CODEX Entry 3701: Bolivian Salt Flats
These are the world’s largest salt flats, at over 10,000 square kilometres (3,900 sq mi) in area at an elevation of 3,656 meters (11,995 ft) above sea level. There were formed around 30,000 years ago when the salt lake Minchin either drained into the Atlantic via the Pilcomayo River and Rio de la Plata, or it drained out into the Pacific Ocean through its southwestern corner before it was obstructed by volcanism. It is covered by a few meters of salt crust, which has an extraordinary flatness with the elevation variations of less than a meter over the entire area. The crust sits upon a pool of brine, which contains 7% of the world’s lithium. Rain transforms the flat into the world’s largest mirror, 129 kilometers (80 miles) across.