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Introduction to glaciers

Although, there are thousand of glaciers in our planet, not everybody has the privilege to observe them closely. If you have never seen one you may have heard of them to illustrate examples of global warming on Earth. Because of their extreme vulnerability to climate changes, in the last decade a great number of glaciers have disappeared. Practically all of them have reduced their volume because of the accelerating growth in temperatures experienced in the last century. The ecological value of glaciers is not known to everybody: its ice constitutes the 90% of available water in the whole world. Bearing in mind that other sources of fresh water are diminishing, glaciers are in fact an essential resource for everyone’s future.

The protagonism of glaciers on Earth are directly proportional to the magnitude of glaciations. The glaciations are cyclic climate events lasting for thousand years where low temperature conditions and humidity produce a visible growth on the total ice mass of the planet –in the last glaciation the ice covered a quarter of the continental land. After each glaciation precedes a mild climate period, and as a consequence the ice caps are reduced. Nowadays, we know that the most important moment in the last glaciation happened “just” 18,000 years ago -a very short period in geological terms- and this situates us as recent spectators of its effects on Earth.

The glacier formation process starts in places where a great accumulation of snow can remain all year-round, in other words, the snow does not melt completely because the surround average temperatures are cold enough. In these areas –called accumulation areas– winter by winter the snow is compressed by its own weight, loosing the air trapped between its crystals and forming bigger and compact granules. Gradually this corpuscles loose air between their particles and these continue fusing. So, the immaculate whiteness and light weight appearance of the snow are left behind to form a dense and opaque mass, called firn –the intermediate stage between snow and ice. As the miniscule portions of air still trapped in the interior of the firn are removed because of the compression, the firn turns solid and translucent, reaching a gel state known as sponge ice. The last stage of this compacting process is the glacier ice, with its characteristic blue color. The older the ice, less air there would be in its interior and more blue would be its tint.

Even though glaciers seem static, they are in permanent movement, although imperceptible. From the heights where they originate, glaciers move by simply responding to the gravity action. As they were ice rivers, the glaciers follow their course depending on the inclination of the terrain and the power of their mass. Looking for the same destiny as other water courses, many times glaciers end up in lakes, lagoons or in the sea.

If the erosive action of the water in its liquid form is as powerful as to create geographic features -as we see them today in the coastal sea or delta of rivers- imagine how powerful is in its solid form! Like bulldozers that raze all in their way, glaciers -together with volcanic activity and continental plates movement- are the main forces shaping patagonian landscapes. After their drawing back, great depressions and caved courses on the terrain were flooded to form big lakes, lots of channels and fiords; vast areas of land were compressed by thousand of tons of ice leaving extensive valleys with a U form and big plateaus… practically the whole geographical forms were affected by the glacier strength -even though today in smaller proportions comparing to great glaciation times- show us a force which is still alive.

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Last update: 2007/02/02

El Chaltén,
November 21, 2017

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