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Glaciers and How They Form

Updated on March 15, 2017
Margerie Glacier, a 21-mile long glacier, in Glacier Bay, Alaska.
Margerie Glacier, a 21-mile long glacier, in Glacier Bay, Alaska. | Source

What is a Glacier?

A glacier is a large body of ice, created by the accumulation of snow, that persists over several years, often lasting centuries. Glaciers occur in the earth's polar regions as well as mountainous areas.

There are a number of phases that these massive chunks of ice go through which include their initial formation, continual growth, and flow. This process is called glaciation.

Glaciers are an important indication of climate change, so scientists often monitor and study them in an effort to better understand the effect humans have on the earth's climate. While not much is known in regards to why glaciers are disappearing, scientists do know how they are created.

Where glaciers can be found (in blue.)
Where glaciers can be found (in blue.) | Source

Where Can Glaciers Be Found?

Glaciers only form in areas of colder temperatures where snow is unable to completely melt. 1 Polar regions such as Antarctica or Greenland are known for having most of the world's glaciers. This is because these areas are so cold that any snow that accumulates doesn't melt away.

Glaciers can also be found in areas of high altitude, where the air is cold year-round. For example, a number of glaciers are located in the Himalayas, the Alps, and the Andes.

Since the creation of glaciers depends heavily on snowfall, they do not exist in cold deserts. While these areas often experience frigid weather, because it does not often snow, glaciers are unable to form.

Each summer, gravel is deposited on top of the Cavell Glacier. Each streak along this glacier represents one year.
Each summer, gravel is deposited on top of the Cavell Glacier. Each streak along this glacier represents one year. | Source
A chunk of ice falls from the Perito Moreno Glacier in Argentina.
A chunk of ice falls from the Perito Moreno Glacier in Argentina. | Source

How Glaciers Form

When snow does not melt, it accumulates. As more and more snow builds up, its weight is pressed down onto older layers. This compression causes the snow to crystallize and become more dense, essentially turning sheets of snow into compacted ice.2

Compressed snow is called firn. New firn, found in the upper layers of a glacier, is made up of granules of ice, each about the size of a grain of sugar. As firn is further compressed by new snowfall, the granules fuse together creating even larger crystals of ice. As it further compresses, it becomes considerably more dense than the newer firn. After enough compression, it turns into what is called glacial ice.

How much weight and pressure is needed to cause firn to become glacial ice? Firn usually turns into glacial ice when it's around 150 feet deep. This is when the weight of the upper layers of the glacier puts so much pressure on the older firm that it's crystallized into solid ice.

A huge crack in Antarctica’s Pine Island Glacier
A huge crack in Antarctica’s Pine Island Glacier | Source

Did you know?

If Antarctica's ice sheet completely melted, the oceans would rise about 210 feet!

The Movement & Anatomy of Glaciers

In mountainous regions, gravity and deformations in the ice cause the top layers of glaciers to flow downward to the valley below. This very slow process causes stress on various parts of a glacier which often causes deformities like crevasses and seracs.

The area where the glacier originates is called the glacier head, or the accumulation zone. As the ice flows away from the accumulation zone, it is replaced by new firn, which will eventually become a part of the glacier as well.

As glaciers move, glaciers often carve their way through soil and rock, creating unique landforms. They also sometimes pick up and carry large rocks and boulders, which are left behind when the glacier eventually melts.3 Because of this, huge boulders left by glaciers that occurred thousands of years ago can be found all over the world!

Glaciers melt as they move to warmer areas, and provide the land with fresh water, an invaluable resource. As you may have guessed, glaciers are major storehouses of water. In fact, they store about 69% of the world's freshwater!4

The "glacier foot" is where the glacier ends. The glacier can end in a valley where the foot may melt (creating "meltwater") or end in a large body of water, where chunks of ice often break off and float away (icebergs.)

The Greenland Ice Sheet, taken near Kangerlussuaq, Greenland
The Greenland Ice Sheet, taken near Kangerlussuaq, Greenland | Source

References

  1. "Where Glaciers Are Found." NPS.gov. National Park Service.

  2. "How Are Glaciers Formed?" NSIDC.org. National Snow & Ice Data Center.

