( 314 ) [July, 
II. GOLD IN CALIFORNIA. 
By J. Arraur Puruirs. 
THE principal gold-producing portion of California extends, on the 
western slope of the Sierra Nevada, from the Téjon Pass to the 
northern extremity of the state. 
The slates of which it is mostly composed have been shown by 
the officers of the Geological Survey to belong chiefly to the Jurassic 
period, although the occurrence of Triassic fossils in the auriferous 
rocks of certain sections of the belt renders it probable that some of 
the slates in the heart of the gold region belong to that age. 
These sedimentary rocks for the most part consist of various 
slates and schists, more or less metamorphosed, and sometimes con- 
taining nodules of feldspar ; sandstones are also frequently met with, 
and these are often transformed into quartzites. Black talcose 
schists with slates, exhibiting a well-defined cleavage, together with 
bands of more or less crystalline limestone, also occur. 
Lying between the band of metamorphic slates and the great 
granitic mass of which the Sierra Nevada principally consists, are 
found various crystalline rocks, such as syenites and porphyries. 
All of these rocks in the vicinity of the sedimentary deposits enclose 
numerous veins of quartz which contain, in addition to gold, iron 
pyrites, and other metallic sulphides. The quartz veins of the 
crystalline rocks are comprised within a narrow zone, extending from 
south to north, along the western flank of the Sierra, above the 
band of auriferous slates, and are found, in the vicinity of the line 
of junction, throughout nearly its whole extent. 
The veins of the metamorphosed slates occupy a lower position 
on the western slope of the range, and are exceedingly numerous 
and important. ‘They are not, however, by any means equally dis- 
tributed throughout the region of slates, but are, for the most part, 
concentrated in a belt having a width, from east to west, of about 
fifteen miles, and extending from south to north throughout the 
length of the formation. They in general follow the direction of 
the strata in which they are enclosed, but this parallelism is seldom 
absolute ; besides which they frequently throw off branches and 
offsets, cutting through the bedding of the slates at very consider- 
able angles. 
It is also to be remarked that wherever the slates have been 
tilted so that the bedding has become almost perpendicular, and 
where they have generally been subjected to the largest amount of 
metamorphic action, the veins are usually most productive. In fact, 
although there are exceptions to the rule, gold veins enclosed in 
stratified rocks are generally productive in proportion to the 
