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There are links down the right hand side to other posts which, may I say, I'm sure you'll find just as interesting :) - I'd suggest taking a look at the post on Supervolcanoes!

Simply a site about geography, for geography lovers.

Rivers of Ice that Plough through Mountains

Glaciers are huge masses of ice which moves over land like a very slow river. They are formed where snow accumulates over many years and through it's own weight is compressed into ice. Glaciers are so special because they aren't just packs of ice sitting at the poles, they move as a river does, flowing down towards sea level, carving valleys as they go. These valleys are stunning, and are usually much larger than river valleys.

Glacial Valley:


Glacial valleys, also called glacial troughs, have flatter valley bottoms and are relatively straight compared to river valleys. These valleys have impressive, steep slopes on either side gouged out by the huge erosional forces involved. They are commonly called 'u-shaped valleys'. River valleys are instead called 'v-shaped valleys'.

Despite what you might think, glaciers are found in mountain ranges of every continent on the planet, even Africa (e.g. the Futtwangler Glacier in Tanzania) and Australasia (e.g. the Franz Josef Glacier in New Zealand). They vary greatly in size and some reach over a hundred kilometres long. 

The worlds largest glacier is the Lambert Glacier in East Antartica:
  • 400 kilometres long
  • 100 kilometres wide
  • 2500 metres deep
  • At it's fastest point it reaches a speed of 1200 metres per year.

Position of the Lambert Glacier (17/02/09):


Due to its size, the Lambert glacier is a very important source of information on the effects of climate change on Antarctica. It drains over 8% of the total ice volume of the East Antarctic meaning it is very sensitive to changes to the ice of the East Antarctic. Changes would affect the speed of the glaciers movement, the thickness of the glacier and more cracks may appear due to increased internal pressures. It is monitored very closely, in fact it is one of the most closely watched glaciers in the world.

Glacial Velocities at the Lambert Glacier:

Glaciers are a very good indicators of a warming planet as they need the cold temperatures to exist. The majority of glaciers round the world are in retreat and are decreasing in mass which isn't a good sign, as they are the largest reservoir of fresh water on the Earth, and only second to the oceans and seas in terms of the total water stored.

Retreat of Athbasca Glacier, Canada:
First image - 1919; Second Image - 2005

However copyright is owned by Gary Braasch, National Archives of Canada

A time-lapse view of glacial movement:

If Antarctica melted sea levels would rise by around 65 metres - however, luckily for us, much of this region has an average temperature of -37C so melting is unlikely. However, glaciers (which includes ice sheets) in Greenland could rise sea level by around 6 metres and this is much more likely as it is closer to the equator.

Alpine Glacier changes since 1970:


The Lambert Glacier flows into Prydz Bay and the Amery Ice Shelf, and contributes an astounding 35 square kilometres of ice to the bay each year in the form of icebergs. Many of these icebergs are the size of small countries - it is hard to grasp these vast sizes.

There are three kinds of glacier. Alpine glaciers (form on mountain slopes), ice sheets (cover the entire landscape beneath them) and tidewater glaciers (glaciers that terminate in the sea creating icebergs).

The largest iceberg ever recorded was photographed by a satellite in 2000. It measured 295 kilometres long by 37 kilometres wide, with a surface area of 11,000 square kilometres. The mass was estimated at an astounding three billion tonnes. Even after a decade, parts still have not melted. The source of these emense floating objects..? Glaciers. Whether they come from ice sheets or alpine glaciers, they are equally astounding.

Iceberg breaking off Lambert Glacier:


The above image doesn't seem very impressive, until you take note of the scale in the bottom left - at which point you realise that that iceberg is around 30 kilometres by 15 kilometres in size and the glacier is of an incomprehensible magnitude. Glaciers are stunning features of nature themselves, and along their path they gouge out equally stunning glacial valley landscapes.

Further Reading:

A quote to have a think about:
We can say that the glacier was ripping out a huge amount of material and dumping it into the ocean. And rather than taking evidence from a single instant, we can for the first time see an integral of hundreds of thousands of years. So this is a new way to get at the rate at which glaciers do their work.
(Ken Farley - Professor of Geochemistry)

The GeoMessenger

1 comment:

  1. glaciers effect so much of what goes on in the world today - and have littraly shapped our world!!! fascinating stuff!