Glaciers form in places where the climate is cold enough for year-round snow.
Instead of flowing down a mountainside, they creep over a great part of the land mass. Imagine being surrounded by ice and snow as far as you can see. That’s probably what an ice age is like.
Greenland and Antarctica are the only two areas on Earth where continental glaciers remain.
The glaciers are miles thick in the center and, under pressure, ooze over the landscape. The edges of the glacier are much thinner and sometimes extend into the ocean.