STATE AGRICULTURAL SOCIETY. 363 



Bear Mountain Eange is prolonged far to the north into Calaveras 

 County, and there proves the separation between the Yalley of Cop- 

 peropolis, traversed by the Eeed or Union copper lode, and the gold 

 quartz region of Angel's Camp and Carson Hill. The whole belt of 

 formations from Amador County, northeastward, through Calaveras, 

 Tuolumne, and Mariposa Counties, is an interesting field for a geologist 

 to work up, to show not only the geographical extent of the rocks and 

 the veins, but the structure or folding of the Avhole. The two lines of 

 hai'd conglomerate forming the high ridges, are distinct for nearl}^ the 

 whole distance. The serpentine rocks which accompan}- the gold forma- 

 tion are probably the result of local metamorphic action, for they often 

 occur in lenticular or elipsoidal patches in the other rocks. So also the 

 greenstone, in places, appears to be an altered portion of rocks, which at 

 other points are distinct!}" sedimentary, and exhibit slaty stratification. 



[Note. — Professor Whitney, finding that his time was so much pre-oecupied with his duties as 

 State Geologist that he could not prepare the article on the Ph3'&ical Geography of the State, so 

 notified the Board. Professor Blake was substituted as Geologist to the Board for eighteen hun- 

 dred and sixty-six, and has very kindly contributed the foregoing article for eighteen hundred 

 and sixty-fire.] 



