Modified presentation from another slideshare user.

2. What is a Rock?
• Naturally-occurring mixtures
of minerals. Sometimes include
organic matter.

3. What is a Rock?
• Rocks are divided into 3
groups based on how they
were formed:
• IGNEOUS
• SEDIMENTARY
• METAMORPHIC

4. What is the difference
between a rock and a
mineral?
• Rocks are made up of ONE or
MORE minerals.

5. Once a rock is formed, does it
stay the same rock forever?
• NO!

6. • Rocks are continually changed by many
processes, such as weathering,
erosion, compaction, cementation,
melting, and cooling
• Rocks can change to and from the
three types

7. What is the process through
which rocks change?
• The Rock Cycle—earth materials
change back and forth among the
different types of rocks

10. • No set path a rock takes to become
another kind of rock

11. IGNEOUS
Weathering, Erosion,
Compaction, Recrystallization
Cementation
Melting,
Solidification Melting,
Solidification
Recrystallization
SEDIMENTARY METAMORPHIC
Weathering, Erosion,
Compaction,
Cementation

12. • “Ignis” = Latin for “fire”
• Formed from the cooling of either
magma or lava
• The most abundant type of rock
• Classified according to their origin and
composition

13. ORIGIN— Where IGNEOUS rocks
are formed
2 TYPES OF IGNEOUS ROCK:
1) Below ground = from magma
(intrusive igneous rock)
• Usually have LARGE crystal grains (they
cooled slowly)

14. 2) Above ground = from lava (extrusive
igneous rock)
Usually have SMALL or NO crystals (they
cooled too quickly)

15. Peridotite: Intrusive or
Extrusive? Why?

16. Granite: Intrusive or
Extrusive? Why?

17. Obsidian: Intrusive or
Extrusive? Why?

18. • Formed from sediments
(rock fragments, mineral
grains, animal & plant
remains) that are pressed
or cemented together or
when sediments precipitate
out of a solution.

19. • These sediments are moved by wind,
water, ice or gravity.
• Sedimentary rocks represent 7% of the
Earth’s crust, but they cover 70% of the
Earth’s surface.
• Sedimentary rocks are fossil-carrying
rocks.

20. What turns sediments into solid rock?
1)Water or wind breaks down and
deposits sediment (erosion & deposition)

21. 2)The heavy sediments press down on
the layers beneath (compaction)

22. 3)Dissolved minerals flow between the
particles and cement them together
(cementation)

23. How can sedimentary layers help us
understand the age of fossils?
• As sedimentary rocks
are deposited, they
form horizontal
layers
• Scientists know that
the layers on top
(and the fossils in
the top layer) are
YOUNGER than the
fossils in lower
layers.

24. • Rocks that have changed due to
intense temperature and pressure
• “Meta” means “change” and morphosis
means “form” in Greek
• Igneous, sedimentary and other
metamorphic rocks can change to
become metamorphic rocks

25. What occurs in the Earth to
change these rocks?
• Pressure from overlying rock layers
• High heat, but not enough to melt the rock
• Rocks may be flattened or bent or atoms may
be exchanged to form new minerals.

26. • *You can think of metamorphic rocks
as a squished peanut butter & jelly
sandwich in your lunch.

27. Bill Nye Video

28. QUESTIONS
1. What are the three types of rocks?
2. What type of rocks hold fossils?
3. What are the 2 kinds of igneous rocks?
4. What kind of igneous rocks are formed below the
earth’s surface?
5. What kind of rock has the Grand Canyon formed
in?
6. What are rocks made of?
7. Will an igneous rock stay an igneous rock
forever?