2
2. Relief
31
When tectonic plates collide they buckle
3
, forming mountain ranges. India and Asia collided 55 million years ago,
causing the slow formation of the Himalayas, the highest mountain system on the planet. While the plates continue to
collide, the mountains continue to rise. For example, Mount Everest, the highest mountain on the planet, will probably
be a little higher tomorrow, than it is today.
National Geographic
(Adapted)
The results of orogeny vary, depending on the characteristics of the rocks:
❚
When the rocks are plastic or flexible, they deform, creating
folds
.
❚
When the rocks are very rigid and hard, they break apart when pushed. These
break lines are called
faults
.
Most mountain ranges are formed by folds and faults.
If the faults are very deep, the fracture can penetrate the crust or the mantle, where
magma is found. Magma can rise to the surface through these fractures, forming
volcanoes
, which emit ash and
lava
(magma which comes from the Earth’s interior).
Earthquakes
occur when two sides of a fault collide or separate. The areas with the
most volcanoes and strongest earthquakes are areas close to plate boundaries where
tectonic plates meet or separate.
2.2. Orogeny and its effects
Fold
Fault
Themovements of the tectonic plates creates the process called
orogeny
. Orogeny
creates
large units of relief
such as
mountain ranges
and
plateaus
.
Did you know?
Analyse
4.
Look at the map on the previous page and identify the tectonic plates
that affect America.
5.
Which are the two largest tectonic plates? What continents sit on
these plates?
6.
Look at the arrows on the map. Which plates are colliding? Which
plates are separating?
7.
What phenomenon is produced in the area of contact between the
Eurasian plate and the Pacific and Indo-Australian plates? In what other
areas of the world is this phenomenon produced by the contact of
tectonic plates?
Create
8.
Find out why the east coast of
South America seems to fit into
the western coast of Africa.
9.
Iceland is located on the line
between the Eurasian and the
North America plate. Consult
the Internet and other sources
and find out if there is a volcano
there. What is it called?
