The document provides information about landforms in South Africa. It discusses the Karoo region, describing its three main areas as the Great Karoo, Little Karoo, and Succulent Karoo. It then focuses on the Vredefort Dome, the largest known meteorite impact crater on Earth. The dome was formed 2 billion years ago by the impact in the center of an original 300 km wide crater. Finally, it briefly touches on valleys, cliffs, and mass movement, which is the downslope movement of material under the force of gravity.

1. © 2015 Pearson Education, Inc.
SOUTH AFRICAN
GEOMORPHOLOGY
PART 2
GR2BFET
2022

2. © 2015 Pearson Education, Inc.
In Part 2
6. Desert Landscapes – The Karoo
7. Dome
8. Valley
9. Cliff
10.Mass Movement

3. © 2015 Pearson Education, Inc.
• South Africa’s Karoo is a biologically distinct ‘country’ that
sprawls over 400 000 km², making it a little bigger than
Germany
• The name Karoo is thought to have come from a Khoi word
of uncertain meaning, popularly thought to mean Land of
Thirst.
• It is acknowledged as one of the world’s biodiversity
hotspots, with 6 000 plant species (of which 40% are
endemic) and critically endangered mammals.
Video: The Karoo of South Africa
Duration: 7:20
https://youtu.be/fIKo329sM-U
6.2 The Karoo

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6.2 The Karoo
It is roughly divided into three main areas –
1. the Great Karoo (also called the Central Karoo),
2. the fertile Little Karoo (also called Klein Karoo) and
3. the Succulent Karoo (sometimes referred to as
Namaqualand), notable for its very high plant biodiversity

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• Orange shows the Great Karoo, and pink shows the highly
biodiverse succulent Karoo (also known as Namaqualand).
Green is the Kalahari
6.2 The Karoo

6. © 2015 Pearson Education, Inc.
– the fertile Little Karoo
6.2.1 The Little Karoo
• The Little Karoo is a 350 km long, and 40 to 60 km wide
valley
• and is almost completely surrounded by mountains.
• Little Karoo is a semiarid region that is located between the
Langeberg, Outeniqua and Tsitsikamma mountains to the
south and the Swartberg mountains to the north.
• Despite relatively low average annual rainfall, attributed to
the rain shadow created by the surrounding mountain
ranges, the Little Karoo is one of South Africa’s prime
agricultural areas

7. © 201 Pearson Education, Inc.
– the Succulent Karoo
(also called
Namaqualand),
Video: The Nature of
Namaqualand and the Incredible
Succulent Karoo | Conservation
South Africa (CSA)
Duration: 2:19
https://youtu.be/r_twh3jB8pw
6.2.2 The Succulent Karoo

8. © 2015 Pearson Education, Inc.
• The Succulent Karoo is an internationally recognized
biodiversity hotspot and is the world's only arid hotspot.
• The biome extends from the south-west through the north-
western areas of South Africa and into southern Namibia.
• The rich biodiversity of the Succulent Karoo is due to an
extensive and complex array of habitat types derived from
topographical and climatic diversity in the region's rugged
mountains, semi-arid shrublands, and coastal dunes.
• Geologically and paleontologically, it is already one of the
most famed areas in the world
• About 253 million years ago, the Karoo was a vast inland
basin, a lush Okavango of unimaginable size, bracketed north
and south by huge mountain ranges
6.2.3 The Succulent Karoo

9. © 201 Pearson Education, Inc.
6.2.2 The Great Karoo
• Also called the Central Karoo, an
ancient formation of largely
sedimentary deposits covering
much of south east South Africa.
• The Great Karoo is itself divided
by the Great Escarpment into the
Upper Karoo (generally above
1200–1500 m) and the Lower
Karoo on the plains below at 700–
800 m.
• At 30° S, and located on the
west of the continent, it is in a
similar position to other
semidesert areas on earth.
• The arid climate is as a result of
the region being in the rainfall
shadow of the Cape Fold
Mountains along the western
coastline, .

