Saturday, July 19, 2008

Hot - water fountains in the earth


On a bare, rocky patch of land sits a cone-shaped hump of rock with a hole in its top. Suddenly, with a hiss, a great, silvery spray of steam shoots up out of the hole. A geyser has erupted.

Geysers are the earth's hot-water fountains. Some geysers shoot out steam every few months. Others go off several times an hour. Some of the most famous geysers shoot steam more than a hundred feet (30 meters) into the air.

Geysers are found in groups in several parts of the world. They are near places where cold water from a river or lake drains down into the ground until it reaches hot rocks below the earth's crust. The hot rocks turn the water into steam. The steam pushes up through cracks in the earth and comes shooting out into the air. Sometimes the steam cools off before it reaches the surface. Then, hot water comes bubbling up out of the ground.

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