A sinkhole, also known as a cenote, sink, sink-hole, swallet, swallow hole, or doline (the different terms for sinkholes are often used interchangeably), is a depression or hole in the ground caused by some form of collapse of the surface layer. Most are caused by karst processes – for example, the chemical dissolution of carbonate rocks or suffosion processes. Sinkholes vary in size from 1 to 600 m (3.3 to 2,000 ft) both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may form gradually or suddenly, and are found worldwide.
Sinkholes may capture surface drainage from running or standing water, but may also form in high and dry places in specific locations. Sinkholes that capture drainage can hold it in large limestone caves. These caves may drain into tributaries of larger rivers.
The formation of sinkholes involves natural processes of erosion or gradual removal of slightly soluble bedrock (such as limestone) by percolating water, the collapse of a cave roof, or a lowering of the water table. Sinkholes often form through the process of suffosion. 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 the Minyé sinkhole in Papua New Guinea or Cedar Sink at Mammoth Cave National Park in Kentucky, an underground stream 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 limestone or other carbonate rock, salt beds, or in other soluble rocks, such as gypsum, that can be dissolved naturally by circulating ground water. Sinkholes also occur in sandstone and quartzite terrains.
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.
On 2 July 2015, scientists reported that active pits, related to sinkhole collapses and possibly associated with outbursts, were found on the comet 67P/Churyumov-Gerasimenko by the Rosetta space probe.
Collapses, commonly incorrectly labeled as sinkholes also occur due to human activity, such as the collapse of abandoned mines and salt cavern storage in salt domes in places like Louisiana, Mississippi and Texas. More commonly, collapses occur in urban areas due to water main breaks or sewer collapses when old pipes give way. They can also occur from the overpumping and extraction of groundwater and subsurface fluids.
Sinkholes 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 a collapse of the roof of an existing void or cavity in the subsurface, resulting in development of a sinkhole.
Sinkholes tend to occur in karst landscapes. Karst landscapes can have up to thousands of sinkholes within a small area, giving the landscape a pock-marked appearance. These sinkholes drain all the water, so there are only subterranean rivers in these areas. Examples of karst landscapes with a plethora of massive sinkholes include Khammouan Mountains (Laos) and Mamo Plateau (Papua New Guinea). The largest known sinkholes formed in sandstone are Sima Humboldt and Sima Martel in Venezuela.
Some sinkholes form in thick layers of homogenous limestone. Their formation is facilitated by high groundwater flow, often caused by high rainfall; such rainfall causes formation of the giant sinkholes in the Nakanaï Mountains, on the New Britain island in Papua New Guinea. On the contact of limestone and insoluble rock below it, powerful underground rivers may form, creating large underground voids.
In such conditions, the largest known sinkholes of the world have formed, like the 662-metre (2,172 ft) deep Xiaozhai Tiankeng (Chongqing, China), giant sótanos in Querétaro and San Luis Potosí states in Mexico and others.
Unusual processes have formed the enormous sinkholes of Sistema Zacatón in Tamaulipas (Mexico), where more than 20 sinkholes and other karst formations have been shaped by volcanically heated, acidic groundwater. This has produced not only the formation of the deepest water-filled sinkhole in the world—Zacatón—but also unique processes of travertine sedimentation in upper parts of sinkholes, leading to sealing of these sinkholes with travertine lids.
The U.S. state of Florida in North America is known for having frequent sinkhole collapses, especially in the central part of the state. Underlying limestone there is from 15 to 25 million years old. On the fringes of the state, sinkholes are rare or non-existent; limestone there is around 120,000 years old.
The Murge area in southern Italy also has numerous sinkholes. Sinkholes can be formed in retention ponds from large amounts of rain. An analysis of a case of sinkhole formation under a retention pond due to a large amount of rain can be seen in a sinkhole collapse study.
Sinkholes have been used for centuries as disposal sites for various forms of waste. A consequence of this is the pollution of groundwater resources, with serious health implications in such areas. The Maya civilization sometimes used sinkholes in the Yucatán Peninsula (known as cenotes) as places to deposit precious items and human sacrifices.
When sinkholes are very deep or connected to caves, they may offer challenges for experienced cavers or, when water-filled, divers. Some of the most spectacular are the Zacatón cenote in Mexico (the world's deepest water-filled sinkhole), the Boesmansgat sinkhole in South Africa, Sarisariñama tepuy in Venezuela, the Sótano del Barro in Mexico, and in the town of Mount Gambier, South Australia. Sinkholes that form in coral reefs and islands that collapse to enormous depths are known as blue holes and often become popular diving spots.
