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Earth’s volume. It includes magma, which is molten rock. The core is
the deepest layer.
The Earth’s surface is composed of rigid plates that move relative
to each other. The plates have three main motions with different

results.
1) when two plates collide, one may be forced under the other
causing ocean trenches, volcanic islands and mountain ranges.

2) when two plates move away from each other, rifts occur.
3) when two plates slide past each other, there are faults. Features,
such as volcanoes and earthquakes exist mainly along the plate
boundaries.

What scientists call relief or terrain includes all the major features
or landforms of a region. If you look at the Earth’s surface and take
away the water in the oceans, you will see that the surface has two

distinctive features: continents and the ocean basins.
The continents are large land areas extending from high
elevations to sea level. The ocean basins extend from the edges of the

continents down steep slopes to the ocean floor and into deep
trenches.
The Earth’s relief is not only the result of movements inside the

Earth, but also external forces, such as water or wind.
• Water is the main external agent acting on the land. The effects
of rain, ice, waves, tides and marine currents can be intense and
diverse.

• Wind erodes rock and transports small particles, such as sand
and dust, to other places.
• The roots of trees penetrate the ground and can split rocks. They

can also hold the soil and rocks in place.
The Earth’s relief is diverse: mountains, plateau, plains,
depressions, continental shelves, deep-sea trenches, oceanic ridges,
etc.

Task 3. Answer the questions, using the active vocabulary.

1. What do you know about the main Earth layers?

2. What are the results of plate’s motions?
3. What is relief?
4. How do continents and ocean basins look like?
5. What are the external forces that influence the Earth’s relief?

6. What belongs to the Earth’s relief?

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