Complete the following sentences, using words and phrases from the text

1. Batholiths are composed of_____________________.

2. Laccoliths are very similar to sills, but sills__________________.

3. Granites belong to the group of_______________.

4. Pegmatites are also____________.

5. Dykes are intrusive bodies which ___________.

6. Extrusive rocks have been formed from_________.

7. The origin of intrusive rocks __________________.

8. The grain size of igneous rocks may be different because_____________.

3.2.7 Answer the following questions and give more / extra information.

1. How are igneous rocks formed?

2. Which types of igneous rocks do you know?

3. What does the grain size of igneous rocks depend on?

4. What are batholiths, dykes, sills, laccoliths, and pegmatites?

5. How are the above-mentioned rocks formed?

4. LISTENING COMPREHENSION

4.1 You will hear a radio report about volcanic rocks. Answer statements 1-10 by writing T (for True) and F (for False):

1. Extrusive rocks occur chiefly at volcanic vents.

2. When magma cools and hardens it becomes coarse-grained or glassy rock.

3. Basic lavas are rich in silica.

4. The best-known product of basic lava is basalt.

5. Basalt is formed by melting of rhyolite.

6. Hawaiian Islands are a result of a fixed plume of magma punching through the Pacific plate.

7. Acid lavas are active and quick flowing.

8. During the last 2000 years, more than 800 known volcanoes have erupted.

9. Dormant are volcanoes not erupting in recent times.

10. Long-inactive volcanoes are said to be extinct.

4 .2. Listen to the report once more. Then, for questions 11-17, complete the notes, which summarize what the speaker says. You will need to write a sentence in the blanks, which has been removed from the text. The sentences are after the text.

Extrusive igneous rocks occur at volcanic vents. Magma erupts as lava. (11)---------------. Basic lavas are rich in metallic elements. They flow easily and erupt gently. (12) ------------. Partial melting of peridotite forms basalt. (13)--------------. Basalt wells up from oceanic spreading ridges and builds new ocean floor.

Acid lavas appear at destructive plate margins. (14)-------------. They produce such rocks as dacite, rhyolite and obsidian.

Intermediate lavas stem from partial melting of certain minerals in subducted oceanic crust. (15)------------.

More than 850 known volcanoes have erupted in the last 2000 years. Those emitting continuously are active. (16)----------------. Volcanoes not erupting in recent years are dormants. (17)------------. Some volcanoes occur where colliding plates fused together.

a. Long-active volcanoes are said to be extinct.

b. Acid lavas are explosive and slow-flowing.

c. It cools and hardens quickly on the surface.

d. They may form a “Ring of Fire” around the Pacific Ocean.

e. The best-known product is basalt.

f. This process formed the lava – andesite.

g. It is the chief rock of the upper mantle

4.3 Listen to the lecture in geology at the Aberdeen University. The topic of the lecture is intrusive igneous rocks. Complete the following chart with the missing information.