About forty years ago,scientists exploring the seafloor found that it is full of tall mountains and deep trenches. A single seafloor mountain chain circles Earth and contains some of Earth’s tallest mountains.
Along this mountain chain is a deep crack in the top layers of Earth. Here the seafloor is pulling apart and the two parts are moving in opposite directions, carrying along the continents and oceans that rest on top of them. These pieces of Earth’s top layer are called tectonic plates. They are moving very slowly, but constantly. (Most plates are moving about as fast as your fingernails are growing -- not very fast!) Currently Earth’s surface layers are divided into nine very large plates and several smaller ones.

When the tectonic plates under the continents and oceans move, they carry the continents and oceans with them. Can you trace the paths of the continents during the last 225 million years?

The edges of some plates are moving apart, and the space between them is being filled in by new rock from deep within Earth. Other plate edges are smashing together. Sometimes when this occurs, one plate is pushed under the edge of another plate. The lower plate is forced into the very hot interior of Earth where it is destroyed. Other times the plates slide past each other, one moving in one direction and the other in the opposite direction.
Volcanoes and earthquakes occur in large numbers and mountain ranges sometimes are formed by the stress of plates pushing against each other.
Scientists were able to prove that the rocks nearest the mid-ocean mountains were younger than the rocks farther away by using the magnetic information recorded in rocks to find their age. The fact that rock is younger close to the areas where the plates are separating helped prove that Earth’s plates really are moving.

The colored sections are Earth's tectonic plates. Watch the map to see the continents appear in black. Can you find North America, South Amercia, Africa, Australia, Europe, Asia, and Antarctica?

The Recycling Plates...