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Boiling Springs is a census-designated place (CDP) in South Middleton Township, Cumberland County, Pennsylvania, United States, and is part of the Harrisburg metropolitan area. The population was 3,225 at the 2010 census,〔(【引用サイトリンク】 title=Geographic Identifiers: 2010 Census Summary File 1 (G001): Boiling Springs CDP, Pennsylvania )〕 up from 2,769 at the 2000 census. ==Hydrogeology== Boiling Springs is located on the eastern side of South Middleton Township at , on the north side of Yellow Breeches Creek. Pennsylvania Route 174 passes through the town as 1st Street and leads northeast to Mechanicsburg and west to Shippensburg. Carlisle, the Cumberland County seat, is to the northwest via Front Street/Forge Road. According to the United States Census Bureau, the CDP has a total area of , of which is land and , or 0.49%, is water.〔 Boiling Springs gets its name from the natural artesian well springs located in and around the town. Boiling Springs ranks seventh in size of springs in the Commonwealth of Pennsylvania. About of water flows per day from a total of 30 springs dotted across approximately . The impression of "boiling" does not result from the temperature of the water, which stays at year-round, but rather from a unique hydrogeological feature. Two vertical diabase dikes, made up of highly impermeable igneous basalt parent rock, cut through the limestone bedrock in the area and form a subterranean "V", with Boiling Springs located at the interior tip of the V.〔Flippo, H. N., Jr. (), ''Springs of Pennsylvania'', Pennsylvania Department of Environmental Resources, Office of Resources Management, Water Resources Bulletin 10, 46 p.〕 The dikes were formed around 200 million years ago, during the late Triassic and early Jurassic periods, when Pangaea broke apart: the same period of geological activity that formed the Palisades Sill. What is now eastern North America began to separate from what is now north-western Africa. Deep faults formed in the earth's crust as the continental sections pulled apart. Magma was generated through decompression melting, and this molten rock pushed up to fill the faults. The cooler temperatures of the upper crust quickly solidified the hot rock, preventing it from reaching the surface. This geological process created large, thin, subvertical sheets of impermeable basalt, or diabase dikes.〔http://www.priweb.org/ed/TFGuide/NE/topo/topo_files2/topo_pdfs/ne_topo2.pdf Paleontological Research Institution, "Topography of the Appalachian/Piedmont: Region 2", p. 117〕 When precipitation flows down South Mountain, a large amount of groundwater is produced. Much of the water, which has an acidic pH, is able to erode the valley's limestone bedrock and continue flowing at about below the soil. However, some of the water is trapped by the impermeable diabase dikes, which act as a hydrologic barrier. The water becomes progressively confined by the dikes as it nears the tip of the "V". Due to the positive pressure created by this confinement, water is pushed up to the surface and out of the artesian aquifer, giving the impression of "boiling" springs. The springs have a median flow of per minute. One of the most prominent springs in this area is called the "Bubble". It is located directly behind the Boiling Springs Tavern, at the intersection of 1st Street and Front Street. The name of the Boiling Springs High School mascot, "The Bubblers", was inspired by this spring. 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「Boiling Springs, Pennsylvania」の詳細全文を読む スポンサード リンク
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