[TYRRELL] FROZEN MUCK IN THE KLONDIKE 43 



sequence it offered great resistance to all erosive agents. The smaller 

 streams flowing in the valleys froze to the bottom every winter as 

 they do at the present time. When the water again began to flow in 

 the spring, it ran over the top of the ice and gradually cut into it and 

 melted it away, and thus during the spring flood the water had little 

 or no erosive efl'ect on the bed of its channel, and did not carry down 

 broken masses of ice to assist in scoring the banks. These remarks 

 do not, of course, apply to larger streams such as the Stewart and 

 Yukon rivers, for they do not, and probably never did, freeze to the 

 bottom, and in the spring floods they have always carried down 

 enormous masses of broken ice. In times of flood both smaller and 

 larger streams must have often overflowed their banks, and have 

 covered the adjoining alluvial flats. The torrential waters doubtless 

 broke down trees and shrubs, and carried along sticks, leaves and 

 vegetable material of all kinds that might be lying loose on the surface, 

 and distributed these over the boggy flats. The constant growth of 

 moss then incorporated these broken branches etc., and such trees as 

 might naturally fall, into the bog and preserved them from rapid decay. 



Thus the material which at this time was washed down by the 

 streams and spread over the alluvial flats was very largely vegetable 

 debris of one kind or another, though some sand or clay might be mixed 

 with it, but the proportion of sand would be greater in the valleys of 

 the larger than of the smaller streams, for the former had the assistance 

 of floating ice as an erosive agent to cut down their banks. Most of 

 the wood which fell on, or was scattered over, the alluvial flats undoubt- 

 edly decomposed, but decomposition is not rapid in that northern 

 country, and when the conditions were favorable some of it has been 

 preserved in the "muck." 



The conditions outlined above are such as now occur in the bottoms 

 of the larger valleys of the Klondike district, like Bonanza and Sulphur 

 Creeks, where muck varies from 5 to 40 feet in depth. 



The following were the depths of muck observed on some of the 



mining claims in the Klondike District between 1898 and 1905 : 



Dominion Creek. Mining Claim No. 2 below Lower Discovery 18 ft. 



„ ,) » » )) 30 " " » ?7 



Gold Run „ „ „ „ 110 40 



II 2§ 



» » » " " - ^; 



Sulphur „ „ „ 30 & 45 _ 26 



Hunker „ » » ~" * "" 



Bear 



» 

 Bonanza 



Average 



about 15 



