Snow and ice from the Andes Mountains move downstream at around 70 cm a day. When they accumulate to the point where they block the flow of the river, melting spring snow from upstream is trapped behind them and forms a lake.
安地斯山脈的冰雪因重力、隨水流下移，每天前推約七十公分；當冰雪堆積到足以使河流阻塞時，春季雪溶的上游無處渲洩，即形成湖泊。