salt lakes
TRANSCRIPT
Makgadikgadi Pans Botswana
Thousands of years ago
there was a lake
here SO HUGE that
Switzerland could have
fitted inside it!
Hundreds of new fish species are thought to have originated in
this massive lake
Eventually all the water dried up,
Over thousands of years the climate
become hotter and drier and the lake lost
its water source
As the water evaporated Lake Makgadikgadi gradually begun to dry up, leaving only a
thick layer of salt, sand and animal remains
All that is left today is a series of huge salt flats
covering 12,000 km2
Although the main lake has dried up there is still enough water during the rainy season
to provide an important breeding ground for flamingos
The Makgadikgadi
Salt Pans are so huge they can be seen from
space! Can you see them?
Can you name any other
features or countries?
Makgadikgadi Salt Pans
Can you name any other
features or countries?
Kalahari DesertNamib Desert
Makgadikgadi Salt Pans
Okavango Delta
Mad
agas
car
Lake Kariba
Lake Malawi
Cape Fold Mountains
Benguela Current
Let’s find out what the Makgadikgadi is like… (Otherwise you won’t be able to do your exam and
you will DIE!)
Top Gear Botswana Special
Make sure you note down any key facts or
characteristics that are mentioned as you will be tested after!
MA K ADI K ADI
Just add a G (for top Gear) after each K
G G
Can you help me remember any key information from
the video?
What are the characteristics of a
salt lake?
A salt lake is a lake that has a very high salt content
It can vary greatly in size. Some are very large and permanently have water, e.g. the Dead Sea between Jordan and Palestine/Israel, which is fed by the River Jordan.
Others are much smaller or shallower and only exist when it rains (ephemeral salt lakes). In the dry season there is just a salt pan.
A salt pan is a large, flat, featureless plain with a hard crust of salt on the surface giving it a white appearance. Underneath this hard crust is a thick layer or mud and sediment.
How do salt lakes form?
A salt lake may form when rainwater collects in a deflation hollow
Or it could be the end point of river in an endoreic drainage basin (where the water drains into a lake instead of the sea) such as the Dead Sea. Makgadikgadi also used to be a permanent lake fed by a river.
If the rate of evaporation exceeds the rate at which water is added the lake will gradually dry up and become a salt pan/salt flat.
How do salt lakes form?
As the water evaporates it leaves behinds salt minerals. These are precipitated from the salts that were dissolved in the water.
At the same time the evaporation encourages capillary action – the upward movement of water in the soil. This brings even more salt to the surface where it accumulates as a hard crust of salt. This is usually white in colour and may crack into polygonal shapes.
More and more salt accumulates as ephemeral salt lakes form and dry up over and over.
Salt flats provide breeding grounds, natural resources of salt minerals as well as flat land for speed records!
They can take thousands of years to form, which is why environmentalists accused Jeremy Clarkson of permanently
scarring the Makgadikgadi salt pans and encouraging environmentally insensitive behaviour.
Oops!
Salt Mining in Salar de Uyuni,
Bolivia
The Dead Sea
Hiro Koiso Land sp
eed
re
cord on the
Bonneville
Salt
Flats
Utah
Creative photography in the Uyuni Salt Flats showing the polygonal cracks on the surface
Can you answer this question?
Describe the characteristics and explain the formation of salt lakes
(7 marks)
I was too busy
destroying the
landform to learn
how it formed…
1. Start by describing what they’re like
e.g. size, shape, colour, location, if/when they
contain water
Describe the characteristics and explain the formation of salt lakes (7 marks)
2. Then explain how they are formed
Try to give a sequence of steps and give a sense of time using
words like ‘gradually’Try to use key words
and give some specific examples
Crust Ephemeral
Capillary actionEvaporation
Deflation hollowEndoreicSalt pan
PolygonalPrecipitated
Perennial