Sunset over Red Clay Mesa, Arizona, north of Chinle. A mesa (Spanish for "table") is an elevated area of land with a flat top and sides that are usually steep cliffs. It is a characteristic landform of arid environments, particularly the southwestern United States. Differences in the ability of different types of rock to resist weathering and erosion cause the weaker types to erode away, leaving the more resistant types of rocks topographically higher relative to their surroundings. This process is called differential erosion.