Download Igneous rock - WordPress.com

Unit 9 Lesson 3 How Can Rocks Be Classified?
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Igneous Rock
• Rock is a natural solid that
is made of one or more
minerals.
• Rocks are classified by how
they form.
• There are three types of
rocks: igneous,
sedimentary, and
metamorphic.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Igneous Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Igneous Rock
• Igneous rock forms when melted
rock, called magma or lava, cools
and hardens.
• Igneous rocks can form deep
inside Earth as magma slowly
cools.( example :Gabbro- Granite)
• Igneous rocks can also form on
Earth’s surface when a volcano
erupts and the lava cools fast.
( example :Rhyolite- Basalt)
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Igneous Rock
• When magma cools slowly
beneath Earth’s surface, large
mineral crystals form.
• When lava at Earth’s surface cools
quickly, mineral grains do not
have time to grow, and so the
crystals remain small.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Igneous Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Igneous Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Igneous Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Sedimentary Rock
• Sedimentary rock forms
from sediment, or particles
of weathered rock, that gets
cemented or glued together
under pressure.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Sedimentary Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Sedimentary Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Sedimentary Rock
• Some sedimentary rocks, such as rock
salt and limestone, form through
chemical processes when minerals
dissolved in water come out of
solution.
• Limestone is often formed from the
shells of sea animals. These shells,
which are made of mineral calcite, are
crushed and cemented together.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Sedimentary Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Sedimentary Rock
• Sedimentary rock can
contain fossils.
• Fossils are the remains or
signs of a living thing,
such as a bone, shell, leaf
imprint, or fossil
footprint.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Sedimentary Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Metamorphic Rock
• A rock that forms when Earth
processes change the texture and
the mineral content of rock is called
metamorphic rock.
• Metamorphic rock can form from
high pressure, high temperature, or
a combination of both.
• Metamorphic rock can also form
when super-hot fluids come into
contact with rock.(but not high
enough to melt the rock)
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Metamorphic Rock
• Mountains can form when two
large pieces of Earth’s crust
push against each other,
causing rocks in the growing
mountains to change.
• Pressure builds up and rock
layers may bend, twist, and
break.
• Over time, many of the rocks
become metamorphic rocks.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Metamorphic Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Metamorphic Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Metamorphic Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
The Rock Cycle
• Any type of rock can become
another type of rock. The
continuous process of rock
changing from one type to
another is known as the rock
cycle.
• For example, after igneous rock
is formed, weathering and
erosion can break it down to form
sediment which later forms rock.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
The Rock Cycle
• Metamorphic rock can be broken down
in the same way to become sediment,
which can be broken down, transported,
and deposited to become new
sedimentary rock.
• Temperature and pressure can also
transform any type of rock into
metamorphic rock.
• Any rock can be melted and cooled to
form igneous rock.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
The Rock Cycle
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
The Rock Cycle
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Uses of Rock
• Many monuments and statues,
such as the Lincoln Memorial in
Washington, D.C., are made of
marble, a relatively soft
metamorphic rock.
• Toothpaste is made from several
minerals that are extracted from
rocks. These minerals have natural
cavity-fighting properties.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Uses of Rock
• Many old buildings and
monuments, such as the
Egyptian pyramids, are made of
limestone. Today, limestone is
used in many homes and office
buildings.
• Many building materials, such as
cement and concrete, are made
from rocks.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Uses of Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Uses of Rock
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 9 Lesson 3 How Can Rocks Be Classified?
Copyright © Houghton Mifflin Harcourt Publishing Company