226 THE JOURNAL OF GEOLOGY. 



through them from one depression in the glacier to another. In 

 some instances they are floored with debris, some of which is 

 partially rounded. As melting progresses this material is con- 

 centrated at the surface as a moraine. 



The ice in the various portions of the glacier was observed to 

 be formed of alternate blue and white bands, as is the rule in 

 glacial ice generally. The blue bands are of compact ice, while 

 the white bands are composed of ice filled with air cavities. The 

 banded structure is usually nearly vertical, but the dip, when 

 noticeable, is northward. Nearly parallel with the blue and white 

 layers, but crossing them at low angles, there are frequently bands 

 of hard, blue ice several hundred feet long and 2 or 3 inches in 

 thickness which have a secondary origin, and are due to the freez- 

 ing of waters in fissures. 



The rapid melting of the surface produces many curious phe- 

 nomena, which are not peculiar to this glacier, however, but com- 

 mon to many ice bodies below the line of perpetual snow. The 

 long belts of stone and dirt forming the moraines protect the ice 

 beneath from the action of the sun and air, while adjacent sur- 

 faces waste away. The result of this differential melting is that 

 the moraines become elevated on ridges of ice. The forms of 

 the ridges vary according to the amount and character of the 

 debris resting upon them. In places they are steep and narrow, 

 and perhaps i 50 or 200 feet high. From a little distance they 

 look like solid masses of debris, and resemble great railroad em- 

 bankments, but on closer examination they are seen to be ridges 

 of ice, covered with a thin sheet of earth and stones. The sides 

 of such ridges are exceedingly difficult to climb, owing to the 

 looseness of the stones, which slide from beneath one's feet and 

 roll down the slopes. The larger bowlders are the first to be dis- 

 lodged by the melting of the ice, and, rolling down the sides of 

 the ridges, form a belt of coarse debris along their margins. In 

 this way a marked assortment of the debris in reference to size 

 and shape frequently takes place. In time the narrow belts of 

 large bowlders become elevated in their turn and form the crests ' 

 of secondary ridges. Rocks rolling down the steep slopes are 



