438 RESOURCES OF CALIFORNIA. 



worn every day. There are not more than a dozen days in 

 the year too warm for comfort at mid-day, and the oldest 

 inhabitant cannot remember a night when blankets were not 

 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 moun- 

 tains the winters are much colder. By traveling a few hun- 

 dred miles, the Californian can find almost any temperature 

 that he may desire great warmth in winter, and icy coldness 

 in summer. 



The rocks of this State are chiefly granite and slate in the 

 Sierra Nevada, and cretaceous and tertiary sandstone in the 

 Coast Range and valleys. Veins of auriferous quartz are 

 numerous in the State near the granite, and they have sup- 

 plied by erosion the gold now found in the placers or alluvial 

 workings. Gold has been found in nearly every county ; but 

 the districts which are or have been rich in auriferous de- 

 posits, cover an area of 10,000 'square miles. The annual 

 gold yield of California is about $20,000,000. 



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 

 universal use. Large rivers are turned out of their beds ; 

 mountains are pierced by tunnels ; hills are washed away ; 

 and the rivers roll thick with mud to the sea through summer 

 and winter. 



The State has rich and productive mines of silver and quick- 

 silver ; valuable beds of borax, sulphur, asphaltum, and fire 

 olay ; and numerous mineral springs of powerful medicinal 

 qualities. 



