 A mass of fractured ice, 100–130 m thick, blocked the Upper Karmadon Springs and moved into the upper parts of the Glenadon valley, travelling at 20–50 m per day.By January 1970 it had stopped but, by then, the glacier had extended its length by 4.1 km and descended 800 m.

The most catastrophic surge to date occurred on September 20, 2002, when a mass of ice, water and rocks streamed down a 4 km stretch of the valley with an icy mudflow travelling a further 12 km.Ice within the debris began to melt almost immediately, creating new lakes and flooding some settlements which, contrary to the old traditions, had been built on the valley floor.