The Earth’s Plates
It may seem that the earth’s crust is one gigantic piece of rock. But the outer shell of the earth is divided into about 30 large and small pieces that fit together like a puzzle. These pieces are called tectonic plates.
The plates move on a very hot layer of rock within the mantle. The plates move very slowly, only from 1.3 to 20 centimetres per year.
The continents sit on top of the plates. When the plates move, they take the continents with them. But the plates aren’t only under the continents. They are also under the ocean floor. They are under water on the continents, such as lakes and rivers, too.
Under land, the plates are about 100 kilometres thick in most places. In some places in the world’s oceans, they may be less than 8 kilometres thick.
As the plates move, the continents and oceans slowly change. Scientists think that in 50 million years, South America and Africa will be further apart. They think the Atlantic Ocean will be wider, and the Pacific Ocean will be smaller.
Picture Credit : Google