



EXPLANATION OF PLATE XVIII 



Wh< 



GLACIATED ROCKS 



Upper Figure. A portion of the east wall of the valley containing 

 Muir Glacier, at a point nearly opposite the end of the glacier in 1899. 

 The conspicuous polished surfaces are 200 to 300 feet above tide-level, 

 and were probably covered by ice a century ago. The direction of 

 movement was from left to right. See page 207. 



The axis of the camera was elevated. Photographed by G. K. Gil- 

 bert, June 9, 1899. Negative NO. 243, United States Geological 

 Survey. 



Lower Figure. The foreground shows an ice-worn prominence 

 of the east wall of Muir Valley, just south of the Dirt Glacier. It is 

 viewed from the up-stream side. Its altitude is about 550 feet. It 

 was probably covered by ice a century ago. See page 208. 



The distance shows Muir Inlet and its western wall, with a foreland 

 of water-laid gravels an ancient moraine delta. 



Photographed by G. K. Gilbert, June 9, 1899. Negative NO. 269, 

 United States Geological Survey. 



\ in m 



. 



t 



