The jeeps gather to cross the Salar ... they prefer to travel in pairs ... if one breaks down, it is a long way from anywhere ... and back in 1999 there were no mobile phones out there ...
From Wikipedia -
Salar de Uyuni (or Salar de Tunupa) is the world's largest salt flat at 10,582 square kilometers (4,086 sq mi). It is located in the Potosí and Oruro departments in southwest Bolivia, near the crest of the Andes, and is elevated 3,656 meters (11,995 ft) above the mean sea level.
The Salar was formed as a result of transformations between several prehistoric lakes. It is covered by a few meters of salt crust, which has an extraordinary flatness with the average altitude variations within one meter over the entire area of the Salar. The crust serves as a source of salt and covers a pool of brine, which is exceptionally rich in lithium. It contains 50 to 70% of the world's lithium reserves, which is in the process of being extracted. The large area, clear skies and exceptional surface flatness make the Salar an ideal object for calibrating the altimeters of the Earth observation satellites. The Salar serves as the major transport route across the Bolivian Altiplano and is a major breeding ground for several species of pink flamingos.
Formation, geology and climate
Salar de Uyuni is part of the Altiplano of Bolivia in South America. The Altiplano is a high plateau, which was formed during uplift of the Andes mountains. The plateau includes fresh and saltwater lakes as well as salt flats and is surrounded by mountains with no drainage outlets.
The geological history of the Salar is associated with a sequential transformation between several vast lakes. Some 30,000–42,000 years ago, the area was part of a giant prehistoric lake, Lake Minchin. Its age was estimated from radiocarbon dating of shells from outcropping sediments and carbonate reefs and varies between reported studies. Lake Minchin (named after the Juan B. Minchin of Oruro) later transformed into paleolake Tauca having a maximal depth of 140 meters (460 ft), and an estimated age of 13,000–18,000 or 14,900–26,100 years depending on the source. The youngest prehistoric lake was Coipasa, which was radiocarbon dated to 11,500–13,400 years. When it dried, it left behind two modern lakes, Poopó Lake and Uru Uru Lake, and two major salt deserts, Salar de Coipasa and the larger Salar de Uyuni. Salar de Uyini spreads over 10,582 square kilometers (4,086 sq mi), which is roughly 25 times the size of the Bonneville Salt Flats in the United States. Lake Poopó is a neighbor of the much larger lake Titicaca. During the wet season, Titicaca overflows and discharges into Poopó, which, in turn, floods Salar De Coipasa and Salar de Uyuni.
Underneath the surface of the Salar is a lake of brine 2 to 20 meters (7 to 66 ft) deep. The brine is a saturated solution of table salt, lithium chloride and magnesium chloride in water. It is covered with a solid salt crust with a thickness varying between tens of centimeters to a few meters. The center of the Salar contains a few "islands", which are the remains of the tops of ancient volcanoes which were submerged during the era of lake Minchin. They include unusual and fragile coral-like structures and deposits that often consist of fossils and algae.
The area has a relatively stable average temperature with a peak at 21 °C (70 °F) in November-January and a low of 13 °C (55 °F) in June. The nights are however cold all through the year with temperatures between -9 and 5 °C (16 and 41 °F). The relative humidity is rather low and constant throughout the year at 30–45 %. The rainfall is also low at 1–3 millimeters (0.039–0.12 in) per month between April and November, but it may increase up to 70 millimeters (2.8 in) in January. However, except for January, even in the rainy season the number of rainy days is below 5 per month.
Salt production at the Salar
The Salar contains large amounts of sodium, potassium, lithium and magnesium (all in the chloride forms of NaCl, KCl, LiCl and MgCl2, respectively), as well as borax. Of those, lithium is arguably most important as it is a vital component of many electric batteries. With estimated 5,400,000 tonnes (5,310,000 LT; 5,950,000 ST), Bolivia holds about half of the world's lithium reserves; most of those are located in the Salar de Uyuni. Lithium is concentrated in the brine under the salt crust at a relatively high concentration of about 0.3%. It is also present in the top layers of the porous halite body lying under the brine; however the liquid brine is easier to extract, by boring into the crust and pumping out the brine. The brine distribution has been monitored by the Landsat satellite and confirmed in ground drilling tests. Following those findings, an American-based international corporation has invested $137 million to develop lithium extraction. However, lithium extraction in the 1980s and 1990s by foreign companies met strong opposition of the local community. Despite their poverty, locals believed that the money infused by mining would not reach them. There is currently no mining plant at the site, and the Bolivian government doesn't want to allow exploitation by foreign corporations. Instead, it intends to build its own pilot plant with a modest annual production of 1,200 tonnes (1,200 LT; 1,300 ST) of lithium and to increase it to 30,000 tonnes (30,000 LT; 33,000 ST) tonnes by 2012.
Salar de Uyuni is estimated to contain 10 billion tonnes (9.8 billion LT; 11 billion ST) tonnes of salt, of which less than 25,000 tonnes (25,000 LT; 28,000 ST) is extracted annually. All miners working in the Salar belong to Colchani's cooperative.
Because of its location, large area and flatness, the Salar is a major car transport route across the Bolivian Altiplano.
