A
sinkhole, also known as a
sink,
shake hole,
swallow hole,
swallet,
doline or
cenoteA cenote is a deep natural pit, or sinkhole, characteristic of Mexico and Central America, resulting from the collapse of limestone bedrock that exposes groundwater underneath...
, is a natural depression or hole in the Earth's surface caused by
karst processesKarst topography is a geologic formation shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite, but has also been documented for weathering resistant rocks like quartzite given the right conditions.Due to subterranean drainage, there...
— the chemical dissolution of carbonate rocks or
suffosionSuffosion is one of the two geological processes by which subsidence sinkholes or dolines are formed, the other being "dropout" , with mostsinkholes formed by the suffosion process. Suffosion sinkholes are normally associated with karst topography although they may form in other types of rock...
processes for example in
sandstoneSandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
. Sinkholes may vary in size from 1 to 600 m (3.3 to 1,968.5 ft) both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may be formed gradually or suddenly, and are found worldwide. The different terms for sinkholes are often used interchangeably.
Formation mechanisms
Sinkholes may capture surface
drainageDrainage is the natural or artificial removal of surface and sub-surface water from an area. Many agricultural soils need drainage to improve production or to manage water supplies.-Early history:...
from running or standing water, but may also form in high and dry places in a certain location
The mechanisms of formation involve natural processes of
erosionErosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
or gradual removal of slightly soluble bedrock (such as
limestoneLimestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
) by percolating water, the
collapseSubsidence is the motion of a surface as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation...
of a
caveA cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...
roof, or a lowering of the
water tableThe water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...
. Sinkholes often form through the process of suffosion. Thus, for example, groundwater may dissolve the carbonate cement holding the sandstone particles together and then carry away the lax particles, gradually forming a void.
Occasionally a sinkhole may exhibit a visible opening into a cave below. In the case of exceptionally large sinkholes, such as Minyé sinkhole in
Papua New GuineaPapua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...
or Cedar Sink at
Mammoth Cave National ParkMammoth Cave National Park is a U.S. National Park in central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world. The official name of the system is the Mammoth-Flint Ridge Cave System for the ridge under which the cave has formed. The park was established...
, USA, a
streamA stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...
or river may be visible across its bottom flowing from one side to the other.
Sinkholes are common where the rock below the land surface is
limestoneLimestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
or other
carbonate rockCarbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite and dolostone, which is composed of the mineral dolomite .Calcite can be either dissolved by groundwater or precipitated by...
,
salt bedsHalite , commonly known as rock salt, is the mineral form of sodium chloride . Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on the amount and type of impurities...
, or rocks that can naturally be dissolved by circulating ground water. As the rock dissolves, spaces and caverns develop underground. These sinkholes can be dramatic because the surface land usually stays intact until there is not enough support. Then, a sudden collapse of the land surface can occur.
Sinkholes also form from human activity, such as the rare but still occasional collapse of abandoned
mineMining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
s in places like
West VirginiaWest Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...
, USA. More commonly, sinkholes occur in
urban areaAn urban area is characterized by higher population density and vast human features in comparison to areas surrounding it. Urban areas may be cities, towns or conurbations, but the term is not commonly extended to rural settlements such as villages and hamlets.Urban areas are created and further...
s due to water main breaks or
sewerA sanitary sewer is a separate underground carriage system specifically for transporting sewage from houses and commercial buildings to treatment or disposal. Sanitary sewers serving industrial areas also carry industrial wastewater...
collapses when old
pipePipeline transport is the transportation of goods through a pipe. Most commonly, liquids and gases are sent, but pneumatic tubes that transport solid capsules using compressed air are also used....
s give way. They can also occur from the overpumping and extraction of groundwater and subsurface fluids. They can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created; the substantial weight of the new material can trigger an underground collapse of supporting material, thus, causing a sinkhole.
Occurrence
Sinkholes are usually but not always linked with
karstKilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...
landscapes. In such regions, there may be hundreds or even thousands of sinkholes in a small area so that the surface as seen from the air looks pock-marked, and there are no surface streams because all drainage occurs sub-surface. Examples of karst landscapes dotted with numerous enormous sinkholes are Khammouan Mountains (
LaosLaos Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ Sathalanalat Paxathipatai Paxaxon Lao, officially the Lao People's Democratic Republic, is a landlocked country in Southeast Asia, bordered by Burma and China to the northwest, Vietnam to the east, Cambodia to the south and Thailand to the west...
