What Is a Butte and How Does It Form?
In geomorphology, a butte is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller landforms than mesas, plateaus, and tablelands. 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 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. A related geological feature is the mesa, which is distinguished from the butte by its much larger size. Buttes, for example, usually have a surface area of less than 10,000 square feet. Mesas, on the other hand, can have as much as four square miles of surface area.
Both buttes and mesas are formed by the scientific process of physical weathering of rock formations. Weathering refers to the process by which rocks are broken down into smaller pieces without substantial movement. Buttes and mesas, for example, are formed when the surface material of a hill or a mountain — called the cap rock — resists physical weathering but underlying materials (usually softer rock) do not. Over time, the underlying materials break down through a process called erosion, leaving an isolated, flat-topped hill called a butte (or a mesa if it’s really large).
Buttes and mesas are usually found in fairly dry areas. When plants and ground cover are scarce, the softer rock layers of buttes and mesas are left exposed to running water. Over time, softer rock erodes, leaving steep, vertical sides and gently-sloping bases where the eroded rock collects.
The Mitten Buttes of Monument Valley in Arizona are two of the most distinctive and widely recognized buttes. Monument Valley and the Mittens provided backgrounds in scenes from many western-themed films, including seven movies directed by John Ford. 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 in Nebraska which is actually a collection of five bluffs, Crested Butte which is a 12,168 ft (3,709 m) mountain in Colorado, and Elephant Butte which is 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, Black Butte, Oregon, and the Sutter Buttesin California. 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, examples of which are Kamiak Butte and Chelan Butte in Washington state.