Jökulhlaup

[2] Similar processes on a very large scale occurred during the deglaciation of North America and Europe after the last ice age (e.g., Lake Agassiz and the English Channel), and presumably at earlier times, although the geological record is not well preserved.

This erosive environment is consistent with creation of tunnels over 400 m deep and 2.5 km wide, as have been observed in the Antarctic.

[3] Piotrowski has developed a detailed analytic model of the process, which predicts a cycle as follows:[5] A subglacial lake in Iceland was inadvertently triggered by a borehole drilled through the overlying ice.

The authors suggested that hydrofracturing crevasses and flooding of moulins by precipitation events may be natural triggers of jökulhlaups.

The categories of origin are:[17]: 2 [18] In July 1994, an ice-dammed surface lake drained via a subglacial tunnel through Goddard Glacier [sv], in the British Columbian Coast Mountains, resulting in a jökulhlaup.

The flood surge of from 100 to 300 m3/second flowed 11 km through Farrow Creek to terminate in Chilko Lake, causing significant erosion.

[19] As the Laurentide Ice Sheet receded from its maximum extent from around 21,000 to 13,000 years ago, two significant meltwater rerouting events occurred in eastern North America.

Though there is still much debate among geologists as to where these events occurred, they likely took place when the ice sheet receded from the Adirondack Mountains and the St. Lawrence Lowlands.