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Elephant Rocks State Park
Elephant Rocks State Park is a state-owned geologic reserve and public recreation area encompassing an outcropping of Precambrian granite in the Saint Francois Mountains in the U.S. state of Missouri. The state park is named for a string of large granite boulders which resemble a train of pink circus elephants.〔 The park was created following the donation of the land to the state in 1967 by geologist John Stafford.〔 The park is used for picnicking, rock climbing, and trail exploration. It is managed by the Missouri Department of Natural Resources.〔
==Geology==
Geologically, Elephant Rocks State Park consists of a tor, which is a high, isolated rocky peak, usually of jointed and weathered granite. The alkaline granite here was formed in the Proterozoic 1500 million years ago from a dome of molten magma. Nearly vertical fractures formed in the stone as it cooled, and uplift of the formation enhanced the fracturing. Eventually the overlying strata were removed through erosion, exposing the granite dome. With exposure, water and ice worked to weather and erode the surface of the granite along fracture joints. Spheroidal weathering of the granite and later erosion of the resulting saprolite that once surrounded these corestones left the elephant rocks as boulders perched on the ground surface.
The reddish or pink granite has been quarried in this area since 1869, and two abandoned granite quarries are within the park. These and others nearby have provided red architectural granite for buildings in states from Massachusetts to California, but most particularly in St. Louis, including stone for St. Louis City Hall and the piers of the Eads Bridge. Stones unsuitable for architectural use were made into shoebox-sized paving stones that were used on the streets of St. Louis as well as on its wharf on the Mississippi River. Stone quarried in the area currently is used for mortuary monuments and is known commercially as Missouri Red monument stone.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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