|
Wizard Island is a volcanic cinder cone which forms an island at the west end of Crater Lake in Crater Lake National Park, Oregon. The top of the island reaches above sea level, about above the average surface of the lake. The cone is capped by a volcanic crater about wide and deep. The crater was named the "Witches Cauldron" by Will G. Steel in 1885, who also gave Wizard Island its name at the same time.〔 〕 The land area of the island is . == Formation == Wizard Island was created after Mount Mazama, a large stratovolcano, erupted violently approximately 7,700 years ago, forming its caldera which now contains Crater Lake. Following the cataclysmic caldera-forming eruption, which left a hole about deep where the mountain had once stood, a series of smaller eruptions over the next several hundred years formed several cinder cones on the caldera floor. The highest of these cones, the only one to rise above the current lake level, is Wizard Island, which rises over above the lowest point on the caldera floor and the deepest point in the lake. Another large cinder cone, Merriam Cone, is located in the northeast part of the lake. Although Merriam Cone rises about above the caldera floor, its summit is still below the average lake level. Its surface features and lack of a crater indicate that Merriam Cone formed under water. 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「Wizard Island」の詳細全文を読む スポンサード リンク
|