[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 sheet formed and grew to cover most of Canada and Northern United States.
The last great episode of the Ice Age ended about 10,000 years ago. Called the "Wisconsin Glaciation," it radically altered this landscape. Creeping ice excavated vast quantities of rock and soil. When the ice melted, the debris it carried was deposited to form an amazing variety of glacial features.
[graphic of] National Scientific Reserve Sites
Ice Age National Scientific Reserve preserves evidence of the great glaciers. The Reserve consists of nine sites administered by the Wisconsin Department of Natural Resources, in cooperation with the National Park Service. Here, present and future generations may study and enjoy their glacial inheritance.
Mill Bluff Unit
[map of unit]
The great glaciers of the most recent Ice Age never reached Mill Bluff, but its meltwaters did. Ice dammed drainage channels just north of Devils Lake and caused volumes of meltwater to back up into a large lake - Glacial Lake Wisconsin.
Mill Bluff, the steep sandstone promontory in front of you, stood as an island in Glacial Lake Wisconsin. From an overlook on top of Mill Bluff you can look out over the drained lake bed and see other picturesque bluffs that were Ice Age islands. Stone steps just ahead lead to its overlook. The walk up takes about 5 minutes.