LAKE CHELAN 



421 



etc., which fall upon it from its walls. In its long journey from 

 its source to its melting point, a journey which may occupy 

 many years, large quantities of such material accumulate, and 

 it naturally falls mainly upon the edges of the glacier, forming- 

 lateral moraines. Where two branches join, the two lateral mo- 

 raines on the inside join and form a medial moraine, and thus 

 in a complicated glacier system the main glacier below the junc- 

 tion of a number of branches may bear upon its surface many 



3T SIDE OE HORSESHOE BASIN 



moraines lying lengthwise with the glacier. At the melting- 

 point all these moraines are dropped in a confused heap, form- 

 ing the terminal moraine. This may extend for a considerable 

 distance up and down the valley, because the foot of the glacier 

 moves backward and forward according to the season. In a wet, 

 cold season the foot advances down the gorge, while in a warm, 

 dry season it retreats toward its source. 



Herein we may see another point of similarity between the 



