page_title: Proglacial lake
section_title: Moraine-dammed
hierarchical_section_title: Proglacial lake / Moraine-dammed
context_page_description: In geology, a proglacial lake is a lake formed either by the damming action of a moraine during the retreat of a melting glacier, a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice. At the end of the last ice age about 10,000 years ago, large proglacial lakes were a widespread feature in the northern hemisphere.
context_section_description: The receding glaciers of the tropical Andes have formed a number of proglacial lakes, especially in the Cordillera Blanca of Peru, where 70% of all tropical glaciers are. Several such lakes have formed rapidly during the 20th century. These lakes may burst, creating a hazard for zones below. Many natural dams (usually moraines) containing the lake water have been reinforced with safety dams. Some 34 such dams have been built in the Cordillera Blanca to contain proglacial lakes. 
  Several proglacial lakes have also formed in recent decades at the end of glaciers on the eastern side of New Zealand's Southern Alps. The most accessible, Lake Tasman, hosts boat trips for tourists.
  On a smaller scale, a mountain glacier may excavate a depression forming a cirque, which may contain a mountain lake, called a tarn, upon the melting of the glacial ice.
caption: Glacial action forming a cirque to become a tarn, upon melting