Earth On Fire

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Every time a volcanic eruption hits the headlines, we are reminded of the fact that we live on a ball of fire, with only a thin layer of rock separating us from the furnace deep inside our planet. Volcanoes serve as the earth's vents, opening up when the pressure of magma trying to rise to the surface from the depths of the planet gets too strong. But lava-spewing mountains are...(展開全部) Every time a volcanic eruption hits the headlines, we are reminded of the fact that we live on a ball of fire, with only a thin layer of rock separating us from the furnace deep inside our planet. Volcanoes serve as the earth's vents, opening up when the pressure of magma trying to rise to the surface from the depths of the planet gets too strong. But lava-spewing mountains aren't the only evidence of the heat and activity inside the earth: there are also geothermal areas with hot springs and bubbling mud pools, steaming acid lakes in often perfectly circular craters, as well as encrustations of bright yellow sulphur crystals and multi-coloured landscapes that owe their many hues to a wide variety of minerals. Huge cracks in the earth, many kilometres long, are also the result of volcanic activity, as are the vast mountain ranges that have formed over millions of years on the bottom of the ocean, where 80 per cent of magma emerges. Atolls grow on the eroded cones of once-active volcanoes that have gradually disappeared underneath the surface of the sea, while the black sand found on the beaches of volcanic islands simply consists of lava rocks that have been ground down by the waves. About ten per cent of the world's population live near an active volcano, and people have long been fascinated by the these awe-inspiring but devastating forces of nature, without knowing what causes them. Plato thought that volcanic eruptions were the result of battles being fought between the elements of earth, fire and air, while Aristotle's theories on the subject involved undergro

Earth On Fire

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