The SALAR DE UYUNI is not a lake in the conventional sense: though below the surface it is largely saturated by water, its uppermost layer consists of a thick, hard crust of salt, easily capable of supporting the weight of a car. Driving across this perfectly flat white expanse, with unbroken chains of snowcapped mountains lining the far horizon, it’s easy to believe you’re on another planet, so harsh and inhospitable is the terrain. When dry, the dazzling salt surface shines with such intense whiteness that it appears to be ice or snow, while by night the entire landscape is illuminated by the eerie white glow of moonlight reflected in the salt. When it’s covered in water after rain (Dec to April), the Salar is turned into an enormous mirror that reflects the surrounding mountain peaks and the sky so perfectly that at times the horizon disappears and the mountains appear like islands floating in the sky.
No less strange are the tenacious ecosystems that survive around its arid and salty margins, including colonies of cacti and other hardy plants, rabbit-like viscachas and flamingos that nest here during the rainy season. Equally hardy are the isolated communities of Aymara and Quechua campesinos eking out a marginal existence here.
The Salar de Uyuni occupies what was once the deepest part of an enormous lake, known as Lago Tauca, which covered the southern Altiplano until 12,000 years ago. Reaching depths of up to 70m, Lago Tauca existed for a thousand years and covered the area now occupied by Lago Poopó, the Salar de Coipasa and the Salar de Uyuni – and was itself the successor to an earlier lake, Lago Minchín. The Salar was formed when the last waters of Lago Tauca evaporated, leaving behind salt that had been leached into the lake from the surrounding mountains, where it had been deposited millions of years ago before the Andes were formed, when what is now Bolivia was beneath the ocean.
According to studies, the salt extends to depths of up to 120m, packed in layers sandwiched between sedimentary deposits. In the dry season, the surface of the Salar, up to a depth of 10–20cm, becomes extremely hard and dry. Beneath this crust, though, the salt remains saturated with water. As the top layer dries, it contracts, forming cracks which draw the underlying salt water up by capillary action, thereby forming the strange polygonal lines of raised salt that cover the Salar in the dry season. As well as salt, the Salar is also home to the world’s largest deposit of lithium (a mineral used in mobile phones, laptops, iPods, electric cars and many other devices). The Bolivian government has started extraction projects – and international mining conglomerates would dearly like to do so too – but there are fears that mining could have disastrous consequences for the fragile ecosystems surrounding the Salar.
For the campesinos living on the shores of the lake, explanations of the Salar’s origin are rather different. Legend has it the mountain goddess Yana Pollera – the nearest peak to Uyuni – was amorously involved with both Thunupa, the volcano on the north shore of the Salar, and a second volcano named Q’osqo. When she gave birth to a child, the two male volcanoes fought bitterly over who was the father. Worried for the child’s safety, Yana Pollera sent it far away to the west. Then, concerned that her child would not survive alone, she flooded the plain between them with her milk so it could feed. Eventually the milk turned to salt, and the lake – traditionally known as the Salar de Thunupa – came into being.