The Salar of #uyuni ( #bolivia ) was formed as a result of transformations between several prehistoric #lakes that existed around forty thousand years ago but had all evaporated over time. It is now covered by a few meters of #salt crust, which has an extraordinary flatness with the average elevation 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