Salar is salt flat in Spanish and Uyuni originates from the Aymara language and means a pen (enclosure). Thus Salar de Uyuni can be loosely translated as a salt flat with enclosures, the latter possibly referring to the "islands" of the Salar. Uyuni is also the name for a town of 10,600 people, which serves as a gateway for tourists visiting the Salar.
Aymara legend tells that the mountains Tunupa, Kusku and Kusina, which surround the Salar, were giant people. Tunupa married Kusku, but Kusku ran away from her with Kusina. Grieving Tunupa started to cry while breast-feeding her son. Her tears mixed with milk and formed the Salar. Many locals consider the Tunupa an important deity and say that the place should be called Salar de Tunupa rather than Salar de Uyuni.
Flora and fauna
The Salar is virtually devoid of any wild life and vegetation. The latter is dominated by giant cacti (Echinopsis atacamensis pasacana, Echinopsis tarijensis, etc.). They grow at a rate of about 1 centimeter (0.39 in) per year to a length of about 12 meters (39 ft). Other shrubs include Pilaya, which is used by locals to cure catarrh, and Thola (Baccharis dracunculifolia), which is burned as a fuel. Also present are quinoa plants and quenua bushes.
Every November, Salar de Uyuni is the breeding grounds for three species of pink South American flamingos: the Chilean, Andean and rare James's Flamingos, their color presumably originating from feeding on pink algae. There are about 80 of other bird species present, including the horned coot, the Andean goose and the Andean Hillstar. Andean fox (culpeo) is a representative animal, and the "islands" of Salar (in particular the Incahuasi island, which is also called Isla del Pescadores) host a colony of rabbit-like viscachas.
Salar de Uyuni attracts tourists from around the world. As it is located far from the cities, a number of hotels have been built in the area. Due to lack of conventional construction materials, many of them are almost entirely (walls, roof, furniture) built with salt blocks cut from the Salar.
The first such hotel was erected in 1993-1995 in the middle of the salt flat, and soon became a popular tourist destination. However, its location in the center of a desert produced sanitary problems, as most waste had to be collected manually. Mismanagement caused serious environmental pollution and the hotel had to be dismantled in 2002. New salt hotels were built near the periphery of the Salar, closer to roads, in full compliance with environmental rules.
One major tourist attraction is an antique train cemetery. It is 3 kilometers (1.9 mi) outside Uyuni and is connected to it by the old train tracks. The town served in the past as a distribution hub for the trains carrying minerals enroute to Pacific Ocean ports. The rail lines were built by British engineers arriving near the end of the 19th century and formed a sizeable community in Uyuni. The engineers were invited by British-sponsored Antofagasta and Bolivia Railway Companies, which is now Ferrocarril de Antofagasta a Bolivia. The rail construction started in 1888 and ended in 1892. It was encouraged by Bolivian President Aniceto Arce, who believed Bolivia would flourish with a good transport system, but it was also constantly sabotaged by the local Aymara indigenous Indians who saw it as an intrusion into their lives. The trains were mostly used by the mining companies. In the 1940s, the mining industry collapsed, partly because of mineral depletion. Many trains were abandoned, producing the train cemetery. There are proposals to build a museum from the cemetery.
Some Earth observing satellites need to be precisely calibrated in terms the distance measurement while in orbit. For example, the primary objective of the NASA’s Geoscience Laser Altimeter System (GLAS), which is installed on the Ice, Cloud and land Elevation Satellite (ICESat), is to detect changes in ice sheet elevations of as little as 1.5 centimeters (0.59 in) per year, over 100-by-100-kilometre (62 × 62 mi) area. A common approach for calibrating the satellite elevation measurements is to compare them to an accurately surveyed terrestrial reference target. Salt flats are ideal for this purpose because they are large, stable surfaces having strong reflection, similar to that of ice sheets. Salar de Uyuni is especially suitable because it is the largest salt flat on Earth. In the low-rain period of from April to November, its skies are very clear, and the air is dry (relative humidity is about 30%, rainfall is roughly 1 millimetre or 0.039 in per month). Absence of large industries and the high elevation also contribute to the clarity of the air. The Salar also has a stable surface which is smoothed by seasonal flooding (water dissolves the salt surface and thus keeps it leveled). As a result, the variation in the surface elevation over the 10,582-square-kilometer (4,086 sq mi) area of Salar de Uyuni is less than 1 meter (3 ft 3 in), and there are square kilometers there which are flat within a few centimeters. The surface reflectivity (albedo) for ultraviolet light is relatively high at 0.69 and shows variations of only few percent during the daytime. Combination of all these features make Salar de Uyuni about five times better for satellite calibration than the surface of an ocean. Using Salar de Uyuni as the target, ICESat has already achieved the short-term elevation measurement accuracy of below 2 centimeters (0.79 in).
With the use of modern GPS technology, it can now be proved that the Salar de Uyuni is not perfectly flat. New measurements revealed previously missed features resembling ridges, hills, and valleys measuring only millimeters in height. They originate from the variation in material density, and thus the gravitational force, beneath the Salar's sediments. Just as the ocean surface rises over denser seamounts, the salt flat surface also rises and falls to reflect the subsurface density variations.