The outside of the earth is a crust of rock which is about 10
to 30 miles thick. When we go down into this crust, we find that it begins to
get hotter. For about every 40 meters we go down, the temperature grows one
degree higher. At two miles below the surface of the earth the temperature is
high enough to boil water!
If it were possible dig down 30 miles, the temperature would
be about 1,200 degrees Centigrade. The crust of the earth has two layers. The upper
layer, which makes the continent, is made up of granite. Under the layer of
granite is a thick layer of very hard black rock called "basalt". This layer
supports the continent and forms the basins that hold the oceans.
At the center of the earth, it is believed that there is a
huge ball of molten iron, with a diameter of about 4,000 miles. How did the
center of the earth get to be this way? According to Most scientists believe
that the earth and sun were once related in some way. Most scientific believe
that the earth get to be this way? According to most scientific theories, the earth
and sun were once related in some way.
Most scientists believe that the earth was once a hot,
whirling mass of gas, liquid, or solid that began its regular trips around the
sun. As years went by, its slowly cooled and the large mass grew smaller. As it
whirled, it slowly took a ball-like shape. It was red-hot and held in its path
by the attraction of the sun.
As the earth cooled, a hard crust formed on the surface. Nobody
knows how long it took for the crust to form. But underneath that crust there
remained the hot center of the earth, and it is still there today.
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