page_title: Lake Tauca
section_title: Duration
hierarchical_section_title: Lake Tauca / Duration
caption_attribution_description: volcán Tunupa ubicado el borde del Salar de Uyuni, en el departamento de Oruro al oeste de Bolivia.
context_page_description: Lake Tauca is a former lake in the Altiplano of Bolivia. It is also known as Lake Pocoyu for its constituent lakes: Lake Poopó, Salar de Coipasa and Salar de Uyuni. The lake covered large parts of the southern Altiplano between the Eastern Cordillera and the Western Cordillera, covering an estimated 48,000 to 80,000 square kilometres of the basins of present-day Lake Poopó and the Salars of Uyuni, Coipasa and adjacent basins. Water levels varied, possibly reaching 3,800 metres in altitude. The lake was saline. The lake received water from Lake Titicaca, but whether this contributed most of Tauca's water or only a small amount is controversial; the quantity was sufficient to influence the local climate and depress the underlying terrain with its weight. Diatoms, plants and animals developed in the lake, sometimes forming reef knolls.
  The duration of Lake Tauca's existence is uncertain. Research in 2011 indicated that the rise in lake levels began 18,500 BP, peaking 16,000 and 14,500 years ago. About 14,200 years ago, lake levels dropped before rising again until 11,500 years ago. Some researchers postulate that the last phase of Lake Tauca may have continued until 8,500 BP.
context_section_description: The existence of Lake Tauca was preceded by a dry period, with minor lake events recorded in Salar de Uyuni in the Late Pleistocene at 28,200–30,800 and 31,800–33,400 BP. The earlier Lake Minchin formed at the site of Lake Tauca. This period was accompanied by the disappearance of ice from Nevado Sajama. A dry period is also noted in Africa and other parts of South America around 18,000 BP, and the retreat of the Amazon rainforest may have produced the lake low-water mark. The era may have been drier than the present. The drying of Lake Minchin left a salt layer about 20 metres (66 ft) thick in the Salar de Uyuni, where gullies formed. Some ooid sediments formed before the Lake Tauca phase. Around 28,000 BP, lake levels rose in Lake Huinaymarca (Lake Titicaca's southern basin), preceding Lake Tauca by about two millennia. During this period, lakes in the Uyuni basin were intermittent. Previous lakes in the basin were generally small and shallow.
  The radiometric age of Lake Tauca ranges from 72,600 to 7200 BP. The duration of the lake highstands may be overestimated due to radiation scatter. Radiocarbon dates have been obtained on crusts containing calcite, gastropod shells, stromatolites and structures left behind by algae. The Lake Tauca shorelines formed over more than century-long periods.
  The first research, by Servant and Fontes in 1978, indicated a lake age between 12,500 and 11,000 BP according to C-14 dating. These were bracketed by dates between 12,360 ± 120 and 10,640 ± 280 BP for the highest deposits at Salar de Coipasa and Salar de Uyuni, and 10,020 ± 160 and 10,380 ± 180 BP for deposits which formed shortly before the lake dried. The reliability of the dates was questioned in 1990, and a later estimate was set at 13,000 to 10,000 BP. In 1990, Rondeau proposed ages of 14,100 to 11,000 BP based on radiocarbon dating and 7,000 to 14,800 BP based on uranium-thorium dating.
  In 1993 it was suggested that Lake Tauca had an earlier phase, with water levels reaching 3,740 metres (12,270 ft), and a later phase reaching 3,720 metres (12,200 ft). Research published in 1995 indicated that the lake was shallow for over a millennium before rising to (and stabilizing at) its maximum level. Water levels between 13,900 and 11,500 BP reached 3,720 metres (12,200 ft); 3,740 metres (12,270 ft) was reached between 12,475 and 11,540 BP, and 3,760 to 3,770 metres (12,340 to 12,370 ft) between 12,200 and 11,500 BP.
  Research in 1999 indicated an earlier start of the Tauca lake cycle, which was subdivided into three phases and several sub-phases. Around 15,438 ± 80 BP (the Tauca Ia phase), water levels in Salar de Uyuni were 4 metres (13 ft) higher than the current salt crust. Lake levels then rose to 27 metres (89 ft) above the salt flat, accompanied by freshwater input (Tauca Ib). Around 13,530 ± 50 BP (Tauca II), the lake reached an altitude of 3,693 metres (12,116 ft),  not exceeding 3,700 metres (12,100 ft). At this time, strong gully erosion and alluvial fans probably formed in Bolivian valleys. Between 13,000 and 12,000 BP, the lake reached its greatest depth—110 metres (360 ft)—of the Tauca III period. Dates of 15,070 BP and 15,330 BP were obtained for the highest shoreline, at 3,760 metres (12,340 ft). After 12,000 BP, water levels decreased abruptly by 100 metres (330 ft). An even-earlier start was proposed by 2001 research, based on sediments in the Uyuni basin, which determined that Lake Tauca began developing 26,100 BP. A 2001 review indicated that most radiometric dates for Lake Tauca cluster between 16,000 and 12,000 BP, with lake levels peaking around 16,000 BP. A drop in oxygen-18 concentration in the Nevado Sajama glaciers has been associated with increased precipitation around 14,300 years ago. A 2005 book estimated the duration of the Lake Tauca phase at between 15,000 and 10,500 BP.
  Research in 2006 postulated that the Lake Tauca transgression began 17,850 BP and peaked at altitudes of 3,765 to 3,790 metres (12,352 to 12,434 ft) between 16,400 and 14,100 years ago. Spillovers into neighbouring basins may have stab
caption: The Tunupa volcano was glaciated during the Tauca episode
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