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A cenote ( or ; ) is a natural
pit Pit or PIT may refer to: Structure * Ball pit, a recreation structure * Casino pit, the part of a casino which holds gaming tables * Trapping pit, pits used for hunting * Pit (motor racing), an area of a racetrack where pit stops are conducted * ...
, or
sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...
, resulting from the collapse of
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...
bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of be ...
that exposes
groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidat ...
. The regional term is specifically associated with the Yucatán Peninsula of Mexico, where cenotes were commonly used for water supplies by the ancient
Maya Maya may refer to: Civilizations * Maya peoples, of southern Mexico and northern Central America ** Maya civilization, the historical civilization of the Maya peoples ** Maya language, the languages of the Maya peoples * Maya (Ethiopia), a popu ...
, and occasionally for sacrificial offerings. The term derives from a word used by the lowland Yucatec Maya—to refer to any location with accessible groundwater. Similar rock-sided sinkholes like cenotes are common geological forms in low-altitude regions, particularly on islands, coastlines, and platforms with young post-
Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...
limestone with little soil development. The term ''cenote'' has also been used to describe similar karst features in other countries such as
Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...
and Australia.


Definition and description

Cenotes are surface connections to subterranean water bodies. While the best-known cenotes are large open-water pools measuring tens of meters in diameter, such as those at
Chichen Itza Chichen Itza , es, Chichén Itzá , often with the emphasis reversed in English to ; from yua, Chiʼchʼèen Ìitshaʼ () "at the mouth of the well of the Itza people" was a large pre-Columbian city built by the Maya people of the Termi ...
in
Mexico Mexico ( Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guate ...
, the greatest number of cenotes are smaller sheltered sites and do not necessarily have any surface exposed water. Some cenotes are only found through small <1 m diameter holes created by tree roots, with human access through enlarged holes, such as the cenotes Cenote Choo-Ha, Tamcach-Ha, and Multum-Ha near Tulum. There are at least 6,000 cenotes in the Yucatán Peninsula of Mexico. Cenote water is often very clear, as the water comes from rain water filtering slowly through the ground, and therefore contains very little suspended particulate matter. The groundwater flow rate within a cenote may be very slow. In many cases, cenotes are areas where sections of the cave roof have collapsed revealing an underlying cave system, and the water flow rates may be much faster: up to per day. The Yucatan cenotes attract cavern and cave divers who have documented extensive flooded cave systems, some of which have been explored for lengths of or more.


Geology and hydrology

Cenotes are formed by the dissolution of rock and the resulting subsurface void, which may or may not be linked to an active cave system, and the subsequent structural collapse. Rock that falls into the water below is slowly removed by further dissolution, creating space for more collapse blocks. Likely, the rate of collapse increases during periods when the water table is below the ceiling of the void, since the rock ceiling is no longer buoyantly supported by the water in the void. Cenotes may be fully collapsed, creating an open water pool, or partially collapsed with some portion of a rock overhanging above the water. The stereotypical cenotes often resemble small circular
pond A pond is an area filled with water, either natural or Artificiality, artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% Aquatic plant, emergent vegetation helps in disting ...
s, measuring some tens of meters in diameter with sheer rock walls. Most cenotes, however, require some degree of stooping or crawling to access the water.


Penetration and extent

In the north and northwest of the Yucatán Peninsula in Mexico, the cenotes generally overlie vertical voids penetrating below the modern water table. However, very few of these cenotes appear to be connected with horizontally extensive underground river systems, with water flow through them being more likely dominated by aquifer matrix and fracture flows. In contrast, the cenotes along the Caribbean coast of the Yucatán Peninsula (within the state of
Quintana Roo Quintana Roo ( , ), officially the Free and Sovereign State of Quintana Roo ( es, Estado Libre y Soberano de Quintana Roo), is one of the 31 states which, with Mexico City, constitute the 32 federal entities of Mexico. It is divided into 11 mu ...
) often provide access to extensive underwater cave systems, such as Sistema Ox Bel Ha, Sistema Sac Actun/ Sistema Nohoch Nah Chich and Sistema Dos Ojos.


