224 Sierra Club Bulletin. 



this was all quite different. The basin of the Eagle Peak 

 Meadows was then filled with ice to a depth of several 

 hundred feet. Strangely, too, the ice mass moved up the 

 basin, or toward Eagle Peak. It was a lobe of the much 

 mightier glacier that came down the valley of Yosemite 

 Creek. That ice stream when at its highest, split upon the 

 Eagle Tower and sent a portion of its volume up into this 

 cul-de-sac. Indeed, it is this glacial occupancy that is 

 responsible for the existence of the swampy Eagle Peak 

 Meadows — they represent ground moraines overgrown 

 with peat. Many high meadows in the Yosemite region 

 are of similar origin. 



The Eagle Peak lobe, apparently, breasted at times 

 against the ridge described, as the occasional glacial 

 cobbles on the same attest. From various places along 

 its front, then, but especially through the central gap, it 

 sent forth the streams that carved the channels to the 

 fall-site. Judging by the size of the channels each of 

 the streams may have equalled Yosemite Creek in volume. 



How long these conditions lasted can only be con- 

 jectured at the best. They obtained only during the 

 earlier ice advances, which were far more extensive in 

 the High Sierra than the later ones. During the latter 

 the glacier in the valley of Yosemite Creek did not rise 

 high enough to send a lobe up into the Eagle Peak 

 Meadows ; instead it threw up lateral moraines across the 

 mouth of that basin — the awkward boulder ridges among 

 which the Eagle Peak trail now turns and twists. 



Whether the Eagle Peak Falls were long-lived or not 

 is, therefore, an indeterminate problem; but, whatever 

 their period of activity may have been, this much is cer- 

 tain, that they were able while they lasted to cut back the 

 wall of the Yosemite trough by a thousand feet or more, 

 leaving a profound embayment that has endured to this 

 day. 



