"Travels in Alaska 



several centuries, in which the successive moraines 

 were formed and shoved together in closer or wider 

 order, I traced the moraine to its northeastern ex- 

 tremity and ascended the glacier for several miles 

 along the left margin, then crossed it at the grand 

 cataract and down the right side to the river, and 

 along the moraine to the point of beginning. 



On the older portions of this moraine I discovered 

 several kettles in process of formation and was pleased 

 to find that they conformed in the most striking way 

 with the theory I had already been led to make from 

 observations on the old kettles which form so curious 

 a feature of the drift covering Wisconsin and Minne- 

 sota and some of the larger moraines of the residual 

 glaciers in the California Sierra. I found a pit eight or 

 ten feet deep with raw shifting sides countersunk 

 abruptly in the rough moraine material, and at the 

 bottom, on sliding down by the aid of a lithe spruce 

 tree that was being undermined, I discovered, after 

 digging down a foot or two, that the bottom was rest- 

 ing on a block of solid blue ice which had been buried 

 in the moraine perhaps a century or more, judging by 

 the age of the tree that had grown above it. Probably 

 more than another century will be required to com- 

 plete the formation of this kettle by the slow melt- 

 ing of the buried ice-block. The moraine material of 

 course was falling in as the ice melted, and the sides 

 maintained an angle as steep as the material would 

 lie. All sorts of theories have been advanced for the 

 formation of these kettles, so abundant in the drift 

 over a great part of the United States, and I was glad 



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