3^4 



PRINCIPLES OF STRATIGRAPHY 



parable to streams, and, like them, are confined in more or less 

 definite channels. Their length may be ten miles or more. The 

 most typical form is that of the valley glacier or alpine glacier, 

 extending from the mountain flanks or from a plateau through a 

 well-defined valley. They may be simple throughout or multiple 

 in the upper reaches, where several streams unite to form one 

 master stream of ice. At the foot of the valley they may spread 



Fig. 59. Map of the Malaspina Glacier and of Yakutat Bay, Alaska; the 

 type of a piedmont glacier. (After Russell.) 



out into glacier fans or piedmont glaciers, which may be simple, 

 i. €., resulting from a single glacier, or compound, when formed by 

 the confluence of two or more glaciers from adjoining valleys. 

 (Example, Malaspina glacier, generally regarded as a typical pied- 

 mont glacier. Fig. 59.) Of secondary rank among true glaciers 

 are cM glaciers (Gehiingegletscher), resting in the depressions at 

 the foot of cliffs on the mountain flanks, and never descending to 

 a valley; cirque glaciers (Kargletscher) in deep mountain hollows 

 or cirques surrounded by high peaks, and raz'ine glaciers {Schlucht- 

 gletscher), resting in deep gorges with precipitous walls. 



