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POPULAR SCIENCE MONTHLY. 



beautiful lakes that now exist there, flowed far out upon the vol- 

 canic mesa at the foot of the scarp, which here has very nearly 

 obliterated the latter feature. The moraines are apparent for a 

 number of miles, but just how far they extend has not yet been 

 determined. This ice stream was probably the largest of any which 

 issued from the mountains, a fact due in great part to the elevation 

 of the mouth of the canon. Lakes fill all the depression in the bed 

 of this ancient glacier, illustrating how much the present scenic fea- 

 tures of the Sierras are due to ice action. As we go south from the 

 head of Owen's River into the valley of the same name it is apparent 

 that only at its northern end did the glaciers reach as low as the 



Glacial Moraines, Head of Owen's River. 



mouths of the canons and flow out upon the debris cone. Opposite 

 the highest and most rugged portion of the Sierras in the lower part 

 of Owen's Valley, it is evident that the temperature was too high 

 to permit the glaciers to reach an elevation as low as the valley 

 floor. The size and symmetry of many of the moraines reaching 

 into the valleys in the region of Mono Lake strike the attention at 

 once. The Green Creek glacier in particular left morainal walls 

 of great size and regularity. At the mouth of the canon the flat 

 valley is about half a mile wide, with steep and even walls of 

 bowlders and gravel rising three hundred to four hundred feet. 



