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〕 |footnotes =Coordinates and elevation from the Geographic Names Information System〔 }} Basin is a census-designated place (CDP) in Jefferson County, Montana, United States. It lies about southeast of the Continental Divide in a high narrow canyon along Interstate 15 about halfway between Butte and Helena. Basin Creek flows roughly north to south through Basin and enters the Boulder River on the settlement's south side. The population was 255 at the 2000 census. Archaeologists have discovered evidence of human habitation from 10,000 years ago at a site near Clancy, from Basin. From about 2000 BCE through the mid-19th century, nomadic tribes hunted bison in the grassy valleys that trend east, away from the Rocky Mountains and into the plains. By the time miners found gold in the streams in and near Basin, most of the these tribes of Indians had been forced onto reservations by the U.S. government. Basin rests above the Boulder Batholith, the host rock for many valuable mineral ores found in this part of Montana. After the town became a hub of gold and silver mining, Basin's population peaked at about 1,500 in first decade of the 20th century but gradually declined as the mines were depleted. Abandoned mining equipment, closed or barricaded mine portals, and the ruins of a smelter and ore concentrator remain in Basin in the 21st century. Historic buildings from Basin's heyday form much of the core of the CDP's small business district, which includes a fire station, a post office, two restaurants, a bar, a commercial gallery, small specialty shops. Basin has a small elementary school, its own water system, and a low-power radio station. Local volunteers and elected trustees provide limited services to the settlement, but it relies on the government of Jefferson County, Montana, for law enforcement and other services. From 1993 through 2011 Basin was home to the Montana Artists Refuge. == Geography and geology == Basin, in Jefferson County, is part of the Helena Micropolitan Statistical Area. It lies at an elevation of above sea level〔 along Interstate 15 about north of Butte and south of Helena in the narrow canyon of a small river. The community is largely surrounded by the Beaverhead-Deerlodge National Forest.〔 Basin Creek flows south through the center of Basin to its confluence with a larger stream, the Boulder River, which flows east along the south side of Basin. No paved roads except the interstate highway, which runs along the river canyon, connect Basin to other towns.〔 About upstream on Basin Creek lies the Continental Divide.〔 According to the United States Census Bureau, the CDP has a total area of , all land.〔(【引用サイトリンク】url=http://www.census.gov/geo/maps-data/data/gazetteer.html )〕 In the late Cretaceous (roughly 81 to 74 million years ago), molten rock (magma) rose to the Earth's surface in and near what later became Jefferson County and eventually formed an intrusive body of granitic rock up to thick and in diameter. This body, known as the Boulder Batholith, extends from Helena to Butte, and is the host rock for the many valuable ores mined in the region. As the granite cooled, it cracked, and hot solutions infiltrated the cracks to form mineral veins bearing gold and other metals. Millions of years later, weathering allowed gold in the veins to wash down to the gravels in Basin Creek, Cataract Creek, and the other creeks near Basin, as well as the Boulder River. The Basin area is underlain by the quartz monzonite of the Boulder Batholith. The batholith is overlain by dacite from the Paleogene and Neogene periods (roughly 66 million to 1.8 million years ago) and andesite from the late Cretaceous. The andesite and monzonite are cut by dikes of dacite and rhyolite. 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「Basin, Montana」の詳細全文を読む スポンサード リンク
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