Perito Moreno Glacier facts for kids

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

Map of the glacier with the internation border made in 1998.

The Perito Moreno Glacier is a giant moving field of ice in South America. It is located inside Los Glaciares National Park in southwest Santa Cruz Province, Argentina. A small part begins in the Magallanes Region of Chile inside Bernardo O'Higgins National Park. It is also known as the Francisco Gormaz or Bismarck Glacier. People consider it one of the most famous natural wonders in Argentine Patagonia.

This ice giant covers an area of 250 km² (97 sq mi). It stretches for a length of 30 km (19 mi). It is one of 48 glaciers fed by the huge Southern Patagonian Ice Field. That field rests high within the jagged peaks of the icy Andes mountains. Together, these frozen mountains form the world's third largest reserve of natural fresh water.

The glacier sits about 78 kilometres (48 mi) away from the colorful town of El Calafate. It was named after an Argentine explorer and scientist named Francisco Moreno. He studied the wild region during the 19th century. He also helped resolve a border question in the 1902 Arbitral award of the Andes between Argentina and Chile.

How Glaciologists Study the Giant Ice Sheet

Scientists who study ice formations around the globe are known as glaciologists. For many decades, this body of ice surprised these curious experts. Most valley glaciers shrink rapidly because global temperatures continue to rise over time.

For a very long period, this icy giant remained in a rare balanced state. It gained new snow at its top at the same rate it lost ice. However, starting around 2020, its northern edge began retreating backward toward the mountains. Scientists believe warmer air and shifting wind patterns contribute to this modern melting process.

The front edge, or terminus, is about 5 km (3.1 mi) wide across the water. It rises an average of 74 m (240 ft) above the water of Argentino Lake. The entire structure has an amazing ice depth of 170 metres (558 ft).

History and Discoveries of the Glacier

In 1879, a captain in the Chilean Navy named Juan Tomás Rogers first sighted it. He gave it the name "Francisco Gormaz" after a naval hydrographic director. Years later, a surveyor named Rudolph Hauthal visited the towering frozen river. He decided to call it "Bismarck" after the famous leader Otto von Bismarck.

Governments worked to divide the vast wild landscapes during late nineteenth century explorations. Both nations agreed upon rules in the Boundary Treaty of 1881 between Chile and Argentina. They placed natural dividing lines along high continental peaks of the Andes mountain range. The main body runs east and drains directly into the waters of Lake Argentino.

Before this historic agreement was signed, land ownership was argued during border debates. These discussions were known as the East Patagonia, Tierra del Fuego and Strait of Magellan Dispute. Later on, an Argentine hydrographic expert named Lieutenant Iglesias officially suggested the current name. He named it in 1899 to honor the groundbreaking work of Francisco Moreno.

Later border talks settled the boundary line in the Southern Patagonian Ice Field dispute. The nations signed a peace agreement during the late twentieth century in 1998. The official line leaves a tiny origin point in Chile while Argentina holds the rest.

The Spectacular Rupture of the Ice Dam

A glacier cave at the edge of the glacier

Glacier calving happens when large chunks of ice collapse into the body of water as the glacier advances

The glacier slowly pushes forward across the chilly fjord of deep Lake Argentino. It reaches land on the opposite side at the Península de Magallanes. When it hits the opposite shore, it splits the giant lake into two parts. One side becomes Brazo Rico, while the other side is Canal de los Témpanos.

The icy barrier forms a solid wall that blocks all moving water completely. Water flowing into Brazo Rico has no natural exit path toward the sea. As rainfall and melting ice gather, the lake level rises by 30 meters. This huge difference puts massive physical pressure against the frozen natural wall.

Eventually, rising water begins carving tunnels beneath the weak spots of the ice. A wonderful natural bridge of blue ice forms high over the opening water. Torrents of rushing water pour violently beneath this frozen natural archway.

Soon, the thinned arch collapses completely with an earth-shaking roar into the lake. Water rushes furiously out toward the Atlantic Ocean through the wide Santa Cruz river. This repeating cycle of damming, bridging, and breaking happens every few years.

The glacier naturally advances from June to December when freezing winter temperatures arrive. It recedes slightly between December and April during the warm, sunny summer months. Over decades of observation, experts noticed three major discharge styles during these flood breaks.

