This document describes the three main types of rocks: sedimentary, igneous, and metamorphic. Sedimentary rocks form from the compaction and cementation of sediments and sometimes contain fossils. Igneous rocks form from cooled magma, either extruding from volcanoes as lava or slowly cooling underground. Metamorphic rocks are formed by heat and pressure acting on existing rocks, changing their composition and structure.

1. Types of Rocks
Sedimentary, Igneous, Metamorphic

2. Sedimentary Rocks
• Made up of smaller rocks cemented
together
• Sometimes have fossils
• Usually have layers.

3. Sedimentary Rocks
• Form when loose sediment (rocks, sand) is
deposited by water, compacted, and
cemented together.
• Form as a chemical reaction in the water
that leaves a chemical deposit, usually on
an ocean bottom.
• Form along beaches, by rivers, or under
the water in lake or oceans.

4. Sedimentary Rocks

5. Examples of Sedimentary Rocks

6. Igneous Rocks
• Some were once liquid magma that erupted
from volcanoes. They cooled very quickly.
(Extrusive)
• Others were once liquid magma, but they
did not erupt from volcanoes. Instead, they
cooled slowly underground. (Intrusive)

7. Igneous Rocks
• Extrusive:
– Rocks that are from cooled lava (above ground.
– They cooled very quickly, therefore formed
small crystals
• Intrusive
– Rocks that are from cooled magma (below
ground)
– They cooled very slowly, therefore formed
large crystals.

8. Igneous Rocks
• Which is extrusive and which is intrusive?
Extrusive
Intrusive

9. Igneous Rocks

10. Examples of Igneous Rock

11. Metamorphic
• Form when igneous, sedimentary, or other
metamorphic rocks are heated and/or
squished, forming a new rock type.
• Usually has interlocking crystals and layers
(called foliation)

12. Metamorphic
• This can either happen underground or
above ground.
– Underground: high pressure and heat
– Above ground: volcano erupting
• When classifying metamorphic rocks, they
always come from a parent rock.

13. Metamorphic Rocks

14. Examples of Metamorphic Rocks

16. Review
• What are the three rock types?
• What are sedimentary rocks?
• What are igneous rocks?
• What are the two types of igneous rocks?
• What are metamorphic rocks?

17. Copyright Information
• All information was retrieved from
research done on the internet in
February 2007.
• All pictures were retrieved from a
Yahoo image search in February 2007.