Howlock Mountain in central Oregon’s Cascade Range, just north of Mount Thielsen on the Cascade Crest, is the deeply eroded remnant of a shield volcano rather than simply an isolated peak. Its modern shape was formed chiefly by Ice Age glaciation, which stripped away much of the volcano’s sides and left a rugged terrain of deep cirques surrounding a central ridge. That ridge is capped by several sharp horns, giving the mountain its striking profile. The summit stands on the boundary between Douglas County and Klamath County.