Southern Patagonian Ice Field in the area, among which are the Upsala (765 km), Viedma (978 km) and Perito Moreno (258 km) in the Los Glaciares National Park in Argentina, and the Pío XI Glacier or Bruggen Glacier (1,265 km, the largest in area and longest in the southern hemisphere outside of Antarctica), O'Higgins (820 km), Grey (270 km) and Tyndall (331 km) in Chile. The glaciers going to the west flow into the fjords of the Patagonian channels of the Pacific Ocean; those going to the East flow into the Patagonian lakes Viedma and Argentino, and eventually, through the rivers "de la Leona"
Patagonian Desert appeared at the edges of the desert. The most important was established at Chubut River's outflow by Welsh immigrants in 1860. Perito Moreno explored the desert in the 1870s. In the 1870s the Argentine army undertook the Conquest of the Desert campaign, massively defeating Mapuche warlords. The Conquest of the Desert was followed by a sharp decline in the indigenous population of the desert; some were chased into Chile and peripheral areas in the Andes. It is estimated that the Conquest of the Desert caused the death of about 1,000 Native Americans. Additionally 10,000 Native Americans were taken prisoner of