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The Aleutian Islands (; possibly from Chukchi ''aliat'', "island") are a chain of 14 large volcanic islands and 55 smaller ones belonging to both the United States and Russia.〔(【引用サイトリンク】title=Aleutian Islands )〕 They form part of the Aleutian Arc in the Northern Pacific Ocean, occupying an area of 6,821 sq mi (17,666 km2) and extending about westward from the Alaska Peninsula toward the Kamchatka Peninsula in Russia, and mark a dividing line between the Bering Sea to the north and the Pacific Ocean to the south. Crossing longitude 180°, at which point east and west longitude end, the archipelago contains both the westernmost part of the United States by longitude (Amatignak Island) and the easternmost by longitude (Semisopochnoi Island). The westernmost U.S. island in real terms, however, is Attu Island, west of which runs the International Date Line. While nearly all the archipelago is part of Alaska and is usually considered as being in the "Alaskan Bush", at the extreme western end, the small, geologically related Commander Islands belong to Russia. The islands, with their 57 volcanoes, are in the northern part of the Pacific Ring of Fire. Physiographically, they are a distinct section of the larger Pacific Border province, which in turn is part of the larger Pacific Mountain System physiographic division. ==Geography== The islands, known before 1867 as the Catherine Archipelago, comprise five groups (east to west): *the Fox Islands *Islands of Four Mountains *Andreanof *Rat Islands, and *Near Islands All five are located between 51° and 55° N latitude and 172° E and 163° W longitude. The largest islands in the Aleutians are Attu (the furthest from the mainland), and Unalaska, Umnak, and Unimak in the Fox Islands. The largest of those is Unimak Island, with an area of 1,571.41 mi² (4,069.9 km²), followed by Unalaska Island, the only other Aleutian Island with an area over 1,000 square miles. The axis of the archipelago near the mainland of Alaska has a southwest trend, but near 179° its direction changes to the northwest. This change of direction corresponds to a curve in the line of volcanic fissures that have contributed their products to the building of the islands. Such curved chains are repeated about the Pacific Ocean in the Kuril Islands, the Japanese chain, and in the Philippines. All these island arcs are at the edge of the Pacific Plate and experience much seismic activity, but are still habitable; the Aleutians lie between the Pacific and North American tectonic plates. The general elevation is greatest in the eastern islands and least in the western. The island chain is a western continuation of the Aleutian Range on the mainland. The great majority of the islands bear evident marks of volcanic origin, and there are numerous volcanic cones on the north side of the chain, some of them active; many of the islands, however, are not wholly volcanic, but contain crystalline or sedimentary rocks, and also amber and beds of lignite. The coasts are rocky and surf-worn, and the approaches are exceedingly dangerous, the land rising immediately from the coasts to steep, bold mountains. These volcanic islands reach heights of . Makushin Volcano () located on Unalaska Island, is not quite visible from within the town of Unalaska, though the steam rising from its cone is visible on a (rare) clear day. Residents of Unalaska need only to climb one of the smaller hills in the area, such as Pyramid Peak or Mt. Newhall, to get a good look at the snow-covered cone. The volcanic Bogoslof and Fire Islands, which rose from the sea in 1796 and 1883 respectively, lie about west of Unalaska Bay. File:Aleutians-space.jpg|Image of the islands taken by the STS-56 crew. File:Aleutian Clouds.jpg|These cloud formations were seen over the western Aleutian Islands. File:Alaska's Aleutian Island (ASTER).jpg|ASTER image of the islands. File:Aleutian Islands amo 2014135 lrg.jpg|Aleutian Islands on May 15, 2014, by NASA’s Aqua satellite. 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「Aleutian Islands」の詳細全文を読む スポンサード リンク
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