Large and visually unusual sinkholes have been well-known to local people since ancient times. Nowadays sinkholes are grouped and named in site-specific or generic names. Some examples of such names are listed below.
The 2010 Guatemala City sinkhole formed suddenly in May of that year; torrential rains from Tropical Storm Agatha and a bad drainage system were blamed for its creation. It swallowed a three-story building and a house; it measured approximately 20 m (66 ft) wide and 30 m (98 ft) deep. A similar hole had formed nearby in February 2007.
This large vertical hole is not a true sinkhole, as it did not form via the dissolution of limestone, dolomite, marble, or any other water-soluble rock. Guatemala City is not underlain by any carbonate rock; instead, thick deposits of volcanic ash, unwelded ash flow tuffs, and other pyroclastic debris underlie all of Guatemala City. The dissolution of rock did not form the large vertical holes that swallowed up parts of Guatemala City in 2007 and 2010.
The Guatemala City holes are instead an 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 to 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 mechanically 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.
Some of the largest sinkholes in the world are:
Akhayat (also known as Aşağı Dünya Obruğu) is a sinkhole in Mersin Province, Turkey.
The Akhayat Sinkhole is located in a rural area of the Silifke district, to the north of Atayurt town. Its visitors (if there are any) are often from Mersin, and to get to the sinkhole site they follow the Turkish state highway . As for tourism nowadays, it isn't a particularly popular sight, as there is hardly any touristic activity apart from people driving past and see it out of their window, but the Silifke governor mentioned that the site will soon be opened to tourism. There are other, more popular sinkholes in the area, such as Cennet and Cehennem; compared to those, Akhayat is relatively less known.Cave of Zeus, Aydın
The Cave of Zeus (Turkish: Zeus Mağarası) is a show cave located in Kuşadası, Aydın Province, in the Aegean Region of western Turkey.
The cave is within Dilek Peninsula-Büyük Menderes Delta National Park, immediately west of the town of Güzelçamlı in Kuşadası district. It is situated about 200 m (660 ft) west of the national park's entrance at Dilek Peninsula. The cave is reached by a 20 m (66 ft) long slippery, stoney trail southwards. The cave's mouth is hidden from view, as it is covered with trees, plants and flowers. The cave can be accessed from the district's center of Kuşadası via dolmuş, which shuttle the route to and from Güzelçamlı regularly.The cave was formed as a result of a sinkhole eroding a kalk formation by a subterranean river. Its base has the shape of a pool. The blue-green colored carbonated mineral water of the cave is a brackish mixture of spring water from the mountain and salty seawater. The deep pool attracts the attention of local and foreign visitors year-round for bathing and swimming. The cave is 10–15 m (33–49 ft) deep and 10–13 m (33–43 ft) wide with a length of 20 m (66 ft).According to Ancient Greek mythology, Zeus, the Olympian ruler of the skies, used to hide in the cave to escape the fury of his brother Poseidon, the ruler of the seas after Zeus angered him. Poseidon, in his wrath, would unleash very high waves and other dangerous water conditions with his trident. As a popular habit, visitors tie a cloth piece on a wishing tree next to the cave's mouth in the hope that their wish comes true.Cennet and Cehennem
Cennet and Cehennem (English: heaven and hell) are the names of two large sinkholes in the Taurus Mountains, in Mersin Province, Turkey. The sinkholes are among the tourist attractions of the province.Devil's Sinkhole State Natural Area
Devil's Sinkhole State Natural Area is a natural bat habitat near the city of Rocksprings in Edwards County in the U.S. state of Texas. Home to the Mexican free-tailed bat, access to the area is available only through advanced reservations.Egma Sinkhole
EGMA Sinkhole (Turkish: EGMA Düdeni), a.k.a. Peynirlikönü Sinkhole, is a sinkhole and the deepest cave in Turkey. It is located at Sugözü village of Anamur, Mersin. The sinkhole is 1,429 m (4,688 ft) deep and 3,118 m (10,230 ft) long. EGMA stands for Evren Günay - Mehmet Ali Özel Sinkhole.
