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Stone Mountain is a quartz monzonite dome monadnock and the site of Stone Mountain Park in Stone Mountain, Georgia. At its summit, the elevation is MSL and above the surrounding area. Stone Mountain is well-known not only for its geology, but also for the enormous rock relief on its north face, the largest bas-relief in the world.〔"(Stone Mountain )." ''georgia.gov,'' retrieved February 2007.〕 The carving depicts three Confederate figures during the Civil War: Stonewall Jackson, Robert E. Lee, and Jefferson Davis. Stone Mountain was once owned by the Venable Brothers and was the site of the founding of the second Ku Klux Klan in 1915. It was purchased by the State of Georgia in 1958. Stone Mountain is more than in circumference at its base. The summit of the mountain can be reached by a walk-up trail on the west side of the mountain or by the Skyride aerial tram. ==Geology== Stone Mountain is a pluton, a type of igneous intrusion. Primarily composed of quartz monzonite, the dome of Stone Mountain was formed during the formation of the Blue Ridge Mountains around 300-350 million years ago (during the Carboniferous period), part of the Appalachian Mountains. It formed as a result of the upwelling of magma from within the Earth's crust. This magma solidified to form granite within the crust five to ten miles below the surface. Stone Mountain pluton continues underground at its longest point into Gwinnett County. Numerous reference books and Georgia literature have dubbed Stone Mountain as “the largest exposed piece of granite in the world". This misnomer is most likely a result of advertisement by granite companies and early park administration. Stone Mountain, though often called a pink granite dome, actually ranges in composition from quartz monzonite〔Herrmann, L.A. 1954. Geology of the Stone Mountain-Lithonia District, Georgia. Georgia Geological Survey Bulletin 61. Atlanta, GA.〕 to granite and granodiorite.〔Grant, W.H. 1962. Field excursion, Stone Mountain-Lithonia district. Georgia Geologic Survey Guidebook 2. Atlanta, Georgia〕 The minerals within the rock include quartz, plagioclase feldspar, microcline and muscovite, with smaller amounts of biotite and tourmaline. The tourmaline is mostly black in color, and the majority of it exists as optically continuous skeletal〔''Skeletal Tourmaline, Undercooling, and Crystallization History of the Stone Mountain Granite, Georgia, U.S.A.,'' Kristen M. Longfellow and Samuel E. Swanson (incomplete ref)〕 crystals, but much larger, euhedral pegmatitic tourmaline crystals can also be found in the mountain's numerous, cross-cutting felsic dikes. Embedded in the granite are xenoliths or pieces of foreign rocks entrained in the magma. The granite intruded into the metamorphic rocks of the Piedmont region during the last stages of the Alleghenian Orogeny, which was the time when North America and North Africa collided. Over time, erosion eventually exposed the present mountain of more resistant igneous rock. This intrusion of granite also gave rise to Panola Mountain and Arabia Mountain, both in DeKalb County, smaller outcroppings further east of Stone Mountain. 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「Stone Mountain」の詳細全文を読む スポンサード リンク
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