EXPLANATION OF PLATE VI 
Upper Figure. — Profile of Hidden Glacier 
Shows the relation of the glacier snout in June, 1899, to topo¬ 
graphic details of the south wall of the valley. In the foreground are 
bedded gravels that have been overridden, eroded, and grooved by the 
enlarged glacier, and are now being trenched by running water. 
The amphitheater high in the mountain shows familiar forms of 
aqueous sculpture but is not continued downward in a gorge of com¬ 
mensurate size. The gorge probably once existed, but the containing 
spurs were removed by ice erosion at a time when the glacier was much 
larger than now. 
See page 52, and compare figure 28. 
Photographed by G. K. Gilbert, June 20, 1899. Negative no. 368, 
United States Geological Survey. 
Lower Figure. — Section of Moraine 
Shows the structure of one of the ridges of the northern lateral mo¬ 
raine of Hidden Glacier. See page 56. 
Photographed by G. K. Gilbert. Negative no. 370, United States 
Geological Survey. 
