Ice Age National Scientific Reserve

[A map in the upper left corner of the marker shows the extent of glaciation over North America and Wisconsin's position. Below it, a map shows the extent of glaciation in Wisconsin, with the locations of National Scientific Reserve Sites ...

Ice Age National Scientific Reserve

[graphic of] Prominent Glacial Features

Deep winter in Wisconsin lasts about three months. But during the last two million years, dramatic shifts in climate produced periods with longer winters. These cold spells lasted thousands of years. As snow accumulated an ice ...