What are the different ways that rocks are formed?
There are three different ways that rocks can form:
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 rocksthey were deposited
together with the sediments! Watch the animation to see how it happens!
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!
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 rocksmetamorphic is Greek for "change of form." Watch the animation below to see how it happens!
Learn more in Rex the Dino Detective's "Mystery of the Floating Rock"
© The Children's Museum of Indianapolis, 2000