10. © 2015 Pearson Education, Inc.
• A dome is a round or oval-shaped formation that has
risen above the ground around it.
• A dome can be formed in three ways:
1. It can be formed by the impact of a meteor.
– This can break up the layers of rock under the ground,
so that pressure and the weight of the ground and
rock layers nearby can push the area upward.
– The broken layers of rock have less resistance to
underground pressure and the land may lift upward to
form a dome shape.
– This may take thousands of years to occur after an
impact.
7. Dome

11. © 2015 Pearson Education, Inc.
2. Another way that a dome is formed is by geological
stress that cause folding of the land.
This folding can take place from different directions at
different times.
When folds of land run in different directions, this can
cause an uplift of the land where they meet to form a
dome-like area.
3. A dome can also be formed when there is a difference
in the density of material underground.
If there is an area that contains material that is less dense
or lighter than the rock and ground around it, this can
cause the material to rise.
7. Dome

12. © 2015 Pearson Education, Inc.
7. Dome

13. © 2015 Pearson Education, Inc.
7. Dome
The weight of the heavier rock around the material can force
it upward, and it may push the ground layers above it
upward to form a dome.
This may take many thousands of years to occur.
Video: The Kaapvaal Craton - Genesis of Life
Duration: 3:16
https://youtu.be/WfwSferEJiE

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7. Dome
Video: Life in the World's
largest Crater - Vredefort
Dome PROMO
Duration: 1:07
https://youtu.be/Tgu-dGsxLQI

15. © 201 Pearson Education, Inc.
7.1 Vredefort Dome
• The largest known impact
crater on Earth is the
Vredefort Dome It
encircles Vredefort, South
Africa and was more than
290 km in diameter when
visible.
• A 70 km wide dome
formed in the centre
where the impact
occurred about 2 billion
years ago.
• Only portions of the dome
remain

16. © 2015 Pearson Education, Inc.
• The dome created in the centre of the crater was
originally thought to be the result of a volcanic explosion
but geological surveys proved that the site was subject to
a meteorite impact.
• The Vredefort Dome with its unique multi-ringed structure
makes it one of its kinds on earth though such impact
craters are common in the Solar System, found on
Jupiter’s moon and Earth’s moon.
• Earlier multi-ring craters which have been formed on
earth have largely been destroyed by erosion and other
such geological processes
7. Vredefort Dome

17. © 2015 Pearson Education, Inc.
• The meteorite impact that happened in the Free State
made a crater that was about 300 km wide (from
Johannesburg to Welkom!).
• This is the biggest meteorite impact that geologists have
yet found on Earth and it is nearly twice as big as the
impact that killed the dinosaurs 65 million years ago.
• The Vredefort Dome is only the central part of the impact
crater. It is called a dome because the rock layers were
bent into the shape of an upside-down bowl
7.1 Vredefort Dome

18. © 201 Pearson Education, Inc.
8. Valley
• Down in the valley, the land is depressed—scoured and
washed out by the conspiring forces of gravity, water, and
ice.
• The scars left behind are known by their shapes and where
they lie.
• Some hang; others are hollow. They all take the form of a
"U" or "V”
Video: How are Valleys Formed
Duration: 2:11
https://youtu.be/f0pkIf2YbS0

19. © 2015 Pearson Education, Inc.
• A valley is a hollow or surface depression of the earth
bounded by hills or mountains, a natural trough in the
earth's surface that slopes down to a stream, lake or the
ocean, formed by water and/or ice erosion.
• Systems of valleys extend through plains, hills, and
mountains.
• Rivers and streams flowing through valleys drain interior
land regions to the ocean.
• At the bottom of many valleys is fertile soil, which makes
excellent farmland.
• Most valleys on dry land are formed by the running water
of streams and rivers.
8. Valley

