THE VICINITY OF LA PORTE AND GIBSONVILLE. 449 
thoroughly acquainted with all the geological features of the district, nor could I make the careful 
and detailed survey upon which the decision of such an important question ought to be founded. 
I must be content with describing as clearly as I can those things which I actually observed, 
with cautiously expressing the opinions to which my observations led, aud with suggesting some 
of the more important points as to which further information must come from further explorations. 
My present opinion is that the ridge of lava between La Porte and Gibsonville covers an old 
channel, and that none of the gravel deposits in the valley of the Feather River can be regarded as 
belonging to the system of drainage which had its outlet by way of La Porte. 
Trustworthy statistics in regard to the amount of gravel that has been removed from the mines 
of this vicinity, and in regard to the yield of gold in gross or per cubic yard, are hard to get. All 
accounts agree in estimating the yield of the district by millions of dollars, though it is not pos- 
sible to say in just what way the aggregate yield ought to be credited to the different mining 
camps. La Porte has been one of the principal shipping centres for the gold obtained, not only 
from its own immediate vicinity, but also from the extensive deposits of gravel near Gibsonville 
and on the opposite side of Slate Creek between Potosi and Portwine. To give some idea of the 
past value of these mines, I will quote a few sentences from a sworn statement of Dr. S. T. Brew- 
ster, the proprietor of the stage-line from La Porte to Marysville from 1855 to 1871. Dr. Brewster's 
statement as to the business of those years is: “.... from books and accounts in my possession 
I find that there has been transported for the banking-house of John Conly & Co. [of La Porte] 
over $40,000,000 worth of gold-dust and bullion. I get this account valuing gold-dust at 
$20,000 for the 100 pounds, making 100 tons of treasure for that house alone.” Other bank- 
ing-houses shipped about half as much more, and a large amount was taken by private hands ; 
so that the total shipments must have amounted to at least $60,000,000, or an average of 
nearly $4,000,000 a year. In more recent years the yield has not exceeded $1,000,000 per 
year. 
The following data in respect to the yield of gold per cubic yard of gravel I obtained from Mr. 
Hendel, who personally assured me of their accuracy. In one of the La Porte claims a piece of 
ground 250 by 100 feet square and with banks of about thirty feet in height yielded $87,000, an 
average of $3.13 per cubic yard of gravel washed. In another claim a piece of ground 125 by 100 
feet square was drifted to a height of six feet, and yielded $57,500; this corresponds to the enor- 
mous value of $20.87 per cubic yard. At another drift mine, not in the immediate vicinity of La 
Porte, however, the yield amounted to $4.20 per cubic yard. When these values are compared 
with those obtained at Forest City, they do not seem to be overestimated. 
From another source I learned that in the year 1864 or 1865 the sum of $300,000 was 
obtained by the washing of a portion of the Secret Diggings gravel, 300 by 100 feet square. 
The bank was 140 feet high. The average yield per cubic yard, therefore, was nearly two dollars 
for the whole bank. 
(II.) I have already expressed the opinion that the lava ridge above La Porte covers a channel 
of gravel. The grounds for this opinion are mainly hypothetical, for, so far as I could learn, no 
one has any positive knowledge of what underlies the lava for a distance of at least five miles, 
that being about the distance from La Porte to the ‘Go-ahead shaft.” I went over the road be- 
tween La Porte and Gibsonville twice in each direction. On one occasion I was the guest of Mr. 
S. Wheeler, one of the proprietors of the Bank of La Porte, and a gentleman interested in many 
of the mining operations in the vicinity. I am also indebted to him for many other favors. 
The stage-road from La Porte, after crossing the gravel mines, follows up one of the forks of 
Rabbit Creek, and soon gets above the level of the exposed bed-rock. For the rest of the way, 
until a point near Gibsonville is reached, nothing but volcanic rock is seen along the road. The 
summit of the road has an altitude of 5,583 feet, but this is several hundred feet below the crest 
of the ridge. From several points striking and impressive views of the old channel on the oppo- 
site side of Slate Creek can be obtained. 
About a mile from La Porte there is a remarkable erratic boulder of large size by the side of 
