Geography South Africa Geomorphology Notes

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SOUTH AFRICAN
GEOMORPHOLOGY
PART 1
GR2BFET
2022

2. © 2015 Pearson Education, Inc.
1. Landscapes
2. The characteristics and processes associated with the
development of horizontally layered rocks
3. Hilly landscapes
4. Basaltic plateaus
5. Canyon landscapes
6. Desert Landscapes
– The Kalahari
– The Karoo
7. Dome
8. Valley
9. Cliff
10.Mass Movement
In this theme, you will learn about:

3. © 2015 Pearson Education, Inc.
1. Landscapes
2. The characteristics and processes associated with the
development of horizontally layered rocks
3. Hilly landscapes
4. Basaltic plateaus
5. Canyon landscapes
6. Desert Landscapes – The Kalahari
Video: Gr 11: Geomorphology-
Horizontally layered rocks
Duration: 51:09 (Very long)
https://www.youtube.com/watch?v=SpJpVIoOtdw
In Part 1:

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1. Landscapes
• A landscape is part of the
Earth’s surface that can
be viewed at one time
from one place.
• It consists of the
geographic features that
mark, or are
characteristic of, a
particular area.
• A natural landscape is
made up of a collection of
landforms, such as
mountains, hills, plains,
and plateaus.
• Lakes, streams, soils,
and natural vegetation
are other features of
natural landscapes

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• You learned about the Rock Cycle – Metamorphic
(change), Igneous (lava), and sedimentary (layered
sediment).
• When this rock is exposed, the horizontal layers of
visible rock are called strata (alternating horizontal layers
of rock)
• Layers of horizontal rock can also be formed from lava
flows. When this type of rock is eroded, it forms canyons
and plateaus.
2. The characteristics and processes associated
with the development of horizontally layered rocks

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The parallel layers are formed by sediments accumulating over
a long geological period
There are a number of landscapes associated with horizontally
layered rocks. These will be briefly discussed.

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• Hilly landscapes are regions where the strata have a
similar or equal resistance to erosion results in hills with
steep rounded slopes.
• These regions typically have high rainfall, with the water
eroding and smoothing the hills creating domed peaks.
• An example of such a landscape can be found in KwaZulu-
Natal’s Valley of a Thousand Hills.
3. Hilly landscapes

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3.1 Valley of 1000 Hills - KZN
• The Valley of a Thousand Hills – steep and deep valleys,
some still wild, others densely populated
• Comprises a highly dissected ridge of crystalline
basement, measuring roughly 30 x 25 km, and now eroded
below the level of the surrounding countryside.

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• The main players in the formation of this spectacular valley
system are the down-cutting Mgeni River
• The deeply weathered basement, constitutes rocks that are
far more easily eroded than the overlying hard Natal
sandstone
3.1 Valley of 1000 Hills - KZN
Video: Valley of a
1000 Hills by Drone
| Cinematic | HD
Duration: 2:35
https://youtu.be/Em
PE9sUYR04

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3.2 Drakensberg Escarpment
• Around 160 mya, immense
pressure deep within the Earth
caused Gondwanaland to begin
to split apart.
• vast lava flows poured out
through fractures in the Earth’s
crust and hardened into layers
of basalt.
• Along the escarpment, erosion
followed fracture planes that
formed deep within the rock and
broad cliff faces formed.
• Today, towering basalt peaks
remain.
• Sediments formed the small
cliffs in the foothills of the
Drakensberg.

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3.2 Drakensberg Escarpment
Video: Drakensberg, South Africa in 4K Ultra HD
Duration: 7:21
https://youtu.be/fIHjo2g6R-c

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• The layers are easily recognised
due to the way they sparkle in
the sun.
• The glistening is due to tiny
quartz crystals, which form a
cement between the sand grains
• These layers also contain early
dinosaur fossils - can be found in
the sandstone caves of the
foothills.
• The eroded debris from this long
process has been churned into a
black soil that supports the
grasses that cover the slopes
below.
3.2 Drakensberg Escarpment

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• Basaltic plateaus are large high-lying regions formed initially
from lava flows covering thousands of square kilometres.
• This rock is eroded predominantly by water forming high, flat
landforms and deep canyons.
• Other landforms formed by erosional processes are mesas,
buttes and domes.
4. Basaltic plateaus

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• Most of South Africa is a plateau,
with high ground on all but its
northern border. This high land
drops steeply towards the coast.
• As the South African plateau heads
south, three parallel steps form the
rim, each separated by a strip of
level ground between them.
• The Great Karoo makes up the
largest of these gaps between
steps. The Karoo and the Kalahari
Desert (perched on the plateau)
are dry and arid.
4. Basaltic plateaus

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• For canyons to form, the original layers of rock are level.
• The harder layers of rock resist erosion and the softer layers or
faults are susceptible to erosion, especially from the action of
water.
• The down cutting action by rivers, maintains the narrow, vertical
profile, thus creating a canyon or gorge.
• The freezing and expansion of water trapped in the cracks and
faults of the rock strata, results in physical weathering.
• This process is also responsible in the formation of canyons
and gorges
5. Canyon Landscapes

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• The Blyde River (also known as the Motlatse) Canyon
Nature Reserve is situated in Mpumalanga.
• It is the third largest canyon on Earth and is situated below
the confluence of the Blyde and Treur rivers
• It extends for 25kms along the lip of the great African
escarpment.
• It is on average, around 750 metres deep.
• Blyde River Canyon is the largest 'green canyon' due to its
lush subtropical foliage.
• It is the second largest canyon in Africa, after the Fish River
Canyon in Namibia, and is known as one of the great
wonders of nature on the continent.
5.1 Blyde River Canyon

