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Glacier Peak or Dakobed (known in the Sauk Indian dialect of Lushootseed as "Tda-ko-buh-ba" or "Takobia") is the most isolated of the five major stratovolcanoes (composite volcanoes) of the Cascade Volcanic Arc in the U.S state of Washington. Located in the Glacier Peak Wilderness, the volcano is visible from the west in Seattle, and from the north in the higher areas of eastern suburbs of Vancouver such as Coquitlam and Port Coquitlam. The volcano is the fourth tallest peak in Washington state, and not as much is known about it compared to other volcanoes in the area. Local Native Americans have recognized Glacier Peak and other Washington volcanoes in their histories and stories. When foreign explorers reached the region, they learned basic information about surrounding landforms, but did not initially understand that Glacier Peak was a volcano. Positioned in Snohomish County, the volcano is only northeast of Seattle. The only volcano closer to Seattle is Mount Rainier, but as Glacier Peak is set farther into the Cascades and almost shorter, it is less noticeable than Mount Rainier. Glacier Peak is one of the most active of Washington's volcanoes. The volcano formed during the Pleistocene epoch, about one million years ago, and since the most recent ice age, it has produced some of largest and most explosive eruptions in the state. When continental ice sheets retreated from the region, Glacier Peak began to erupt regularly, erupting explosively five times in the past 3,000 years. It has erupted repeatedly during at least six periods; two of these eruptions have been among the largest in Washington. == Geology == Remnants of past, prehistoric lava domes are main components of the summit of the volcano, in addition to its false summit, Disappointment Peak. Past pyroclastic flow deposits are easily visible in river valleys near the volcano, likely caused by lava dome collapse, along with ridges found east of the summit consisting of ash cloud remains.〔 On its western flank, the volcano also has a lahar, or mudflow deposit, which runs for about into the White Chuck River Valley around 14,000 years ago. 10 other pyroclastic flow deposits are visible, all identified as relatively 10,000 years old. There is also a considerably newer mudflow, about 5,500 years old, which covers an area of between the same river valley, along with two small incidents both under 3,000 years old. Another lahar, of unidentified age, was rich in oxyhornblende dacite; and continued for into the Sauk River. There are also ash cloud deposits on the opposite eastern flank of the volcano. Studies of the mountain have to date been unable to find any correspondence with pyroclastic flows, but several past mudflows have been identified. In the Dusty Creek, located by the mountain, there is a lahar at least thick, containing pyroclastic flow deposits and other mudflows. However, this large mudflow is part of a thick concentration of past incidents at the volcano that spans the Dusty and Chocolate Creek. In the area at least ten cubic kilometers of lithic debris are contained.〔 Tephra deposits are for the most part constrained to the left flank of the volcano, and at least nine past incidents have been identified. These form several layers of tephra constructing the mountain. Smaller eruptions involving tephra occurred between 6,900-5,500 years ago, 3,450–200 years ago, and as recent as 316–90 years ago.〔 On the mountain, three additional cinder cones, Dishpan Gap, Indian Pass, and White Chuck, are located about up. The volcano has also caused such thermal events such as hot springs. There were three hot springs on the mountain: Gamma, Kennedy, and Sulphur, but Kennedy Hot Springs was destroyed and buried in a slide.〔(【引用サイトリンク】url=http://www.fs.usda.gov/recarea/mbs/recarea/?recid=17760 )〕 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「Glacier Peak」の詳細全文を読む スポンサード リンク
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