
Cenote
Cenote is a flooded sinkhole of karstic origin. There are several types of cenotes: open, semi-open and underground or in a cave. This classification is directly related to the age of the cenote, being the mature cenotes those that are completely open and the youngest those that still preserve their intact dome. Like many other geomorphological structures, the cenotes are transitory structures, which can finally end up filled and dried, becoming part of what is known as a paleokarst.
Formation
Its morphology is typically typically subcircular, and with abrupt walls. Due to the evolution of the karstic massif, the cenote begins as an underground chamber produced by the dissolution of the limestone rock by the infiltration of rainwater. Finally, as the cavity increases in size, the cenote may end up surfacing due to the collapse of the dome.
The cenotes were formed during the times of lowering of sea level during the Pleistocene glacial pulses. Cenotes are, in most cases, widening of complex underground river networks. In these, the sea water, denser than the sweet, can penetrate through the bottom of the water table. For this reason, there are cenotes in which, from a certain depth, the water passes from sweet to salt, even many kilometers from the coast. This surface contact between fresh and marine water is called halocline, and causes interesting visual effects.
Interconnected systems
The speleology has shown the existence of interconnections between the cenotes and between these and the sea, evidencing a true system of underground drainage.
Cenotes are typical geomorphological structures of limestone platforms. There are also cenotes in different parts of the world although they often receive different names. This is the case of the plains of Nullarbor, north of the Great Australian Bay and, also in the Bahamas, where they are known as blue holes or blue holes. In the state of Yucatan, where the cenotes have been exploited, it is estimated that there are more than 2,400 formations of this type and there is a whole program to inventory them, preserve them and make them available to visitors whose number increases every day.
Fuente: https://es.wikipedia.org