fa 
wiht favor no one of them appears to give full satisfaction, as 
strong objections have been brought against each one and not 
one of them can be said to be established satisfactorily. 
Among the different hypotheses might be enumerated the 
following: 1. The earth in its passage through space may have 
passed through colder portions that would produce glacial cli- 
mate and warmer portions that would produce interglacial per- 
iods. 
2. The sun is said to be a variable star and the glacial per- 
iod may correspond to one of the periods of decrease of the sun’s 
heat. 
3. The earth’s axis of rotation is not fixed and it may have 
shifted sufficiently to move the frigid zone into the now North 
Temperate latitudes. 
These three hypotheses might be put in the same category as 
they are all purely speculative without any positive evidence in 
their favor. They are now working hypotheses and have never 
been received with much favor by the scientific world. 
Among the explanations that have been received with more 
favor might be mentioned: 4. The elevation of the land area 
in northern latitudes which might cause the accumulation of snow 
and thus cause a glacial climate. The evidence in favor of the 
elevation is found in the deeply eroded river channels of the 
north. All through northern United States are many old stream 
channels now filled to a depth of several hundred feet with glacial 
debris. We are now standing or sitting over one of these old 
valleys. We are told that wells have been sunk at least 400 feet 
in the glacial debris in the old Onondaga Valley in Syracuse. It 
has been argued, however, with some show of reason that this 
elevation was not sufficient to cause glaciation, nor is it definitely 
known that this elevation did not take place a considerable length 
of time before the glacial period. While, in the light of our pres- 
ent knowledge on the subject, the elevation of the land does not 
appear in itself to be a sufficient cause to account for glaciation it 
is probable that either directly or indirectly it is an important 
influence and possibly deserving of greater credit than is ordin- 
arily given to it. 
