Volcanic pipe Volcanic pipe Volcanic pipes are subterranean geological structures formed by the violent, supersonic eruption of deep-origin volcanoes. They are considered to be a type of "diatreme". Volcanic pipes are composed of a deep, narrow cone of solidified magma (described as "carrot-shaped"), and are usually largely composed of one of two characteristic rock types — kimberlite or lamproite. These rocks reflect the composition of the volcanoes' deep magma sources, where the Earth is rich in magnesium. Volcanic pipes are relatively rare. They are well known as the primary source of diamonds, and are mined for this purpose. Volcanic pipes form as
Lemei Rock around Lemei Rock include the Indian Heaven Wilderness, which is known for the high mountain meadows among its scattered volcanic peaks. The Pacific Crest National Scenic Trail passes north/south through the volcanic field and the Indian Heaven Wilderness, which is known for its lakes and views of four nearby volcanoes: Mount Adams, Mount Hood, Mount St. Helens, and Mount Rainier. Major trails at Lemei Rock are the Lemei Trail, which climbs up the east side of Lemei Rock; and Wapiki Trail, which descends from the Lemei Trail to the deep blue Wapiki Lake, the "crater lake" of Lemei Rock. The