) and Mamo Plateau (Papua New Guinea). The largest known sinkholes formed in sandstone are
Sima HumboldtSima Humboldt is an enormous sinkhole located on the summit of the plateau of Sarisariñama tepui in Bolívar State, Venezuela. It is unusual for several reasons, including its enormous size and depth, its location on the top of the only forested tepui, having a patch of forest on its base and also...
and
Sima MartelSima Martel is an enormous sinkhole located on the summit of plateau of Sarisariñama tepui, in Bolívar State, Venezuela. It is unusual due to several factors including its enormous size and depth, location on the top of the only forested tepui and having a patch of forest on its base and also due...
in
VenezuelaVenezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
.
The most impressive sinkholes form in thick layers of homogenous limestone. Their formation is facilitated by high groundwater flow, often caused by high rainfall – such high rainfall causes formation of the giant sinkholes in Nakanaï Mountains,
New BritainNew Britain, or Niu Briten, is the largest island in the Bismarck Archipelago of Papua New Guinea. It is separated from the island of New Guinea by the Dampier and Vitiaz Straits and from New Ireland by St. George's Channel...
island in Papua New Guinea. On the contact of limestone and insoluble rock below it there form powerful underground rivers which may create large underground voids.
In such conditions have formed the largest known sinkholes of the world, like the 662 metres (2,171.9 ft) deep Xiaozhai tiankeng (Chongqing, China), giant sótanos in
QuerétaroQuerétaro officially Estado Libre y Soberano de Querétaro de Arteaga is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 18 municipalities and its capital city is Santiago de Querétaro....
and
San Luis PotosíSan Luis Potosí officially Estado Libre y Soberano de San Luis Potosí is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 58 municipalities and its capital city is San Luis Potosí....
states in Mexico and others.
Unusual processes have formed the enormous sinkholes of Sistema Zacatón in
TamaulipasTamaulipas officially Estado Libre y Soberano de Tamaulipas is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 43 municipalities and its capital city is Ciudad Victoria. The capital city was named after Guadalupe Victoria, the...
(Mexico) – here more than 20 sinkholes and other karst formations have been shaped by volcanically heated, acidic groundwater. This has secured not only the formation of the deepest water-filled sinkhole in the world –
ZacatónZacatón is thermal water filled sinkhole belonging to Zacatón system - group of unusual karst features located in Aldama Municipality in the northeastern state of Tamaulipas, Mexico. It is the deepest known water-filled sinkhole in the world with a total depth of...
, but also unique processes of travertine sedimentation in upper parts of sinkholes, leading to sealing of these sinkholes with travertine lids.
The state of
FloridaFlorida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
in the USA is known for having frequent sinkholes, especially in the central part of the state. The Murge area in southern Italy also has numerous sinkholes. Sinkholes can be formed in retention ponds from large amounts of rain.
Sinkholes have been used for centuries as disposal sites for various forms of
wasteWaste is unwanted or useless materials. In biology, waste is any of the many unwanted substances or toxins that are expelled from living organisms, metabolic waste; such as urea, sweat or feces. Litter is waste which has been disposed of improperly...
. A consequence of this is the
pollutionPollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
of
groundwaterGroundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
resources, with serious
healthHealth is the level of functional or metabolic efficiency of a living being. In humans, it is the general condition of a person's mind, body and spirit, usually meaning to be free from illness, injury or pain...
implications in such areas. In contrast, the
Maya civilizationThe Maya is a Mesoamerican civilization, noted for the only known fully developed written language of the pre-Columbian Americas, as well as for its art, architecture, and mathematical and astronomical systems. Initially established during the Pre-Classic period The Maya is a Mesoamerican...
sometimes used sinkholes in the
Yucatán PeninsulaThe Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...
(known as cenotes) as places to deposit precious items and sacrifices.
