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A butte // is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller than mesas, plateaus, and table landforms. In some regions, such as the Midwestern United States and Northwestern United States, the word is used for any hill. The word butte comes from a French word meaning "small hill"; its use is prevalent in the Western United States, including the southwest, where "mesa" is also used for the larger landform. Because of their distinctive shapes, buttes are frequently landmarks in plains and mountainous areas. In differentiating mesas and buttes, geographers use the rule of thumb that a mesa has a top that is wider than its height, while a butte has a top that is narrower than its height.
The Mitten Buttes of Monument Valley in Arizona are two of the most distinctive and widely-recognized buttes. Monument Valley and the Mittens formed the background in scenes from many western-themed films, including seven movies directed by John Ford.[note 1] The Devils Tower in northeastern Wyoming is a laccolithic butte composed of igneous rock rather than sandstone, limestone or other sedimentary rocks.
Three other notable formations that are either named butte or may be considered buttes even though they do not conform to the formal geographer's rule are Scotts Bluff (actually a collection of five bluffs) in Nebraska, Crested Butte (a 12,168 ft (3,709 m) high mountain) in Colorado, and Elephant Butte (now an island in Elephant Butte Reservoir) in New Mexico.
Among the well-known non-flat-topped buttes in the United States are Bear Butte, South Dakota, and Black Butte, Oregon. In many cases, buttes have been given other names that do not use the word butte, for example, Courthouse Rock, Nebraska. Also, some large hills that are technically not buttes have names using the word butte, an example of which is Kamiak Butte in Washington State.
Buttes are formed by erosion when hard caprock overlies a layer of less resistant rock that is eventually worn away. The hard rock resists erosion. The caprock provides protection for the less resistant rock below from wind abrasion which leaves it standing isolated. As the top is further eroded by abrasion and weathering, the excess material that falls adds to the scree or talus slope around the base. On a much smaller scale, the same process forms hoodoos.
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