6
Analyse
2.
Ocean ridges are impressive oceanic landforms. Find out what they
are and how they are formed. Write a summary.
3.
Find the meaning of these terms:
craton
,
continental shelf
,
trench
,
continental rift
. Write the definitions and give specific examples of
each one.
4.
Mountain ranges are the most significant continental landforms. Why
is it possible to find marine fossils in the rocks?
5.
Investigate and explain what the sonar technique consists of.
6.
What consequences would there be if the Earth had only type of
crust?
1.
RELIEF AND ITS EVOLUTION
Our planet has features that make it a unique planet in our solar system. The most
significant feature is the presence of a hydrosphere and an atmosphere. The Earth’s
relief is also unique. This is partly due to the external action of the hydrosphere and
atmosphere on the surface, and also to internal activity resulting from the heat
stored
1
in the Earth’s interior. This internal activity builds and creates the features
of the Earth’s relief.
The most significant and evident feature of the Earth’s relief is the presence of
continents
and
oceans
. This is due to the two different types of crusts: the
continental crust, which is thicker and lighter and therefore above the oceanic crust,
which is thinner and denser. As a result, the average elevation of the continents is
800 m above sea level, but average depth of the oceans is 3800 m.
In the continents and oceans, we find the main features of relief as shown in the
diagram below. Many of these, such as the mountain ranges, ocean ridges, or
trenches do not exist on any other planet in the solar system. Remember that until
the 1960s, when the ocean floor was studied by using sonar, we knew more about
the surface of the moon than the relief of the ocean floor.
slip faults
rift
subduction
subduction
trench
island arc
ocean ridge
abyssal plain
continental shelf
mountain range
craton
continental
rift
trench
Main features of the Earth’s relief
Relief
is the change of elevation of the Earth’s surface, produced by a
combination of geographical landforms, such as mountains, valleys, plains,
or plateaus.
Landscape
is the combination of the relief, the vegetation that
covers it and the effect of human activity.
The surface of the Moon
Understand
1.
What are the most
significant features of
lunar relief? How were
they formed? Why aren’t
there many on Earth?
1
stored
:
produced inside and
accumulated
