The Perito Moreno Glacier is a glacier located in the Los Glaciares National Park in southwest Santa Cruz Province, Argentina. It is one of the most important tourist attractions in the Argentinian Patagonia.The 250km2 ice formation, and 30km in length, is one of 48 glaciers fed by the Southern Patagonian Ice Field located in the Andes system shared with Chile. This ice field is the world’s third largest reserve of fresh water.The Perito Moreno Glacier, located 78km from El Calafate, was named after the explorer Francisco Moreno, a pioneer who studied the region in the 19th century and played a major role in defending the territory of Argentina in the conflict surrounding the international border dispute with Chile.StatusThe glacier is unusual in that it is advancing, while most glaciers worldwide are retreating. The reason remains debated by glaciologists. The terminus of the Perito Moreno Glacier is 5km wide, with an average height of 74m above the surface of the water of Argentino Lake, in Argentina. It has a total ice depth of 170m.RupturePressures from the weight of the ice slowly pushes the glacier over the southern arm of Argentino Lake, damming the section and separating it from the rest of the lake. With no outlet, the water level on the “Brazo Rico” side of the lake can rise by as much as 30 meters above the level of the main body of Argentino Lake. Intermittently, the pressure produced by the height of the dammed water breaks through the ice barrier causing a spectacular rupture, sending a massive outpouring of water from the Brazo Rico section to the main body of Lake Argentino. As the water exits Brazo Rico, the scored shoreline is exposed, showing evidence of the height of the water build-up. This dam – ice-bridge – rupture cycle recurs naturally between once a year to less than once a decade.