Rocks of Southern California,—Hershey. 287 
have Desert granite belt, are doubtlessly a part of the so- 
called “Archean complex” of gneiss and schist which Turner 
and others have found to underlie the Lower Cambrian rocks 
in Inyo county and to form the basement crystalline complex 
in Nevada, Arizona and the Rocky Mountain region in gen- 
eral. It is a feature common to the Klamath schist series, the 
Pelona schist series and this “Archean” series near Barstow 
that they have been subjected to intense thermo-metamorphism 
without profound dynamical deformation and have never been 
so thoroughly sheared and closely folded as later rocks, (not- 
ably the Calaveras,) remaining yet in positions usually far 
from vertical. 
THE QUARTZYTE-LIMESTONE SERIES OF ORO GRANDE, 
A group of abrupt, very rocky mountains just east of Oro 
Grande, in San Bernardino county, was examined to five miles 
east of the village and found to be composed of two forma- 
tions, quartzyte and limestone. The quartzyte is a hard, fine- 
grained rock, white underground, but stained pink and dull 
red on the surface, giving rise to dark rugged peaks. Under 
a small hand microscope, it shows secondary enlargement of 
quartz grains like the Baraboo quartzyte of Wisconsin, but 
the grain is finer. It is unlike anything ever before observed 
by m@gin California in that there is a large body of pure quartz- 
yte wkich was originally a very pure quartz sand. Its general 
appearance is similar to the quartzytes just east of Ogden, 
Utah. 
The limestone is hard, blue and crystalline from meta- 
morphism. It is massive as the bedding planes are generally 
destroyed. Its purity is unusual for California limestones and 
it is extensively quarried and burned in kilns at Oro Grande. 
In the limestone are some bands of dark gray fine micaceous 
schists—highly altered clay shales. 
The quartzyte and limestone are folded to a moderate de- 
gree and somewhat broken up by small faults. A strip of the 
limestone extends east from Oro Grande. It is 100 to 800 feet 
in width, but the real average thickness of the limestone is 
probably no more than 200 feet. This band is at the axis of 
a shallow and narrow syncline and the limestone clearly over 
lies the auartzyte. A quarryman told me that another lime- 
stone mountain occurs on the north and still another line of 
