What are the different ways that rocks are formed?
There are three different ways that rocks can form:

1) When rocky fragments and sediments are deposited together by wind, water or ice, they gradually (over thousands or more years) cement together into new rocks, called sedimentary rocks. Limestone and sandstone are common sedimentary rocks. You can often find fossils embedded in these rocks—they were deposited together with the sediments! Watch the animation below to see how it happens!

Don't see the sedimentary animation? Click here.

2) When molten rock called magma rises up from the earth's mantle deep underground, it forms igneous rocks. Some igneous rocks erupt from volcanoes as lava or pumice. Others, like granite, form in underground magma chambers. Watch the animation below to see volcanoes create pumice!

Don't see the igneous animation? Click here.

3) Sometimes sedimentary and igneous rocks are changed dramatically by forces inside the Earth. Extreme heat or pressure underground can bake, squeeze, or fold rocks into something new. Then they are called metamorphic rocks—metamorphic is Greek for "change of form." Watch the animation below to see how it happens!

Don't see the metamorphic animation? Click here.

Learn more in Rex the Dino Detective's "Mystery of the Floating Rock"

© The Children's Museum of Indianapolis, 2000