The Rock Cycle

Rocks may seem like they never change, but they do. The rock cycle is a slow process that changes rocks from one type to another. It takes millions of years. Heat, pressure, weathering, and melting all play a part. The rock cycle has been happening since Earth first formed.

How Rocks Change

Igneous rocks can be broken down by wind and rain into tiny pieces. Those pieces settle in layers and form sedimentary rocks. If sedimentary rocks get pushed deep underground, heat and pressure can change them into metamorphic rocks. If metamorphic rocks get hot enough, they melt into magma and can become igneous rocks again.

A Never-Ending Cycle

The rock cycle has no beginning or end. Any type of rock can become any other type. A piece of granite could become sandstone, then slate, then melt and become granite again. The cycle keeps going as long as Earth has heat inside it and weather on its surface.

Fun Facts

• It can take millions of years for a rock to go through the full rock cycle.
• The rock cycle is powered by heat from inside the Earth and energy from the Sun.
• Rocks on the ocean floor are recycled back into Earth's interior at subduction zones.

Did You Know?

Some of the atoms in the rocks around you today may have been part of many different types of rocks over billions of years. A single atom could have traveled through the rock cycle hundreds of times!