I recently took a flight from Australia to South Africa. Here is the Antarctic pack ice as seen from the air.
The legendary XKCD is, by turns, funny and educational. The above entry (full-size image and mouse-over text here) illustrates brilliantly the thickness of the Laurentide ice sheet during the height of the Wisconsin glaciation. The enormous weight of that ice sheet had an impact of course – as the diagram below indicates, the continent is still rebounding. At quite a few millimetres per year.