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Task 2. Read the text. Talk about the formation of Earth’s Crust. Pay
special attention to the pronunciation of the following words, transcribe them:
basalt, granodiorite, peridotite, lithosphere, asthenospher, oxygen, silicon, sulphur.
The crust, Earth’s relatively thin, rocky outer skin, is of two different types—
continental crust and oceanic crust. The oceanic crust is roughly 7 km thick and
composed of the dark igneous rock basalt. The continental crust averages about 35 km
thick but may exceed 70 km in some mountainous regions such as the Rockies and
Himalayas. Unlike the oceanic crust, which has a relatively homogeneous chemical
composition, the continental crust consists of many rock types. Although the upper crust
has an average composition of a granitic rock called granodiorite, it varies considerably
from place to place. More than 82% of Earth’s volume is contained in the mantle, a
solid, rocky shell that extends to a depth of nearly 2900 km. The dominant rock type in
the uppermost mantle is peridotite. The upper mantle extends from the crust-mantle
boundary down to a depth of about 660 km. The upper mantle can be divided into two
different parts. The top portion of the upper mantle is part of the stiff lithosphere, and
beneath that is the weaker asthenosphere. From a depth of 660 km to the top of the core,
at a depth of 2900 km, is the lower mantle. The rocks within the lower mantle are very
hot and capable of very gradual flow. The composition of the core is thought to be an
iron-nickel alloy with minor amounts of oxygen, silicon, and sulfur—elements that
readily form compounds with iron. The core is divided into two regions that exhibit
very different mechanical strengths. The outer core is a liquid layer 2270 km thick. It is
the movement of metallic iron within this zone that generates Earth’s magnetic field.
The inner core is a sphere having a radius of 1216 km.

Task 3. Look at Figure 2.2. Try to analyze Earth’s layered structure. What
does the right side of the large cross section show? What does the left side of the
large cross section show? Mind that the block diagram to the left of the large cross
section shows an enlarged view of the upper portion of Earth’s interior.

Task 4. Fill in the gaps with on from the suitable words:

Lithosphere, mantle, layers, core, crust
Earth’s internal structure is divided into … based on differences in chemical
composition and on the basis of changes in physical properties. Compositionally, Earth
is divided into a thin outer …, a solid rocky …, and a dense …. Other layers, based on
physical properties, include the …, asthenosphere, lower mantle, outer core, and inner
core.
Task 5. Discuss the following:
1. The oceanic crust.
2. The continental crust.
3. The upper mantle.
4. The core.
Individual work

Task 1. Read the text and translate it into Ukrainian (in written form).
Build up a list of key terms to the text.

Earth’s Mantle
The mantle is a solid, rocky shell that extends to a depth of nearly 2900 km. The
boundary between the crust and mantle represents a significant change in chemical
composition. The dominant rock type in the uppermost mantle is peridotite, which is
richer in the metals magnesium and iron than the minerals found in either the

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