Studies in the Sierra 



195 



cending strice which measure the angle of ascent made by the 

 bottom of their glaciers in their outflow are still clearly visible. 



Fig, I is the horizontal sec- 

 tion of the end of a Yosem- 

 ite valley, showing the ordi- 

 nary boat-shaped edge, and 

 lateral moraines (MM) ex- 

 tending from the lips. The 

 moraines and arrows indicate 

 the course pursued by the 

 outflowing ice. Fig. 2 repre- 

 sents the right lip of Yosem- 

 ite, situated on the upper 

 Merced below the confluence 

 of Cathedral tributary. The 

 whole lip is polished and stri- 

 ated. The arrows indicate the direction of the strice, which 

 measure the angle of ascent made by the outflowing ice. 



Fig. 2. 



In the presentation of these studies, we have proceeded thus 

 far with the assumption that all the valleys of the region are 

 valleys of erosion, and that glaciers were the principal eroding 

 agents ; because the intelligible discussion of these propositions 

 requires some knowledge of the physiognomy and general con- 

 figuration of the region, as well as of the history of its ancient 

 glaciers. Our space is here available only for very brief out- 

 lines of a portion of the argument, which will be gradually de- 

 veloped in subsequent articles. 



