GLACIAL PHENOMENA IN THE ADIRONDACKS 399 
for its progress, and to become stagnant in narrow passes.?. The 
St. Lawrence valley was therefore a natural channel for ice mov- 
ing from Labrador, and in the same way at the junction of the 
St. Lawrence and Champlain valleys two broad outlets of easy 
progress were afforded. The Adirondack highlands, with their 
steep-sided, narrow passes were most unfavorable to glacier 
motion. 
STRIZ’ AND GENERAL NATURE OF ADIRONDACK ICE MOVEMENT. 
Striz in the Champlain valley are somewhat variable in direc- 
tion. The prevailing direction is southwest, but cross striz are 
found, and southeast directions are not uncommon. This is 
what might be expected on the hypothesis that the Adirondacks 
were filled with nearly stagnant ice. The ice stream coming 
down the St. Lawrence would be forced either to turn aside to 
the south or to push on in its own direction against a great 
immovable mass. The northern part of the Champlain valley 
would therefore be a critical point, and slight variations in the 
amount of ice, or in temperature, or other variable factors, might 
make great differences in the direction of motion. 
Upon the crystalline rocks of the Adirondacks proper the 
direction is uniformly southwest. No striz were observed in 
this region in other directions, except those which could be 
clearly shown to be influenced by some topographic variation of 
local character. There appears to be no change in direction 
with altitude. The approach to the high and rugged mountains 
is marked by a conspicuous decrease in the number of striz, 
which is what would be expected if the ice were stagnant in the 
valleys. Chamberlin observes that ice movements as a rule are 
from the basins to the highlands, due to the increase in relative 
rate of waste with the retardation of the ice mass. In the 
Adirondacks this appears to have had but slight expression ; such 
data as are available indicate that ice which had once passed the 
critical point at the boundary of the region, passed on toward 
T, C. CHAMBERLIN, “ Rock Scorings of the Great Ice Invasion,” Seventh Annual 
Report, U. S. Geol. Surv., 1885-86, pp. 155-248. 
