Lake Minchin

Lake Minchin is a name of an ancient lake in the Altiplano of South America. It existed where today the Salar de Uyuni, Salar de Coipasa and Lake Poopó lie. It was formerly considered the highest lake in the Altiplano but research indicated that the highest shoreline belongs to the later Lake Tauca instead.

The concept of a "Lake Minchin" was first coined in 1906 and it is based on John B. Minchin. The dating of the lake varies but probably lasted until 22,000 – 21,000 BP. A glacier advance was in progress in the Andes during that timeperiod.

The name "Minchin" has also been used in other contexts, and it has been proposed that the lake was actually a combination of several different paleolakes.

The name "Lake Minchin" has been used inconsistently to refer to either a lake existing 45,000 years ago, the highest lake in the Altiplano or sediment formations, leading to calls to drop the usage of the name "Minchin". An alternative theory postulates that Lake Minchin was formed by several lakes , including Ouki and Inca Huasi. Sometimes the term "Minchin" is also applied to the whole hydrological system Titicaca-Rio Desaguadero-Lake Poopo-Salar de Coipasa-Salar de Uyuni, or to the highest ancient lake in the Altiplano (usually known as Lake Tauca). There are also contradictions between lake level records in different parts of the system.

During its history a number of lakes appeared and then disappeared on the Altiplano. Lake Minchin was one of the first of these ancient lakes to be described. These lakes were identified by the lake terraces, sediments and bioherms. Earlier lakes such as Lake Escara are documented from drill holes in the Salar de Uyuni. Later lakes include Lake Tauca and Lake Coipasa. As early as 1861 there are reports that lake deposits exist on the Altiplano. John B. Minchin in 1882 reported the existence of encrustations around Lake Poopo and the salars south of Coipasa. He postulated a lake with a surface area of 120,000 square kilometres (46,000 sq mi) left these encrustations and that the nitrate deposits in the Atacama and Tarapaca were likewise formed by water draining for this lake. Some estimates of the size of this lake claimed that it reached from Lake Titicaca as far as 27° south. The name "Lake Minchin" was applied in 1906 by Steinmann, who applied it to the Uyuni basin, while naming the lake covering the Poopo and Coipasa basins "Lake Reck". The name was applied in honour of John B. Minchin. Later it was found that Lake Titicaca was not part of Lake Minchin and the theory was put forward that meltwater from glaciers had formed the lake. A different lake Lake Ballivian was also defined which encompassed Lake Titicaca. The relationship between various deposits in the southern Altiplano and these around Lake Titicaca was unclear at the beginning of the research history.

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