PRECIOUS METALS 81 



Gold in the Placers: The gold has usually been deposited 

 where the current of a stream has been checked. A broad basin 

 above a steep-walled canyon is more likely to carry gold than the 

 valley below the canyon, provided the bed rock source of the gold 

 is above the basin. Coarse gold is more likely to be found at the 

 head of a filled basin than near its outlet. The same holds true 

 of a stream that debouches on a coastal plain which will deposit 

 the coarse gold it may carry near the head of its delta. 



A. J. Collier and F. L. Hess give the following classification 

 of the placers in Seward Peninsula: 



(1) Creek Placers: Gravel deposits in the beds and interme- 

 diate flood plains of small streams. 



(2) Bench Placers: Gravel deposits in ancient stream channels 

 and flood plains which stand from 50 to several hundred feet 

 above the present streams. 



(3) Hillside Placers: A group of gravel deposits intermediate 

 between the creek and bench placers. Their bed rock is slightly 

 above the creek bed and the surface topography shows no sign of 

 benching. 



(4) River-bar Placers: Placers on gravel flats in or adjacent 

 to the beds of large streams. 



(5) Gravel-plain Placers: Placers found in the gravels of the 

 coastal or other lowland plains. 



(6) Sea-beach Placers: Placers reconcentrated from the coastal 

 plain gravels by the waves along the seashore. 



(7) Ancient beach Placers: Deposits found on the coastal 

 plains along a line of elevated beaches. 



Klondike. This important mining field lies a little to the east 

 of the Alaskan boundary and in the valley of the Yukon. The 

 auriferous gravels of the district occupy about one-tenth the area 

 of those in Seward Peninsula. In fact the number of miles of 

 creeks bearing placer gold in the Klondike has been catalogued 

 as 50 in comparison with 750 on Seward Peninsula. The placers 

 of such creeks as the Eldorado and Bonanza averaged richer than 

 any deposits on Seward Peninsula. It was the exploitation of 

 these almost fabulously rich and relatively shallow placers that 

 the Klondike gold output went up with a bound, and it is their 

 quick exhaustion that has caused so marked a decline in their 

 annual yield. There are extensive deposits of lower grade 

 gravels, but these are not likely to make the annual yield again 

 equal to that of the banner year. (See Fig. 60.) 



