Pilot Rock is an isolated volcanic plug in southwestern Oregon near Siskiyou Summit, formed about 25.6 million years ago when andesitic magma cooled below the surface and later stood exposed as surrounding rock eroded away. Rising 570 feet above nearby hills and visible for more than 40 miles, it became one of the defining landmarks of the Cascade-Siskiyou country. The Takelma knew it as Tan-ts'at-seniphtha, and in the nineteenth century it guided explorers and pioneers on the Applegate Trail, giving rise to its enduring name. Now protected within the Cascade-Siskiyou National Monument and Soda Mountain Wilderness, it remains notable for its geology, history, and recreation.