AURIFEROUS QUARTZ—METAMORPHIC LIMESTONE—SOLUTION OF THE ROCK. 255 
sixty horse-power, eighteen stamps, and a Chillian mill. The gold is chiefly caught upon 
blankets, and in ripple-boxes provided with amalgamated copper cleats. Shaking-tables and 
bowls are not used. The veins trend N. and N. 22° E., and the quartz contains cavities stained 
black with oxides of iron and manganese. Several specimens in which the gold was distinctly 
visible were shown to me by Mr. Smith, the superintendent; but in general the quartz is much 
stained by the decomposition of pyrites, and the gold does not appear. The pile of ore ready 
for the stamps was almost identical in its appearance with the quartz from the upper parts of 
the veins in Virginia and the Carolinas. 
SONORA TO MURPHY’S. — 
August. 6.—We left Sonora and travelled towards Murphy’s, passing through Shaw’s Flat, 
Springfield, and Columbia. Extensive outcrops of white limestone were passed, and the town 
of Columbia is built upon this formation. The town was completely destroyed by fire in July 
last, only two buildings having escaped; but it is now nearly rebuilt, and business is going 
forward as before. Fire-proof brick stores are in progress, and Gothic cottage residences grace 
the outskirts of the place. 
The white limestone which underlies the vicinity is peculiarly compact and finely granular, 
and is seamed and veined with blue; in some parts appearing like a mixture of blue and white 
| grains, forming a marble of good quality. The blue lines are, however, generally parallel, or 
in layers corresponding to the trend of the beds. The surface wears unequally, so that it is fur- 
rowed in long lines, making the trend of the outcrops still more distinct. These layers, or 
beds, brought out so distinctly by weathering, are probably the result of deposition, and the 
rock gives many evidences of sedimentary origin, except fossils. The crystalline structure does 
not favor this view of its origin, but it is doubtless metamorphic. 
The gold from the vicinity of Columbia is very fine, and commands high prices ; $18 and 
$18 50 being paid for it by theounce, at the express offices. Nearly all of the gold is taken 
from the deep crevices and fissures of the limestone, at variable depths from the surface—from 
four to twenty-five feet, The peculiarly irregular character of the underground surface of the 
limestone is worthy of particular notice, and it is well exposed to view by the excavations. 
Wherever the earth is removed, irregular columns and sharp pinnacles of the rock are left 
standing ; some of them being supported on a narrow neck at the base, and are thus in a con- 
IRREGULAR SURFACE OF LIMESTONE EXPOSED BY MINING. x: 
dition to be easi] y overturned when the surrounding rock is removed. The fissures or spaces 
between some of the masses are so narrow and crooked that the rock has to be broken away to 
permit the removal of the gravel and gold from the bottom. Many masses are found entirely 
loose and disconnected from the subjacent rock, and are found to end in a long, sharp point 
projecting downwards, while the upper portions are several feet in diameter. "These loose 
Masses are broken up and removed by the miners, and are generally supposed to be boulders 
T transported fragments. It is evident, however, that they are not erratics, but that they are 
