The three different types of rocks will be discussed with their specific characteristics and examples.

1. CLASSIFICATION
OF ROCKS

2. WHAT ARE
ROCKS?
Hard substance of
different materials or
minerals held together
(Muneerkpalp, 2015).

3. Does a rock
stay the same
rock type
forever once it
formed?
(Heath, 2016)
No! Due to the rock cycle!

4. Rocks classified
according to origin
1)Igneous Rock:
Rock formed when molten
material cools and
hardens and is associated
with volcanic activity.
Cooling rate controls the
crystals size (Soreda,
2016).
Basalt

5. How are
Igneous rocks
formed?
(Teach5ch, 2008)

6. Intrusive igneous rock
Deep-lying magma under high pressure,
close to the heat source with a slow cooling
process.
Large crystal formation with granular, coarse
texture.
Once overlying layers are removed, crystals
can be seen.
Eg: granite, diorite.
diorite

7. Extrusive igneous rocks:
More rapid cooling causing smaller
crystals to form or no crystals.
Volcanic activity is involved.
Eg: basalt found on Drakensburg
peaks in Lesotho.

8. Sedimentary
rock:
Rock formed from
sediments of other
rocks that have been
compressed and
hardened.

9. Sedimentary rocks:
From sediments transported by wind, water,
gravity and ice.
Three agents: break up rocks, remove the
material and deposit this material.
Sediments are bound by pressure and
infiltrating of cementing material creating a
solid rock.
Classified by their origin being:
mechanical, chemical or organic (Rahmany,
2020).

10. Mechanical origin
Formed from particles (Sand or clay)
breaking off existing rocks.
Carried by the river into seas and lakes
where it gradually settles into layers and
becomes compressed.
Wind helps to compress the sediments in
a desert.
Eg: sandstone, shale

11. Chemical origin
Form from left behind sediments after evaporation of
solutions of dissolved materials occurs.
Calcium carbonate is chemically replaced by
magnesium forming calcium magnesium carbonate
and Weak acids dissolve limestone.
When it evaporates underground in caverns such as
Congo caves forms stalactites and stalagmites.
Eg: limestone, gypsum
Limestone
Calcium Magnesium carbonate

12. Organic origin
Formed by plant and animal remains that
accumulated on the sea floor.
Coal is formed from dead plant matter.
Oil formed from animal remains.
Limestone is compacted shells.
Oil as well as natural gas is found in
sedimentary rocks.

13. Common Characteristics
Deposited in layers (Strata) and Contains
fossils.
The softest and erodes easily.
Often form fertile soil.
Able to be folded or bent forming fold
mountains.
Layers are porous and differ in grain size and
colour.

14. Uses
Coal: For a heat and power source
Sandstone: For building
Shale: For making roads or paths
Salt: Domestic purposes or in chemical
industry.
Limestone: Cement and fertilisers.
Crude oil: Power source

15. METAMORPHIC
ROCK:
Rock developed from
igneous or sedimentary
rocks that have been
altered by heat or
pressure.

16. Metamorphic rocks
Sedimentary or igneous rock has been
exposed to great heat or pressure or both
causing their structure to be changed.
Magma is forced up, intense heat changing
the surrounding rocks Heat combined with
pressure to form metamorphism is regional
metamorphism.
Eg: Magaliesberg mountain with quartzite
ridges

17. Rock changes:
Great pressure:
1)Shale -> Slate
2)Limestone -> Marble
3)Sandstone -> Quartzite
4)Soft coal -> Anthracite
Great heat:
1)Granite -> Gneiss
2)Basalt -> Schist

18. Uses
Stone chips for road surface.
Slate on roof or garden paths
Marble on buildings or sculptures
All Gold is found in this rock and is
therefore called the banket.

20. https://youtu.be/R-Iak3Wvh9c

21. REFERENCES
Heath, S. (2016). Rock types. Available from:
https://www.slideshare.net/stevenheath148/rock-types-
67699695?from_search=15. (Accessed 2023/08/18).
Muneerkpalp. (2015). The rock and its types. Available from:
https://www.slideshare.net/muneerkpalp/the-rock-and-its-types. (Accessed
on 2023/08/18)
Rahmany, A. (2020). Types of rock. Available from:
https://www.slideshare.net/ArbazRahmany/types -of-rock-227474239.
(Accessed 2023/08/18).
Soreda, C. M.(2016). The three types of rocks. Available from:
https://www.slideshare.net/cyrasoreda/the-three-types-of-rocks-lets-rock-n-
roll?from_search=7. (Accessed 2023/08/18).
Teach5ch. (2008). Rock types. Available from:
https://www.slideshare.net/Teach5ch/rock-types-
presentation?from_search=8. (Accessed 2023/08/18).