Many sinkholes are found in Northern Michigan. These are prominent in Alpena County in Northeast Michigan. In Lachine, Michigan there are five sinkholes that are found to be very deep and within 2 miles (3.2 km) from each other. Alpena's visitor information cites their sinkholes as an attraction for visitors to the area. In August 1998 a 16 year old Alpena boy survived a 200 feet (61 m)+ fall in an open sinkhole 0.75 miles (1.2 km) from Leer road in Lachine, Michigan. A majority of sinkholes in Alpena are also found underwater. Many divers explore these on a regular basis.
When sinkholes are very deep or connected to caves, they may offer challenges for experienced cavers or, when water-filled,
diversCave diving is a type of technical diving in which specialized equipment is used to enable the exploration of caves which are at least partially filled with water. In the United Kingdom it is an extension of the more common sport of caving, and in the United States an extension of the more common...
. Some of the most spectacular are the
ZacatónZacatón is thermal water filled sinkhole belonging to Zacatón system - group of unusual karst features located in Aldama Municipality in the northeastern state of Tamaulipas, Mexico. It is the deepest known water-filled sinkhole in the world with a total depth of...
cenote in Mexico (the world's deepest water-filled sinkhole), the
BoesmansgatBoesmansgat, also known in English as "Bushman's Hole", is believed to be the third-deepest submerged freshwater cave in the world, approximately 270 metres deep...
sinkhole in South Africa,
SarisariñamaThe Sarisariñama tepui is a mountain in the Jaua-Sarisariñama National Park at the far south-west of Bolívar State, Venezuela, near the border with Brazil. Altitude: 300 - 2,350 metres. The name of the mountain originates from the tale of local Ye'kuana Indians about an evil spirit living in caves...
tepuy in Venezuela, and in the town of
Mount Gambier, South AustraliaMount Gambier is the largest regional city in South Australia located approximately 450 kilometres south of the capital Adelaide and just 17 kilometres from the Victorian border....
. Sinkholes that form in coral reefs and islands that collapse to enormous depths are known as
Blue HoleBlue Hole is a diving location on east Sinai, a few kilometres north of Dahab, Egypt on the coast of the Red Sea.The Blue Hole is a submarine sinkhole , around 130 m deep. There is a shallow opening around 6 m deep, known as 'the saddle', opening out to the sea, and a 26 m long...
s, and often become popular diving spots.
The
overburdenOverburden is the material that lies above an area of economic or scientific interest in mining and archaeology; most commonly the rock, soil, and ecosystem that lies above a coal seam or ore body. It is also known as 'waste' or 'spoil'...
sediments that cover buried cavities in the aquifer systems are delicately balanced by
groundwaterGroundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
fluid pressure. The water below ground is actually helping to keep the surface soil in place. Groundwater pumping for urban water supply and for irrigation can produce new sinkholes in sinkhole-prone areas. If pumping results in a lowering of groundwater levels, then underground structural failure, and thus sinkholes, can occur.
Local names of sinkholes
Large and visually unusual sinkholes have been well known to local people since ancient times. Also nowadays sinkholes are grouped and named in site specific or generic names. Some examples of such names are:
- cenote
A cenote is a deep natural pit, or sinkhole, characteristic of Mexico and Central America, resulting from the collapse of limestone bedrock that exposes groundwater underneath...
s. Characteristic water filled sinkholes in Yucatán PeninsulaThe Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...
, BelizeBelize is a constitutional monarchy and the northernmost country in Central America. Belize has a diverse society, comprising many cultures and languages. Even though Kriol and Spanish are spoken among the population, Belize is the only country in Central America where English is the official...
and some other regions. Many cenotes have formed in limestone which deposited in shallow seas created by ChicxulubThe Chicxulub crater is an ancient impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named...
meteorite impact.
- tiankengs. These are extremely large sinkholes which are deeper and wider than 100 m, with mostly vertical walls, most often created by the collapse of underground caverns. This term is proposed by Chinese geologists as many of the largest sinkholes are located in China. The largest tiankeng is the 662 m deep Xiaozhai tiankeng, which is also the largest known sinkhole of the world.
