A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a more resistant layer or layers of harder rock, e.g. shales overlain by sandstones. The resistant layer acts as a caprock that forms the flat summit of a mesa. The caprock can consist of either sedimentary rocks such as sandstone and limestone; dissected lava flows; or a deeply eroded duricrust. Unlike plateau, whose usage does not imply horizontal layers of bedrock, e.g. Tibetan Plateau, the term mesa applies exclusively to the landforms built of flat-lying strata. Instead, flat-topped plateaus are specifically known as tablelands.[1][2][3]

Ground-level view of mesas in the Canyonlands National Park, Utah, known as the "Islands in the Sky"
Aerial view of mesas in Monument Valley, on the Colorado Plateau

Names, definition and etymologyEdit

As noted by Bryan in 1922, mesas "...stand distinctly above the surrounding country, as a table stands above the floor upon which it rests".[4] It is from this appearance the term mesa was adopted from a Spanish word meaning table.[2]

A mesa is similar to, but has a more extensive summit area than, a butte. However, there is no agreed size limit that separates mesas from either buttes or plateaus. For example, the flat-topped mountains, which are known as mesas, in the Cockburn Range of North-Western Australia have areas as much as 350 kilometres (220 mi). In contrast, flat topped hills, which are as small as 0.1 kilometres (0.062 mi) in area, in the Elbsandsteingebirge, Germany, are described as mesas.[1][2][3]

Less strictly, a very broad, flat-topped, usually isolated hill or mountain of moderate height bounded on at least one side by a steep cliff or slope and representing an erosion remnant also have been called mesas.[3]

In the English language geomorphic and geologic literature, other terms for mesa have also been used.[1] For example, in the Roraima region of Venezuela, the traditional name, tepui, from the local Pomón language, and the term table mountains have been used to describe local flat-topped mountains.[5][6] Similar landforms in Australia are known as tablehills, table-top hills, tent hills, or jump ups (jump-ups).[7][8][9] The German term Tafelberg has also been used in the English scientific literature in the past.[10]

FormationEdit

 
Har Qatum, a mesa located on the southern edge of Makhtesh Ramon, Israel

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.[11] This process is called differential erosion. The most resistant rock types include sandstone, conglomerate, quartzite, basalt, chert, limestone, lava flows and sills.[11] 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.[11]

The differences in strength of various rock layers are what give mesas their distinctive shape. Less resistant rocks are eroded away on the surface into valleys, where they collect water drainage from the surrounding area, while the more resistant layers are left standing out.[11] A large area of very resistant rock, such as a sill may shield the layers below it from erosion while the softer rock surrounding it is eroded into valleys, thus forming a caprock.

Differences in rock type also reflect on the sides of a mesa, as instead of smooth slopes, the sides are broken into a staircase pattern called "cliff-and-bench topography".[11] The more resistant layers form the cliffs, or stair steps, while the less resistant layers form gentle slopes, or benches, between the cliffs. Cliffs retreat and are eventually cut off from the main cliff, or plateau, by basal sapping. When the cliff edge does not retreat uniformly but instead is indented by headward eroding streams, a section can be cut off from the main cliff, forming a mesa.[11]

Basal sapping occurs as water flowing around the rock layers of the mesa erodes the underlying soft shale layers, either as surface runoff from the mesa top or from groundwater moving through permeable overlying layers, which leads to slumping and flowage of the shale.[12] As the underlying shale erodes away, it can no longer support the overlying cliff layers, which collapse and retreat. When the caprock has caved away to the point where only a little remains, it is known as a butte.

Examples and locationsEdit

AustraliaEdit

 
Mount Conner, a mesa located in Northern Territory, Australia
 
Amadiya, Iraq, a city in its entirety built on a mesa

GermanyEdit

IraqEdit

Republic of IrelandEdit

IsraelEdit

United KingdomEdit

United StatesEdit

ArizonaEdit

CaliforniaEdit

ColoradoEdit

 
Mesa in Colorado

NevadaEdit

OklahomaEdit

TexasEdit

UtahEdit

WisconsinEdit

On MarsEdit

 
A mesa in Noctis Labyrinthus on Mars, viewed by HiRISE

A transitional zone on Mars, known as the fretted terrain, lies between highly cratered highlands and less cratered lowlands. The younger lowland exhibits steep walled mesas and knobs. The mesa and knobs are separated by flat lying lowlands. They are thought to form from ice-facilitated mass wasting processes from ground or atmospheric sources. The mesas and knobs decrease in size with increasing distance from the highland escarpment. The relief of the mesas range from nearly 2 km to 100 m depending on the distance they are from the escarpment.[25]

See alsoEdit

  • Amba
  • Archipelago – Collection of islands
  • Butte – Isolated hill with steep, often vertical sides and a small, relatively flat top
  • Dissected plateau – Plateaux area that has been severely eroded so that the relief is sharp
  • Mensa (geology) – Flat-topped prominence with cliff-like edges
  • Mesa Verde National Park – U.S. national park in Colorado
  • Nor'Wester Mountains
  • Potrero (landform) – Long mesa that at one end slopes upward to higher terrain
  • Table (landform) – Raised landforms that have a flat top
  • Table Mountain – Flat-topped mountain overlooking the city of Cape Town, South Africa
  • Tepui – Table-top mountain or mesa in the Guiana Highlands of South America
  • Tundra – Biome where plant growth is hindered by cold temperatures
  • Tuya – Flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet

