172 Glaciation of Mountains^ Etc. — Upham. 
one time wholly ice-covered, as is demonstrated for Mt. "Wash- 
ington, the time cff the glacial envelopment was very brief, not 
sufficing for the removal of the loose masses which have been 
fractured by frost from the underlying rock. The second and 
most common type is represented by Monadnock, where the 
moving ice-sheet has carried away all the rock-fragments 
which before the Ice Age doubtless presented generally on all 
our mountain tops the same appearance as the present sum- 
mits of Katahdin and Washington ; instead of which the 
surface is now left bare, and rounded in smooth low hummocks 
of rock on the stoss side, — that is, in New England the north 
and northwest side exposed to the glacial current, — while on 
the lee side the slopes are more precipitous and jagged, not 
being deeply worn by the ice, though usually denuded of their 
preglacial frost-riven blocks. A third and infrequent type ie 
represented by the northwest slope of Mt. Carrigain, where 
deposits of glacial drift, analogous with the till of lower areas 
cover the bed-rock. 
Many bowlders and small fragments of Oriskany sandstone, 
containing characteristic fossils, were found by Hitchcock, 
Packard, and De Laski,' in the drift on the southern slope of 
Katahdin up to a bight of about 4,000 feet. They were 
derived from ledges that occur on lakes Webster and Telos, 
about twelve miles distant toward the northwest. The cur- 
rent of the ice-sheet is thus shown to have moved from north- 
west to southeast ; and in the transportation of these bowlders 
through so short a distance they were carried upward about 
3,000 feet, passing around the west side of the mountain to 
the slope where they were found. 
Special search for these fossiliferous bowlders is reported 
by professor C. E. Hamlin, in his admirable description of the 
physical geography and geology of this mountain.^ He wrote 
as follows : "Outside of the slides, I have never found drift 
upon the flanks of the mountain; but it reappears higher up, 
in very small amount on the Table-Land, but principally upon 
the northern summits, sparsely strewn among the broken 
granite that covers them. Neither on slides nor summits is 
the drift ever found in large bowlders, but always as fragments 
^ American Journal of Science, III, 1872. vol. iii, pp. 27-31. 
^ Bulletin of the Museum of Comparative Zoology at Harvard College, 
1881, vol. VII. 
