Three Fingered Jack is a jagged summit in Oregon’s Cascade Range, the eroded remnant of an ancient shield volcano formed during the Pleistocene from basaltic andesite. Its eruptive history began with pyroclastic activity, continued with lava flows and later explosive eruptions, and ended more than 100,000 years ago. Glaciation then carved away much of the cone, exposing internal dikes and plugs and creating the mountain’s sawtoothed profile. The area has long been part of the Molala homeland. Known non-Indigenous visitors reached it in the 1820s, and the first recorded ascent came in 1923. Today it remains a hazardous but valued landmark and a vivid record of Oregon’s volcanic and glacial past.