EXPLANATION OF PLATE XVIII 
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. 
