Making mountains
Mountain ranges cover about a fifth of the Earth’s
land surface. They have built up over millions of
years, as massive tectonic plates crash into one
another. Many ranges, such as the Himalayas,
are still being pushed upward.
LIFT AND FOLD
Most mountains are fold
mountains, which have been
created by the movement of
tectonic plates across the Earth’s
surface. When two tectonic plates
push against each other, the rock
of the Earth’s crust lifts up and
folds over on itself. The folds get
bigger and bigger over time. CROSS SECTION This cliff face in
Dorset, England, shows how rock strata
twisted and folded over as the African and
European plates collided millions of years ago.
This same collision gave birth to the Alps.Shifting sand This experiment below
uses layers of sand on a sheet of paper
to show how rock strata buckle and
double over as a mountain forms.
Each layer of sand represents a layer
of the Earth’s crust. The paper is pulled
along slowly, at a rate of ½ inch (1 cm)
per 100 seconds. As the paper moves,
it drags the sand with it. This is similar
to the way the Earth’s slowly flowing
upper mantle pulls along the crust. MOUNTAIN MACHINE The
paper and sand are held between fixed
wooden blocks inside a tank. SEDIMENTS Layers of sediment are laid
down evenly on top of the paper. ZIGZAGS The moving paper makes wrinkles in the bottom layer
of sand. These are magnified into Z-shaped folds in higher layers. HIGHER AND HIGHER The sand folds
build up on top of each other, making
large loops.FACT FILE
OMountains are home to approximately
one-tenth of the world’s people.
OMountains occur in 75 percent of the
world’s countries.
OMany mountains are permanently
capped in ice and snow.
OFor every 330 ft (100 m) you climb
upward, it gets 2°F (1°C) cooler.
OThe strongest wind recorded on a
mountain was 231 mph (372 km/h) on
Mt. Washington, New Hampshire.EARTH
(c) 2012 Dorling Kindersley. All Rights Reserved.(c) 2012 Dorling Kindersley. All Rights Reserved.