The seas around the Antarctic are littered with ice. The pack ice on the surface is frozen seawater and in winter it forms a solid cover over the sea. Icebergs, on the other hand, are freshwater and have split off from glaciers on Antarctica that are flowing into the sea. Antarctica is bigger than Europe and seems almost devoid of life. But not all of Antarctica is snow and ice. In parts of the interior there are valleys were almost no snow ever falls. Here it is drier than the centre of the Sahara, dark for half the year and scoured by a never-ending wind. The wind here deposits particles of salt under flakes of granite on the rock and as the salt crystals grow, the flakes of granite break loose. The wind then sweeps the granite flakes up and hurls them at the rock face, eroding it even further. And yet there is life here. Algae grows on the undersides of rock, away from the drying wind, absorbing the sunlight it needs through the translucent rock. There is even algae within the rock, where it has penetrated the microscopic spaces between the rock's constituent particles. Glaciers flow down these dry valleys, fed by the icecap that covers the centre of the continent. They are amongst the fastest moving glaciers in the world, advancing as much as 300 feet in a year. During the summer the sun is strong enough to melt a little of the glacier's surface, and where the water accumulates in pools, there grows blue-green algae, its dark colour absorbing the sun's rays. These pools are the only place on the whole continent where life flourishes in any abundance. Yet here in the dry valley there lies the corpse of a seal that looks comparatively fresh. But it is actually around 300 years old and simply been freeze-dried. It must have misguidedly crawled up from the coast 25 miles away.
Available since: Fri 18 Feb 2011