mesas

A mesa is a landform characterized by a flat-topped, elevated area with steep sides. The term comes from the Spanish mesa, meaning table. In geology, mesas are isolated, flat-topped hills or plateaus formed by erosion, typically in arid or semi-arid regions.

Mesa formation results from differential erosion. A resistant caprock, such as sandstone, limestone, or basalt, overlies softer, more easily eroded rock. Erosion gradually wears away the surrounding terrain and undercuts the sides, leaving a flat, horizontal summit and near-vertical cliffs. Climate conditions with limited rainfall and strong winds aid the process by reducing the rate of weathering while exposing fracture networks.

Size and distinctions: Mesas are usually larger than buttes, though the boundary is not strictly defined. They range from tens to hundreds of meters in height and can span kilometers in width. When erosion produces smaller, isolated remnants with steeper profiles, they are often called buttes or towers; when the top remains relatively broad, the term mesa is preferred.

Distribution and examples: Mesas are common in the American Southwest, especially on the Colorado Plateau (as seen in Monument Valley and surrounding landscapes). They also occur in deserts of Patagonia, Africa, and Asia, often as components of plateau or highland regions. Mesas are of interest to geologists for studying layered sedimentary sequences and erosion histories, and they are familiar landscape features in tourism and photography.