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Mount Dana is a small stratovolcano of the Alaska Peninsula, United States, located northeast of Canoe Bay inlet at the head of Pavlof Bay. It was the source for a major eruption about 3840 years ago that produced a pyroclastic flow that filled valleys south and west of the volcano's crater and reached the sea at Canoe Bay. == Geography and geology == Dana is northeast of the Canoe Bay inlet, as it sits at the top of Pavlof Bay. It is from Anchorage.〔(【引用サイトリンク】title=Dana description and statistics )〕 The United States has the most active volcanoes in the world, many of them geologically young. In Alaska, at least 50 volcanoes, including those in the Aleutian archipelago, have erupted in historical time. The state accounts for ~80% of the United States' volcanoes, excluding the seamounts in the area, ~8% of world volcanoes, and most of these are located among the Aleutian Islands.〔 The Aleutian Islands arc serves as the northern boundary of the Pacific Ring of Fire,〔 where tectonic activity generates earthquakes and volcanic eruptions in masses. Made up of intermediate composition calc-alkaline rocks, the volcano hosts remnants of an andesite-based dome, just off the western side of the crater and east of Knutson Lake. It resides on submarine sandstone and shale, timed at the Jurassic and Cretaceous eras.〔Kienle and Wood, p. 54.〕 Rising , the volcano is topped by a crater 1.5 kilometers in height by 2 kilometers in width. To the southwest of the caldera, an exposed sector reveals a layer of sedimentary Mesozoic era stone.〔 Mount Dana is easily accessible from Canoe Bay, at any time of the year.〔Kienle and Wood, p. 55.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mount Dana (Alaska)」の詳細全文を読む スポンサード リンク
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