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Rio La Venta, Chiapas
Rio La Venta, Chiapas


Due to the abundance of acquatic habitats and the diversity of the terrain, the Cuatrociénegas valley supports basin grasslands, acquatic plants, sedge borders and marshes, gypsum dune assemblages, Chihuahuan desert scrub and chaparral.


Rio La Venta, Chiapas


The international scientific
and conservation community is interested in the flora and fauna of the valley, and fears that many of the current land use practices (irrigation, agriculture, ranching, mining and bathing) are putting the biota at risk of extinction.


Rio La Venta, Chiapas


Much has been written about Cuatrociénegas but the area is practically unknown from a hydrogeological and speleological point of view, so that the “water in the desert” is still a “mystery”.


Rio La Venta, Chiapas


Photo arch. La Venta

      Cuatrociénegas valley
Cuatrociénegas is a wide intermontane valley of approximately 150,000 hectares situated in the Sierra Madre Oriental, on the eastern edge of the Chihuahuan desert in the Mexican state of Coahuila. The valley floor averages 740 meters above mean sea level, and is surrounded by massive limestone mountains with peaks which reach up to 3000 meters (Sierra San Marcos y Pinos, La Purissima, La Fragua, La Madera and Menchaca).


Climate
Climatically arid, Cuatrociénegas receives less than 200 mm of precipitation yearly, most of it occurring between May and September, and in the last fifty years rainfalls have kept decreasing. Temperatures are extreme, exceeding 44 °C during summer and dropping to below zero during winter, with an yearly average temperature of 22 °C.

Subterranean water
Even though it receives little rain, the valley has abundant subterranean water emerging to the surface in 165 small pools, locally called pozas, ranging in depth from less than a meter to over 15 meters and extending in diameter from 3 to over 20 meters, with a unique biota of great interest. For the most part, the ground water has high concentrations of minerals, dominated by calcium sulfate, with smaller amounts of sodium, magnesium and chloride, whereas temperatures range betwen 18.7 - 35.4 °C

Flora
Due to the abundance of acquatic habitats and the diversity of the terrain, the valley supports basin grasslands, acquatic plants, sedge borders and marshes, gypsum dune assemblages, Chihuahuan desert scrub and chaparral. Scientific literature mentions 879 taxa distributed among 860 species in 456 genera from 114 families, and as many as thirthy species are endemic.

Fauna
Endemism in the fauna is found especially in fish, reptiles, snails and crustaceans. Stromatolites grow in many of the pools and are considered to be globally rare. For all these reasons, the Cuatrociénegas valley has been touted as “México’s desert aquarium” in an article of National Geographic of 1995.


Research and protection
The international scientific and conservation community is interested in the flora and fauna of the valley, and fears that many of the current land use practices (irrigation, agriculture, ranching, mining and bathing) are putting the biota at risk of extinction.

Scientists have repeatedly called for the protection of the ecosystem of the area; finally, to preserve the natural habitats and the most fragile ecosystems of the region and to establish a field station for scientific investigation, on November 4th 1994, the Mexican government decreed the valley of Cuatrociénegas a Natural Protected Area, with the character of Area of Protection of Flora and Fauna.


Hydrogeological and speleological aspects
Much has been written about Cuatrociénegas but the area is practically unknown from a hydrogeological and speleological point of view, so that the “water in the desert” is still a “mystery”.

The researchers of the association La Venta, basing upon a short field work carried out in November 1998 and May 1999, ended up to the conclusion that Cuatrociénegas is a huge karst ecosystem. So, to contribute to the understanding of the undergrond mechanism regulating the huge basin of the valley, in november 2000 La Venta undertook a long-term project subdivided into survey of the caves in the high mountains and canyons and cave diving exploration of lakes and pools.

esplorazione speleosubacquea
During this expedition we surveyed some canyons of the Sierra Purissima (Pedregoso) and of the Sierra San Marcos y Pinos (Las Mulas, Los Mimbres, La Cueva, Los Cuates, Las Colmenas, Tomas, El Rosillo and others). At the present time the explored caves sum up to a total of about 5 kilometers of development; most of them will be further surveyed during our next expedition.

Some small pits blowing hot humid air seem to be particularly important; locally called “volcanoes”, they represent a fundamental object of our explorations. Besides, several cave dives were carried out in the main pozas of the valley (Churinche, Bonita, Mojarral, Becerra, Poza Azul, Anteojo, Orozco, Escobedo, Tio Candido, Hundidos, Campana, Santa Tecla, Venado, La Vega e Pozas Azules), collecting water samples for chemical-physical analyses.

Poza Azul 7 and 8, with stromatolites, were explored to the depth of –10 and –14 respectively, reaching a mud bottom.
La Campana, previously dived by unknown explorers who let the life line in place, was further explored to the depth of –19, and a detailed mapping was carried out. La Poza Azul, the best known and most touristic of the valley, was descended to –5, where three significant though impassable karst channels opened on the bottom.


 

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