THE GEAVEL: IN PLUMAS COUNTY. 



215 





the divide between these two Forks is occupied by a mass of basaltic lava, 

 some three or four miles in length, in the neighborhood of the Buckeye 

 House ; and below that, as far as Oroville, nothing but bed-rock was seen. 



To the east of Quincy the geology is very difficult to decipher. The 

 ranges are mostly capped with lava, the main portion of their mass being 

 made up of granitic, granitoid, and various highly metamorphic rocks, with 

 intercalated porphyries and altered volcanic beds, the whole forming a 

 series of the greatest possible complication, as may have been inferred from 

 what has been said in a previous chapter in regard to the geological age of 



the fossiliferous strata in this country. 



The distribution of the gravel in Plumas north of the Middle Feather is as 

 hard to make out as is the geology of the bed-rock. So far as the writer 

 could discover from a rapid reconnoissance of the region, the gravel interests 

 were of very secondary importance ; at least from an economical point of 

 view. The scientific features of the volcanic and detrital deposits in this re- 

 gion, however, are as interesting as anywhere in the State, and their careful 

 study will undoubtedly throw light on some important points which are yet 

 ob 



scure. 



The results of the writer's investigations in Plumas County would seem to 

 indicate that, north of the Middle Yuba, gravel occurs chiefly in isolated 

 patches, at very high elevations ; that these patches are the remains of a 

 former extensive system of channels ; and that the amount of erosion which 

 has taken place since the gravel was deposited in these channels has been 

 astonishingly great. 



These inferences will be, in some degree at least, substantiated from the 

 description of two of the localities of gravel examined in 1866 by the writer; 

 one of these is on the summit of Clermont, the other on Spanish Peak. 



Clermont is a lofty mass, the highest point of the range between Quincy 

 and the Middle Fork of the Feather, and having an elevation of 6,844 feet 

 above the sea.* It seemed to have no point of equal altitude anywhere m 

 the immediate vicinity, but is slightly overtopped by Pilot Peak, eight miles 

 farther south, by Spanish Peak, ten miles distant on the west, and perhaps 

 by some points in the range to the northwest which lies between Indian and 

 American valleys, and of which Mount Taylor and Mount Hough are two 





of the dominating 



peaks. 



* At the time this observation was taken there was no station barometer nearer than Copperopolis, so 

 that the result can be received only as an approximation. 



