Cenote – Ts’ono’ot – Dzonot: The water hole or holy spring
The Spanish word "Cenote" is derived from the Mayan word "Dzonot" and means something like "holy spring". In ancient Mayan culture, people believed that the cenotes were the entrances to the underworld "Xibalba", where their rain god "Chac" lived. Therefore, the Mayas also performed rituals and sacrificial offerings in some cenotes to live in harmony with their god "Chac"; so that it rains enough and drinking water is always available. One of the cenotes on the site of the huge pyramid complex of "Chichen Itza" is especially known for such offerings. At that time, the heydays of the Mayas, people did not know yet that they actually live on the largest freshwater reservoir in the world and therefore would have enough drinking water available at all times. Basically, the Yucatán Peninsula is nothing more than a huge sponge, whose interior is soaked with clearest fresh water.
It all started many millions of years ago, when the Yucatán Peninsula was nothing more than a huge coral reef. During several ice ages, the sea level dropped, exposing the coral reef and causing it to die. Thus, over the course of time, a limestone plateau with a thickness of approximately 1,5 kilometres was formed that was flooded again after the ice ages. This process repeated many times and every time the coral reef was dry, atmospheric carbon dioxide fused with rain to form carbonic acid, which penetrated the soft limestone and dissolved it. Since all water flows towards the sea, the limestone was dissolved bit by bit. Thus over the course of time an underground river system was formed, which flows through a gigantic tunnel system into the sea. Due to the shifting of the earth's plates, the Yucatán Peninsula has not been flooded for 44 million years and has remained as we know it today. But the dissolution process of the caves has continuously advanced and during further ice ages, the last one was approximately 18.000 years ago, the water level in the caves decreased and increased again and again. As a result, many of the cave systems were not filled with water inside for long periods of time, because the water level at that time was about 10 meters lower than it is now. During this dry season the impressive stalactites, stalagmites and even dripstone columns were formed by the same dissolution process that originally formed the caves.
On the way between the surface and the ceiling of the cave the acid rain has dissolved the limestone, thus liquefying it and converting it into the mineral calcium carbonate. When the drop of water was hanging from the ceiling of the cave for about 20 minutes before it dripped down, it released the previously liquefied mineral calcium carbonate onto the cave ceiling and thus, drop by drop a stalactite was formed. The same drop, when it hit the ground, also released the mineral calcium carbonate there and a stalagmite grew up from below. If this process took place often enough over the course of time, stalagmite and stalactite eventually joined together in some places to form impressive dripstone columns. This process is very long and depends on the amount of rainfall and the porosity of the limestone. Basically one can say that a stalactite grows on average between 1 and a maximum of 10 centimetres in 100 years! The thicker a stalactite is, the slower it grows - so thin, filigree stalactites grow many times faster.
The cenotes are mostly created by the collapse of the cave ceiling - a so-called "cave collapse". At a time when the water level was lower and the cave ceiling was very thin, the weight of the cave ceiling and the jungle became too much and the cave ceiling simply gave way. These "sinkholes" (cenotes) then filled with water and opened the entrance to the caves. Other, particularly deep cenotes are most likely due to meteorite impacts about 64 million years ago north of the Yucatán Peninsula in what is now the Gulf of Mexico. The immense force of the impacts blasted deep holes into the limestone. The cenote at "Chichen Itza" is probably the most famous cenote that was created by a meteorite impact. The green algae water is very striking in these cenotes. The impact hole is filled with rainwater and since no underground river allows the water to drain away, unlike the cenotes formed by a cave collapse, no water exchange takes place and the water in the cenote becomes algae. Even if the data varies greatly depending on the source, it is said that between 1,500 and 2,500 cenotes are now known by name and statistically recorded. However, experts estimate that there are about 10'000 cenotes on the Yucatán Peninsula!
In the meantime, most of the cave systems on the Yucatán Peninsula have filled up again with clearest rainwater, which is extremely filtered on the approximately 4-day journey from the earth's surface down into the huge cave systems. Due to the dissolution of the limestone it contains a lot of calcium carbonate and therefore has no drinking water quality (by today's standards), although it is crystal clear. Due to the facts that the Riviera Maya is located by the sea, and the river speed in the caves is very low (1.5 - 2.5 kilometers in 24 hours), the sea continuously pushes salt water into the caves. Thus, from a depth of 10 meters there is salt water in many of the caves around here. Between salt and fresh water an intermediate layer is formed in which the water species mix, the so-called "halocline". In its untouched state it appears like a surface in the water and when illuminated with a lamp it conjures up a white line on the limestone of the cenote.
Adapted from Stefan Ullrich