At its farthest end, glaciers meet to dump their effluvia into the milky grey glacial water, launching massive icebergs into the lake. The Mount Fitz Roy (named after the captain of Charles Darwin’s ship, the Beagle), Upsala, Onelli, Spegazzini, and the majestic Perito Moreno Glaciers (named for a 19th-century explorer), calve into the icy lakes. Both lakes are fed by water from melting glaciers and by rivers and their unique colour is attributed to ‘glacier milk’: suspended fine sediment produced by the abrasion of glaciers rubbing against rock.
The most striking sight of the landscape is epitomized where the Perito Moreno Glacier meets Lake Argentino. Located on a narrow channel that separates the main body of Lake Argentino from its southern arm, the glacier, up to 60 metres high, forms a natural ice dam when it advances slowly, constantly to the extent that it reaches the other side of the channel, creating two separate bodies of water. Once the dam is formed, water and ice commence a kind of duel: water from melting glaciers drain into the trapped section of lake, and the pressure of the rising waters inevitably becomes too much and the ice dam rapture naturally, gives way to crushing lake waters trapped behind it and finally breaking apart.
The crackling sound of sheets of ice and regular thunderous ruptures of the glacier tongue crashing into the lake, creating new floating ice formation and forming impressive waves, is an audiovisual spectacle.
The park is an excellent example of the significant process of glaciation, as well as of geological, geomorphic and physiographic phenomena caused by the ongoing advance and retreat of the glaciations that took place during the Pleistocene epoch in the Quaternary period, and the neo-glaciations corresponding to the current epoch or Holocene. These events have modelled the area landscape and may be recognised by the lacustrine basins of glacial origin, the moraine systems deposited on the plateaux, or by more recent systems pertaining to the current valleys, and, the many large glacier tongues fed by the Andes Ice Fields.
Adjacent to the East, where the park transitions into the steppes of the lower elevations near the lakes, there is a National Reserve divided into three distinct units,
- “Viedma” in the north,
- a “Central Zone” and
- “Zona Roca” to the South.
This park is adjacent to the two national parks of Torres del Paine and Bernardo O’Higgins on the Chilean side, effectively forming a contiguous protected areas complex of impressive scale stretching across the border.
Despite the name’s focus on the impressive glaciers, there is a remarkable landscape diversity encompassing a large altitudinal gradient of more than 3000 metres and very diverse ecosystems. The park is an extensive and fairly well-conserved sample of several types of flora:
- Against the backdrop of rugged, towering mountains, the main ecosystems are subantarctic or Magellanic forests. Sometimes also referred to as cold Andean-Patagonian forests, they are dominated by various species of Southern Beech, some of which display dramatic colours in the autumn of the Southern hemisphere.
- After a transitional zone of woodland and scrub, the lower elevations further east mark the beginning of the vast semiarid Patagonian steppes.
- Next to the peaks and glaciers there are highly specified high-altitude vegetation, the subantarctic xerophytic cushion grasses.
The Puma and the elusive Andean Cat, locally known as Guiña, roam the park, as does the elusive Huemul, a rare native deer species of the Southern Andes. There is a rich bird fauna of more than 1,000 species, including important breeding populations of the emblematic Andean Condor and Darwin’s Rhea, sometimes called the “South American Ostrich” and locally known as Choique.
The integrity of the park is enhanced by its associated cultural and biodiversity values. A magnificent peak, known as Cerro Chaltén, is based on the native Aonikenk word for “smoking mountain”. Many place names go back to the Aonikenk, but petroglyphs and other artifacts are reminiscent of even earlier original inhabitants.