Bonin Islands Pacific Plate is subducting under the Philippine Sea Plate, which creates an oceanic trench to the east of the islands: the Bonin Trench. The crust of the Ogasawara Islands was formed by volcanic activity when subduction began 45–50 million years ago, and is composed mostly of an andesitic volcanic rock called boninite, which is rich in magnesium oxide, chromium, and silicon dioxide. The Ogasawara Islands may represent the exposed parts of an ophiolite that has not yet been emplaced on oceanic crust. The rocks of the Volcano Islands are much younger; Iwo Jima is a dormant volcano characterized by rapid
The Volcano (British Columbia) The Volcano being one of the three having erupted in the last few hundred years. Tseax Cone, which last erupted in the 18th century, is the southernmost volcano in the province, while Prindle Volcano in easternmost-central Alaska, which erupted more than 10,000 years ago, is generally considered the northernmost. At least two phases of volcanic activity have been identified at The Volcano. Each event was followed by the eruption of lengthy basaltic lava flows that flowed down steep granitic flanks of the mountain ridge on which The Volcano lies. After this took place, they travelled through the Lava Fork valley