Fold mountains are formed over millions of years when two tectonic plates collide and push material upwards, creating mountain ranges. The largest fold mountains include the Himalayas, Alps, Andes, Rockies, and Urals. Fold mountains are formed through the upward and downward folding of crustal material. Once formed, mountains undergo weathering and erosion that slowly shape the landscape over time.

1. The Formation of Fold Mountains
Watch the following
Cheesy clip and add
annotations to your worksheet
Did you know…….the following are all
examples of fold mountains:
Himalayan Mountains in Asia
the Alps in Europe
the Andes in South America
the Rockies in North America
the Urals in Russia

2. ANSWER!
• Large mountain ranges are formed by slow but gigantic
movements of the earth's crust
• Fold mountains are the most common type of mountain.
These ranges were formed over millions of years.
• Fold mountains are formed when two plates collide head on,
and their edges crumbled. The material is pushed upwards
creating a mountain range.
EXTENSION:
• The upward folds are known as anticlines, and the downward
folds are synclines.
Summarise in note
form in your
exercise books,

3. THE MAIN EVENT
• In pairs you are going to build a fold mountain
range using plasticine.
• You are going to show how mountain ranges are
formed and make a movie of the process using a
mini-IPAD, using the STOP MOTION APP.
• Use your worksheet and your notes to help you
make your movie as accurate and detailed as
possible.

4. AIR DROP
• Watch some brilliant examples as a class.
And SAVE here:
O:PupilsworkGeographyY9 mountain formation

5. Mountains come in all shapes and
sizes…………………….
• Some, like the Rockies in the North American west or the
Himalayas in Nepal, are tall, rocky and pointy.
• Others, like the Appalachians in the eastern United States or
the Great Dividing Range in New South Wales, are shorter and
more rounded off.
• Once mountain ranges are formed, other factors act upon
them to wear away and erode the environment.

6. Read the following information on
your hand-out…….
• Mechanical processes can break the rock apart as these processes are governed by physical forces. Thermal expansion is an example of a mechanical
weathering. As rock is exposed to sunlight during the day, it heats up and the heat causes it to expand. At night, however, the rock cools down and
contracts. Repeated expansion and contraction causes stress in the rock, making cracks and causing parts to fall off.
•
• Another example of mechanical weathering that is very common in the mountains involves water. When water freezes, it expands. Any liquid water
that seeps into the cracks of rocks and freezes causes stress to the rocks as well, breaking off parts.
•
• Another type of weathering is called chemical weathering. Instead of attacking the rock itself, this form of weathering attacks the chemicals that
make up the rock on a molecular level. Some minerals are water soluble, meaning they can be dissolved in water. As water runs over certain rocks,
some of the minerals in them are dissolved. Another kind of chemical weathering occurs when weak acid is applied to rock, causing the chemicals in
the rock to break apart into different chemicals. Acid is usually brought to the rock through rainfall. Usually, rain becomes acidic as it falls through the
atmosphere by combining with carbon dioxide to make weak carbonic acid. This acid reacts with certain kinds of rock to decay it. In recent years,
pollution has created conditions for sulphuric acid and other sorts of stronger acids to form as rain falls, creating a phenomenon known as acid rain.
Acid rain has caused the decay of certain historical artefacts, such as old buildings and ancient ruins. Acid rain can also cause natural rock to decay
more quickly.
•
• The last kind of weathering is biotic weathering. This is the way that living things affect the rock. These effects can be very large or very small and
often involve mechanical and chemical factors as well. Tree roots, for example, can alter rock mechanically by breaking it apart or pushing it aside.
Burrowing creatures such as worms or rabbits can move rock, rock fragments and soil around. Mosses and lichens cover rocks, creating different
microenvironments underneath and changing the kinds of chemical reactions that take place in the rock. Bacteria sometimes eat into rock and create
hollows for water and other chemicals to enter.
• Once rock has been weathered, it is more susceptible to erosion. Erosion is the act of water or wind taking rock, soil and sand from one area and
moving it to another. As rock is weathered on an exposed mountainside, wind and water can carry the weathered rock and soil away. Gravity also has
an erosive effect on mountainsides, for example, on some slopes there is a phenomenon called soil creep. Soil creep takes place very slowly, so
slowly that the effects can only be seen over a long period of time. Wind, water and gravity push the soil downhill, carrying rock particles away from
the hill or mountain. While this is a slow process, when soil becomes very wet, it can speed up drastically. This can cause landslides. Landslides force
many tonnes of material down a mountainside, which changes the shape of the slope.
• Rivers have major erosive effects on mountains as well. Many rivers, including some of the world's largest, have mountain sources. Rivers form when
water (usually in the form of rain or snow) falls within the drainage basin. Rain tends to fall on the windward side (the side closest to the ocean) of a
mountain, keeping the leeward side (the other side) dry. Drainage basins, therefore, are often found on the windward side of mountains. Water that
falls high up in mountains flows downhill (due to the forces of gravity) and becomes streams. These streams are joined by water from melted
glaciers, springs and additional rainfall. Rivers erode the mountainside into deep channels called valleys. They are very important to both the
environment and humans because they provide water to many low-lying areas.
Highlight the
important
information and ask
for clarification
where necessary.
Another force that affects the shape of
mountains is glaciation.
You will learn about this next lesson.

7. COUNTDOWN
E A W T H G I N R E
COUNTDOWN CLOCK

8. Did you get it?
W E A T H E R I N G
Find a challenging word from the article, jumble
it up and see if the person next to you can guess
what it is?

9. Homework – watch this clip and then
complete the worksheet
• Weathering and Erosion