The first glaciation occurred around 3,500,000 years ago, then a much bigger glaciation occurred 1,200,000 years ago, and at last between 20.000 y 10,000 years ago there were a series of glaciations of less importance but they were responsible for giving shape to the actual patagonic scenery, eroding and polishing the islands and mountains, leaving under the sea glacier valleys and moraines.
The most important heritage of all this period was the Southern Ice Field, a huge mass of continental glacier ice, which spills six of its 49 glaciers inside Torres del Paine National Park, from north to south: Dickson Glacier, Grey Glacier, Pingo Glacier, Zapata Glacier, Tyndall Glacier and Geike Glacier.
The Southern Ice Field is the third resource of fresh water in the world, after the Antarctic Glaciers and Greenland. It extends from north to south as far as 350 km, with an extension of 16.800 km2, the 85% belongs to Chile and the rest belongs to Argentina.
Most of the huge masses of ice are found at 2,500 m over sea level, but the glaciers in the Southern Ice Field and in Torres del Paine are found at 1,500 m. over sea level and descend until 200 m. over sea level, making it an easy and unique access and view.
The glaciers behave like a river of ice, it is said that a glacier is retreating when the ice accumulated is less than the ice detached. Most of the glaciers of the Southern Ice Field are retreating, due, basically to Global Warming and the natural cycles of the earth.