340 RESOURCES OF CALIFORNIA. 



pieces of driftwood, and from drift trees with the tops point- 

 ing down stream. We find such marks in live streams, and 

 they cannot be attributed in the Dead Blue, as it is sometimes 

 called, to any influence save that of a strong current flowing 

 southward. 



It was a stream of wonderful force, far exceeding in power 

 any of its size now known. The miners find strata of bould- 

 ers, many of which weigh a ton, deposited over a width of a 

 quarter of a mile, and a length of sixty miles ; above that is 

 another stratum of boulders, in which half a ton is a com- 

 mon weight, and so on, until ten feet above the bed-rock we 

 find boulders a foot through. We do not know, nor are we 

 justified in supposing, that the Columbia or the Mississippi 

 could distribute such boulders with such regularity. The 

 entire depth of the gravel is from 200 to 400 feet deep, aver- 

 aging 300. 



The bed of the Dead Blue, at Forest Hill, is 2,700 feet, and 

 at Little Grizzly, the most northern point to which it has been 

 distinctly traced, 4,700 feet high a descent of 2,000 feet in 

 65 miles, or 37 feet in a mile. A fall of five feet in a mile 

 makes a swift river ; with one foot in a mile a canal eats away 

 its banks. The country in which the Dead -Blue runs has 

 been raised by subterranean forces, or contractions of the earth's 

 crust, and the upper end may have been elevated more than 

 the lower; though the Sierra Nevada down to 36 has been 

 raised more than that to the northward. 



North of Sierra County, the Dead Blue River is covered 

 with lava, or otherwise hidden, while south of Placer, it has 

 been washed away or covered with later alluvium. 



The dead rivers are much richer in gold than the live ones. 

 They were larger ; they eroded greater masses of rock, and had 

 access to larger bodies of quartz, probably auriferous. The 

 streams of the present day have cut down through those 

 of the Pliocene era, and are invariably much richer below 

 the intersection than above. 



