MINES AND MINING 



From Redding south, if the route be by the east 

 side of the valley, or if the traveler come from the 

 east by way of the Western Pacific, he will see at 

 Oroville one of the famous gold-dredging fields. Of 

 the total gold production, of about $20,000,000 per 

 annum that California now yields, 37%% is won by 

 the dredges. These are huge machines mounted on 

 boats floating in ponds, and digging as much as 65 

 feet below water level by means of a continuous 



Figure 8 

 The gold dredging region of the Sacramento Valley. 



chain of heavy steel buckets which scrape up or 

 break off the gold-bearing gravel. It is delivered by 

 the buckets to a big revolving trommel screen from 

 which the fine material passes over riffles while the 

 coarse rock is delivered, by means of a belt con- 

 veyor, to the rock pile in the rear. Most of the boats 

 are held against the bank by steel masts or "spuds" 

 dropped into the loose ground at the rear of the 

 boat. The dredges are swung backward and for- 

 ward across the face of the cut by wire ropes 

 manipulated by winches. The whole machine is 

 driven by electricity. Other important dredging 

 fields occur east of Marysville, and at Auburn and 

 70 