  3. "Glaciers." Niu.edu. Northern Illinois University.

  4. "Glaciers and Icecaps: Storehouses of Freshwater." USGS.gov. US Geological Survey, 9 March, 2012.

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    • Suhail and my dog profile image

      Suhail Zubaid aka Clark Kent 4 years ago from Mississauga, ON

      What a beautiful and informative hub!

      I read a lot about glaciers, because the geographical features close to where I live, known as Niagara Escarpment, were also impacted by a glacier millions of years ago. Then also Baltoro Glacier in the Karakorums of Pakistan is the one that I hiked to back in the late 80s.

      I read three books recently that familiarized me to the world of glaciers.

      Tristan Gooley's 'Natural Explorer' narrates some important features of glaciers, such as valleys formed by glaciers are 'u' shaped, as opposed to 'v' shaped valleys formed by rivers.

      Kieran Mulvaney introduces readers to Polar Bears and to the world of arctic glaciers and ice in his book 'The Great White Bear'.

      Tom Avery, in his book 'To the end of the Earth', takes his readers on a journey to the North Pole along with his team of 5 humans and 16 sled dogs and in the process them to the tough world of glaciers and exceptionally difficult trek across them.

      Thank you Mel, for keeping my interest in glaciers alive.

    • tammyswallow profile image

      Tammy 4 years ago from North Carolina

      These are so beautiful to look at, but I wouldn't want to climb one. This is an informative hub with wonderful photos!

    • Marcy Goodfleisch profile image

      Marcy Goodfleisch 4 years ago from Planet Earth

      I've always been fascinated by glaciers - and one of my goals is to do an Alaskan cruise, so this is a compelling hub for me! You always have great hubs about interesting topics, Mel!

    • Vin Chauhun profile image

      Vin Chauhun 4 years ago from Durban

      great, interesting article.....i wonder if any of my long time extinct relatives are buried under any of those mammoth glaciers,,,,,

    • melbel profile image
      Author

      Melanie 4 years ago from New Buffalo, Michigan

      I had a blast writing on this topic, so I'm glad you guys enjoy it! It makes me want to go trekking in Patagonia or just take a trip up to Alaska to see Margerie Glacier!

    • TENKAY profile image

      TENKAY 5 years ago from Philippines

      I just hope all these glaciers won't melt because of global warming. It's going to wipe our country from the map.

      This is an informative hub and I love the pictures.

      Voted up and interesting.

    • Danette Watt profile image

      Danette Watt 5 years ago from Illinois

      Great article on glaciers, which I've always found interesting anyway. They are so huge, massive, I can't imagine standing near one. I know there is concern in the scientific community about their melting. Who said climate change isn't a reality. Great photos too

    • JKenny profile image

      James Kenny 5 years ago from Birmingham, England

      You're right Bob. I live in the Midlands, and if another ice age struck, then my house would be buried by a mile of ice. The rest of the UK will turn into Arctic tundra, so we'll have to learn how to hunt musk ox and dodge polar bears. We'll no longer walk dogs, instead we'll have them pushing sleighs in sub zero temperatures. Or, we could all just move to Spain, I wouldn't mind that.

    • diogenes profile image

      diogenes 5 years ago from UK and Mexico

      Good explanation about glacier formation and life.

      If we do get a new ice age in the UK and it follows previous patterns, it would cut off two thirds of the country.

      That would be embarrasing for the Brits: they have 700 people per square mile now! But at least they's keep warm.

      Bob

    • JKenny profile image

      James Kenny 5 years ago from Birmingham, England

      Really interesting article, well laid out and presented. Interesting info about the Antarctic ice cap, 210 feet, my god. That would drown most of Britain, I'd retreat to the Scottish Highlands to continue my writing career. Although, I do remember reading that it would take 10,000 years of continuous warming to melt the ice cap completely, so hopefully we'll be fine. Voted up and shared.

    • Lord De Cross profile image

      Joseph De Cross 5 years ago

      210 Feet? Oh My God! I live In NJ, and that would end my writing career. Pretty much well explained Melanie. I wonder if they will ever melt if our poles ever shift, which is likely to happen. Great hub!

      LORD

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