Why are mesas flat

Mesas consist of flat-lying soft sedimentary rocks covered by more resistant layers or layers of hard rock. For example, shales overlaminated by sandstones.

The resistant layer functions as a caprock that forms the flat summit of the mesa. The caprock can consist of either sedimentary rock such as sandstone or limestone or a deeply eroded duricrust. A butte is also a flat-topped hill with steep sides, though smaller in area than a Mesa. However, there is no acceptable way to separate mesa from butte or the plateaus. For example, the flat-topped mountain known as mesa, in the Cockburn range of North-Western Australia has an area as much as km mi in opposition to flat-topped hills which is as small as 0.

A mesa is an isolated, high plateau with a flat top and steep slides that has been separated by the broadening of canyons. Mesas are generally formed when the horizontal stratification of rock is pushed upwards by tectonic force.

Erosion and weathering then act on these rocks, and the weaker layer of rocks are eroded away, leaving behind more resistant rocks which become elevated above their surroundings in a process known as differential erosion. The more resistant rock types include conglomerate, sandstone, quartzite, basalt, limestone, lava flows, chert, and sills. The elevated land can rise for thousands of feet above the surrounding area to form what is referred to as table mountain or table hill.

Mesas typically exist in arid environments and can be found in the western United States, South Africa, Spain, and Australia. Grand Mesa, a flat-topped mountain in Colorado, is the largest mesa is the world. A mesa is usually formed when a horizontal stratification of rock is pushed upwards by tectonic forces.

Erosion and weathering then act on these rocks, and the weaker layers of rocks are eroded away, leaving behind the more resistant rocks which become elevated above their surroundings in a process known as differential erosion. These erosion resistant rocks form the distinct flat-top that characterize a mesa. Some common rocks which make up a mesa are basalt, sandstone, chert, conglomerate, lava flows, and spills.

All of these types of rock are highly resistant to weathering and erosion. The mesa formation process is very lengthy, and can take several million years. The variation in rock types during the formation of a mesa also affects the steepness of the sides of the mountain. Though ringed by volcanic features, very few volcanoes, managed to penetrate into the interior of the plateau.

Home Arizona Articles Menu. Photo credit: See The Southwest Illustration When traveling in the Southwest, you will discover plenty of the geologic and landscape features that end with the word butte, mesa or plateau — for instance, Coyote Butte, Grand Mesa, Colorado Plateau.

Share on facebook. Share on twitter. Share on linkedin. Share on whatsapp. Top Blog Posts. Visiting Lowell Observatory. Albuquerque International Balloon Fiesta.