The former, as is well known, owes its origin to the action of ice on the mountains of Norway in the glacial period.
If the glacial period were uniformity, what was catastrophe?
Again, as Chamberlin suggests, let it be supposed that a Krakatoan eruption every two years would produce a glacial period.
I cannot see the difficulty about the cessation of the glacial period.
The glacial period was not one and simple, but comprised several phases.
I have been particularly struck by your remarks on the glacial period.
So conversely it will be with the northern hemisphere, while the southern passes through a glacial period.
I did not then know of the glacial period, or the actions of glaciers.
Yet such changes appear to have occurred during and since the glacial period.
But surely these changes are not comparable to the conditions of the glacial period.