Rocks formed

Engagement
OBSERVE THE SAMPLE
ROCKS AND CHOOSE ONE
AND WRITE A DESCRIPTION.
(USING YOUR FIVE SENSES)


OBJECTIVE:
Students will observe and classify
characteristics of rocks and read text
pp. 198-199 in order to create a “3
Tab” foldable.


Rocks

In this lesson you will learn about the rock cycle
and what some kinds of rocks there are on Earth.
First thing we will begin with is identifying the
three main different kinds of rocks.

Below are three different kinds of rocks. Using what you
already know about rocks, can you determine what kind is
which?


Group Work
Classify the rocks by looking at their physical
properties. (The properties or rocks include
Color

What mineral they are made of
Texture


The three main types of
rocks are Igneous,
Metamorphic, and
Sedimentary.


Igneous rock
Igneous rock forms from a red-hot
mixture of melted minerals and gases.


Sedimentary Rock
Forms in layers one layer at a time.

Limestone is considered
a sedimentary rock.


Metamorphic Rock
Has been changed by heat, pressure,
or both.

This metamorphic
rock is called gneiss.

Believe it or not, but all of these kinds of rocks are related. Their
relationship to one another is called The Rock Cycle. Study the
picture and see how one type of rock can be changed to another kind.


Igneous Rocks
The formation of igneous rocks depends solely on magma.
As you can see from this diagram, an oceanic plate drives itself
underneath the continental plate. This is called a fault. The oceanic
plate is more dense than the continental plate making it go underneath
the lighter continental plate. The oceanic plate activates the zone of
magma generation, causing it to come up through the Earth’s crust
and create a volcano. The magma that reaches the surface is
called lava, and when it cools, it forms igneous rock.


Here are some examples of igneous rocks.

This igneous rock is called basalt. It
is generally found on the surface of
the Earth, composed of cooled lava.

Granite is a common form of igneous
rock found. Below is a picture of
Granite in a close-up view.


Metamorphic Rocks

Metamorphic rocks are rocks that were once of one kind but because

of heat, pressure, or a chemical change, they were changed into
something else. These rocks are called metamorphic rocks because
they are “morphed,” or changed to a different kind of rock. The rocks
could have been either igneous, sedimentary, or even another
metamorphic rock to begin with.

This rock is called granite.
It is an igneous rock. Because
of heat and pressure, it can be
changed to a metamorphic rock
called marble.

This is what becomes
Of granite when it is
“morphed.” This is marble.

This is a close-up of
a section of marble
rock.


Sedimentary Rocks
Sedimentary rocks are made from other rocks that have been
weathered. Weathering is the breaking down of rock pieces into
smaller pieces. These small pieces of rock are then cemented
together, compacted tightly, crystallized again to form new
sedimentary rock.
This is a close-up view of sandstone,
a type of sedimentary rock. Notice
the different colored particles

that this rock is made up of. This
gives the impression that it is made
up of many different kinds of rock
that have been broken down into small
pieces and have been compacted
tightly together.


Sedimentary rocks are often formed in layers. This occurs
because the rocks were formed underwater. A river or stream picks
up sediment along its path. When the river or stream drains into a
large body of water, the sediment falls to the floor and accumulates.
Different kinds of sediment are carried downstream at different times.
This causes layers of different colored particles to accumulate.


Group Work
Reclassify the rocks into the three
main groups. (Igneous Rock,
Sedimentary Rock, Metamorphic
Rock.


Today you have learned about the rock cycle and some information
about igneous, metamorphic, and sedimentary rocks.

Use what you know about rocks and go out into the world and
see if you can identify what kind of rocks are where.

Check Point

• What are rocks made
of?


Why do the Textures of
different types of rock
vary?


You have found two rocks. One
is gray, lightweight, and has lot
of holes throughout. The other is
heavy and mad up of pieces of
different colors. Are these most
likely the same king of rock.


Check Point

• A rock collector shows you a
rock changed by heat and
pressure from another kind of
rock deep inside the Earth.
What kind of rock is it?


How does igneous rocks
form?

Two fossils are found in
different layers of
sedimentary rock. The rock
layers have not been
disturbed. Which is older the
fossil in the lower layer or
the one in the upper layers?


Igneous Rock


Sedimentary Rock