Do you play on rocks? When you are an adult will those rocks be the same? The answer is yes. The secret is that they are changing. Rocks change very slowly. It takes millions of years for rocks to change. Rocks change in the rock cycle. There are three kinds of rocks. The three kinds are igneous, sedimentary, and metamorphic.

Igneous rocks come from melted rock deep inside the earth. Melted rock is called magma. When magma shoots out of a volcano it is called lava. Lava cools on the ground. It becomes solid rock. Any rock that comes from cooled magma is igneous rock. Most of the earth is made of igneous rocks.

Sedimentary rocks form when sand and dirt pile up in layers. These layers are pushed together for a very long time. After a long time, these layers become very heavy. All that weight puts a lot of pressure on the layers until they become solid rock. They are called sedimentary rock. Most of the Earth's land surface is covered by sedimentary rock.

Metamorphic rocks are rocks deep inside the earth. The top layer of the earth is called the crust. It is always moving. When it moves it pulls rocks deep into the earth. Down under the earth's surface it is very hot. The deeper the rocks are pulled the hotter they get. That heat and pressure changes the rocks. That’s how metamorphic rocks are formed.

As soon as rocks are formed they begin to change again. Rocks break down into smaller pieces because of weathering. Weathering is heat, wind and even water freezing and thawing. All of this can crack rocks apart. Also, plants break rocks apart when their roots grow. Animals break down rocks when they dig. The small pieces of rocks can be swept away by water. Sometimes they are blown away by wind. Many years later these pieces of rocks are buried. Heat and pressure turns them into new rock. Then the rock cycle begins all over again.

Now you know the secrets about rocks. So the next time you climb on rocks stop and think. They are always changing. Take a moment to wonder about those rocks. Where will they be in the future? What will they look like in the far away future? Keep on rockin’!