Freshwater/seawater interface

The Yucatán Peninsula contains a vast coastal
aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials ( gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characteri ...
system, which is typically density-stratified. The infiltrating meteoric water (i.e., rainwater) floats on top of higher-
density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...
saline water Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish water, ...
intruding from the coastal margins. The whole aquifer is therefore an anchialine system (one that is land-locked but connected to an ocean). Where a cenote, or the flooded cave to which it is an opening, provides deep enough access into the aquifer, the interface between the fresh and saline water may be reached. The density interface between the fresh and saline waters is a halocline, which means a sharp change in salt concentration over a small change in depth. Mixing of the fresh and saline water results in a blurry swirling effect caused by
refraction In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomen ...
between the different densities of fresh and saline waters. The depth of the halocline is a function of several factors: climate and specifically how much meteoric water recharges the aquifer, hydraulic conductivity of the host rock, distribution and connectivity of existing cave systems, and how effective these are at draining water to the coast, and the distance from the coast. In general, the halocline is deeper further from the coast, and in the Yucatán Peninsula this depth is below the water table at the coast, and below the water table in the middle of the peninsula, with saline water underlying the whole of the peninsula.


Types

In 1936, a simple morphometry-based classification system for cenotes was presented. * ''Cenotes-cántaro'' (Jug or pit cenotes) are those with a surface connection narrower than the diameter of the water body; * ''Cenotes-cilíndricos'' (Cylinder cenotes) are those with strictly vertical walls; * ''Cenotes-aguadas'' (Basin cenotes) are those with shallow water basins; and * ''Grutas'' (Cave cenotes) are those having a horizontal entrance with dry sections. The classification scheme was based on morphometric observations above the water table, and therefore incompletely reflects the processes by which the cenotes formed and the inherent hydrogeochemical relationship with the underlying flooded cave networks, which were only discovered in the 1980s and later with the initiation of cave diving exploration.


Flora and fauna

Flora and fauna are generally scarcer than in the open ocean; however, marine animals do thrive in caves. In caverns, one can spot mojarras, mollies, guppies,
catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...
, small eels and
frog A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" '' Triadobatrachus'' is ...
s. In the most secluded and darker cenotes, the fauna has evolved to resemble those of many cave-dwelling species. For example, many animals don't have
pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic comp ...
ation and are often blind, so they are equipped with long feelers to find food and make their way around in the dark.


Chicxulub crater

Although cenotes are found widely throughout much of the Yucatán Peninsula, a higher-density circular alignment of cenotes overlies the measured rim of the Chicxulub crater. This crater structure, identified from the alignment of cenotes, but also subsequently mapped using geophysical methods (including gravity mapping) and also drilled into with core recovery, has been dated to the boundary between the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
and
Paleogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago (Mya) to the beginning of ...
geologic periods, 66 million years ago. This meteorite impact at the Cretaceous–Paleogene boundary is therefore associated with the mass extinction of the dinosaurs and is also known as the
Cretaceous–Paleogene extinction event The Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary extinction) was a sudden extinction event, mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million y ...
.


