The ice age in North America and its bearing upon the antiquity of man5th edwith many new maps and illus., enland rewritten to incorporate the facts that bring it up to date, with chapters on Lake Agassiz and the Probable cause of glaciation . \\A\\\ theice-front on that side, and at about equal distances from eachother, each one rising from the waters edge to the foot of themountain, where they are 408 feet above tide. An inspec-tion of the upper moraine-ridge shows the manner of its for-mation. This transverse ridge is half a mile below the ice-front, and is still underlaid in some portions
The ice age in North America and its bearing upon the antiquity of man5th edwith many new maps and illus., enland rewritten to incorporate the facts that bring it up to date, with chapters on Lake Agassiz and the Probable cause of glaciation . \\A\\\ theice-front on that side, and at about equal distances from eachother, each one rising from the waters edge to the foot of themountain, where they are 408 feet above tide. An inspec-tion of the upper moraine-ridge shows the manner of its for-mation. This transverse ridge is half a mile below the ice-front, and is still underlaid in some portions with masses ofice ninety feet or more in thickness, which are melting awayon their sides and allowing the debris covering them to slidedown about their bases. Kettle-holes are in all stages of for-mation along this ridge. The snbglacial stream emergingfrom the southeast corner of the glacier next the mountainrushes along just in the rear of this moraine-ridge, and infront of a similar deposit in process of formation on the veryedge of the ice where the medial moraines spoken of termi- 58 Tilt: ICE AGE IX NORTH AMERICA. nate. Eventually this stream will break out in the rear ofthat deposit also, and leave another ndge similar to the one. V\B. 26.—Ill ihe foreground on the right is a mass of ice, one half mile in front of the gla-cier, one hundred or more feet thick, covered with gravel, slowly sliding down to formthe rim of a kettle-hole. The mountain back is 3,100 feet high. Near B, Fig. 32. now slowly settling down into position south of it. This firstridge south of the subglacial stream, with its ice still meltingin exposed positions under its covering of gravel, can not bemany years old. Still another sign of the recent date of this whole moraineappears at various places where water-courses, coming downfrom the mountain, are depositing superficial deltas of debrisupon the edge of the glacial deposit. These deltas are verylimited in extent, though the annual deposition is b
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