Shaler.] 
460 
[Jan. 15, 
NOTE ON GLACIAL CLIMATE. 
BY N. S. SHALER. 
[Published by pei-mission of the Director of the U. S. Geological Survey.] 
Evert fragment of evidence, which can serve to show us the 
character of the climatal conditions during the last glacial period, 
is so important that I venture to present certain facts which so far 
as I am aware have hitherto escaped attention. The evidence I 
mean to discuss is found in this country and Europe in the regions 
immediately south of the glaciated areas of the two continents. It 
is a well-known fact that in the present condition of the climates 
of the earth, the decrease in temperature as we rise above the sea 
is about 3° F. for each 1000 feet of altitude. Local circumstances 
may considerably affect this variation, but the range is not great. 
If glaciers were by the refrigeration of the climate restored to the 
surface which they occupied during the last ice period, we should 
expect to find the line of perpetual snow rising as we went south- 
ward about 3030 feet for each degree of latitude. 
If on an inspection of the areas glaciated during the recent ice 
epoch we should find that this principle in the distribution of the 
glacier did not hold, we should apparently be justified in the sup- 
position that the glacial climate was not due to greater cold than 
that which exists at present. Any departure from the normal rate 
of ascent of the perpetual snow line in the region south of the gla- 
cier would be likely to throw some light on the climatal conditions 
prevailing during the time when the continental ice sheets were 
developed. 
Beginning our inquiry with the Appalachian section of eastern 
America, we find there a region in many ways well suited for the 
determination we seek to make. The principal front of the ice 
stretched across the continent on a line which is now well deter- 
mined. It is unmistakably evident that it crossed the valley of the 
Ohio at Cincinnati and extended a little distance south of that 
stream into Kentucky. I have recently reexamined the evidence 
which goes to show the presence of the ice at the above-named point 
and have no doubt as to the goodness of the determination. At 
this point the surface of the country lies at a height at no point ex- 
ceeding 900 feet above the level of the sea. From this position the 
level of the country gradually rises in a southerly direction until in 
the synclinal mountains near Cumberland Gap it attains a height 
