salt lakes

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