Beginning in 1993, the cave was being explored by BÜMAK (Boğaziçi University Speleological Society). A flash flood caused Mehmet Ali Özel to lose his life inside the cave in 2001. In 2004, with the help of members of the Bulgarian Speleological Federation, the BÜMAK team recovered Mehmet Ali's body and also reached the deepest point of the cave.Eshab-ı Kehf Cave
Eshab-ı Kehf Cave, also known as Ashab-ı Kehf Cave or Seven Sleepers' Cave, (Turkish: Eshab-ı Kehf Mağarası, Ashab-ı Kehf Mağarası or Yedi Uyurlar Mağarası) is a show cave situated to the north of Tarsus, an ilçe (district) in Mersin Province , Turkey. The cave is named after the Arabic language word "aṣḥāb al kahf", "people of the cave", for Seven Sleepers of Ephesus, a belief in Christian and Islamic tradition.
The cave is about 14 kilometres (8.7 mi) to Tarsus and about 40 kilometres (25 mi) to Mersin. It is at the foothill of a small hill. The cave is small, not comparable to other caves of the province. However, it is a famed to be the cave of the Seven Sleepers. The exact location of the Seven Sleepers' cave is not known, and there are many other places including some in Turkey claiming to be the cave of the Seven Sleepers. Next to the cave, there is a mosque commissioned by the Ottoman sultan Abdülaziz (reigned 1861–1876), and built in 1873. The mosque's tall minaret with three balconies was added later.The other probable locations of the Seven Sleepers in Turkey are:
Ephesus in İzmir Province
Lice in Diyarbakır Province
Afşin in Kahramanmaraş Province (see Eshab-ı Kehf Kulliye)Estavelle
In karst geology, estavelle or inversac is a ground orifice which, depending on weather conditions and season, can serve either as a sink or as a source of fresh water. It is a type of sinkhole.Gilindire Cave
Gilindire Cave (Turkish: Gilindire Mağarası), also known as Aynalıgöl Cave, is a cave in Aydıncık, Mersin, southern Turkey. It was discovered by a shepherd in 1999. Gilindire was the former name of the town Aydıncık until 1965.Kanlıdivane
Kanlıdivane (ancient Canytelis, Greek: Κανυτελής) is an ancient city situated around a big sinkhole in Mersin Province, Turkey.Karain Cave
For other uses of Karain, see Karain (disambiguation).
Karain Cave (Turkish: Karain Mağarası) is a Paleolithic archaeological site located at Yağca Village 27 km (17 mi) northwest of Antalya city in the Mediterranean region of Turkey.Karst
Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant rocks, such as quartzite, given the right conditions. Subterranean drainage may limit surface water, with few to no rivers or lakes. However, in regions where the dissolved bedrock is covered (perhaps by debris) or confined by one or more superimposed non-soluble rock strata, distinctive karst features may occur only at subsurface levels and be totally missing above ground.
The study of karst is considered of prime importance in petroleum geology because as much as 50% of the world's hydrocarbon reserves are hosted in porous karst systems.List of sinkholes
The following is a list of sinkholes, blue holes, dolines, cenotes, and pit caves. A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. Some are caused by karst processes—for example, the chemical dissolution of carbonate rocks or suffosion processes. Sinkholes vary in size from 1 to 600 m (3.3 to 2,000 ft) both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may form gradually or suddenly, and are found worldwide.Mammoth Site, Hot Springs
The Mammoth Site of Hot Springs, South Dakota is a museum and paleontological site near Hot Springs, South Dakota. It is an active paleontological excavation site at which research and excavations are continuing. The area of Mammoth Site of Hot Springs enclose a prehistoric sinkhole that formed and was slowly filled with sediments during the Pleistocene era. The sedimentary fill of the sinkhole contains the remains of Pleistocene fauna and flora preserved by entrapment and burial within a sinkhole. This site has the greatest concentration of mammoth remains in the world. As of 2016, the remains of 61 mammoths, including 58 North American Columbian and 3 woolly mammoths had been recovered. Mammoth bones were found at the site in 1974, and a museum and building enclosing the site were established. The museum now contains an extensive collection of mammoth remains.National Corvette Museum
The National Corvette Museum showcases the Chevrolet Corvette, an American sports car that has been in production since 1953. It is located in Bowling Green, Kentucky, off Interstate 65's Exit 28. It was constructed in 1994, and opened to the public in September of that year.The museum is located only a quarter mile from the Bowling Green Assembly Plant, where Corvettes have been made since 1981. Public tours of the assembly plant are available. In addition, Chevrolet allows Corvette buyers to take delivery of their new vehicles at the museum, with a VIP tour of the plant and museum included for the buyer and up to three guests.O-Train
The O-Train is a light rapid transit transit system in Ottawa, Ontario, Canada operated by OC Transpo. It currently has one line in operation, the diesel-powered Trillium Line, with a second line, the electrically-operated Confederation Line, under construction and set to open in early 2019.Rideau Street
Rideau Street (French: Rue Rideau) is a major street in downtown Ottawa, Ontario, Canada and one of Ottawa's oldest and most famous streets running from Wellington Street in the west to Montreal Road in the east where it connects to the Vanier district. Rideau Street is home to the Château Laurier, the CF Rideau Centre and the Government Conference Centre (Ottawa's former central train station). Along with Wellington Street and Sussex Drive it was among the first streets in Ottawa to be host to businesses; it was created with the founding of the early town. The Plaza Bridge by the Rideau Canal is at its westmost point and the Cummings Bridge is at its eastmost point.
