The bluffs are formed from eroded drumlins, teardrop-shaped hills of glacial till that were deposited and shaped by glaciers during the most recent ice age. The erosive power of wind, rain, snow, and waves has formed the landscape into sharp pinnacles.[5] Although the pinnacles and cliffs, some of which rise up to 150 feet (46 m) above the lake shore,[6] have existed for thousands of years, they are constantly changing and further eroding.[5]