How do glaciers form?

Snow, intriguing as it looks and as wonderful as it is to play with, has a power that is so great it can cut its own valleys and even reshape entire mountains. Glaciers are fundamentally fuelled by snow, but the conditions have to be just right for them to actually form. The climate has to be cold enough so that newly fallen snow doesn’t melt when the summer months arrive. Year after year fresh snow needs to be able to build up for a glacier to form and finally begin to move. Too steep a slope and the unborn glacier will simply avalanche.

A glacier begins high in mountain valleys in places such as Alaska, New Zealand, and in the polar regions – the Arctic and Antarctic. Tropical glaciers also form across continents such as Africa, and in mountain ranges including the Himalayas. Unfortunately these types of glaciers have been thinning in the latter half of the 20th Century as the result of global warming. Their future prospects are looking somewhat bleak.

Glaciers form by snowfall after snowfall, and countless layers compressing on top of each other. This overwhelming weight of the snow forms a huge swell of ice in a gap between two mountains. The unstable, mountainous river begins to move and flow in a frozen state. Helped by gravity and combined with its own tremendous weight, in a head over heels fashion it slides down the valley and grinds its path in the landscape that confronts it. The ice at the base of a glacier begins to melt, which is down to heat from the earth and the extreme pressure from the ice at the top.

A glacier moves in two ways, either retreating or advancing, though this direction depends on which way its cone-like nose happens to be facing. This is, however, slower than a snail’s pace as it moves towards the sea, or spreads across a plain. But the chopping and remoulding of the landscape is even more severe when a glacial surge occurs. It picks up pace and wipes over its surroundings at a rate of several metres each day for weeks and sometimes even months on end.

It’s not a rare sight to see a glacier take on a blue hue to its ominous appearance. This cool colouring is a sign of its density, with mounting pressure over years of layers compressing into other layers. From beautifully white and fluffy flakes, a glacier takes on an incredible blue ice, as the air between the layers is forced out, and the properties of ice begin to change.

Glaciers are one of the world’s most useful indicators of how our global climate is changing. As global warming takes a firmer grip, most glaciers today are retreating in their movements. In countries such as India the melted glacial ice provides much of their fresh water, but this losing battle could result in desperate measures. This is why a glacier is recognised as one of the most crucial clues to what is happening and what is likely to happen to the future of our world.

How glaciers form
How glaciers form

Glacier facts

10% of the Earth’s surface

The huge number and vast size of the likes of Antarctica means that glaciers spread over an enormous ten per cent of the Earth’s land area.

Alaska, home of the glacier…

The US state of Alaska has as many as 100,000 unnamed glaciers, although thinking up 100,000 different names wouldn’t be an easy task…

70 metres more sea

In a very doomsday-esque scenario, if all global land ice melted, sea levels would rise by approximately 70 metres (230ft).

Formidable freshwater force

Glaciers hold within them up to 75 per cent of the world’s entire freshwater supply, 61 per cent of that lies within the Antarctic ice sheet.

Fastest glacier on Earth

Pakistan’s Kutiah Glacier holds the record for the fastest glacial surge in 1953, at an average of 112 metres each day.

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Plus, take a look at:

When was the last ice age?

How thick is the ice in the Antarctic?

Why is snow white?