An ice arch 70-meters high and 250 meters wide had a spectacular collapse in Patagonia on Thursday. The natural display occurs once every few years and was captured on film at the tip of a glacier in southern Argentina. Phys.org reports: Thousands of tourists had gathered at the Perito Moreno glacier hoping to see the collapse of the pale blue bridge that had formed between the glacier and the shore of Argentino lake. Such arches form roughly every two to four years, when the glacier forms a dam of ice that cuts off the flow of water around it into the lake—until the water breaks through, opening up a steadily wider tunnel that eventually becomes a narrow arch… and then collapses. The phenomenon, which is not linked to climate change, is due to Archimedes’s principle, which holds that the buoyant force exerted on a body immersed in fluid is equal to the weight of the fluid displaced, explained Glaciarium, a research center and glacier museum in the Argentine Patagonia region. “When that force causes the ice to detach from the shore, water begins filtering through and the process of breakdown begins, which is irreversible,” said Glaciarium. The last time such [...]