Everything about Cenote totally explained
A
cenote (pronounced in
Mexican Spanish [seˈnoˌte] and in
English [səˈnəʊˌteɪ], plural:
cenotes; from
Yucatec Maya dzonot) is a type of
sinkhole containing groundwater typically found in the
Yucatán Peninsula and some nearby
Caribbean islands. The term is derived from a word used by the low-land Maya to refer to any location where groundwater is accessible.
Definition and description
Cenotes are surface connections to subterranean water bodies . While the most well-known cenotes are large open water pools measuring tens of metres in diameter, such as those at
Chichén Itzá, the greatest number of cenotes are smaller sheltered sites and don't necessarily have any surface exposed water. The term cenote has also been used to describe similar
karst features in other countries such as
Cuba and
Australia, in addition to the more generic term of
sinkholes.
Cenote water is often very clear, as the water comes from rain water infiltrating slowly through the ground, and therefore contains very little suspended particulate matter. The groundwater flow rate within a cenote may be very slow at velocities ranging from 1 to 1000 meters per year. In many cases, cenotes are areas where sections of cave roof have collapsed revealing an underlying cave system and the water flow rates here may be much faster: up to 10,000 meters per day. Cenotes around the world attract
cave divers who have documented extensive flooded cave systems through them, some of which have been explored for lengths of 100 kilometers or more.
Geology and hydrology
Formation
Cenotes are formed by dissolution of rock which creates a subsurface void, which may or may not be linked to an active cave system, and the subsequent structural collapse of the rock ceiling above the void. The rock that falls into the water below will then be slowly removed by further dissolution, creating space for more collapse blocks. 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 overhang above the water. The stereotypical cenotes often resemble small circular
ponds, measuring some tens of meters in diameter with sheer drops at the edges. Most cenotes however require some degree of stooping if not crawling to access the water.
Freshwater/seawater interface
The Yucatan Peninsula contains a vast density-stratified coastal aquifer where infiltrating
meteoric water (for example, rainwater) floats on top of higher density saline water intruding from the coastal margins. The whole aquifer is therefore an
anchialine system (for example, one that's land-locked, but connected to an ocean). Where a cenote, or the flooded cave it's an opening to, provides deep enough access into the aquifer then 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 due to refraction between the different density 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 the further from the coast. In the Yucatan Peninsula this depth is 10 to 20 meters below the water table at the coast, and 50 to 100 meters below the water table in the middle of the peninsula, with saline water underlying the whole of the peninsula.
Types of cenotes
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 onwards with the initiation of cave diving exploration.
Cenotes and the Maya
Cenotes have long been the principal sources of water in much of the
Yucatán Peninsula. The region has almost no rivers and only a few lakes, often marshy. Cenotes are widely distributed, and supply better-quality water year-round. Major
Maya settlements required access to adequate water supplies, and therefore cities, including the famous
Chichén Itzá, were built around these natural wells. Some cenotes like the
Cenote of Sacrifice in Chichén Itzá played an important role in Maya rites. Believing that these pools were gateways to the other world, 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, an American diplomat who had bought the Chichén Itzá 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, involving
human sacrifice to the
rain gods (
Chaacs) by ritual casting of victims and objects into the cenote.
Cenotes and cave diving
In the north and north-west of the Yucatan Peninsula, the cenotes generally overlie vertically extensive voids penetrating 50 - 100 m 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 Yucatan Peninsula (within the state of
Quintana Roo) often provide access to extensive underwater cave systems, such as
Ox Bel Ha,
Sac Actun,
Nohoch Nah Chich and
Dos Ojos. The cenotes have attracted
cave divers and there are organised efforts to explore and map the underwater systems. The
Quintana Roo Speleological Survey maintains a list of the longest and deepest water filled and dry caves within the state boundaries.
Cenotes and the Chicxulub structure
Although cenotes are found widely throughout much of the Yucatan Peninsula, a ringlike arrangement of cenotes coincides with the theorized rim of the
Chicxulub Crater. This crater structure, suggested by gravity mapping, may be the result of the meteorite that's theorized to be responsible for the
K-T Boundary and the mass dinosaur extinction that occurred 65 million years ago known as the
Cretaceous–Tertiary extinction event.
Notable cenotes
Mexico
Yucatan Peninsula:
Central and Northern Region:
Zacatón, Tamaulipas, Mexico
Canada
Devil's Bath, northern Vancouver Island, Canada
United States
Bottomless Lakes, near Roswell, New MexicoFurther Information
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