20. © 2015 Pearson Education, Inc.
• The bottom of a valley is called its floor and most floors
slope downstream.
• Mountain valleys usually have narrow floors.
• The part of the floor along riverbanks is called flood plain.
• A valley's sides are called valley walls or valley slopes.
• A valley wall is the side slope of a stream or glacial
valley.
• Rain, frost, wind and the atmosphere loosen materials
which fall into the stream and are carried away
• The Valley of 1000 Hills is named after the many hills,
cliffs and valleys, which rise up from the banks of the
Umgeni River as it flows from the distant Drakensberg
mountains to the Indian Ocean
8. Valley

21. © 2015 Pearson Education, Inc.
• A cliff is a tall rock formation with a face that is vertical or
nearly vertical
• A cliff can be formed in a number of ways:
– by glacier movements that cut and shape rock
formations;
– wave action from a river or sea coast can form a cliff
by eroding soft rock formations;
– wind, rain and freezing temperatures can also erode
limestone and other soft rock formations to form a cliff.
Video: Getting Out And Exploring: Cliffs
Duration: 3:08
https://youtu.be/8hf8bT1-cys
9. Cliff

22. © 2015 Pearson Education, Inc.
• When hard rock layers that are more resistant to erosion
lay on top of limestone or other soft rock, this can form a
vertical cliff as the lower layers erode more easily
• South African mountain ranges such as the Drakensburg
and Waterval Boven in Mpumalanga are popular tourist
and adventure tourism areas with their spectacular cliff
faces
9. Cliff

23. © 2015 Pearson Education, Inc.
• Mass movement is the movement of surface material
caused by gravity.
• Landslides and rock falls are examples of very sudden
movements of this type.
• Of course geological agents such as water, wind and ice
all work with gravity to cause a levelling of land.
10. Mass Movement

24. © 2015 Pearson Education, Inc.
• Water aids in the downslope movement of surface
material in several ways.
• Water adds weight to the soil; it fills pore spaces of slope
material and it exerts pressure which tends to push apart
individual grains.
• This decreases the resistance of the material to
movement.
• Landslide is a general term that is commonly broken
down into the more specialized terms such as landslides,
slump, rockslide, debris slide, mudflow and earthflow
Video: Mass Movement
Duration: 4:12
https://youtu.be/YW8BKbpaXPI
10. Mass Movement

25. © 2015 Pearson Education, Inc.
• Mass movements can be very dangerous because they
can happen very quickly and involve entire hillsides.
• Sometimes a mass movement will dam a river.
• A lake will form behind the dam. When the dam bursts,
the lake will drain causing catastrophic flooding.
• Rivers can erode the base of a slope and cause a mass
movement.
• Heavy rain and earthquakes can also trigger a mass
movement
• Landslides annually destroy or damage industrial or
residential developments, forest and agricultural lands
and are often responsible for numerous human
causalities and fatalities
10. Mass Movement

26. © 201 Pearson Education, Inc.
10. Mass Movement
• In South Africa landslides
have been responsible for
fatalities on the
Chapman’s Peak Drive
along the Cape Peninsula
Atlantic coastline
prompting extensive
structural improvements
and removal of loose rock
from the steep slopes
Video: Chapmans Peak
Mudslide 2013
Duration: 0:36
https://youtu.be/FBYsDaBIm
pA

27. © 2015 Pearson Education, Inc.
End of SA Geomorphology
• No Class on Monday
• Online class test next Friday @ 12h00 for
24 hours on SA Geomorphology Part 2

28. © 2015 Pearson Education, Inc.
• Blaauw, M., Brouard, J., Gitlin, A., Gunter, A., Mofokeng, M., and Oberholster, E. (2012): Spot On Geography Learners Book
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2016
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March 2016
References

29. © 2015 Pearson Education, Inc.
• One Geology (nd): Mass Movement. Available online from:
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March 2016
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References