Brian Grogan, age 9, of New Hartford, Conn. for his question:
Does the ocean reach the earth's core?
A geography globe is a very small model of the earth. It shows a good picture of the earth's outside. This is the surface on which we live. But most of the earth's bulk is inside. A globe does not show the core and deep layers under the surface.
The core of the earth is like a huge heavy ball right at the heart of our big round globe. As we stand on the outside of the earth, the core is buried 1,800 m11es below the waves of the ocean and about 1,800 miles below every place on the land. The deepest parts of the seas dip down only about seven miles below the surface waves.
A young traveler may have to strain his brain to think of a line 1,800 miles long. It took the brave ships of Columbus two whole months to sail this distance over the sea. An up to date car can go 60 miles an hour on a wide-open highway. If it travels without stopping, that car takes 30 hours to go 1,800 miles.
Suppose we had a tunnel straight down to the center of our globe with elevators to speed up and down at a mile a minute. Let's begin the trip down at noon on Monday. In seven minutes we are 1ower than the deepest pit in the ocean floor. But we do not reach the outside edge of the core until Tuesday evening at six o'clock. It would take another 35 hours to reach the very center of our globe.
Of course, there is no such tunnel through the earth. So far, our deepest wel1s go down only about five miles. We have not gotten through the rocky layer of the globe. In most places this crusty layer is about 20 miles thick. Some of it is dry land wide continents and wave washed islands. And almost three quarters of the earth's crust is under the wave tossed waters of the salty seas.
The floors of the oceans are hollows in the earth's rocky crust. They begin at the tide washed shores and s1ope gently down to deeper water. At perhaps 50 or 100 miles from the coastline, the seabeds plunge down into deep basins. If the high Himalaya Mountains were set in the sea's deepest pit, their lofty peaks would be a mile below the waves. Yet the deepest parts of the ocean are about 1,800 miles above the earth's core.
The rocky crust is made of the earth's lightest materials. It is wrapped around the g1obe like an onion skin. The light crust sits on a layer ca11ed the earth's mantle, which is the second onion skin. The mantle is about 1,800 miles thick and made of heavy materials. The core is a round ball inside the mantle. It is about 2,000 miles wide and made of the he8v1e3t materials in the entire globe.