The creation of Cenotes

A little geology ...

Cenotes are more than 10.000 water holes scattered in the Yucatan jungle. They mark the entrance to an underground system unique in the world in form, complexity and ramifications. A system corresponds to two cenotes at least connected by a submerged gallery. What makes Yucatan cenotes systems unique in the world are the lengths of tunnels and submerged caves. Actun Cave counts 248 km tunnels and Dos Ojos 83 km, for example!

The Yucatan Peninsula is a limestone plateau resulting from the decomposition of marine organisms, a few million years ago, such as corals, shells and sea urchins which, once dead, formed this very porous, soluble and therefore limestone material. friable. This allowed the rainwater that fell for millions of years on the Yucatan to erode this rock, to dig crevices, then cavities, then caves and tunnels. A cave with a ceiling a little more fragile than others, can no longer support the weight of the jungle which is above and which suddenly collapses, opening a passage to the outside.

Why is this limestone plateau more porous than elsewhere in the world?

A meteorite would have crashed here, in Chicxulub, in the north-west of the peninsula, sixty-five million years ago, creating major rupture zones in the earth's subsurface ... Add to that the water of rain was loaded with carbonic acid due to the vegetable decomposition of the jungle soil. An acid-laden drop of rain that penetrates a friable and soluble area, this is how cenotes began. After having dug them, the rain fills the cenotes, travels from one to the other through the tunnels, creates connections, direct in the mangroves and lagoons, indirect by capillaries in the rock and allows the entry of water salty… This is how we find fresh water in the first ten to twelve meters of the cenotes, salt water below and the phenomenon of the halocline between the two, incredible to observe when diving , with its effects of blur, mirror and mirage ...

A bit of paleontology ...

The cenotes are also a journey into the bowels of America.

At the end of the Pleistocene, in the Quaternary of our prehistory, an ice age saw the level of the sea drop by a hundred meters as well as that of water in general. The cenotes having then served as shelters and refuges for the fauna of the time, we therefore find the bones, in particular the oldest of all the American continent, in Yucatan. This allows paleontologists to study them and understand how they were, their size, what herbs and plants they ate, for example.

Hominid bones have also been found in cenotes. Naya, aged 13.400, is the best known. Note that of the sixteen hominids found on the American continent, ten were in Yucatan!