<P> Mesa (Spanish and Portuguese for table) is the American English term for tableland, an elevated area of land with a flat top and sides that are usually steep cliffs . It takes its name from its characteristic table - top shape . It may also be called a table hill, table - topped hill or table mountain . It is larger than a butte, which it otherwise resembles closely . </P> <P> It is a characteristic landform of arid environments, particularly the Western and Southwestern United States in badlands and mountainous regions ranging from Washington and California to the Dakotas, Wyoming, Utah, Oklahoma, and Texas . Examples are also found in many other nations including Spain, Sardinia, North and South Africa, Arabia, India, and Australia . </P> <P> Grand Mesa is a large mesa located in western Colorado in the Southwest United States . Cerro Negro is a mesa in Argentina . </P> <P> Mesas form by weathering and erosion of horizontally layered rocks that have been uplifted by tectonic activity . Variations in the ability of different types of rock to resist weathering and erosion cause the weaker types of rocks to be eroded away, leaving the more resistant types of rocks topographically higher than their surroundings . This process is called differential erosion . The most resistant rock types include sandstone, conglomerate, quartzite, basalt, chert, limestone, lava flows and sills . Lava flows and sills, in particular, are very resistant to weathering and erosion, and often form the flat top, or caprock, of a mesa . The less resistant rock layers are mainly made up of shale, a softer rock that weathers and erodes more easily . </P>

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