Editing Karst (section)

== Morphology ==
[[File:Rubaksa tufa plug.jpg|thumb|[[Rubaksa]] [[tufa]] plug in Ethiopia]]
The karstification of a landscape may result in a variety of large- or small-scale features both on the surface and beneath. On exposed surfaces, small features may include [[solution flute]]s (or rillenkarren), [[Stream|runnels]], [[limestone pavement]] (clints and grikes), [[Kamenitza (Geomorphology)|kamenitzas]] collectively called karren or lapiez. Medium-sized surface features may include [[sinkhole]]s or [[cenote]]s (closed basins), vertical shafts, [[foibe]] (inverted funnel shaped sinkholes), disappearing streams, and reappearing [[karst spring|spring]]s.

Large-scale features may include [[limestone pavement]]s, [[polje]]s, and karst valleys. Mature karst landscapes, where more bedrock has been removed than remains, may result in [[tower karst|karst towers]], or [[mogote|haystack/eggbox]] landscapes. Beneath the surface, complex underground drainage systems (such as karst [[Aquifer#Porous versus karst|aquifers]]) and extensive [[cave]]s and cavern systems may form.<ref name="thornbury-1969" />

Erosion along limestone shores, notably in the [[tropics]], produces karst topography that includes a sharp makatea surface above the normal reach of the sea, and undercuts that are mostly the result of biological activity or [[bioerosion]] at or a little above [[mean sea level]].<ref>{{cite journal |last1=Mylroie |first1=J.E. |last2=Vacher |first2=H.L. |year=1999 |title=A conceptual view of carbonate island karst |journal=Karst Waters Institute Special Publication |volume=5 |pages=48–57 |url=https://apps.dtic.mil/dtic/tr/fulltext/u2/a369937.pdf#page=56 |archive-url=https://web.archive.org/web/20210429045355/https://apps.dtic.mil/dtic/tr/fulltext/u2/a369937.pdf#page=56 |url-status=live |archive-date=April 29, 2021 |access-date=26 December 2020}}</ref> Some of the most dramatic of these formations can be seen in [[Thailand]]'s [[Phangnga Bay]] and at [[Halong Bay]] in [[Vietnam]].

Calcium carbonate dissolved into water may precipitate out where the water discharges some of its dissolved carbon dioxide. Rivers which emerge from springs may produce [[tufa]] terraces, consisting of layers of calcite deposited over extended periods of time. In caves, a variety of features collectively called [[speleothem]]s are formed by deposition of calcium carbonate and other dissolved minerals.

=== Interstratal karst ===
Interstratal karst is a karst landscape which is developed beneath a cover of insoluble rocks. Typically this will involve a cover of [[sandstone]] overlying limestone strata undergoing solution. In the United Kingdom for example extensive doline fields have developed at [[Cefn yr Ystrad]], [[Mynydd Llangatwg]] and [[Mynydd Llangynidr]] in South Wales across a cover of [[Twrch Sandstone]] which overlies concealed [[Carboniferous Limestone]], the last-named locality having been declared a [[site of special scientific interest]] in respect of it.<ref>{{cite web|url=http://www.blaenau-gwent.gov.uk/documents/Documents_Environment/PH4_SSSI_Notification_Letter.pdf |title=Archived copy |access-date=2013-03-03 |url-status=dead |archive-url=https://web.archive.org/web/20151120022422/http://www.blaenau-gwent.gov.uk/documents/Documents_Environment/PH4_SSSI_Notification_Letter.pdf |archive-date=2015-11-20 }}</ref>

=== Kegelkarst, salt karst, and karst forests ===
Kegelkarst is a type of tropical karst terrain with numerous cone-like hills, formed by cockpits, [[mogote]]s, and [[polje]]s and without strong fluvial erosion processes. This terrain is found in Cuba, Jamaica, Indonesia, Malaysia, the Philippines, Puerto Rico, southern China, Myanmar, Thailand, Laos and Vietnam.<ref>Whittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, 1984, p 292. {{ISBN|0-14-051094-X}}.</ref>

Salt karst (or 'halite karst') is developed in areas where [[salt]] is undergoing solution underground. It can lead to surface depressions and collapses which present a geo-hazard.<ref>{{cite web |last1=Cooper |first1=Anthony H. |title=Halite karst geohazards (natural and man-made) in the United Kingdom |url=https://nora.nerc.ac.uk/id/eprint/6218/2/Halite_karst_geohazards_Cooper_Env_Geol_vol42_505-512.pdf |publisher=BGS/NERC |access-date=9 October 2022}}</ref>

Karst areas tend to have unique types of forests. The karst terrain is difficult for humans to traverse, so that their ecosystems are often relatively undisturbed. The soil tends to have a high pH, which encourages growth of unusual species of orchids, palms, mangroves, and other plants.<ref>{{cite web |last1=Evans |first1=Monica |title=Karst forests: the labyrinthian wildlands of green and bedrock |url=https://news.globallandscapesforum.org/43769/karst-forests-the-labyrinthian-wildlands-of-green-and-bedrock/ |website=Global Landscapes Forum |date=2020-04-15}}</ref>

=== Paleokarst ===
Paleokarst or palaeokarst is a development of karst observed in geological history and preserved within the rock sequence, effectively a fossil karst. There are for example palaeokarst surfaces exposed within the Clydach Valley Subgroup of the [[Carboniferous Limestone]] sequence of [[South Wales]] which developed as sub-aerial [[weathering]] of recently formed limestones took place during periods of non-deposition within the early part of the period. Sedimentation resumed and further limestone strata were deposited on an irregular karst surface, the cycle recurring several times in connection with fluctuating sea levels over prolonged periods.<ref>{{cite book |last1=Howells |first1=M.F |title=British Regional Geology:Wales |date=2007 |publisher=British Geological Survey |location=Keyworth, Nottingham |isbn=978-085272584-9 |page=118}}</ref>

=== Pseudokarst ===
Pseudokarsts are similar in form or appearance to karst features but are created by different mechanisms. Examples include [[lava]] caves and [[granite]] [[tor (geography)|tors]]—for example, Labertouche Cave in [[Victoria (Australia)|Victoria, Australia]]—and [[paleocollapse]] features. [[Mud Caves]] are an example of pseudokarst.