- sótanos. This name is given to several giant pits in several states of Mexico. The best known is the 372 m deep Sótano de las Golondrinas – Cave of Swallows
The Cave of Swallows, also called Cave of the Swallows , is an open air pit cave in the Municipality of Aquismón, San Luis Potosí, Mexico. The elliptical mouth, on a slope of karst, is wide and is undercut around all its perimeter, further widening to a room approximately 995 feet by 440 feet wide...
.
- blue holes. This name initially has been given to the deep underwater sinkholes of Bahamas but often is used for any deep water-filled pits formed in carbonate rocks. Name originates from the deep blue color of water in these sinkholes, which in turn is created by the high lucidity of water and the large depth of sinkholes – only the deep blue color of the visible spectrum
A spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a prism; it has since been applied by...
can penetrate such depth and after reflection return back. The deepest known undersea sinkhole is Dean's Blue HoleDean's Blue Hole is the world's deepest known blue hole with seawater. It plunges in a bay west of Clarence Town on Long Island, Bahamas.-History:The full depth of the cave was reached by Jim King in 1992....
in Bahamas.
- black holes. Group of unique round, water filled pits in Bahamas. These formations seem to be dissolved in carbonate mud from above, by the sea water. Dark color of water is caused by the layer of phototropic microorganisms concentrated in dense, purple colored layer in 15 – 20 metre depth – this layer "swallows" the light. Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
in the layer of microorganisms causes heating of water – the only known case in natural world where microorganisms create significant thermal effects. Most impressive is Black Hole of Andros.
- tomo used in New Zealand karst country to describe pot holes.
Piping pseudokarst
What has been called a "sinkhole" by the popular press formed suddenly in
GuatemalaGuatemala City , is the capital and largest city of the Republic of Guatemala and Central America...
in May 2010. Torrential rains from
Tropical Storm AgathaTropical Storm Agatha was a weak, but catastrophic tropical cyclone that brought widespread floods to much of Central America and was the deadliest tropical cyclone in the eastern Pacific since Hurricane Pauline in 1997. The first storm of the 2010 Pacific hurricane season, Agatha originated from...
and a bad drainage system were blamed for creating the 2010 "sinkhole" that swallowed a three story building and a house. This large vertical hole measured approximately 66 feet (20.1 m) wide and 100 feet (30.5 m) deep. A similar hole had formed nearby in February 2007.
This large vertical hole, called a "sinkhole" in the popular press, is not a true sinkhole as it did not form via the dissolution either of limestone, dolomite, marble, or any other carbonate rock. Guatemala City is not underlain by any carbonate rock; instead, thick deposits of
volcanic ashVolcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...
, unwelded ash flow tuffs, and other pyroclastic debris underlie all of Guatemala City. Thus, it is impossible for the dissolution of carbonate rock to have formed the large vertical holes that swallowed up parts of Guatemala City in 2007 and 2010.
The large holes that swallowed up parts of Guatemala City in 2007 and 2010 are a spectacular example of "piping pseudokarst", created by the collapse of large cavities that had developed in the weak, crumbly Quaternary volcanic deposits underlying the city. Although weak and crumbly, these volcanic deposits have enough cohesion to allow them to stand in vertical faces and develop large subterranean voids within them. A process called "soil piping" first created large underground voids as water from leaking water mains flowed through these volcanic deposits and washed fine volcanic materials out of them, then progressively eroded and removed coarser materials. Eventually, these underground voids became large enough that their roofs collapsed to create large holes.
Notable sinkholes
Some of the largest and most impressive sinkholes in the world are:
- Xiaozhai tiankeng – Chongqing Municipality, China. Double nested sinkhole with vertical walls, 662 m deep.
- Dashiwei tiankeng – Guangxi, China. 613 m deep, with vertical walls, bottom contains isolated patch of forest with rare species.
- Red Lake – Croatia. Approximately 530 m deep pit with nearly vertical walls, contains approximately 280 – 290 m deep lake.
- Minyé sinkhole – East New Britain, Papua New Guinea. 510 m deep, with vertical walls, crossed by powerful stream.
- Sótano del Barro – Querétaro, Mexico. 410 m deep, with nearly vertical walls.
- Cave of Swallows
The Cave of Swallows, also called Cave of the Swallows , is an open air pit cave in the Municipality of Aquismón, San Luis Potosí, Mexico. The elliptical mouth, on a slope of karst, is wide and is undercut around all its perimeter, further widening to a room approximately 995 feet by 440 feet wide...
