310 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mavch 8, 



Fig. 2. — Section across Upper California from the Pacific to the 

 Sierra Nevada. Length about 70 miles. 



Sierra Nevada. 



Gold region. 



vertical ; and their direction is a few points west of north and east of 

 south. The original ravine has been filled up, to a considerable 

 amount, by clay and loose blocks of limestone, &c. (fig. 3). 



Fig. 3. — Section of Auriferous Detritus at Sulivan's Gulch. 



Earth and stones with 

 gold : 50 feet thick. 



Crystalline limestone 



Gneiss. 



Miners have sunk pits to the depth of 1 00 feet without penetrating 

 to the bottom of the debris. It appears to have been filled to its 

 present level by frequent land-slips, the succession of which can 

 sometimes be traced, not only by the colour of the different layers, 

 but likewise by the gold being found in alternating beds of the 

 debris. 



Diggings on the North Fork of the Stanislaus liiver. — In the 



