In June, Canadian officials warned that a nameless lake in the Northwest Territories was about to fall off a cliff. It did. On July 15, a section of ground ice that's been around since the last ice age gave way, sending roughly half of the lake's 1 million cubic feet of water—the equivalent of a dozen Olympic-sized swimming pools—cascading into a valley below in a five-story waterfall that lasted two hours. "Water rushed over the slump debris and down a narrow valley before emptying into a larger lake" about 3 miles downstream, leaving the nearby community of Fort McPherson unscathed, according to the Northwest Territories Geological Survey.
A time-lapse video shows the collapse along with an ooze of mud and water.
A time-lapse video shows the collapse along with an ooze of mud and water.