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Paoha Island is a volcanic island in Mono Lake, an endorheic lake in the U.S. state of California. Formed by a series of eruptions in the 17th century, Paoha is composed of lakebed sediments deposited above volcanic domes. It is one of two major islands in the lake, the other being the smaller Negit Island. Its name comes from a Native American word, ''Pa-o-ha'', describing the abundant hot springs and fumaroles on its surface. ==History and geology== Only about 350 years ago, before the mid-17th century, the present-day Paoha Island did not exist.〔Hill, p. 327〕 Volcanic eruptions on the lakebed gave rise to the island, which eventually rose to above sea level, above the present-day elevation of Mono Lake. The pale color of the island is attributed to lakebed sediments rising above the lake surface along with the volcanic material.〔 The volcanic origin of the island gave rise to many vents, hot springs, fumaroles and mudpots on the surface of the island. An eruption sometime before the twentieth century created a crater lake that is said to be shaped like a heart. Paoha Island is the younger of the two Mono Lake islands; Negit rose about 1,350 years before Paoha.〔Hill, p. 328〕 Paoha Island was named by Israel Cook Russell, a well-known American geologist, in the late 19th century.〔Hill, p. 326〕 It supposedly received its name from the Paiute word, ''pa-o-ha'', for spirits they believed to exist in Paoha Island's hot springs. These spirits, or elves, were described as "diminutive sprites having long, waving hair, that were sometimes seen in the vapor-wreaths escaping from the hot springs."〔Russell, p. 211〕 The surface sediments of Paoha Island consist primarily of clay and marl, which are responsible for the pale surface. Volcanic ash is scattered all around the island and basalt is exposed at some of the lower elevations. There are also river-deposited sediments and granite rocks.〔Russell, p. 212〕 In his semi-autobiographical book Roughing It, writer Mark Twain recounted a "voyage of discovery" to the island while camping on the shores of Mono Lake. He and a companion had been led to believe that on the island "within ten feet of the boiling spring is a spring of pure cold water, sweet and pure," but once there they "found nothing but solitude, ashes, and heartbreaking silence"—and they had already emptied their canteens.〔 Meantime their untethered rowboat began to drift away. Marooned, they would have died of thirst and starvation: it was a twelve-mile swim back to shore and "that venomous () water would eat a man's eyes out like fire, and burn him out inside too, if he shipped a sea."〔 As the wind of a rising storm blew the rowboat past an island cape, Twain's companion managed to jump aboard and recover it.〔 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「Paoha Island」の詳細全文を読む スポンサード リンク
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