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| 17.7 Mountains that explode
Since ancient times volcanoes have struck terror and awe into the heart of man: but scientists tell us they do more good than harm. Many of the islands in the seas and oceans have been thrown up by volcanoes. They have thrown up whole mountain ranges too, some of which are very useful because they increase rainfall. The best thing of all, however, is the way the lava from volcanoes enriches the soil. This explains why farmers crowd the sides of volcanoes, risking death and destruction from new eruptions. They can grow such good crops there that they think the risk well worth while. Some volcanoes are dangerous. Of all the thousands and thousands of them scattered about the earth, only about 500 are active. Perhaps not more than 50 volcanoes are erupting at this moment like Stromboli in the Mediterranean and Izalco in El Salvador 1 . Such volcanoes are watched by scientists. Most of the great volcanic disasters have been caused by surprise outbursts from volcanoes which have not erupted for so long that everyone imagines them to be quite harmless. In 1952, one of these, Mount Lamington, in New Guinea 2 , erupted and caused six thousand deaths. That disaster was bad but there have been much worse ones. Think of Vesuvius which erupted in 79 A.D. burying the towns of Herculaneum and Pompeii 3 under its ashes. Have you heard of Krakotoa 4 ? Thirty – six thousand lives were lost when Krakotoa erupted, and the smoke and dust from the explosion was so thick that it was blown right around the world. There is so much power in an exploding mountain that man can not attempt to control it. But at least he is learning how to save himself from the volcano’s fury. Scientists are studying volcanoes ways and learning how to tell in advance when they are going to erupt. Thanks to scientists we are not so helpless as people were in earlier days, when they were too often caught before they could even try to get away. жүктеу/скачать 2.09 Mb. Достарыңызбен бөлісу:
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