This small unnamed lake, shown in this undated University of Alberta handout photo, in the Northwest Territories is expected to burst through the rapidly shrinking land holding it in over the next few months and plunge 200 metres into the Mackenzie Valley. It's just one of a new wave of giant-sized permafrost slumps that are changing the territory's landscape on a scale not seen since the last Ice Age. (Scott Zolkos/THE CANADIAN PRESS)