ReferencesEdit

  1. ^ a b c Duszyński, F., Migoń, P. and Strzelecki, M.C., 2019. Escarpment retreat in sedimentary tablelands and cuesta landscapes–Landforms, mechanisms and patterns. Earth-Science Reviews,' no. 102890. doi.org/10.1016/j.earscirev.2019.102890
  2. ^ a b c Migoń, P., 2004a. Mesa. In: Goudie, A.S. (Ed.), Encyclopedia of Geomorphology. Routledge, London, pp. 668. ISBN 9780415272988
  3. ^ a b c Neuendorf, Klaus K.E. Mehl, James P., Jr. Jackson, Julia A.. (2011). Glossary of Geology (5th Edition). American Geosciences Institute. ISBN 9781680151787
  4. ^ Bryan, K. (1922). "Erosion and Sedimentation in the Papago Country, Arizona". US Geological Survey Bulletin (730): 19–90.
  5. ^ Briceño, H.O. and Schubert, C., 1990. Geomorphology of the Gran Sabana, Guayana Shield, southeastern Venezuela. Geomorphology, 3(2), pp.125-141.
  6. ^ Doerr, S.H., 1999. Karst-like landforms and hydrology in quartzites of the Venezuelan Guyana shield: Pseudokarst or" real" karst?. Zeitschrift fur Geomorphologie, 43(1), pp.1-17.
  7. ^ Jack, R.L., 1915. The Geology and prospects of the Region to the South of the Musgrave Ranges, and the Geology of the Western Portion of the Great Australian Artesian Basin. Geol. Survey South Australia Bulletin 5, pp. 72.
  8. ^ Macquarie dictionary : Australia's national dictionary online, Macquarie Library, 2021, retrieved 11 March 2021
  9. ^ "Land Zones of Queensland". Queensland Government. 2012. pp. 62–63. Retrieved 11 March 2021.{{cite web}}: CS1 maint: url-status (link)
  10. ^ King, L.C., 1942. South African Scenery. A Textbook of Geomorphology. Oliver and Boyd, Edinburgh, London (340 pp.).
  11. ^ a b c d e f Easterbrook, Don J. (1999). Surface Processes and Landforms. Upper Saddle River, NJ: Prentice Hall. ISBN 9780138609580.
  12. ^ Choreley, Richard J.; Stanley A. Schumm; David E. Sugden (1985). Geomorphology. New York: Methuen.
  13. ^ Burbridge, Andrew; Mckenzie, NL; Kenneally, Kevin F (1991). Nature Conservation Reserves in the Kimberley, Western Australia. Department of Conservation and Land Management. ISBN 9780646033747. Retrieved 4 July 2021.
  14. ^ Report. The Department. 1966.
  15. ^ https://www.google.co.uk/books/edition/Kindred_by_Choice/HV4DAAAAQBAJ?hl=en&gbpv=0 Kindred by Choice Germans and American Indians Since 1800, Glenn H Penny, 2013]
  16. ^ https://www.nationalpark-saechsische-schweiz.de/besucherinformation/ausflugsziele/lilienstein-ein-tafelberg-mit-symbolcharakter/?lang=en Lilienstein – a mesa with a symbolic character]
  17. ^ a b c Jancewicz, Kacper. "Morphological diversity of mesas in Elbsandsteingebirg". ResearchGate. Retrieved 4 July 2021.
  18. ^ a b c Journal of Earth Sciences Royal Dublin Society. (1980). Ireland: The Society.
  19. ^ "Masada - Definition, History, Siege & Facts". Encyclopedia Britannica. Retrieved 4 July 2021.
  20. ^ Karst Rock Features. Karren sculpturing: Karren sculpturing. Zalozoba ZRC. 2009. p. 286. ISBN 9789612541613. Retrieved 4 July 2021.
  21. ^ https://www.google.co.uk/books/edition/Lakeland/U_pEAAAAYAAJ?hl=en&gbpv=0&bsq Lakeland - The Wildlife of Cumbria, Derek A Ratcliffe]
  22. ^ a b Reading, H. G. (1954) The stratigraphy and structure of the syncline of stainmore, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/9349/
  23. ^ National Geographic Encyclopedia (2016)
  24. ^ "Floating Mesa, Bushland, Texas". Atlas Obscura. Retrieved 19 October 2021.
  25. ^ Baker, David M. Morphological Analyses of Mesas and Knobs in the Northwest Fretted Terrain of Mars; Constraints on the Presence and Distribution of Ice-Facilitated Mass-Wasting. Ed. Alexander K. Stewart and James W. Head. Vol. 40. Issue 2. pp. 72. United States: Geological Society of America (GSA) : Boulder, CO, United States, 2008.