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If you have ever been lucky enough to fly on a clear day over Patagonian lands, you have surely seen enormous masses of ice, from which glacial tongues hang down and reach a lake or the sea. These are Campo de Hielo Norte and Sur, which are responsible for the vast majority of the glaciers that you will see on your route along Carretera Austral. But do you really know what they are and their importance?

1. Why are they formed?

A glacier is a thick mass of ice that originates on the Earth's surface by accumulation, compaction and recrystallization of snow. For them to exist, two conditions are required: that they have temperature averages so low as to allow snow to accumulate from one year to the next and that they have sufficient rainfall.

2. They are great sculptors

Glaciers currently cover almost 10% of the Earth's surface, but in the recent geological past, they covered enormous areas with ice thousands of meters thick, which is known as the Last Ice Age (which would have ended about 12 thousand years ago). ). Its melting carved out the landscape, forming fjords like those of Patagonia or Norway, valleys, large lakes and, in general, all that rugged geography that you will see on your visit to Carretera Austral. Glaciers continue to sculpt and change, as they are in a constant process of advances and retreats, generating changes in their environment.

3. What is an ice field?

There are several ways to classify glaciers, but the most general is according to their size and how they relate to the topography that they cover and that surrounds them. For example, there is talk of caps or islandis, ice fields, valley glaciers and cirque glaciers. Ice fields are smaller than a cap (like Antarctica) and their shape is controlled by the topography of the terrain they cover. In Chile there are three: North Ice Field, South Ice Field and Cordillera Darwin Ice Field.

4. South Ice Field

Only 10% of the Earth is covered in glaciers. In Patagonia, the Southern Ice Field is the third largest area of continental ice in the world after those of Antarctica and Greenland.

Greater extensions of continental ice:

• Antarctica.

• Greenland.

• Southern Patagonian Ice Field (Chile and Argentina).

• Vatnajökull (Iceland).

• Austfonna (Svalbard, Norway).

• Penny Ice Cap (Baffin Island, Canada).

• Northern Patagonian Ice Field (Chile).

• Cordillera Darwin Ice Field (Tierra del Fuego, Chile).

5. Do they advance or retreat?

Glaciers grow with the addition of snow and other types of ice and lose mass by melting ice into water and the dismemberment of ice floes, so they are constantly moving. In general, glaciers, due to the effect of climate change, are retreating, with the exception of some such as Pío XI (Magallanes Region) and Perito Moreno (Argentina).

6. Why is ice blue and snow white?

One of the most impressive characteristics of glaciers is their variety of shades of blue. It has nothing to do with the age of the ice, as is often believed, but rather with its density.

White light is made up of all the shades of the rainbow, from red to violet. Snow looks very white because its surface reflects all the sunlight that reaches it. Have you picked up a freshly fallen snowflake? It is light and has a lot of air inside. The bubbles that fill the gaps reflect the rays many times and all the colors of the spectrum “leak away.” That is why the light we see is white.

On the other hand, in ice, due to the high compression of the ice by the weight of the accumulated snow, it prevents the formation of air bubbles and, therefore, light no longer bounces like in snow. Red or yellow photons, which are low in energy, penetrate less and are absorbed sooner, but blue photons, which are the most energetic, “resist” all the way and become visible. The longer the path that light travels through the ice, the bluer it will appear.

7. Glacier or Snowdrift?

The correct thing is to talk about a glacier. The term blizzard is explained by the fact that these large frozen masses generate blizzards due to the changes in local pressures they generate, which led people to name them blizzards. In Chile and Argentina, “hanging” mountain glaciers, such as the one in Queulat National Park, are usually called glaciers.

8. What is an Iceberg?

Also known as icebergs, it refers to masses of ice that have broken off from a glacier and remain floating in the sea or a lake. Icebergs have 8/9 of their mass under water, so navigating between them requires skill and experience.

9. Why are glaciers important?

They are essential because they act as a climate regulator, because they reflect between 45% and 85% of the sunlight that comes from space, cooling the planet. The second important role is that glaciers are the world's great reserve of fresh water. Although 75% of the planet's surface is made up of water, 97.5% of that water is salty and within the remaining 2.5%, 70% is ice.

10. Which are the biggest?

Pius XI. It has an area of 1263 km2 and its front wall is 6 km long and walls are 80 m long. It is located near Puerto Edén, in the Magallanes Region.

Viedma. It is the second largest in the southern hemisphere with an area of 977 km². The front of the glacier is 2.5 km wide and 50 m high. It is located in Argentina, in the Los Glaciares National Park.

Uppsala. It has an area of 840 km², two glacial fronts of approximately 4 km, with walls of about 50 m. It is located in Argentina, in the Los Glaciares National Park.

O'Higgins. It has an ice surface of 820 km², with a wall of 3.5 km and 80 m high. It is located in Chile, on Lake O'Higgins.

SOURCE: Carretera Austral Blog | Published on 04/13/2023

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