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Video: Three Rondavels, Blyde River Canyon,
South Africa.
Duration: 2:44
https://youtu.be/z6CzX_npZd0
5.1 Blyde River Canyon

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• In geography, a desert is a landscape form or region that
receives very little precipitation.
• Generally deserts are defined as areas that receive an
average annual precipitation of less than 250 mm.
• 'True deserts' where vegetation cover is exceedingly sparse,
correspond to the 'hyperarid regions of the earth, where
rainfall is exceedingly rare and infrequent eg. Sahara Desert
• Deserts are however part of a wider classification of regions
that, on an average annual basis, have a moisture deficit
(i.e. they can potentially lose more than is received).
• These areas are collectively called 'drylands.’
Video: Deserts 101 | National Geographic
Duration: 3:52
https://www.youtube.com/watch?v=n4crvs-KTBw
6. Desert landscapes

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6.1 Kalahari Desert
Kalahari Desert
• Stretches approximately
900 000 km² across
Botswana, Namibia and
South Africa.
• The Kalahari Desert is
not a true desert
because it receives too
much rainfall - between
120 and 250 mm annually

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6.1 Kalahari Desert
• The Kalahari sand dunes,
some of which stretch west
to the Namib Desert,
compose the largest
continuous expanse of sand
on earth. That is because
although the Sahara Desert
is larger overall, sand
dunes make up only about
15% of its area
• In summer, the heat can top
45 degrees Celsius; on
winter nights, lows can drop
to -15 degrees Celsius

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6.1. Kalahari Desert - Physiography and geology
• The Kalahari Desert is a featureless, gently undulating,
sand-covered plain, 900 metres or more above sea level.
• Bedrock is exposed only in the vertical-walled hills,
called koppies, that rarely but conspicuously rise above
the general surface
• Aside from the koppies, three surfaces characterize
virtually all of the Kalahari:
– sand sheets,
– longitudinal dunes, and
– vleis (pans).
Video: The Kalahari, Northern Cape (to give you an idea of the different
landscapes)
7:44
https://www.youtube.com/watch?v=33ApWjlEpYM

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6.1 Kalahari Desert - The sand sheets
• sandy flat areas
• formed during
the Pleistocene (about
2,588,000 to 11,700 years
ago), and they have been
fixed in place since then.
• In some areas they appear
to have been of fluvial
origin, the result of sheet
flooding in times of much
greater precipitation, but by
far the greater part of them
were wind-formed.
• They occupy the eastern
part of the Kalahari.
• Their surface elevation
varies only slightly
• the sand is red, the result
of a thin layer of iron oxide
that coats the grains of
sand.

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6.1 Kalahari Desert - Sand dunes
• a hill of sand near an
ocean or in a desert that is
formed by the wind
• The entire western Kalahari
Desert is characterized by
long chains of dunes,
oriented roughly to the
north or northwest.
• The dunes measure at
least 1.6km in length,
several hundred metres in
width, and 6m to 60m in
height.
• Each dune is separated from
its neighbour by a broad
parallel depression locally
called a straat (“street,” or
“lane”), because
each constitutes the easy
way to travel.

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6.1 Kalahari Desert - Vleis, or pans
• are the terminal (end) features of desert drainage
systems, the “dry lakes” at the end of short-
lived streams.
• Many are remnant features from an earlier period of
greater precipitation.
• Very little water ever flowed to the sea from the
Kalahari.
• Rather, each stream ended its course in a slightly
lower depression from which there was no outlet.
• As the stream dried up, the fine silt particles carried in
suspension by the sluggish stream were deposited
along with soluble calcium minerals and salts
precipitated out of the evaporating water.

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6.1 Kalahari Desert - Vleis, or pans
• As the stream dried up, the
fine silt particles carried in
suspension by the sluggish
stream were deposited
along with soluble calcium
minerals and salts
precipitated out of the
evaporating water.
.
• The results are pans—flat
surfaces devoid of vegetation
that are gleaming white when
dry, hardened by the
cementing action of the
soluble minerals, and, on
occasion, covered by a
shallow layer of standing
water.
• Where the salt content is low,
pans may become covered
with grasses after a rain

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6.1 Kalahari Desert - soil
• Soils in the Kalahari Desert are largely based on sand,
are reddish in colour, and are low in organic material.
• Chemically, they are relatively alkaline, and they are
extremely dry.
• In and near the pans, the soils tend to be highly
calcareous or saline, and frequently they are toxic to
most vegetation.

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End of Part 1
• Online class test on SA Geomorphology
Part 1 on Monday 1st August 2022 @
12h00 

28. © 2015 Pearson Education, Inc.
• Blaauw, M., Brouard, J., Gitlin, A., Gunter, A., Mofokeng, M., and Oberholster, E. (2012): Spot On Geography Learners Book
Grade 11. Heinemann Publishers (Pty) Ltd, Sandton.
• Britannica online for Kids (2016): The Columbia Plateau. Accessed online from http://kids.britannica.com/comptons/art-
149596/The-Columbia-Plateau-is-uniformly-covered-with-basaltic-lava-flows on 27 January 2016.
• Durban Tourism (2012): 1000 Hills Experience. Available online from:
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2016
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dome Accessed 02 March 2016
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Accessed 02 March 2016
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• News24 (2013): PICS: Severe mudslide on Chapman's Peak Drive. Article featured online on 16 November 2013:
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March 2016
References

29. © 2015 Pearson Education, Inc.
• One Geology (nd): Mass Movement. Available online from:
http://www.onegeology.org/extra/kids/earthprocesses/massMovements.html Accessed 21 March 2016
• PEI Education (2016): Valleys: face of the earth. Available online from: http://www.edu.pe.ca/southernkings/face.htm Accessed 21
March 2016
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• https://www.britannica.com/place/Kalahari-Desert
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References