EARTH UNIT
Lesson 5 – Igneous Rock
OBJECTIVES
• Students will identify the
characteristics of igneous rock.
• Students will understand how
rocks are formed.
VOCABULARY
• Igneous rock: rocks formed
when magma from inside the
earth cools and hardens on
the earth’s surface.
• lava: magma that has
reached the surface of the
earth
• magma: hot, liquid rock
formed deep inside the earth
a rock is made of two or
more minerals.
ROCKS ARE DIVIDED INTO THREE
GROUPS BASED ON HOW THE
ROCKS FORMED
HOW ARE ROCKS FORMED?
• Today we will be
using the rock
formation chart to
help us understand
the formation and
location of igneous
rocks.
• Materials:
• red and orange
crayon
• pencil
• formation chart
Igneous rocks or fire rocks are formed
from hot, molten materials called
magma. They can be found where
volcanoes have or do exist.
Igneous rocks are
created when
molten rock (lava)
inside the Earth
pushes through
the crust (like in a
volcanic eruption)
and then cools
INTRUSIVE (PLUTONIC) IGNEOUS
ROCKS
• Intrusive rocks are
made when magma
that is blocked from
reaching the earth’s
surface cools slowly
below the earth’s
surface. Intrusive
igneous rocks cool
slowly deep within the
earth and produces
large crystals.
click here for more examples
INTRUSIVE IGNEOUS ROCKS
QUARTZ
GRANITE
GABBRO
The slow-cooling process creates large crystals
and appear coarse-grained. Some examples
of these are:
EXTRUSIVE (VOLCANIC) IGNEOUS
ROCKS
• Lava is the name for
liquid magma that
reaches the earth’s
surface by flowing out of
volcanoes.
• The lava cools rapidly
forming extrusive rocks
which have small, fine
grained crystals or glassy
appearance.
click here for more examples
EXTRUSIVE IGNEOUS ROCKS
OBSIDIAN
If the cooling is
instantaneous a
glassy texture may
form
PUMICE
BASALT
If gas bubbles are is a fine-grained,
trapped as the
dark-colored
lava rapidly cools extrusive igneous
a vesicular texture
rock
may occur
https://www.youtube.com/watch?v=PrN7jygu4cQ
REVIEW
• With a partner and your chart
explain:
• How igneous rocks are formed
• What magma is and where it can be
found
• What lava is and where it can be
found
• Intrusive and extrusive rocks