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
Davidof Volcano with variations of moss, lichen, and heath. Spread throughout the island are grass and sedges, which cover much of the lower surface. Fungi, liverworts, horsetails, and ferns, can be found on the island, along with flowering plants, such as the narcissus anemone, lupines, and orchids. Seaweed is also common on the island's beaches. Davidof Volcano Davidof Volcano is an inactive stratovolcano and caldera remnant in the Aleutian Islands of Alaska, USA, from Anchorage. Located on the eponymous island, Davidof is part of the Rat Islands sub-chain. It is also part of the "Aleutian Krakatau", a group of four islands formed