Petrology is the branch of geology that studies rocks. Rocks are composed of minerals and there are three main types of rocks: sedimentary, igneous, and metamorphic. Sedimentary rocks form from the compaction and cementation of sediments, igneous rocks form from the cooling and solidification of magma, and metamorphic rocks form from the alteration of existing rocks by heat, pressure, and chemical reactions. Each rock type has different characteristics and uses.

1. PETROLOGY
IS A BRANCH OF GEOLOGY,
WHICH DEALS WITH STUDY OF
ROCKS
PETRO - ROCK
LOGOS - STUDY

2. WHAT ARE ROCKS?
rocks are composed of
minerals, which are
natural inorganic
(nonliving) substances with
specific chemical
compositions and
structures.

3. TYPES OF ROCKS
S
E
D
I
M
E
N
A
R
Y
I
G
N
O
U
S
M
E
T
A
M
O
P
H
I
C

6. EXTRUSIVE ROCKS INTRUSIVE ROCK
obsidian
basalt granite
gabbro

7. USES OF IGNEOUS ROCKS
Granite is still used
today for constructing
buildings.
Obsidian has been used for tool
making by native americans. Some
surgeons use obsidian instead of steel
in their scalpels today because they
cut better and leave a thinner scar.

9. SEDIMENTARY ROCKS
SEDIMENTARY ROCK

11. 1. ORGANIC
2. CLASIC ROCKS
3. CHEMICALLY
FORMED ROCKS

12. CLASTIC
They are formed from
broken bits and pieces of
other rocks that were
eroded and deposited a
long time ago.

13. fossilized
remains of
plants or
animals

14. sediments are
“glued” together
by dissolved
minerals
CHEMICAL

15. Metamorphic rocks are
formed by heat and
pressure changing one
type of rock into another
type of rock.
METAMORPHIC ROCK

16. TWO TYPES OF
METAMORPHISM
1.CONTACT
METAMORPHISM
2. REGIONAL
METAMORPHISM
heat
pressure

17. All types of rock can change
Granite
becomes
Gneiss
Sandstone
becomes
Quartzite
Shale
becomes
Slate

18. foliated non-foliated
CRYSTALS ALIGNED
IN STRIPES
CRYSTALS ARRANGED
IN RANDOM MANNER

19. THE ROCK CYLE