thumb|Aerial view of the glacier, taken two weeks before the 2004 rupture

thumb|Map of the glacier with the [[Southern Patagonian Ice Field dispute#Agreement|internation border made in 1998.]]

The Perito Moreno (), Francisco Gormaz or Bismarck Glacier It is one of the most important tourist attractions in the Argentine Patagonia.

The ice formation, in length, is one of 48 glaciers fed by the Southern Patagonian Ice Field located in the Andes system shared with Chile which has a small part of the origins of the glacier. It was previously one of the few unusual glaciers that maintained a state of equilibrium during the late 20th and early 21st centuries because it was accumulating mass at a rate similar to that of its loss. The reason for its unusually long period of stability remains debated by glaciologists.

The terminus of the Perito Moreno Glacier is wide, with an average height of above the surface of the water of Argentino Lake, in Argentina. It has a total ice depth of .

History

In 1879, the British Chilean Navy captain, Juan Tomás Rogers,

Finally, in 1899, after long years of research, compilation of archaeological material, and surveys of the area, Lieutenant Iglesias, who was in charge of the studies for the Argentine Hydrographic Institute, named the glacier Perito Moreno in homage to Francisco Moreno.

With the Southern Patagonian Ice Field dispute, its origin was in dispute until the signing of the 1998 agreement where the line that was set crosses the origin of the glacier leaving a small part in Chile and all the rest in Argentina.

Rupture

thumb|A [[glacier cave at the edge of the glacier]]

Pressure from the weight of the ice slowly pushes the glacier over the inner fjord of Lake Argentino reaching the coast of Península 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. 2018 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 the twentieth century it continued its progression, managing to close its arm for the first time in 1917, followed by the first break.

Sudden discharge ruptures

In the 21st century, the events of 2004, 2006, 2008 and 2012 are classified as sudden download events. and discharge flow peak had a value of 5000 m³ / s, finishing with matching lake levels after four days. It was estimated that 10,000 tourists watched this event.

A large visitor centre inside the Los Glaciares national park features a walking circuit which allows visitors to view the southern flank and the east-facing edge of the glacier. Tour companies also offer boat tours on the Lago Argentino, passing by the northern flank of the glacier.

In recent years, trekking tours on the ice have gained popularity. The two standard tours are a "mini-trekking" option, consisting of a short walk of about an hour and a half, and a "big ice" version, which is usually about five hours. Tour companies generally provide crampons to customers.

thumb|801x801px|Panoramic view of the glacier taken from the walkway next to the visitor center

Fauna

A small glacier stonefly called Andiperla willinki inhabits the glacier. Also called "the pearl of the Andes" or "dragon of Patagonia" is a kind of plecoptera of the family Gripopterygidae that inhabits the Patagonian glaciers in Argentina and Chile, spending its entire life on the ice. It measures approximately and feeds on bacteria, brought by the wind, that live on the ice.

It was found on the Upsala Glacier and described by Aubert Willink in 1956. Due to its rarity, small size, and extreme habitat, they believed it had become extinct. However, it was rediscovered in 2001 in a Torres del Paine glacier in a 20 m deep recess; on this occasion, it was named by the crew as "Patagonian dragon".

References

  • The Glaciers National Park
  • Perito Moreno Glacier at NASA Earth Observatory, November 21, 2021
  • Pictures of Perito Moreno Glacier