Archaeology and anthropology

In 2001–2002 expeditions led by Arturo H. González and Carmen Rojas Sandoval in the Yucatán discovered three human skeletons; one of them, Eve of Naharon, was carbon-dated to be 13,600 years old. In March 2008, three members of the ''Proyecto Espeleológico de Tulum'' and Global Underwater Explorers dive team, Alex Alvarez, Franco Attolini, and Alberto Nava, explored a section of ''Sistema Aktun Hu'' (part of Sistema Sac Actun) known as the pit ''Hoyo Negro''. At a depth of the divers located the remains of a mastodon and a human
skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, t ...
(at ) that might be the oldest evidence of human habitation in the region. The Yucatán Peninsula has almost no rivers and only a few lakes, and those are often marshy. The widely distributed cenotes are the only perennial source of potable water and have long been the principal source of water in much of the region. Major
Maya Maya may refer to: Civilizations * Maya peoples, of southern Mexico and northern Central America ** Maya civilization, the historical civilization of the Maya peoples ** Maya language, the languages of the Maya peoples * Maya (Ethiopia), a popu ...
settlements required access to adequate water supplies, and therefore cities, including the famous
Chichen Itza Chichen Itza , es, Chichén Itzá , often with the emphasis reversed in English to ; from yua, Chiʼchʼèen Ìitshaʼ () "at the mouth of the well of the Itza people" was a large pre-Columbian city built by the Maya people of the Termi ...
, were built around these natural wells. Some cenotes like the Sacred Cenote in Chichen Itza played an important role in Maya rites. Believing that these pools were gateways to the afterlife, the Maya sometimes threw valuable items into them. The discovery of golden sacrificial artifacts in some cenotes led to the archaeological exploration of most cenotes in the first part of the 20th century. Edward Herbert Thompson (1857–1935), an American diplomat who had bought the Chichen Itza site, began dredging the Sacred Cenote there in 1904. He discovered human skeletons and sacrificial objects confirming a local legend, the
Cult of the Cenote The Cult of the Cenote was a legendary tradition by the Mayan particularly under the rulership of the Mayapan in the Yucatán Peninsula. The tradition includes throwing selected people in the city's cenote as a human sacrifice as well as precious st ...
, involving
human sacrifice Human sacrifice is the act of killing one or more humans as part of a ritual, which is usually intended to please or appease gods, a human ruler, an authoritative/priestly figure or spirits of dead ancestors or as a retainer sacrifice, wherei ...
to the rain god Chaac by the ritual casting of victims and objects into the cenote. The remains of this cultural heritage are protected by the UNESCO Convention on the Protection of the Underwater Cultural Heritage.


Scuba diving

Cenotes have attracted cavern and cave divers, and there are organized efforts to explore and map these underwater systems. They are public or private and sometimes considered "National Natural Parks". Great care should be taken to avoid spoiling this fragile ecosystem when diving. In Mexico, the
Quintana Roo Speleological Survey The Quintana Roo Speleological Survey (QRSS) was established in 1990 for the safe exploration, survey and cartography of the underwater and dry caves and cenotes of Quintana Roo, Mexico, supported by the National Speleological Society. The survey ...
maintains a list of the longest and deepest water-filled and dry caves within the state boundaries. When cavern diving, one must be able to see natural light the entire time that one is exploring the cavern (e.g. Kukulkan cenote near Tulum, Mexico). During a cave dive, one passes the point where daylight can penetrate and one follows a safety guideline to exit the cave. Things change quite dramatically once moving from a cavern dive into a cave dive. Too many divers, even experienced ones, have died for ignoring safety recommendations. Contrary to cenote cavern diving, cenote cave diving requires special equipment and training (certification for cave diving). However, both cavern and cave diving require detailed briefings, diving experience, and weight adjustment to freshwater buoyancy. The cenotes are usually filled with rather cool fresh water. Cenote divers must be wary of possible halocline; this produces blurred vision until they reach a more homogeneous area.


Notable cenotes


Australia

* Ewens Ponds, near Mount Gambier,
South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...
* Kilsby Sinkhole, near Mount Gambier, South Australia * Little Blue Lake, near Mount Schank, South Australia


Bahamas

* Thunderball Grotto, on Staniel Cay


Belize

* Great Blue Hole


Canada

* Devil's Bath is the largest cenote in Canada at a size of 359 meters in diameter and 44 meters in depth. It is located near the village of Port Alice,
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...
on the northwest coastline of
Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest by ...
. Devil's Bath is continuously fed by an underground spring and is connected by underwater tunnel to the Benson River Cave.


