300 E. C. ANDREWS. 



lacking the steepness of the walls farther upstream. From 

 Inspiration Point the stream has a very steep channel slope 

 to El Portal, eleven miles below El Oapitan. In this dis- 

 tance the valley floor has fallen from 3,950 feet to 1,850 

 only above sea level. At this spot only extremely faint 

 signs of ice action are apparent in the form of incipient 

 facetting or truncation of the lower valley-spur points. 

 Around El Portal the general impression gained is that of a 

 great upland valley level sunken well into an old peneplain, 

 the wide upland valley itself being well dissected by great 

 lfc canon in canon " formations, the inner canons presenting 

 a marked overlapping of spurs. 



But to return to Yosemite proper. The great chasm 

 commences in the confluence of three streams, namely, the 

 Tenaya, the Merced and the Illilouette. The Tenaya has 

 a meadow base and sheer walls like Yosemite along its 

 lower course, but very early recedes on a steep declivity, 

 and is mainly V-shaped in cross-section. The Merced 

 channel base rapidly rises, especially by the two valley 

 "steps" of the Nevada and Vernal Falls. The Illilouette 

 is a comparatively weak stream and discharges into the 

 Merced channel over an enormous cliff. Just below the 

 confluence of these rivers the weak Yosemite stream is 

 picked up after discharging itself over a double cliff some 

 2,600 feet in height. 



There appears to be evidence of several ice flood visita- 

 tions in the Yosemite locality, but notice of one only is 

 here made. It is that of an ice volume which only really 

 commenced its work owing to the smallness of the time 

 factor involved. Whether it marks a second Period of Ice 

 advance or the waning stage of a flood only, is immaterial 

 to our purpose. In either case temporary adjustment of 

 channels marked the weakening phase and then later came 

 corrasion adjusted to the strength of the younger stream. 



