How are Fold mountains formed?
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Fold mountains form along plate boundaries as a result of great Earth
movements.
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The general theory is:
Two plates with landmasses on them move towards each other
The plates push layers of accumulated sediment in the sea into folds between
them
This becomes a fold mountain range. Most fold mountains continue to grow as
the plates constantly move
Examples: the Himalayas (Asia), Rockies (USA), Andes (South America),
Alps (Europe)
More detailed explanation of how Fold mountains form
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Large depressions called geosynclines form between plates.
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Seas filled the geosynclines and rivers flowing into them carried sediments
(sand and silt) which built up on the sea bed.
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Over millions of years the sediments were compressed, by their own weight,
into sedimentary rocks, eg. Shells into Limestone, sand into sandstone. These
rocks form fold mountains today.
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The tectonic plates moved toward each other forcing the sediments to be
pushed upwards. This forms the fold mountains with a series of anticlines
(upfolds) and synclines (downfolds).
Influence of Fold Mountains on human activities
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They often act as climatic barriers. Regions on one side of a mountain range
may have an entirely different climate form that on the region on the other
side.
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They often receive heavy rain/snow which may give rise to important rivers.
These rivers may be used for irrigation or for developing hydro-electric power
(HEP).
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Some mountains and their plateaus may contain minerals.
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They may act as barriers to communications or they can make the construction
of communications (roads, airport etc) difficult.
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Some mountain ranges have valuable timber resources.
Problems of Fold Mountain areas
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Fold Mountains, like the Andes, tend to have low population densities
because:-
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The high altitude and steep slopes make it difficult to build houses and
communication links, and to locate industries. Roads and railways need
expensive tunnels and passes.
There is little flat land for farming and the use of machinery is difficult.
The climate is also cold and wet with heavy snowfall and strong winds,
especially at high altitudes. The growing season is therefore short and travel
can be difficult, especially in the winter. Avalanches and rock falls can block
roads.
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FOLD MOUNTAINS
CONTINENT
Andes
South America
Rockies
North America
Alps
Europe
Atlas
Africa
Himalayas
Asia
Pyrenees
Europe