Where did the ocean come from?
Scientists tell us that billions of years ago the earth was a ball of
bare, sizzling-hot rock, with no air or water on it. The outside of the
earth slowly cooled, but the inside stayed fiercely hot. Volcanoes
roared and rumbled, throwing out tons of melted rock and enormous clouds
of hot gases. One of these gases was steam—water so hot it is gas.
When steam cools it turns into water.
Some scientists think the steam rose up in clouds. When these clouds
cooled, they became water that fell as rain. Slowly, the low parts of
the earth’s rocky crust filled up with water, forming the ocean.
Other scientists think the steam cooled as it came out of the earth.
When it became water, it trickled downhill. During many millions of
years, the low places filled up to form the ocean.
Whichever way it happened, the ocean was formed by steam from inside the
earth—steam that cooled and became water.
