q 
: 
3 
1 
the South and Middle Yuba, California. 9 
eight millions of dollars. But the total area of the various 
places where gravel deposits have been worked on this ridge is 
estimated by Mr. Black as equal to fifteen square miles, all of 
which, and much more, is controlled by the water of the Eu- 
reka Lake Co., or of the Middle Yuba Canal. If this area is esti- 
mated at an average of forty yards in depth (it varies from 
eighty to two hundred and two hundred and fifty feet in depth), 
we shall have one thousand eight hundred fifteen million nine 
hundred and thirty-six thousand cubic yards of gravel, and if 
this be estimated to yield only thirty cents per yard, we reach 
the grand aggregate of five hundred and forty-four million six 
hundred and ten thousand dollars as its probable yield in gold. 
e average cost of the water required to wash away one 
eubic yard of gravel has heretofore been seven and a half cents: 
but if its price is reduced to six and a quarter cents (=1632 cents 
for one miner’s inch of water) for each cubic yard, the cost of 
the water to perform this work will be nearly one hundred and 
twenty millions of dollars ($119,316,320). It is easy to see 
from these statements that the amount of gold contained in the 
deep placers of the Yuba alone is probably greater than the 
aggregate of all the gold yet exported from the whole Pacific 
coast, which (including silver) amounted on the first of Janu- 
ary, 1865, to $695,944,786.° Mr. Black’s estimate of the area 
town, situated on the north bank of the Middle Yuba, immedi- 
ately opposite Snow Point, the volcanic ash bed covers the 
‘great Blue Lead’ (part of the ancient auriferous gravel,) where 
it has yielded almost fabulous wealth to the explorers. The 
* Mercantile Gazette for January 12, 1865. 
Am. Jour. Sc1.—Seconp Series, Vou, XL, No. 118.—Juny, 1865. 
2 
