1890 .] 
463 
[Shaler. 
the Carolina mountains. It seems to me, however, that in the 
existing state of our knowledge of the distribution of the glacial 
sheet in the Cordilieran section, we cannot attach much importance 
to this evidence. 
We have now to consider the possible explanation of the facts 
above adduced. Assuming that the relative height of the surface 
occupied by the glacier, when it crossed the Ohio River and that 
of the region within two hundred miles south of it, even during the 
ice epoch, were what they are at the present da} r , it at first sight 
seems necessary to suppose that there was a rapid change in the 
temperature in passing from the ice front towards the Gulf of 
Mexico. Before we adopt this consideration, however, we must 
bear in mind the fact that the ice sheet of the last glacial period 
probably advanced for a considerable distance south of the perpet- 
ual snow line, in substantially the same way in which an Alpine 
glacier descends in many cases to the depth of a thousand feet or 
more below the fields of enduring snow by which it is fed. Ac- 
cepting the elevation of the continents as they now exist and al- 
lowing 3° of temperature for each 1000 feet of altitude, it seems 
likely that the snow line just touched the summit of the Carolina 
mountains and came to the surface of the sea near the southern 
end of Hudson’s Bay. In other words, the protrusion of the ice 
to the south of this glacial snow line carried it at a distance of 
near 1000 miles south of the gathering ground. This supposition, 
however, is of little value, for the reason that the level of the con- 
tinent was clearly much disturbed during the glacial period, the 
surface declining to the northward within the glacial envelope and 
probably rising to the southward of the ice front. 
It seems to me most likely that during the occupation of the 
northern part of the continent by glaciers, the southern portion of 
the continent was considerably elevated. All the streams which 
discharge into the ocean south of the former ice front between New 
York and the Rio Grande show in their lower parts only moderate 
accumulations of alluvium which has been deposited since the close 
of the glacial period. They generally enter bays which appear to 
be the lower parts of gorges which were formed during the period 
when the area was more elevated than it is at the present time. 
These facts make it probable that if the mountains of North Caro- 
lina varied in elevation from the present height, they were more 
elevated than at this day. All the facts are against the supposi- 
