North Polar Glaciation
"Velikovsky had suggested that the polar ice was generated in a very short time span by massive freezing rains. ...
"Velikovsky's suggestion actually made much more sense than many other theories, as, for example, basing northern glaciation on the fact that it snows constantly at the North Pole (it does not), or invoking Milankovitch's cycles of changing global temperatures (but cold temperatures do not make glaciers), or on the long-term changes in the Sun's sun-spot cycle. None of these causes hold up to explain glaciation.
... But there were some drawbacks to this theory which continued to nag at me. For one thing, polar glacial ice is not frozen rain; it is compacted snow. Additionally, Northern Asia has never been glaciated, even though it is clearly within the Arctic Circle just like Greenland.
"Whatever the cause of the glaciation, we can account for its persistence (as opposed to its deposition) only by having the Earth revolve around the Sun with the polar axis tilted at an angle. At a minimum, you would need a winter season of no sunlight (as we have today) to retain snow and eventually compact it to ice." (Cook, Chapter 4)
30 million years ago
Glacial maximum -- close of 40,000 years of sporadic glaciation