– San Luis Potosí, Mexico. 372 m deep, round sinkhole with overhanging walls.
- Zacatón
Zacatón is thermal water filled sinkhole belonging to Zacatón system - group of unusual karst features located in Aldama Municipality in the northeastern state of Tamaulipas, Mexico. It is the deepest known water-filled sinkhole in the world with a total depth of...
– Tamaulipas, Mexico. Deepest water-filled sinkhole in world, 339 m deep. Floating travertineTravertine is a form of limestone deposited by mineral springs, especially hot springs. Travertine often has a fibrous or concentric appearance and exists in white, tan, and cream-colored varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot...
islands.
- Sima Humboldt
Sima Humboldt is an enormous sinkhole located on the summit of the plateau of Sarisariñama tepui in Bolívar State, Venezuela. It is unusual for several reasons, including its enormous size and depth, its location on the top of the only forested tepui, having a patch of forest on its base and also...
– Venezuela. Largest sinkhole in sandstone, 314 m deep, with vertical walls. Unique, isolated forest on bottom.
- Teiq sinkhole – Oman. One of the largest sinkholes in the world by volume – 90 million cubic metres. Several perennial wadis fall with spectacular waterfalls into this 250 m deep sinkhole.
- Dean's Blue Hole
Dean's Blue Hole is the world's deepest known blue hole with seawater. It plunges in a bay west of Clarence Town on Long Island, Bahamas.-History:The full depth of the cave was reached by Jim King in 1992....
– Bahamas. Deepest known sinkhole under the sea, depth 203 m. Popular location for world championships of free diving.
- Blue Hole – Dahab, Egypt. A round sinkhole or blue hole, 130m deep. Includes an extraordinary archway leading out to the Red Sea at 60m, renowned for freediving and scuba attempts, the latter often fatal. Also see Bell's to Blue Hole drift dive.
- Great Blue Hole
The Great Blue Hole is a large submarine sinkhole off the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll from the mainland and Belize City. The hole is circular in shape, over across and deep...
– Belize. Spectacular, round sinkhole, 124 m deep. Unusual features are tilted stalactites in great depth, which mark the former orientation of limestone layers when this sinkhole was above the water level.
- Kingsley Lake
Kingsley Lake is an almost circular lake of about in North Central Florida, about six miles east of Starke, Florida. According to some sources, it is the oldest and highest lake in Florida, located on the edge of the Trail Ridge formation. The lake is a very stable lake with a sandy bottom. Its...
– Florida, USA. 2000 acres (8.1 km²) in area, 90 ft (27.4 m) deep and almost perfectly round.
- Gypsum Sinkhole – Utah, USA. Nearly 50 ft (15.2 m) in diameter and approximately 200 ft (61 m) deep.
- Harwood Hole
Harwood Hole is a cave system located in the northwest of the South Island of New Zealand. It is one of several important cave systems in Takaka Hill, between Golden Bay and Tasman Bay. Starting at the surface as a 50 metre round entrance and descending 183 metres, Harwood Hole is New Zealand's...
- Abel Tasman National ParkAbel Tasman National Park is a national park located at the north end of the South Island of New Zealand. The park was founded in 1942, largely through the efforts of ornithologist and author Perrine Moncrieff to have land reserved for the purpose. With a coverage of only 225.3 square kilometres,...
, New Zealand, 183 m deep
- Bimmah Sinkhole - Wadi Shab and Wadi Tiwi
Wadi Shab is a wadi in Oman that is located between the capital Muscat and the town of Sur, Oman. More precisely it lies in Niyabat Tiwi, wilayat of Sur, and is 26 km from Qurayyat. It is easy to reach this wadi from the Qurayyat-Sur highway. The wadi combines the attractions of coastal areas...
, Oman, 80 m deep
See also
- Blue hole
A blue hole is a cave or underwater sinkhole. They are also called vertical caves. There are many different blue holes located around the world, typically in low-lying coastal regions...
