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Arabia Mountain is a monadnock in DeKalb County, Georgia. The peak is 954 feet (290m) above sea level, rising 170 feet (52m) above Arabia Lake reservoir. It is now part of the Davidson-Arabia Mountain Nature Preserve, a DeKalb County park. ==Geology and history== Arabia Mountain is one of Metro Atlanta's three monadnocks, which includes Stone Mountain, Panola Mountain, and Arabia Mountain. The unique topography and geology of this monadnock allows for unusual plant and animal species to thrive. Arabia Mountain has five species that are listed as both state and federally endangered, including the bright-red diamorpha plant that lives in small pools of water (known as vernal pools or solution pits) that form on the monadnock.〔arabiaaliance.org〕 Panola Mountain is 3.63 miles (5.84 km) to the southwest. While designated as one peak on USGS maps, most users familiar with the area consider the rock formation to be two peaks: Arabia Mountain to the northeast, and Bradley Mountain to the southeast, connected by a low saddle. Arabia Mountain appears to be composed of granite, like other nearby peaks such as Stone Mountain and Panola Mountain. Although made of metamorphic rock, the mountain is actually composed of migmatite, metamorphosed at higher temperatures than gneiss but not sufficiently melted to become granite. The resulting ''swirl pattern'' made the rock a popular building stone and many buildings in the region were constructed with stone quarried from the Lithonia district quarries.〔(Arabia Mountain National Heritage Area, ''Granite & Technology'' )〕 Like Stone Mountain, Arabia Mountain was quarried for decades before the property was turned over to the DeKalb park system. Structures and excavations from the quarry operations can be seen throughout the park. The stone quarried from Arabia Mountain, officially called "Tidal Grey", was prized for its high structural density and compressive strength as well as its "swirl" pattern. Tidal Grey Arabia Mountain can be seen in the construction of buildings for the U.S. Naval Academy, the Brooklyn Bridge, and street curbing in Atlanta as well as many other Georgia cities.〔arabiaalliance.org〕 Prior to 1880, the stone was hand quarried but starting in 1879, workers used drills, dynamite and air compressors to “raise a ledge” or sever a large block of stone from the mass. That allowed more control over the size of the stone and large stones could be used for dimensional or building construction.The proximity to the rail road meant that the Tidal Grey could be easily transported across the country. Another advancement to the quarrying industry at Arabia Mountain was the discovery that adding granite grit to chicken feed helped with the birds’ digestion. The Davidson family, which owned several quarries in the area, became the largest supplier of chicken grit in the world. They claimed that the sparkling particles of mica in the Stonemo grit attracted the eye and helped the chicken’s gizzard break down food. The company was so successful in distributing their feed additive, a TIME Magazine article from 1941 reported the U.S. government allowed them to continue to operate during WWII in the name of national defense.In 1949, the Lithonia district produced nearly 1.5 million tons of granite valued at the time at $3 million.〔http://arabiaalliance.org/themes/granite-technology/〕 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「Arabia Mountain」の詳細全文を読む スポンサード リンク
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