Ice Age glaciers covered a sizable portion of North America. They played a major role in shaping the modern landscape of Wisconsin, advancing and retreating numerous times over the centuries. They carved out hills and valleys, scraped plains, created lakes, and shifted the course of rivers.
The last major glacial advance in North America is known as the Wisconsin Glaciation. It featured "lobes" of compacted snow and ice that reached as far as Illinois. In some places, the glaciers were many hundreds of feet thick and their weight literally pushed the land downward!
Here is a link to a great activity to understand the flow dynamics of glaciers (how they move).
Megafauna (huge animals)
Many of Wisconsin's Ice Age animal species grew to incredible size, including the short-faced bear pictured.
Note the size of the man!
A pretty interesting article about 3-D modeling of Ice Age creatures. There is a nice illustration of dozens of Pleistocene (Ice Age) species in the middle of it.