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Jewel Cave National Monument contains Jewel Cave, currently the third longest cave in the world, with of mapped passageways. It is located approximately west of the town of Custer in South Dakota's Black Hills. It became a national monument in 1908.〔(【引用サイトリンク】title=The National Parks: Index 2009–2011 )〕 ==History== Frank and Albert Michaud, two local prospectors, discovered the cave in 1900, when they felt cold air blowing out of a small hole in a canyon. It is unknown whether any previous inhabitants of the area were aware of the natural cave opening, which was not large enough for a person to enter.〔Jewel Cave brochure; National Park Service; GPO, WDC〕 After enlarging the cave entrance with dynamite, the Michauds found a cavern lined with calcite crystals, which led them to name it "Jewel Cave." The brothers tried to capitalize on the discovery, widening the opening, building walkways inside, and opening it to tourists. Although their venture was unsuccessful, news of the discovery eventually reached Washington. President Theodore Roosevelt proclaimed Jewel Cave a National Monument on February 7, 1908. The area around the natural entrance to the cave was further developed by the Civilian Conservation Corps in the 1930s. The National Park Service assumed management of the monument in 1933 and began offering tours in 1939.〔 As recently as 1959, less than of passageway had been discovered. That year, however, Herb and Jan Conn, local rock climbers, began exploring, and within two years had mapped . Much of the new discoveries lay outside the boundaries of the monument, under land managed by the United States Forest Service. The two agencies performed a land swap in 1965, establishing the present boundaries of the park, and enabling the development of a new part of the cave. The Park Service sunk a elevator shaft to a previously remote cave area, and built concrete walks and metal stairs and platforms along a one-half-mile loop. The "Scenic Tour" was opened in 1972. Most modern-day visitors tour that part of the cave. In August 2000, an forest fire burned 90% of the monument and the surrounding area. The visitor center and historic buildings were spared. 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「Jewel Cave National Monument」の詳細全文を読む スポンサード リンク
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