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〕 | mouth_elevation_imperial = 1384 | mouth_elevation_note = 〔 | length_imperial = | length_round = 0 | length_note = | watershed_imperial = | watershed_round = 1 | watershed_note = | discharge_location = | discharge_imperial = | discharge_round = | discharge_note = | discharge_max_imperial = | discharge_min_imperial = 1 | discharge1_location = | discharge1_note = | map = | map_size = 300 | map_caption = |map_alt = | map1 = Oregon Locator Map.PNG | map1_size = 300 | map1_caption = Location of the mouth of Hells Canyon in Oregon and Idaho | map1_alt = Hells Canyon lies between northeastern Oregon and south-central Idaho. | map1_locator = Oregon | commons = }} Hells Canyon is a wide canyon located along the border of eastern Oregon, eastern Washington and western Idaho in the United States. It is part of the Hells Canyon National Recreation Area and is North America's deepest river gorge at . The canyon was carved by the waters of the Snake River, which flows more than below the canyon's west rim on the Oregon side and below the peaks of Idaho's Seven Devils Mountains range to the east. Most of the area is inaccessible by road.〔 ==Geology== The geologic history of the rocks of Hells Canyon began 300 million years ago with an arc of volcanoes that emerged from the waters of the Pacific Ocean. Over millions of years, the volcanoes subsided and limestone built up on the underwater platforms. The basins between them were filled with sedimentary rock. Between 130 and 17 million years ago, the ocean plate carrying the volcanoes collided with and became part of the North American continent. A period of volcanic activity followed, and much of the area was covered with floods of basalt lava, which smoothed the topography into a high plateau. The Snake River began carving Hells Canyon out of the plateau about 6 million years ago. Significant canyon-shaping events occurred as recently as 15,000 years ago during a massive outburst flood from Glacial Lake Bonneville in Utah.〔(【引用サイトリンク】publisher = U.S. Forest Service )〕 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「Hells Canyon」の詳細全文を読む スポンサード リンク
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