de Magallanes and bisecting the lake at an area called the Brazo Rico (Rico Arm) on one side and the Canal de los Témpanos (Iceberg Channel) on the other. 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 and the Santa Cruz river. 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 every decade. The glacier advances between June and December and recedes between December and April. The formation of an ice barrier is a complex process, since there is a feedback mechanism between the glacier and the lake, which affects the oscillations of the position of the glacial front in a fairly stable way. Different behaviors have been observed during the filling and in the processes of discharge of the water, which have been classified into three types: sudden, progressive and minor burst. In a sudden type event, the maximum discharge can reach 8000 m³ per second, while a smaller event only evacuates 123 m³. The ruptures do not have a specific frequency. Traditionally it was estimated one every three or four years, but there have been times where they happened in shorter periods and others in which it didn't occur for many years, causing fears that the phenomenon might possibly have stopped occurring. The ruptures occurred in the years, 1917, 1935, 1940, 1942, 1947, 1952, 1953, 1956, 1960, 1963, 1966, 1970, 1972, 1975, 1977, 1980, 1984, 1988, 2004, 2006, 2008, 2012, 2013 (two events, one in January and one in December), 2016, 2018 and 2019. The first recorded rupture (1917) Evidence from tree rings on the shorelines indicates that there were no major damming and rupture events of the Brazo Rico from about 1635 until the 20th century. The front of the glacier began to move towards the opposite bank at the end of the 19th century. In 1899 it was 750 meters from the Magallanes peninsula. In the first five years of