410 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
constituting from 90 to 99 per cent of the whole, while neighboring 
sections of till show, as usual, that the ground moraine is mainly of 
strictly local origin. As I have previously stated, this contrast is 
what we should expect in any case, since the modified drift has 
been transported by water as well as by ice; but it is also evidence, 
if not complete proof, that its glacial transj^ortation was in part 
englacial. In the eskers to which Davis particularly refers, the 
detritus of relatively local origin is found near the top as well 
as near the bottom of the section, though perhaps less abundantly, 
and that detritus is surely even more of a 
glacial than for the superglacial hypothesis, since it presupposes 
that the subglacial stream could erode the bed rock or till above 
which it had already aggraded its channel from fifty to one hundred 
feet. 
difficulty for the sub- 
LITERATURE. 
Chamberlin, T. C. 
’95. Recent glacial studies in Greenland. Bull. geol. soc. America, vol. 6, 
p. 199-220, pi. 3-10, Feb. 6, 1895. 
Crosby, W. 0. 
’94. Geology of the Boston Basin, vol. 1, part 2 ; Hingham. Occasional 
papers Boston soc. nat. hist., vol. 4, p. 179-288, pi. 10-12. 
’96. Englacial drift. Amer. geologist, vol. 17, p. 203-234. 
Davis, William M. 
’92. The subglacial origin of certain eskers. Proc. Boston soc. nat. hist., 
vol. 25, p. 477-499. 
Nansen, Fridtjof. 
’90. The first crossing of Greenland. 2 vols., ill. 8vo : London. 
Russell, Israel C. 
’91. An expedition to Mount St. Elias, Alaska. National geographical mag., 
vol. 3, p. 53-204, pi. 2-20, May 29, 1891. 
’92. Mt. St. Elias and its glaciers. Amer. journ. sci., 3d ser., vol. 43, p. 
169-182, pi. 4, map. 
’93. Malaspina glacier. Journ. of geol., vol. 1, p. 219-245, Apr.-May, 1893. 
