves have been removed by denudations. This view of the relations of the beds is presented 
with some hesitation, as the probable plication was not recognized in the field, and only became 