Dominican Republic

* Hoyo Azul (Punta Cana) *
Los Tres Ojos The Three Eyes National Park ( es, Parque Nacional Los Tres Ojos) is a 50-yard open-air limestone cave located in the Mirador del Este park, in the Santo Domingo Este municipality of the Dominican Republic. A series of three lakes, or ''ojos'', ...
* Ojos Indigenas (Punta Cana)


Jamaica

* Blue Hole (Ocho Rios)


Mexico


Central and northern regions

* Zacatón,
Tamaulipas Tamaulipas (), officially the Free and Sovereign State of Tamaulipas ( es, Estado Libre y Soberano de Tamaulipas), is a state in the northeast region of Mexico; one of the 31 states which, along with Mexico City, comprise the 32 Federal Entiti ...


Yucatán Peninsula

*
Dos Ojos Dos Ojos (from Spanish meaning "Two Eyes"; officially Sistema Dos Ojos) is part of a flooded cave system located north of Tulum, on the Caribbean coast of the Yucatán Peninsula, in the state of Quintana Roo, Mexico. The exploration of Dos Ojo ...
, Municipality of Tulum * Dzibilchaltun,
Yucatán Yucatán (, also , , ; yua, Yúukatan ), officially the Free and Sovereign State of Yucatán,; yua, link=no, Xóot' Noj Lu'umil Yúukatan. is one of the 31 states which comprise the federal entities of Mexico. It comprises 106 separate mun ...
* Ik Kil, Yucatan * Gran Cenote, Municipality of Tulum * Hubiku, Yucatan * Sacred Cenote,
Chichen Itza Chichen Itza , es, Chichén Itzá , often with the emphasis reversed in English to ; from yua, Chiʼchʼèen Ìitshaʼ () "at the mouth of the well of the Itza people" was a large pre-Columbian city built by the Maya people of the Termi ...
* Xtacunbilxunan, Bolonchén * Cenote Azul, Playa del Carmen * Jardin Del Eden, Bacalar * Choo-Ha, Coba * Zaci,
Valladolid Valladolid () is a municipality in Spain and the primary seat of government and de facto capital of the autonomous community of Castile and León. It is also the capital of the province of the same name. It has a population around 300,000 peo ...
* El Zapote, the site of the Hells Bells bell-like rock formation


United States

* Blue Hole, Santa Rosa,
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...
* Blue Hole,
Castalia Castalia ( grc, Κασταλία), in Greek mythology, was a naiad- nymph, a daughter of Achelous who inhabited the Castalian spring in Delphi. In older traditions, Castalian spring already existed by the time Apollo came to Delphi searching ...
,
Ohio Ohio () is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Of the List of states and territories of the United States, fifty U.S. states, it is the List of U.S. states and territories by area, 34th-l ...
* Bottomless Lakes, near
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, New Mexico * Montezuma Well,
Verde Valley The Verde Valley ( yuf-x-yav, Matkʼamvaha; es, Valle Verde) is a valley in central Arizona in the United States. The Verde River runs through it. The Verde River is one of Arizona's last free-flowing river systems. It provides crucial habita ...
,
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a U.S. state, state in the Southwestern United States. It is the list of U.S. states and territories by area, 6th largest and the list of U.S. states and territories by population, 14 ...


Zimbabwe

* Chinhoyi Caves in
Zimbabwe Zimbabwe (), officially the Republic of Zimbabwe, is a landlocked country located in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Botswana to the south-west, Zambia to the north, and Mozam ...


See also

* * * * * * **


References


Citations


Other sources

* *


External links


Cenotes of Chichén Itzá







Volcanic karstification of Sistema Zacaton, Mexico (Gary, Sharp, 2006)

Year 1999 Cenotes Conference in Perugia, Italy
{{Recreational dive sites, cavsit Cave geology Caves of Mexico Geography of Yucatán Karst caves Locations in Maya mythology Natural history of Mesoamerica Cenote Karst formations of Mexico