- Blyvooruitzicht
Blyvooruitzicht is a gold-mining village in Gauteng, South Africa. It is situated about 3.5 km south of the centre of Carletonville and 80 km westwards from Johannesburg.-History:The name of the village is of Dutch origin meaning "happy prospect"...
- Cave-in
A cave-in is a collapse of a geologic formation, mine or structure which typically occurs during mining or tunneling. Geologic structures prone to cave-ins include alvar, tsingy and other limestone formations, but can also include lava tubes and a variety of other subsurface rock formations.In...
- Cenote
A cenote is a deep natural pit, or sinkhole, characteristic of Mexico and Central America, resulting from the collapse of limestone bedrock that exposes groundwater underneath...
- Dean's Blue Hole
Dean's Blue Hole is the world's deepest known blue hole with seawater. It plunges in a bay west of Clarence Town on Long Island, Bahamas.-History:The full depth of the cave was reached by Jim King in 1992....
- Foiba
Foiba is a type of deep natural sinkhole, doline, sink and is a collapsed portion of bedrock above a void. Sinks may be a sheer vertical opening into a cave, or a shallow depression of many acres which are common in the Kras region, a karstic plateau region shared by Italy, Slovenia and...
- Great Blue Hole
The Great Blue Hole is a large submarine sinkhole off the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll from the mainland and Belize City. The hole is circular in shape, over across and deep...
- Guatemala City Agatha Hole
- Karst topography
Karst topography is a geologic formation shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite, but has also been documented for weathering resistant rocks like quartzite given the right conditions.Due to subterranean drainage, there...
- Lake-burst
A lake-burst is a phenomenon referred to in Irish mythology, in which a previously non-existent lake comes into being, often when a grave is being dug.-Partholón's time:*Loch Laighlinne in Ui mac Uais of Breg*Loch Cuan and Loch Rudraige in Ulaid...
- Lake Peigneur disaster
Lake Peigneur is located in the U.S. State of Louisiana north of Delcambre and west of New Iberia, near the northernmost tip of Vermilion Bay.-History:...
- Oak Island
Oak Island is a island in Lunenburg County on the south shore of Nova Scotia, Canada. The tree-covered island is one of about 360 small islands in Mahone Bay and rises to a maximum of 35 feet above sea level...
- Pipe Creek Sinkhole
Pipe Creek Sinkhole near Swayzee in Grant County, Indiana, is one of the most important paleontological sites in the interior of the eastern half of North America, due to preservation, and the exception from 'typical glacial strata mixing' from glaciation...
- Sarisariñama
The Sarisariñama tepui is a mountain in the Jaua-Sarisariñama National Park at the far south-west of Bolívar State, Venezuela, near the border with Brazil. Altitude: 300 - 2,350 metres. The name of the mountain originates from the tale of local Ye'kuana Indians about an evil spirit living in caves...
- Sinkhole Dersios
The Dersios sinkhole is a sinkhole in Arcadia, Greece.The sinkhole, which has a depth of , has been known since antiquity and is located towards the north end of the plateau of Palaiochora at a height of 750 m above sea level on mount Parnon...
- Subsidence
Subsidence is the motion of a surface as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation...
- Turlough (lake)
A turlough, or turlach, is a unique type of disappearing lake found mostly in limestone areas of Ireland, west of the River Shannon. The name comes from the Irish "tuar", meaning dry, with the suffix "lach", meaning a place . The "lach" suffix is often mistakenly spelled and/or thought to refer to...
- Voçoroca
- Zacatón
Zacatón is thermal water filled sinkhole belonging to Zacatón system - group of unusual karst features located in Aldama Municipality in the northeastern state of Tamaulipas, Mexico. It is the deepest known water-filled sinkhole in the world with a total depth of...
- Sima Humboldt
Sima Humboldt is an enormous sinkhole located on the summit of the plateau of Sarisariñama tepui in Bolívar State, Venezuela. It is unusual for several reasons, including its enormous size and depth, its location on the top of the only forested tepui, having a patch of forest on its base and also...
and Sima MartelSima Martel is an enormous sinkhole located on the summit of plateau of Sarisariñama tepui, in Bolívar State, Venezuela. It is unusual due to several factors including its enormous size and depth, location on the top of the only forested tepui and having a patch of forest on its base and also due...
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