is a
complex volcano that is truncated by two overlapping
calderas, the largest of which is 10 × 11 km wide. The calderas were formed as a result of two major explosive eruptions about 180,000 and 49,000–60,000 years ago.
Lake Ashi lies between the southwestern caldera wall and a half dozen post-caldera
lava domes that arose along a southwest–northeastern trend cutting through the center of the calderas. Dome growth occurred progressively to the south, and the largest and youngest of them, Kami-yama, forms the high point of Hakone. The calderas are breached to the east by the Haya-kawa canyon.
Mount Ashigara is a parasitic cone.