This document discusses the three main rock types: igneous, sedimentary, and metamorphic. It provides details about how each type of rock is formed. Igneous rocks form from the cooling of magma either underground as intrusive rocks or above ground as extrusive rocks from volcanoes. Sedimentary rocks form through the accumulation and compression of eroded sediments over millions of years. Metamorphic rocks were once igneous or sedimentary rocks that were transformed by heat, pressure, and chemical processes deep underground into new rock types.

1. Rock Types
Metamorphic
Igneous
Sedimentary

2. • What are Igneous Rocks?
Igneous rocks are formed from the solidification of
molten rock material.
• There are two basic types:
1) intrusive igneous rocks
2) extrusive igneous rocks
topics

3. • Igneous rocks are called fire rocks and are
formed either underground or above
ground. Underground, they are formed
when the melted rock, called magma, deep
within the earth becomes trapped in small
pockets. As these pockets of magma cool
slowly underground, the magma becomes
igneous rocks.
• Igneous rocks are also formed when
volcanoes erupt, causing the magma to rise
above the earth's surface. When magma
appears above the earth, it is called lava.
Igneous rocks are formed as the lava cools
above ground.
topics

4. Basalt Lava - Basalt is a
hard, black volcanic rock.
Less than ½ of the weight of
basalt is silica (SiO2
Dacite lava
is most often light gray, but
can be dark gray to black.
topics

5. • What are Sedimentary Rocks?
Sedimentary rocks are formed by the accumulation
of sediments.
• There are three basic types of sedimentary rocks:
1) classic sedimentary rocks
2) chemical sedimentary rocks
3) organic sedimentary rocks
topics

6. • For thousands, even millions of years,
little pieces of our earth have been
eroded--broken down and worn away
by wind and water. These little bits of
our earth are washed downstream
where they settle to the bottom of the
rivers, lakes, and oceans. Layer after
layer of eroded earth is deposited on
top of each. These layers are pressed
down more and more through time,
until the bottom layers slowly turn into
rock.
topics

7. Conglomerate is made up of
rounded pebbles cemented
together
Breccia is made up of angular
pebbles cemented together.
topics

8. • What are Metamorphic Rocks?
Metamorphic rocks have been modified by
heat, pressure and chemical process usually
while buried deep below Earth's surface.
• There are two basic types of metamorphic
rocks:
• 1) foliated metamorphic rocks
• 2) non-foliated metamorphic rocks
topics

9. • Metamorphic rocks are rocks that
have "morphed" into another kind
of rock. These rocks were once
igneous or sedimentary rocks. How
do sedimentary and igneous rocks
change? The rocks are under tons
and tons of pressure, which fosters
heat build up, and this causes them
to change. If you exam
metamorphic rock samples closely,
you'll discover how flattened some
of the grains in the rock are.
topics

10. Quartzite is a coarse-grained
metamorphic rock derived from
sandstone.
Marble is a metamorphic rock that
comes from metamorphosed
limestone or dolomite.
topics