34 
VOLCANIC ROCKS OF SOUTH MOUNTAIN. 
Analysis of quart zite. 1 
[bull. 136. 
Per cent. 
Percent. 
Si0 2 (quartz) .... 
KiO., (Combined) . 
TiO~> 
84. 130 
7.870 
.145 
.205 
4.210 
1.800 
CaO 
.040 
1.1 CO 
.160 
.960 
100. 680 
I K 2 
Na 2 .. 
P./), . . 
ALO { . . . 
Total 
Fe 2 3 . . . 
SUMMARY. 
The Cambrian sediments of tlie Monterey district may be classified 
as conglomerate, sandstone, qnartzite, and slate. 
The first two of these phases represent original sedimentary deposits, 
of which the latter has been locally metamorphosed by induration into 
a qnartzite. The slates are in some cases from deposits of a more 
finely divided material, and in other cases they are the product of shear- 
ing. 
There has been a limited and local introduction of new material, 
which shows itself in the production of chlorite and epidote. In every 
case the clastic character of the rock remains indubitable. 
1 Specimen No. 1157, 1| miles S. of W. of the burned sawmill on the Conocochoa^ue. This analysis 
was made by Dr. F. A. Genth, formerly of Pennsylvania University, for the Second Geological Sur- 
vey of Pennsylvania, Vol. CCC, Second Geol. Snrv. Pa. 
