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Prospecting in Atacama karst

Ojo de Opache and Cordillera de la Sal - some notes

By Natalia Morata

The karst phenomenon is relatively rare in Chile. However, one of the most fascinating karst landscapes in the world is found in southern Patagonia, between latitudes 50 and 51 S, facing the Pacific and in one of the rainiest areas of the planet. The fact of finding an area of limestone excavated by water is what gave rise to the expeditions of the French speleological association Centre Terre, which has been exploring the karst of the Diego de Almagro island and the Madre de Dios archipelago since the late 1990s.

Pseudo-karstic phenomena in neighbouring areas, such as the Southern Patagonian Ice Field, can provide relevant information on what it may have been like at the time of the thaw, when this southern limestone was exposed.

Exploration and study of the area and the caves that have formed there have shed light on the fascinating geological history of the site, as well as many other aspects that you can read about in the documentaries, reports and books published by Centre Terre.

Although not abundant, there are other extraordinary karst areas in Chile that have also attracted speleoscientific expeditions, such as the Italian La Venta group in the Cordillera de la Sal in the Antofagasta region.

Valley of the Moon, Salt Mountains Range

Photos: Natalia Morata

In fact, in the north of Chile, in the middle of the Atacama Desert, there is karst. And "karst" means that there are probably caves. And the fact that there are caves is an irresistible attraction for any caver.

So when Raúl Painén told me that it would be interesting to go and see some "holes" he had located, I didn't hesitate. Professionally, Raúl works in the rescue group of the GOPE (Special Police Operations Group) in Calama. In 2021 he completed the module II of the caving workshop in Santiago and, from that moment on, he became even more interested in seeing the possibilities of applying caving techniques and equipment in his area of work.

Mining shaft Photos: Raúl Painén, Natalia Morata

So it was that on 22 and 23 March 2022 we organised two intense days of prospecting. The objective was twofold: on the one hand, to see places to organise a future caving course for northern rescue groups; and on the other hand, to see the potential of the site to organise a future Centre Terre expedition to the area.

The places chosen by Raul could not have been better: the Ojo de Opache canyon (just 13 km west of Calama) and a cave in the Cordillera de la Sal, near San Pedro de Atacama. He also took me to another of his practice areas: a mining pit.

Ojo de Opache - Loa karst

It is a beautiful karst canyon that is in the process of being declared a Nature Sanctuary for being one of the wetlands of singular relevance.

Climbing area, west of Ojo de Opache

Photos: Natalia Morata

From a karstic point of view, it is curious to observe how the limestone has emerged after a process of karstification that seems very old, but which left all the marks of the passage of large quantities of water through the area (grooves, notches, etc.).

Ojo de Opache

Ojo de Opache

Photos: Raúl Painén, Natalia Morata

The spring, located on the east side of the canyon, has small galleries parallel to the watercourse with formations and a limestone that appears purer than the surface limestone.

Spring Ojo de Opache

Photos: Natalia Morata

In addition to its value in terms of biodiversity, the site is a jewel that allows us to observe various aspects of karstification phenomena in the open air!

Gas cave - Salt Mountains Range

On the east side of the CH-23 road from Calama to San Pedro de Atacama, a large hole has opened up.

Some say that a meteorite was the cause of this great hole; others say that it was formed by the action of water... What is certain is that this imposing pit opens up in the middle of a landscape of salt, gypsum, clay, quartz... From the entry, a black hole can be seen at the base of the first shaft, which seems to indicate that the cavity continues. And the only way to check this is by descending it...

Gas cave, provisionally named in the absence of a known name

Photos: Raúl Painén, Natalia Morata

In 2014, during the search operation for Kurt Martinson, a tourist guide who disappeared in San Pedro de Atacama (and who was never found), the GOPE installed deep stakes a few metres from the entry of the pit in order to descend it. The type of terrain made it impossible to install bolts, so we used the same stakes as head anchors and rope protectors for the areas of greatest friction, thus preventing the rope from sinking too deep.

Descend into the Gas cave

Fotos: Raúl Painén, Natalia Morata

At the base of the first shaft, a rock served as a natural anchor to allow us to descend the two ledges that allowed us to continue our descent. No draught was perceptible, but the conduit seemed to continue on a sandy ramp, judging by the sound of the stones we threw. After the first ledge of about two metres, a more compact rock appears which, if necessary, would allow anchors to be installed. However, after descending the second ledge of about three metres, I had to turn back quickly after smelling an intense gas smell (similar to when one mixes chlorine bleach with toilet cleaner). The sensation was one of dizziness and shortness of breath.

Base of the shaft and one of the stakes.

Photos: Raúl Painén, Natalia Morata

Such a finding was to be reported. However, that particular site does not appear to be under the administration of any agency or community and therefore it was not clear to whom to give the information. CONAF and GOPE have been notified. Ideally, a gas survey should be carried out.

The Valley of Death - Salt Mountains Range

Between San Pedro de Atacama and Quitor lies the Valley of Death, a beautiful landscape of gypsum, clay, salt and quartz chiselled and washed away by the action of water. Walking through it is a bit like walking through the grooves and tormented lapiaces of Madre de Dios, only under a blazing sun, on extremely fragile and unstable terrain, and in the middle of the driest desert in the world, at 2000 m.a.s.l.

Valley of Death

Photos: Raúl Painén, Natalia Morata

<div><br class="Apple-interchange-newline">In short, the places chosen by Raúl are extraordinary both for organising courses (Ojo de Opache) and for exploring. The exploration is quite delicate and exposed, so it is not recommended to do it without the company of experienced cavers.

As for Centre Terre, we are now focused on preparing the Ultima Patagonia 2023 expedition, but Atacama is already firmly on our radar...

Special thanks to Lorena and Rayén for their hospitality, to the GOPE Calama for their excellent predisposition, information and support and to Raúl for his professionalism and for being such a good companion in our adventures.</div>


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