What is Mesa?
A mesa is a flat-top tableland with one or more steep sides commonly found in Colorado Plateau regions of the United States. 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 350 km (220 mi) in opposition to flat-topped hills which is as small as 0.1 kilometers (0.062 mi) in area, in the Elbsandsteingebirge, Germany.
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Define Mesa
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 mostly found in the drier southwestern states of New Mexico, Colorado, Utah, and Arizona.
Mesa Formation
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. Lava and sills, in general, are very resistant to weathering and erosion, and often form the flat top, or caprock of the mesa. The less resistant rock layers are generally made up of shale, a softer rock that weathers and erodes easily.
The mesa formation is quite a lengthy process and can take millions of years. The variation in different types of rocks during the formation of mesa also affects the steepness and sides of mountains. More resistant rock layers form cliffs whereas less resistant rock types form gentle slopes. Eventually, the basal sapping causes the cliffs to be cut off from the mesa.
Mesa on Mars
Mesas are not restricted to Planet Earth, as these geographical features have been found on an extraterrestrial location known as Mars. A translation zone on Mars lies between highly cratered highlands and low cratered lowlands. The younger lowland manifests steep-walled mesas and knobs. The mesas and knobs are departed by flat-lying lowlands. They are considered to form from ice-facilitated mass wasting processes from the ground or atmospheric sources. The mesas and knobs diminish in size with escalating distance from the highland escarpment. The relief of the mesas ranges from nearly 2 km to 100 m depending on the distance they are from the escarpment.
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How Mesas are Related to Two Landforms: Butte and Plateaus?
Mesas are closely related to two landforms known as butte and plateaus. The basic difference between these landforms is size. The surface area of mesas ranges between 11.251 square feet and four square miles whereas plateaus are larger, i.e., more than 4 square miles, and buttes are smaller (11,250 square feet or less).
The simple difference between mesa and butte is that some say mesa has more width than its height whereas others say a butte has more height than its width.
The three landforms mesa, butte, and plateaus are also related to the sense that over time, one landform can transform into another. For example, a plateau can be eroded into various forms. Similarly, a mesa can be eroded multiple times until its height is greater than its width, at this point it is considered a butte. A butte will ultimately erode into a peak, which will ultimately crumble and fall to the surface.
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Did You Know?
The largest mesa in the world is Grand Mesa, found in Western Colorado in the United States.
A mesa on Mars can be viewed easily from satellites.
The term Mesa is used to describe flat-topped mountains in the Southwestern United States.
FAQs on Mesa
1. What is a mesa in geography?
A mesa is an isolated, flat-topped hill with steep, cliff-like sides. The word 'mesa' is Spanish for 'table', which accurately describes its distinctive shape. These landforms are typically found in arid or semi-arid regions and are formed through a process of differential erosion, where a resistant layer of rock protects the softer layers beneath it from being worn away.
2. How is a mesa formed?
A mesa is formed over millions of years through erosion. The process begins with a large, elevated area of land, such as a plateau. Here’s a step-by-step breakdown:
Resistant Cap Rock: The top layer of the land consists of a hard, durable rock like sandstone or basalt. This is called the cap rock.
Softer Under-layers: Beneath the cap rock lie softer, more easily eroded layers of rock, such as shale or siltstone.
Erosion: Wind and water erode the surrounding softer rock layers at a faster rate, leaving behind isolated sections of the original plateau protected by the hard cap rock. The steep sides are formed as the softer layers are carved away, while the top remains flat.
3. What is the difference between a mesa, a butte, and a plateau?
The main difference between a mesa, a butte, and a plateau lies in their size and scale, though all are formed by similar erosional processes. A simple way to distinguish them is by their width relative to their height:
Plateau: A very large, elevated area of flat land. It is the most expansive of the three.
Mesa: An eroded remnant of a plateau. A key characteristic of a mesa is that it is wider than it is tall.
Butte: An eroded remnant of a mesa. A butte is taller than it is wide, representing a later stage of erosion.
Essentially, erosion can turn a plateau into several mesas, and further erosion can shrink a mesa into a butte.
4. What kind of rocks are mesas typically made of?
Mesas have a layered geological structure. The composition typically includes a hard, weather-resistant cap rock that forms the flat top. This layer is often made of sedimentary rocks like sandstone and limestone, or igneous rocks like basalt. Beneath this protective cap, the steep slopes are composed of softer, more easily eroded rocks such as shale, siltstone, or mudstone.
5. Why are mesas geographically significant?
Mesas are geographically significant for several reasons. They serve as natural laboratories for studying geological history, as their exposed rock layers (strata) provide a clear record of past environmental conditions. They also create unique ecosystems with distinct flora and fauna adapted to the high, arid environment. Culturally, many mesas, especially in the American Southwest, hold deep historical and spiritual importance for Indigenous peoples, often being sites of ancient dwellings and ceremonies.
6. How does a mesa eventually disappear?
A mesa is not a permanent landform; it is part of a continuous cycle of erosion. Over time, weathering and erosion attack the edges of the hard cap rock, causing it to break and fall away. As the protective cap rock shrinks, the softer layers on the sides become more exposed to wind and water. This process causes the mesa to narrow. Eventually, it becomes a butte (taller than it is wide). With continued erosion, the butte will further shrink into a slender rock pinnacle or spire, which will ultimately crumble and disappear, leaving a level plain.
7. Where are some famous mesas located?
Mesas are most famously found in the arid regions of the southwestern United States. The Colorado Plateau, which covers parts of Arizona, Utah, Colorado, and New Mexico, is home to numerous mesas. A notable example is the Grand Mesa in western Colorado, which is considered one of the largest flat-topped mountains in the world. Other examples include Monument Valley's iconic formations on the Arizona-Utah border and Acoma Pueblo (Sky City) in New Mexico, which is built atop a mesa.
