3i6 American Geologist. ^^y- '^^^^ 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
Glaciation of the Green Mountains, C. H. Hitchcock, pp. 21, Montpel- 
ier, Vt., 1904. 
Under this title Dr. Hitchcock discusses also the glaciation of the 
Hudson-Champlain valley, of the Adirondacks and of the Canadian ter- 
ritory lying next adjacent on the north. He shows that "there was a 
glacier of continental dimensions, having its starting point in Labrador 
and sending out streams on every side. Part of it moved towards New- 
foundland ; more of it slid into the valley of the St. Lawrence, filled it 
to overflowing and discharged as rapidly as possible over the New Eng- 
land bights, the Champlain-Hudson valley and the Adirondack sum- 
mits. Perhaps the greater portion followed the depressions of the great 
lakes towards the upper Mississippi. The Champlain-Hudson valley 
was the line of least resistance, being at a low level and in the direct 
course, and therefore the ice seems to have followed it over a distance 
of eighty miles out at sea, while the excess pushed southeasterly over 
New England upon one side and southwesterly over the Adirondacks 
upon the other." 
The author shows that this general movement took place notwith- 
standing the mountainous topography that stood in its path, and proves 
it by detailed observations made by himself and by others ; viz : Gush- 
ing, Kemp, Brigham, Dana, Upham, Tarr and Ogilvie. 
Accepting this grand truth, which the author appears to have been 
the first to formulate in print, it appears capable of further westward 
extension. It also may be warrantable to greatly extend the "starting 
point" of the glacier and to assume that the Laurentide ridge, blend- 
ing with the Labrador headland, also contributed to the ice flow further 
west. It is true that to the west as far as the north shore of lake Super- 
ior and into northern Minnesota, the trend of ice-movement during the 
latest ice-invasion was westward and southwestward. This seems 
properly to be called the Laurentide glacier. But there was also anoth- 
er mass of ice that moved, in the northwest at least, from the north, 
apparently colliding with the Laurentide ice and forming some of the 
more massive of the Minnesota moraines. The maximum activity of 
this northern glacier was perhaps anterior to that of the Laurentide 
glacier, but their time relations have not yet been satisfactorily estab- 
lished. 
The generalization of Dr. Hitchcock for New England will certainly 
prove not only to be a valuable aid to the understanding of glacial 
phenomena in the region discussed by him, but its extension westward 
agrees well with many facts of Michigan, Wisconsin and Minnesota. 
N. H. w. 
