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Lake Ilo National Wildlife Refuge (NWR) is located in the U.S. state of North Dakota and is managed from Audubon National Wildlife Refuge by the U.S. Fish and Wildlife Service. The refuge consists of Lake Ilo, surrounding wetlands and some upland range, providing habitat for hundreds of species of birds, and numerous fish and mammal species. An average of over 16 inches (40 cm) of precipitation falls annually, supporting a prairie ecosystem. Archeological work at Lake Ilo NWR in the 1990s resulted in creating one of the largest assemblages of Paleo Indian artifacts found on land managed by the U.S. Fish and Wildlife Service. These artifacts help to educate modern peoples about those who lived in the region more 10,000 years ago, and enhances the refuge with a human culture story that was not anticipated when the region was set aside for wildlife protection. ==History== The refuge region has been inhabited by humans for 11,000 years, and 58,000 stone artifacts from the Folsom period have been recovered from the refuge since 1989. Many of the stone tools are made from what is known as Knife River Flint, a sturdy but relatively easily worked stone from which Paleo Indians fabricated spear points, meat cleavers and other implements. Western North Dakota has the only large concentrations of this glass-like caramel-colored stone, and similar stone tools made from these deposits have been found as far away as the states of New York and New Mexico.〔 The region in which Lake Ilo NWR is located was one of the last to be settled by white settlers on the Great Plains of the United States. By the 1930s, the era of the Dust Bowl brought drought and dust storms to an already arid region. Starting in 1936, local citizens were hired by the U.S. Government to build a dam at the confluence of two creeks, which would help create a more sustainable water supply for the immediate area since no sizeable bodies of water existed in this region of North Dakota. The dam was completed in 1938 and the following year, U.S. President Franklin D. Roosevelt signed a congressional bill designating the new lake and the surrounding area as a National Wildlife Refuge. In the late 1980s, the dam on Lake Ilo was determined to be deficient in a number of ways and the lake was drained in 1989 a total of 7 feet (2 m). A new concrete dam was constructed and soil from the old dam was used to build two small islands to improve nesting habitat for waterfowl. After the lake water was partially drained, numerous Paleo Indian artifacts were discovered, including stone artifacts and even a Tipi ring. Subsequent archeological work resulted in obtaining over 58,000 artifacts by 1994.〔 These artifacts help to reconstruct the lifestyle and culture of the earliest known human inhabitants to the region. Additionally, numerous bones of now extinct mammal species assist in determining the biodiversity of the region at the end of the ice age. 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「Lake Ilo National Wildlife Refuge」の詳細全文を読む スポンサード リンク
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