Topographically, the region is dominated by the Eurasian Plate, except for its eastern part, which lies on the North American, Amurian and Okhotsk Plates. It is divided by three major plains: the West Siberian Plain, Central Siberian Plateau and Verhoyansk-Chukotka collision zone. The Uralian orogeny in the west raised Ural Mountains, the informal boundary between Europe and Asia. Tectonic and volcanic activities are frequently occurred in the eastern part of the region as part of the Ring of Fire, evidenced by the formation of island arcs such as the Kuril Islands and ultra-prominent peaks such as Klyuchevskaya Sopka, Kronotsky and Koryaksky. The central part of North Asia is a large igneous province called the Siberian Traps, formed by a massive eruption occurred 250 million years ago. The formation of the traps coincided with the Permian–Triassic extinction event.