298 
GEOLOGY. 
along the Four Creeks, Tule River, Moore’s and White Creek. Along this part of the route 
there were many indications of gold 5 hut I could not learn that this section had been prospected 
with any success. I “ panned out” some of the gravel and sand from the beds of several of the 
creeks, and did not obtain gold ; hut there was no opportunity for a fair trial, and the result 
could not he considered as conclusive. 
While encamped near Posuncula River, a party of prospectors returned from its headwaters, 
and reported the existence of gold ; since that time, extensive and rich deposits have been 
opened and worked. 
Placers near the San Francisquito Rancho. —The auriferous slates, or talcose and micaceous 
slates, resembling those of the gold regions of the Sierra and of the Atlantic slope, which occur 
in the Bernardino Sierra, at the Pass of San Francisquito, have already been described. That 
region has been known as auriferous for many years, and placer mines were worked there long 
before the gold on the slope of the Sierra Nevada was discovered. 
According to De Mofras, the gold of the San Francisquito Rancho was first explored by M. 
Charles Baric, a Frenchman. He gives its distance in the mountains as six leagues to the 
northward of the Mission of San Fernando, and fifteen leagues' from Los Angeles. He further 
states : “ This vein has an extent of six leagues, following the direction of the ravine where it is 
situated. The gold is found near the surface of the soil, and some pieces weigh two to three 
drachms.” 1 This description leads me to regard the deposit as a placer, along the tsream, 
although it is described as a vein ( filon .) Since the locality was examined, accounts have been 
received from Los Angeles, stating that a placer had been discovered about eighteen miles from 
that city. The gold is described as being in the usual form of fine scales and grains ; hut the 
richness of the placer does not yet compare favorably with those at the base of the Sierra 
Nevada. 
Armagosa Mines, Great Basin. —A vein of auriferous quartz occurs in the Great Basin, not 
far from the Mormon trail to the Great Salt Lake, and about one hundred and seventy miles 
from Los Angeles. This locality has been prospected by parties from San Francisco, and several 
companies have been organized to work it, hut have not been successful, and the mine is now 
abandoned. I have not been able to obtain any reliable information of the quantity, or mine- 
ralogical and geological association of the gold ; except, that it occurs in masses of considerable 
weight, ramifying through the gangue. 
Several small specimens which I have obtained show that carbonate of lime is one of the 
principal minerals of the gangue, and filaments of gold are found penetrating the mineral in all 
directions. A small romhohedron of calc spar, obtained by cleavage, contains a short string of 
gold about the size of a knitting-needle, which protrudes from the opposite faces and appears to 
have been entirely embedded in the calcite. 
The locality is far in the interior, and in the midst of a most forbidding and desolate country. 
It would require a very rich vein to encourage extensive operations ; and they must always be 
attended with great expense, in consequence of the distance from provisions, or land fitted for 
agriculture. 
The fact, however, that gold exists in considerable quantity at this point, so far east of the 
Sierra Nevada, is a significant one, and of great importance. 
The wide expanse of the Great Basin is made up of granitic ridges and their slopes, forming: 
a broad area of hare granitic rocks and their debris. The existence of gold in place, in one of 
1 De Mofras’ Exploration of Oregon and California. 
