An ancient ice shelf has cracked off northern Ellesmere Island, creating an enormous, 66-square-kilometre ice island and leaving a trail of icy blocks in its wake. ''It really is incredible,'' says Warwick Vincent of Laval University, one of the few people to have laid eyes on the scene. ''It's like a cruise missile has come down and hit the ice shelf.'' The breakup was so powerful, earthquake monitors 250 kilometres away picked up the tremors as the 3,000 to 4,500 year-old shelf tore away from its fjord on Ellesmere. It broke up 16 months ago, but no one was present...