For many years, Rideau Street was one of Ottawa's primary retail thoroughfares, containing department stores such as Freimans, Ogilvy's, Woolworth, Caplan's and Metropolitan.
In November 1979, then mayor Marion Dewar examined a plan to create what became the 'Rideau Street Bus Mall.' Sidewalks from Sussex to Dalhousie were enclosed in a continuous glass-and-steel structure. The heated mall was expected to allow pedestrians to shop in comfort year-round. However, the structure had an unanticipated downside, in that it attracted large numbers of homeless and late-night drinkers. Many establishments along the affected stretch of Rideau Street failed as a result. The decision was made to tear the shelters down, and in the end the cost for dismantling them was almost as much as the $6.5 million incurred in their construction. Although the local department stores are gone, Rideau Street still features The Bay department store, the Rideau Centre shopping mall, and the street is adjacent to shops of the Byward Market. The street had been designated Highway 17B before the Ontario government discontinued it in 1998.
To the north of Rideau, east of King Edward Avenue is the traditional Lower Town district of Ottawa, a residential area which in the past was predominantly Francophone, but now has one of Ottawa's largest immigrant populations, notably including many Francophone Africans and Somalis. North of Rideau and west of King Edward is the commercial Byward Market area.
To the south of Rideau Street is the Sandy Hill neighbourhood, with its mix of embassies, older houses, low- and high-rise apartment buildings, and student housing.Ruijin
Ruijin (Chinese: 瑞金; pinyin: Ruìjīn) is a county-level city of Ganzhou in the mountains bordering Fujian Province in the south-eastern part of Jiangxi Province.
It is most famous as one of the earliest centers of Chinese communist activity. After being forced out of Jinggangshan in the late 1920s by the Kuomintang, the Communists fled here, taking advantage of Ruijin's relative isolation in the rugged mountains along Jiangxi's border with Fujian. In 1931, under Mao Zedong's leadership, the Chinese Soviet Republic was established here, with Ruijin serving as its de-facto capital. By 1934, they had again been surrounded by Chiang Kai-shek's forces. It is from here that the famed "Long March" began.Ruijin is a popular destination for red tourism and ecotourism. It is a pilgrimage for Maoists from China and around the globe.Winter Park, Florida
Winter Park is a suburban city in Orange County, Florida, United States. The population was 27,852 at the 2010 United States Census. It is part of the Orlando–Kissimmee–Sanford, Florida Metropolitan Statistical Area.
Winter Park was founded as a resort community by northern business magnates in the late 19th and early 20th centuries. Its main street includes civic buildings, retail, art galleries, a private liberal arts college (Rollins College), museums, a park, a train station, a golf course country club, a historic cemetery, and a beach and boat launch.Çukurpınar Cave
Çukurpınar Cave is a cave in Mersin Province, Turkey.
The cave is in the rural area of Anamur ilçe (district) close to Sugözü village. It is next to Egma Sinkhole. The distance from Anamur is about 40 kilometres (25 mi) and from Mersin is about 260 kilometres (160 mi).
The location is a yayla (temporatry summer camp) of Kükür village and the cave was discovered by a citizen of Kükür. The exploration was carried out between 24 July 1989 and 6 September 1992 in five phases by Bümak, the mountaineering team of Boğaziçi University.The depth of the cave is 1,196 metres (3,924 ft), which makes the cave the third deepst tcave in Turkey. (The first is nearby Egma Sinkhole). Its length is 3,350 metres (10,990 ft). There are two ponds in the cave and the water from the ponds is discharged to Dragon Creek.
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