EXISTING GLACIERS. 27 



amphitheatre, with diameters ranging from thirty to forty 

 miles, and covers an area of about one thousand square 

 miles. From one of the low mountains near its mouth I 

 could count twenty-six tributary glaciers which came to- 

 gether and became confluent in the main stream of ice. 

 Nine medial moraines marked the continued course of as 

 many main branches, which becoming united formed the 

 grand trunk of the glacier. Numerous rocky eminences 

 also projected above the surface of the ice, like islands in 

 the sea, corresponding to what are called " nunataks " in 

 Greenland. The force of the ice against the upper side 

 of these rocky prominences is such as to push it in great 

 masses above the surrounding level, after the analogy of 

 waves which dash themselves into foam against similar 

 obstructions. In front of the nunataks there is uni- 

 formly a depression, like the eddies which appear in the 

 current below obstacles in running water. 



Over some portions of the surface of the glacier there 

 is a miniature river system, consisting of a main stream, 

 with numerous tributaries, but all flowing in channels of 

 deep blue ice. Before reaching the front of the glacier, 

 however, each one of these plunges down into a crevasse, 

 or moulin, to swell the larger current, which may be 

 heard rushing along in an impetuous course hundreds of 

 feet beneath, and far out of sight. The portion of the 

 glacier in which there is the most rapid motion is char- 

 acterised by innumerable crags and domes and pinnacles 

 of ice, projecting above the general level, whose bases are 

 separated by fissures, extending in many cases more than 

 a hundred feet below the general level. These irregu- 

 larities result from the combined effect of the differential 

 motion (as illustrated in the diagram on page 4), and 

 the influence of sunshine and warm air in irregularly 

 melting the unprotected masses. The description given 

 in our introductory chapter of medial moraines and ice- 

 pillars is amply illustrated everywhere upon the surface 



