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Obsidian Cliff
Obsidian Cliff, also known as 48YE433, was an important source of lithic materials for prehistoric peoples in Yellowstone National Park near Mammoth Hot Springs, WY. The cliff was named by Philetus Norris, the second park superintendent in 1878. It was declared a National Historic Landmark in 1996.〔 and 〕〔
The cliff was formed from thick rhyolite lava flow that occurred about 180,000 years ago. The vertical columns are cooling fractures that formed as the thick lava flow cooled and crystallized. The Cliffs at an elevation of nearly 7,400 ft. above sea level and go on for about half a mile. The cliffs also extend between 150 and 200 feet about Obsidian Creek. The flow consists of obsidian, a dark volcanic glass. The obsidian is most abundant at the base of the cliff and slowly tapers off to larger concentrations of pumice at the top. Obsidian from this site was first quarried here about 12,000 years ago. Early natives of North America placed a high value on the obsidian that came from this cliff as well as other similar obsidian deposits in the area because numerous tools could be fashioned from obsidian - most popularly knives, spear/arrow tips, and other sharp edged objects. In fact, obsidian from Obsidian Cliff was so sought after in early America (before the time of Columbus) that it was traded as far away as Ohio and Canada.
Many studies have been done on the composition of the obsidian from Obsidian Cliff and how the obsidian from Obsidian Cliff was distributed. This research has provided evidence of the direction and extent of prehistoric trade networks.
It is located about south of Mammoth Hot Springs, on the east side of the Mammoth-Norris section of the Grand Loop Road.〔 The Obsidian Cliff Kiosk, just north, is also listed on the National Register. Obsidian Cliff is also located on the northern end of Beaver Lake in Yellowstone National Park.
==Notes==
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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