The formation of Lake Tauca depended on a reduction in air temperature over the Altiplano and an increase in precipitation, which may have been caused by shifts in the Intertropical Convergence Zone (ITCZ) and increased easterly winds. It was originally supposed that glacial melting might have filled Lake Tauca, but the quantity of water would not have been sufficient to fill the whole lake. The lake was accompanied by glacial advance, noticeable at Cerro Azanaques and Tunupa. Elsewhere in South America, water levels and glaciers also expanded during the Lake Tauca phase.