岩尾火山群

The Ivao group of cones along the Krishtofovich Ridge of SW Urup Island contains several well-preserved cones of Holocene age. The first of a group of three young cones, at the NW end of the chain, is the Ivao cone. The SE-most cone bisects a glacial valley, forming Lake Ivao. The elongated central cone, Krutaya Mountain, is the youngest, and produced a viscous lava flow that traveled to the east.