GLACIAL PHENOMENA IN THE ADIRONDACKS 407 
notably the Schroon and upper Hudson. The upper terrace of 
the Schroon suggests an origin as a ‘“‘kame terrace,” deposited 
against the side of a mass of stagnant ice. It has been so much 
eroded postglacially (its removed material being often blown 
into dunes on the lower terrace), that its complete history will 
need more careful study than has yet been given. 
Professor Spencer claims to have traced the Iroquois beach 
for some miles north of the Adirondacks,’ his interpretation 
being questioned by Messrs. Gilbert? and Taylor. No thorough 
work has yet been done and the northern deposits are few and 
scattered. The problem, therefore, of the correlation of the 
Pleistocene stratified deposits of the three regions —the Cham- 
plain valley, the plain north and west of the Adirondacks, and 
the Adirondacks proper —is quite unsolved. The question ofa 
Pleistocene subsidence, advocated by Professor Spencer is also 
an open one. 
EROSION HISTORY OF THE ADIRONDACKS. 
Certain main lines of drainage were established before the 
close of Cambrian time. These are tremendously modified by 
later adjustments, notably from faulting and glaciation, but the 
Cambrian drainage can be made out and is in some localities 
remarkably similar to the present. The Cambrian topography 
was mature, streams being located along the soft limestone of 
the Grenville series, while the harder gneisses stood out as 
rounded ridges. As the Adirondack island sank beneath the 
Ordovician sea, these mature rivers were drowned and sediments 
deposited along their courses. At the close of Trenton time the 
region was wholly submerged. No evidence of this complete 
submergence is forthcoming from the Adirondacks themselves, 
t“ The Iroquois Shore North of the Adirondacks,” Bull. Geol. Soc. Amer., Vol. 
ILI (1891), pp. 488-92. 
? Discussion of the above by GILBERT, of. cé¢., pp. 492-95. 
3F.R. Tayior, “Lake Adirondack,” Amer. Geol. (1897), Vol. XIX, pp. 392-96. 
4J. F. Kemp, ‘ Physiography of the Eastern Adirondacks in the Cambrian and 
Ordovician Periods,” Bull. Geol. Soc. Amer., Vol. VIII, 408-12. 
