The great ice mass that began the Ice Age in North America has been called 'a continental glacier'. It was possibly about 15,000 feet thick in its centre. This great glacier probably formed and them melted away at least four times during the ice Age. The Ice Age or glacial period that took place in other parts of the world still has not had a chance to melt away. For example, the big island of Greenland is still covered with a continental glacier, except for a narrow fringe around its edge. So the reason we still have not had a chance to melt away since the Ice Age.
Fact file
There are more than 1,200 glaciers in the Alps of Europe. Glaciers are also found in the Pyrenees, Carpathian and Caucasus Mountains of Europe and in southern Asia. In southern Alaska there are tens of thousnads of such glaciers, some from 25 to 50 miles long.
resources: Tell me why (Chancellor Press)
image 1: https://media.npr.org/assets/img/2017/10/05/6_slide-692800d0b4b8adace3533dd3f704c9a0ebda0ae1-s900-c85.jpg
image 2: https://media.buzzle.com/media/images-en/gallery/countries/austria/1200-140384431-pasterze-glacier.jpg
