Khumbu Icefall

The Khumbu Icefall is an icefall at the head of the Khumbu Glacier. The icefall is found at 5,486 metres (17,999 ft) on the Nepali slopes of Mount Everest not far above Base Camp and southwest of the summit. The icefall is regarded as one of the most dangerous stages of the South Col route to Everest's summit. The Khumbu glacier that forms the icefall moves at such speed that large crevasses open with little warning. The large towers of ice or seracs found at the icefall have been known to collapse suddenly. Huge blocks of ice tumble down the glacier from time to time; they range in size from cars to large houses. It is estimated that the glacier advances 3 to 4 feet (0.91 to 1.22 m) down the mountain every day.

• http://en.wikipedia.org/wiki/Khumbu Icefall