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The Pawnee Buttes are two prominent buttes located within the Pawnee National Grassland in Weld County, of northeastern Colorado. Rising approximately above the surrounding plains, the buttes are erosional remnants left standing in isolation as the surrounding High Plains surface has gradually worn away. The lower portions of the buttes are composed of relatively soft, clay-rich sedimentary rock called the Brule formation. The Brule formation is protected by an overlying layer of sandstone and conglomerate sediments called the Arikaree formation, which are more resistant to weathering.〔Gregory, L. 1996. Colorado Scenic Guide, Northern region, 3rd edition. Boulder: Johnson Books, 208 pp.〕 File:PawneeButtes_1900_USGS.jpg|Pawnee Buttes (1900)〔Darton, N.H. 1905. Preliminary report on the geology and underground water resources of the central Great Plains. United States Geological Survey, Professional Paper 32, 433 pp. (Plate 54-A)〕 File:Pawnee Butte (West).JPG|West Pawnee Butte (2008) File:Pawnee Buttes.jpg|East and West Buttes Panoramic (2008) ==Pawnee Buttes Trail== The Pawnee Buttes Trail is noted for its scenery and birdwatching potential. The Overlook, the Lipps Bluff trail, and the area within 200 yards of the cliffs are closed to hikers from March 1 to June 30, to protect nesting falcons, eagles, and hawks. Hikers are encouraged to keep away from these areas during that time to minimize disturbance to the nesting birds. 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「Pawnee Buttes」の詳細全文を読む スポンサード リンク
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