Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean: Vol. 5, Pt. 2

RICHNESS OF THE PLACER DEPOSITS-ANCIENT RIVER-BEDS.
It would appear from this section that there was an alternation of quiet and running water
The deposition of clay and pumice was interrupted by a swift current bringing gravel and gold,
and this current was probably similar to that which first spread the gold upon the uneven
surface of the slates. It is probable also that the current was sudden and powerful, for if it had
flowed for a long time, the clay would have been swept away before the gravel was laid down.
The gravel must have accompanied the flood, and thus acted as a barrier to the denudation of
the layer of clay below.
Through the kindness and attention of P. C. Currier, esq., I was permitted to examine the
mine of the Washington Tunnel Company, one of the best on the hill, and was allowed to test
the accuracy of somne of the statements regarding the remarkable richness of the deposits of the
hill by mining for a few minutes, on my ownI account, in one of the drifts. The surface of the
bed-rock was worn perfectly smooth by abrasion, and a fine, white, talcose clay and some gravel
rested upon it. With a candle in one hand and knife in the other, I picked away this earth
and threw out, one after another, beautiful water-worn lumps of gold. In ten minutes I had
collected nearly an ounce.
The slate of this vicinity appears to contain many auriferous veins. Quartz in cellular veins,
apparently auriferous, is visible at the entrance to the Washington Tunnel, and a short distance
below the Mameluke Tunnel, a quartz vein, only a foot in width, is very rich in gold. This
quartz was so much decomposed and stained by oxide of iron that it resembled the adjoining
slate, and its presence was not suspected. The claim was worked as a placer deposit, but with
little success. On taking out one panfuill from the vein and washing it, gold became immediately visible, and nearly half an ounce was obtained. This was sharp, angular gold, mixed
with the cellular quartz. The slate on each side is much stained with oxide of iron, and it is
probable that undecomposed pyrites will be found lower down. The course of this little vein is
nearly north and south, and its extreme richness, together with its friable and cellular condition,
render it probable that it will be exceedingly profitable.1
There are many other rich placer deposits in the vicinity of Georgetown. At Cement Hill
there are extensive excavations. The Swiftsure Tunnel is cut for one hundred and twenty feet
in slate, and is four hundred feet in length. The auriferous earth is found under a thick deposit
of fine clay, in which whole trees are imbedded. These are in a state of decomposition or
change, and are dark-brown, looking nearly as black as coal. The hand may be thrust into
them in some places, they are so soft, but in others the toughness of the fibre of the wood
remains. They contain beautiful masses of iron pyrites, in crystalline crusts of great brilliancy;
but these rapidly decompose on exposure. The clay differs from that at Mameluke Hill; it is
nearly pure clay, with a reddish-brown or drab color, and was evidently deposited in quiet
water. It is said to be thirty feet thick.
The Nevada Tunnel, an adjoining mine, is one of the most interesting in that region. It is
cut through about four hundred and fifty feet of slates, and then reaches the "~ lead." The gold
obtained in this mine differs from that found in the placers before described, being in small and
regular scales, and indicating by its form that it was deposited in the bed of a river. This indi cation is verified by the character of the surface of the bed-rock; it is rounded and worn exactly
as in the bed of a river, and, here and there, large, loose boulders are found. It is evidently the
bed ofan ancient river. Above this auriferous deposit we find a compact, brown clay like that
1 It is reported that after we left this vein, the owners of the claim commnenced sinking a shaft on the vein, and oktained over $60,000 before they had reached a depth of fifty feet.
35 F
273