268 
GEOLOGY. 
below. The south banks at this point are nearly vertical, and 2,800 feet high. A fine view of 
the distant ridges of the Sierra was here presented to us. We were on Wisconsin Hill, now 
being settled upon by agriculturists. 
Iowa Hill , Placer county , to NevadaI —A thick deposit of drift is found at Nevada, resting 
upon a bed-rock of gray granite. This granite, as exposed by the mining operations, is very 
much decomposed and softened to a great depth, so that in places it may be removed with the 
pick or shovel. These softened parts, however, contain hard, globular masses, from one or two 
to over eight and ten feet in diameter. They look like great boulders, and lie thickly together 
along the course of the little stream. Wherever the auriferous drift is removed the surface of 
the granite is found to be very uneven, a condition which necessarily results from the manner in 
which the rock decomposes, and not from abrasion or denudation. 
A vast quantity of earth has been washed here by the hydraulic method. One of the principal 
claims is owned by Mr. Laird, formerly of G-eorgia, who has made an extensive excavation 
backwards in the side of a hill formed of the drift. In washing this earth, the ground-sluice 
has been extensively used. They are cut in the surface of the granite and converge from the 
base of different parts of the bluff until they all unite and deliver the water into a board-sluice 
below. These ground-sluices are said to catch and retain the gold more effectually than those 
made of boards. The gold is, however, not so readily obtained or “cleaned up” from them. 
The operations in Nature—the concentration of gold in the beds of streams, from a wide area— 
is thus imitated by these ground-sluices. 
The gold of Coyote Lead is generally in fine scales, and is poor in quality. It is said that it 
is sometimes sent to the southern mines to be mixed with better gold before offering it for sale. 
Water was first brought to the Nevada Hills by the Rock Creek Hitch. This was seven miles 
in length, cost about $14,000, and yielded, from the sale of water, $30,000 in the first two 
months. Water was sold several times over, or, rather, it was used by several parties in suc¬ 
cession, until, from the quantity of fine slime in suspension, it became as thick as pudding, and 
would no longer run. For a supply of eight inches, the first parties paid two ounces a day, 
the second twenty-four dollars, the third one ounce, and so on down to four dollars. The 
aqueduct was afterwards sold for about three times its original cost, and has since paid fair 
dividends, even for California. 2 Water is now sold for fifty cents an inch. The aqueduct of 
the Deer Creek Company is said to have cost $25,000, and to have paid all the expenses of con¬ 
struction in the first three months. 
At Grass Yalley I had the opportunity of visiting several of the principal qu irtz mines and 
mills for the extraction of the gold. These are located along Boston Ravine, the valley of a 
small stream ; but, with one or two exceptions, the quartz is mined at a distance of one or two 
miles, and is carted to the mills. An interesting establishment and mine, on a moderate scale, is 
held by the Empire Company, chiefly composed of gentlemen from New York. Their mill is 
about a quarter of a mile from the town, and three-quarters of a mile from the mine on “ Ophir 
Hill.” 
The rocks between the mill and the mine are not well exposed to view, being chiefly covered 
by soil and a layer of drift. Neither are they seen distinctly upon the surface at the mine, but 
on descending the shaft for seventy-five or one hundred feet, they are found to consist of a hard 
greenstone or trap. In some places along the “ ledge,” or vein of quartz, it is fissile and slaty. 
The ledge appears to trend north 10° to 30° west, and dips westwardly. Its thickness varies 
1 The notes for this part of the trip were all lost. 
s I had these facts from a gentleman who was formerly engaged in mining near Nevada. 
