In geology, a proglacial lake is a lake formed either by the damming action of a moraine or ice dam during the retreat of a melting glacier, or one formed 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 approximately 10,000 years ago, large proglacial lakes were a widespread feature in the northern hemisphere.

In some cases, such lakes gradually evaporated during the warming period after the Quaternary ice age. In other cases, such as Glacial Lake Missoula and Glacial Lake Wisconsin in the United States, the sudden rupturing the supporting dam allowed rapid catastrophic floods, resulting in the formation of gorges and other structures downstream from the former lake.

In Great Britain, Lake Lapworth, Lake Harrison and Lake Pickering are examples of proglacial lakes. Ironbridge Gorge is an overspill channel created when the waters of Lake Lapworth rose high enough to breach the lowest point in the southern watershed.

See also

• List of prehistoric lakes
• Pluvial lake
• Proglacial lakes of Minnesota