Broken Top is a complex stratovolcano. It lies northwest of Ball Butte and southeast of South Sister (part of the Three Sisters complex volcano), which is located at longitude 121.7° W and latitude 44.08° N. It has an elevation of , with a volume of . Like other Cascade volcanoes, Broken Top was fed by magma chambers produced by the subduction of the Juan de Fuca tectonic plate under the western edge of the North American tectonic plate. The mountain was also shaped by the changing climate of the Pleistocene Epoch, during which multiple glacial periods occurred and glacial advance eroded local mountains.