As a result, these bluffs are steep and angular, dissimilar to the rounded terrain more typical of the eastern half of the United States.

Also in the northeast is Ragged Rock, an 80-foot (24 m) tall former bluff whose protective cap was worn away and is eroding into a conical mound.

Similar structures elsewhere in Wisconsin would have been bulldozed away by glaciers, but these bluffs lie in the Driftless Area; that part of the American Midwest which was never glaciated.

It is estimated that the lake was about 60 to 80 feet (18 to 24 m) deep in this area, so the taller bluffs became islands while the shorter ones would have been entirely underwater.

For the 3000 years of the lake's existence waves eroded the edges of the bluffs, giving them their distinctive steep sides.

The flat ground in the park consists of finely sorted sediments that settled to the bottom of Glacial Lake Wisconsin.

Glacial erratics have been found on the former lakebed, which are explained as rocks which were embedded in icebergs that melted as they were floating in the lake.

Mill Bluff State Park was added to the Ice Age National Scientific Reserve in May 1971.

0.8 miles (1.3 km) north on County Road W (Funnel Road) is a pullout for the 1.25-mile (2.0 km) Camels Bluff loop trail, which passes between the two sections of Camels Bluff and leads past the base of Devils Monument and Cleopatra's Needle.