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Rift valley lake: Lake Baikal

A topographical map of Lake Baikal Millions of years ago, Asia split apart and the floor of the Baikal valley dropped away along a series of giant faults, cracks in the Earth’s crust. The bedrock plunges to a depth of at least 9 kilometres (nearly 6 miles), the deepest point on any of the continents. For many millions of years, parts of the lake bottom remained dry, but eventually all of the basin became flooded. Mud and gravel have been settling for at least 16 million years and are now more than 7 kilometres (more than 4 miles) thick. The water level has been slowly rising since a dam was built on the Angara, the only river to flow out of the lake, in 1959.

A view of Lake Baikal

World's largest body of fresh water

Lying in the far east of Russia amidst Siberia’s mountains and forests, Lake Baikal, the world’s deepest lake, is sometimes known as the Blue Eye of Siberia. By area only the ninth largest lake, it is easily the largest body of fresh water in the world. It holds one-fifth of the world total—more than all five of the Great Lakes of North America put together. If all the world’s drinking water ran out, Lake Baikal could supply the world’s population for a further 40 years.
As many as 336 rivers and streams feed into Baikal, but because most of the surrounding mountains are extremely hard rock, very little dissolved substances find their way into the water. The lake is crystal clear and very pure. Only in the south is there man-made pollution, although this is still very slight.

Lake Baikal is the world’s deepest (and clearest) lake, with a deepest point of 1642 m (5386 ft).

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