432 RESOURCES OF CALIFORNIA. 
necessary for a comfortable sleep. The climate is just of that 
character most favorable to the constant mental and physical 
activity of men, and to the unvarying health and continuous 
growth of animals and plants. In the interior, the summers 
are much warmer than near the ocean; while in the mountains 
the winters are much colder. By travelling a few hundred 
miles, the Californian can find almost any temperature that 
he may desire—great warmth in winter, and icy coldness in 
summer. 
The rocks of the state are chiefly granite and tertiary sand- 
stone; the former occupying the high mountains, the latter 
the valleys. In former eras there were .several, or perhaps 
many volcanoes in the range of the Sierra Nevada. Mount 
Shasta was one of them, and it now has hot springs on its 
summit, and sends up sulphurous vapors. On the western 
slope of the Sierra Nevada, about half way between the sum- 
mit and the foot, are numerous beds of slate and veins of 
quartz. The same formations are found in the Klamath basin 
and in other parts of the state; and in nearly every case they 
are auriferous. There is scarcely a. county which does not 
contain gold. The districts which contain enough gold to sup- 
port a mining population, have an area of about ten thousand 
square miles. The gold-yield of the state is about forty-three 
million dollars annually—more than that of any other country, 
save the colony of Victoria, in Australia. 
The number of men engaged in mining may be estimated at 
eighty thousand. Our placers and auriferous quartz veins are 
almost inexhaustible; there are great mountains of gold-bear- 
ing gravel which cannot be washed away for a century to 
come; and the quartz-lodes will last still longer. 
The gold-mining of California is conducted in the most 
thorough and enterprising manner. Although the main prin- 
ciples of the sluice and the hydraulic washing were known and 
used, on a small scale, long before the discovery of gold in 
California, it was here that those modes of working were first 
perfected, applied on an extensive scale, and brought into uni- 
