638 OREGON AND NORTHERN CALIFORNIA. 
to be discovered.* We know nothing respecting the position of the 
manganese ores on the Northwest Coast. The granites passed over by 
us were singularly free from even the more common granite minerals. 
Ancient Sandstone, Shale, and Conglomerate. 
The rocks of this formation were found associated with the ancient 
Plutonic rocks, and the coarser varieties consist of materials derived 
mostly from the talcose and prasoid beds. 
The largest beds of these conglomerates and sandstone were found 
in the Shasty Mountains, where no other deposits of any kind were 
seen excepting the Plutonic and metamorphic described. Following 
down Destruction River, we travelled for eighteen miles over this 
formation, and left it again for talcose and prasoid beds, about thirty 
miles before reaching the Sacramento plains. On the south fork of 
the Umpqua, the formation was observed with the same characters, 
and associated with similar talcose and prasoid rocks. 
The sandstone is a fine-grained rock, hard and gritty, yet argilla- 
ceous in its appearance, and presenting brownish or bluish-black and 
erayish-green colours. ‘Though dull, it glistens faintly with minute 
scales of mica or talc, and with a lens, grains of quartz may be dis- 
* Since the above was written, gold has been found on several of the eastern tributa- 
ries of the Sacramento. It was first detected, in the spring of the present year, (1848,) 
on the “ American fork,” a stream forded by us just before reaching Sutter’s, a settle- 
ment on the Sacramento, about eighty miles above San Francisco. Since then, not only 
the affluents of this fork, and ravines opening into it, but other streams, flowing from the 
same great range, the Sierra Nevada, have been found to be highly auriferous. The gold 
occurs in the sand and gravel in grains, and occasionally in pieces weighing several 
ounces. There is little doubt that this gold district will be found to have very wide 
limits. The upper prairie of the Sacramento, from where we reached the Sacramento 
plains, was everywhere covered with the kind of quartzose pebbles that indicated a wide 
prevalence of the same rocks of the talcose series that we had traversed for a long dis- 
tance in the Shasty Mountains and farther north. 
The rocks most likely to afford gold are more or less slaty in structure, being either 
talcose, chloritic or micaceous slates, or argillite, and containing white quartz in inter- 
laminations and beds, and also in large or small veins. The quartz, the common matrix 
of the gold, is frequently cellular, and is sometimes rusty from the decomposition of 
pyrites. True granites and gneiss having quartz veins may afford gold, but this is not 
common. ‘The puddingstone described on page 6389, is not an unlikely place for gold, 
judging from the gold region of Brazil and other countries. 
The extensive mines of cznnabar recently discovered in this region, about twelve miles 
south of San José, will add greatly to the convenience of gold mining. 
