Aspen Butte is a steep-sided shield volcano in southern Oregon’s Cascade Range, rising more than 4,000 feet above Upper Klamath Lake. Its modern form was heavily shaped during the Ice Age, when glaciers carved three large cirques into its north and northeast sides, erasing most of the original summit area and leaving no clear crater. The mountain’s highest point now lies along a curving ridge rather than on a classic summit cone. It is the highest of four overlapping shield volcanoes in the Mountain Lakes Wilderness that were altered by ice, and nearby Mount Carmine and Little Aspen Butte are parts of the same volcanic mass.