Sudden Discharge Breaks

In a sudden discharge event, rushing water rips through the dam very quickly. The water flow can reach up to 8,000 cubic meters every single second. These dramatic flood events empty the high lake back to normal in days.

The rupture in 2004 was an unforgettable sudden discharge watched by thousands. Lake water had reached an astounding height of 10.5 meters above normal levels. Rushing floods emptied the lake completely after four days of continuous splashing falls.

Similar fast events occurred during March of 2006, 2008, and early 2012. In 2008, discharge reached a record peak speed of 8,000 cubic meters per second. In 2012, water escaped at 2,000 cubic meters each second across two weeks.

Progressive Discharge Breaks

Crevasse in Perito Moreno Glacier, 1994

Sometimes the dam melts very slowly instead of crashing down all at once. Glaciologists call these slow-motion events progressive discharge breaks because they take months. The subglacial tunnel opens slowly, draining water in a much gentler current.

A great example of this slow drainage took place across several months in 2013. Water had risen 2.2 meters before opening a hidden channel beneath the ice. The draining stream flowed at a calm rate of 205 cubic meters per second. It took 85 long days before both separated lake basins reached the same height.

Minor Discharge Breaks

Sometimes the ice front pushes close to the peninsula without creating a solid barrier. Water cannot flow freely, so small differences in height still appear. These quiet, smaller events are known to scientists as minor discharge leaks.

In October 1996, the lake level behind the ice rose by only one meter. The water pressure carved tiny tunnels without bursting the structure into pieces. It took until April of 1997 for lake levels to equalize across both sides. Similar minor damming events also happened earlier during both 1994 and 1995.

History of Famous Rupture Events

Tree ring patterns show that ruptures did not occur before the twentieth century. Between the years 1635 and 1900, the glacier sat further back in the valley. By 1899, the wall stood 750 meters away from the opposite rocky peninsula. It finally touched the opposite rocky shore for the first recorded break in 1917.

Major collapses followed in 1935, 1940, 1952, 1966, 1988, 2016, 2018, and 2019. Back in late 1939, rising flood waters threatened neighboring farms and livestock fields. Argentine authorities even dropped small explosives onto the ice barrier to speed up drainage. The ice resisted their attempts, breaking away completely naturally the very next year.

The 1966 break poured enormous surges of melted water into local riverbeds. The Santa Cruz river carried over 2,000 cubic meters of rushing water per second.

Visiting the Famous National Park

People participating in a guided tour on the glacier in 2026.

Panoramic view of the glacier taken from the walkway next to the visitor center

This frozen landscape has become one of the most visited destinations on Earth. Travelers from every continent travel far south across Argentina to see its beauty. Tourists gather along elevated wooden walkways constructed safely opposite the tall cracking walls.

The national park stays open during daylight hours to protect nature and travelers. Park rangers safely close the trails after eight o'clock in the evening. Because of this, certain famous collapses happen secretly in the middle of the night.

The nearby town of El Calafate acts as the main base for visitors. It contains modern hotels, an international airport, and numerous local guided travel agencies. Tourists frequently board specially designed boats to view towering icebergs floating in Lago Argentino.

Adventurous explorers can even hike directly upon the white and blue ice sheet. Specially trained mountain guides strap metal spikes called crampons beneath travelers' sturdy boots. These metal spikes prevent hikers from sliding accidentally along slick, steep icy slopes. Visitors choose between shorter ninety-minute mini-treks or intense five-hour big ice mountain expeditions.

Amazing Wildlife Surviving on Ice

Few animals can survive directly on frozen ice sheets, but one tiny insect does. A rare little stonefly named Andiperla willinki lives right inside the frozen cracks. Scientists call this unique creature the "dragon of Patagonia" or "pearl of the Andes."

This hardy bug belongs to an insect order known to biologists as plecoptera. It is a proud member of the cold-adapted insect family Gripopterygidae. It lives its entire life upon the icy surface of glaciers in Argentina and Chile.

The Patagonian dragon measures only about 1.5 cm (0.59 in) in total body length. It survives comfortably in extreme cold without freezing solid like other common insects. It searches the ice surface to eat microscopic bacteria blown in by mountain winds.

A scientist named Aubert Willink first found this small insect during 1956. For many years afterward, people worried this strange mountain bug had gone extinct. However, researchers exploring deep ice crevasses in 2001 happily rediscovered healthy populations living there.

See also

In Spanish: Glaciar Perito Moreno para niños