28 
The American Geologist. 
January, 1896 
The “dirt bands” of the Alpine glaciers, and of the Sierra 
Nevada glaciers as observed by Russell, are probably due to 
such transfer of englacial drift from the glacier bed tohights 
where it becomes exposed by the ablation of the part of the 
glacier below the snow-line. 
These opinions need not here be more fully discussed or 
supported by the evidence which seems to me to be afforded 
by our Pleistocene glacial drift for the action of the ancient 
North American ice-sheet in the ways thus indicated.* All 
that the writer here desires is to call the attention of glacial- 
ists to his former papers on the englacial drift,* and to ask 
that his views receive the added light which this Granulation 
Theory of the ice motion may contribute. 
When the ice-sheet of this continent attained its greatest 
extent, erosion probably was in progress on all the ice-covered 
country, excepting near its limits, being most rapid within 
some such distances as from 100 miles to 200 or 300 miles in¬ 
side the ice border. Deposition prevailed, we may infer, on a 
somewhat broader peripheral belt than during the ensuing 
time of disappearance of the ice-sheet, which was attended by 
the recession of this belt of deposition, estimated to have been 
then 20 to 50 miles wide, across all the previously eroded 
country. The englacial drift supplied by the wide and long 
continued erosion, is supposed, according to my studies of the 
drift formations, to have been then laid down in great part, 
apparently more than half of it all, as the ground moraine of 
subglacial till; and the remainder, which continued to be en¬ 
glacial or superglacial until the ice was wholly melted, is 
thought to have formed the retreatal moraines, kames, and 
eskers, and the valley drift in its varieties of gravel, Sand, 
clay, and loess. 
Effects of the Warm Champlain Climate. 
During the time of accumulation and culmination of the 
ice-sheets, we have proofs, in the depths of fjords and subma¬ 
rine continuations of river valleys, that their areas in both 
North America and Europe were raised 1,000 to 4,000 feet or 
more above their present altitude. To the continuously cool 
^Bulletin, Geol. Society of America, vol. hi, 1892, pp. 131-148; vol. v, 
1894, pp. 71-86. Am. Geologist, vol. viii, pp. 376-385, Dec., 1891: vol. 
x, pp. 339-362, Dec., 1892: vol. xii, pp. 36-43, July, 1893. 
