Little Studies in the Yosemite Valley. 223 



modest scale is that of the deep cove of the tiny Sentinel 

 Fall, not far west of Sentinel Rock. Its real nature is 

 perhaps best appreciated from a study of the new Geo- 

 logical Survey map of the Yosemite Valley. The con- 

 tours, it will be seen, draw in abruptly at this re-entrant, a 

 full quarter m.ile back from the regular valley side. 

 Having accustomed the eye to the meaning of this feature, 

 now glance across to the north side of the valley, to the 

 place where the Yosemite Falls Trail begins its ascent. 

 Its first flight of kinky zigzags leads up into an embay- 

 ment or amphitheater with precipitous walls, almost 

 horseshoe-shaped in plan. It is perhaps not so accentu- 

 ated as the Sentinel Fall recess, but it is of ampler, grander 

 proportions. The debris slope over which the trail 

 ascends, it should be noted further, is of exactly the same 

 nature as that at the foot of the Sentinel Fall. But, while 

 these features alone would seem to suggest a fall-site, still, 

 there is need of corroborative evidence of another sort, 

 namely, some trace of a former stream channel above the 

 cliff. And therein are we not disappointed: the chan- 

 nel, or group of channels, through which the water made 

 its approach, are very much in evidence. Each one of 

 them is carved in solid rock and may be readily followed 

 on the ground to the very spot where its stream plunged 

 over. The strongest lead to the head of the amphitheater, 

 while the lesser ones cascade down the rock slopes nearby, 

 only to enter the horseshoe lower down. There is no 

 shadow of a doubt, then, in the light of this topographic 

 evidence, that we have to do here with the site of an 

 extinct group of falls. 



Whence, however, came the streams that fed the falls? 

 Following the channels upward we find them to be quite 

 short, heading against the ridge that extends from Eagle 

 Peak eastward and connects with the shapeless, timbered 

 height sometimes called Eagle Tower. The principal 

 ones come directly from the low pass in the middle of the 

 ridge. There is no source of water here today — the 

 place is dry and barren ; but in the days of the ice reign 



