|
The Sandhills, often written Sand Hills, is a region of mixed-grass prairie on grass-stabilized sand dunes in north-central Nebraska, covering just over one quarter of the state. The dunes were designated a National Natural Landmark in 1984. The sandhills are found in Arthur, Blaine, Brown, Cherry, Custer, Garden, Garfield, Grant, Holt, Hooker, Lincoln, Keith, Logan, Loup, McPherson, Morrill, Rock, Sheridan, Thomas, and Wheeler counties.〔(【引用サイトリンク】url=http://sandhillstaskforce.org/ )〕 ==Geography== The boundaries of the Sandhills are variously defined by different organizations. Depending on the definition, the region's area can be as small as 19,600 mi2 (50,760 km2)〔(U.S. Fish and Wildlife Service - Sandhills ) undated, URL retrieved on 21 July 2007〕 or as large as 23,600 mi2 (61,100 km2). Dunes in the Sandhills may exceed 330 ft (100 m) in height. The average elevation of the region gradually increases from about 1,800 ft (550 m) in the east to about 3,600 ft (1,100 m) in the west. The Sandhills sit atop the massive Ogallala Aquifer; thus both temporary and permanent shallow lakes are common in low-lying valleys between the grass-stabilized dunes prevalent in the Sandhills. The eastern and central sections of the region are drained by tributaries of the Loup River and the Niobrara River, while the western section is largely composed of small interior drainage basins. The World Wide Fund for Nature (WWF) designated the Sandhills as an ecoregion, distinct from other grasslands of the Great Plains. According to their assessment, as much as 85% of the ecoregion is intact natural habitat, the highest level in the Great Plains. This is chiefly due to the lack of crop production: most of the Sandhills land has never been plowed.〔 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「Sandhills (Nebraska)」の詳細全文を読む スポンサード リンク
|