Antarctica is also the iciest place on Earth and is capped by an ice sheet up to 4,800 metres at its thickest part but on average it is 2,160 metres. It is so heavy that in places it has pushed the land below sea level. It was formed from the compacted accumulation over some 100,000 years of snow over 25 million years ago. The weight of the snow above has turned the snow below to crystal-clear, blue-green, glacier ice. The total volume of ice is over an incredible 30 million cubic kilometres. Due to the ice thickness Antarctica has the highest average altitude of all the continents. It’s hard to believe but here there is approximately 90 per cent of the world’s ice and over 70 per cent of its fresh water in frozen form. If the ice sheet ever melted it would raise the overall sea level by at least 65 metres. The wealthier countries could probably cope but the effect on the poor countries would be absolutely devastating.
Arctic Ocean Map Photo Gallery
There is a constant process of ice movements and recessions and consequently the land rises and changes the coastlines; to geologists this process is termed as isostasy. In winter the surrounding sea totally freezes and, in ice terms, the continent doubles, extending in size to 78 million square kilometres. There is approximately eight times more ice in the Antarctic than the Arctic. Under the ice sheets are the valleys, hills and mountains, the tops of which sometimes stick up above the surface to create rock peaks which are a challenge to any mountaineer.
The ice sheets end at the coastlines in huge ice cliffs and their slow moving glaciers can create massive ice shelves the size of some countries, which in turn create icebergs as large pieces break off and fall into the ocean. The world’s largest glacier, the Lambert Glacier, is in the Antarctic and is over 500 km long, where it reaches the ocean it is 200 km wide. Most of the world’s icebergs are in the Antarctic Ocean and can be enormous lengths with ice 45 metres or more above the water. Some are the size of cathedrals and are wind and water sculpted into inviting caverns and caves of extraordinary design and beauty, but beware ever trying to explore inside for they can be sudden death-traps. More Coleridge Xanudu imagery springs to mind, ‘Caverns measureless to man.’ A 15 metre (50 foot) schooner will appear to be a child’s toy boat in comparison. A very large iceberg might weigh 400 million tonnes and could contain enough fresh water to supply a city of 3 million inhabitants for a year.
Every year the unstoppable iceberg impact totally removes many large animals and microscopic organisms from the marine shallows. This devastation can actually prove to be very beneficial as it enables new life forms to develop and flourish. As the icebergs collide or break up, air, which may have been trapped inside the ice for thousands of years, is suddenly released and can create a sound like a thousand champagne corks popping all at once. These constant ice changes and forces also drive the Southern hemisphere weather patterns, which then modulate the world’s climates and have a major effect on ocean and atmospheric circulations. It is convincingly argued that the world’s climate and weather patterns are materially affected by changes in the Antarctic region over very short periods of possibly between 10 to 100 years.
This enormous area is a treasure trove of information which scientists are only very slowly starting to uncover. Palaeontologists are hoping that perhaps here at last will be found the Holy Grail of evolution the missing fossil halfway between tetrapods, the land-based animals with four limbs and backbones, and their original derivation from fish. When fins became fingers, the pelvis was also rebuilt and became attached to the backbone and the skull completely transformed. It’s even possible that the secret of longevity will one day be unlocked from studies in the Antarctic; if you remove a piece of lichen from a rock in the Antarctic Peninsula you could be destroying a thousand years or more of slow organic growth; the skua gull flying overhead might be 30 years old; the fish you catch could be 12 years old and even the krill living on the bottom of the ocean floors can live to 7 years.
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