Fig. 27 Various modes of occurrence of igneous rocks



Read the following phrases and give the Russian equivalent.

accelerated process unequal hardness
crystallized magma adjacent rocks
weakly deformed minerals mode of occurrence
rapidly cooled rocks volcanic ash and dust
rocks formed by solidification coarse-grained minerals
rocks exposed on the Earth’s surface glassy surface
transformation caused by new conditions rock fissures

Can these terms and phrases be understood without translating?

Why?

Intrusive and extrusive rocks; plutonic intrusion; large crystals; volcanic

rocks; mountain zones; zones of major deformation; mineral grains;

granites and diorites; the group of intrusive or plutonic rocks; straight


parallel walls; gigantic crystals; slowly-cooled batholiths; thick laccoliths; other plutonites; coarse-grained pegmatites; lava flow.

State, which sentences, is T (true) or F (false) according to the text.

1. Igneous rocks have been formed by sedimentation.

2. Intrusive rocks have been formed by the cooling of rocks of the Earth’s crust.

3. Extrusive rocks have been formed the same way as intrusive rocks.

4. The grain size of igneous rocks depends on mode o occurrence.

5. Exposed igneous rocks are numerous in mountain zones.

6. Granites and diorites belong to the group of extrusive rocks.

7. As a rule, granite may occur in dykes.

8. Pegmatites do not belong to the group of plutonic or intrusive rocks.

Match the English terms with the Russian equivalents.

1. adjacent layers a. форма залегания, способ залегания
2. abyssal rocks b.крупнозернистый
3. dimensions of crystals c. зоны крупных нарушений
4. shape and size of grains d. абиссальные (глубинные) породы
5. mode of occurrence e. смежные пласты (слои)
6. coarse-grained f. размеры кристаллов
7. uplifts g. форма и размер зерен
8. zones of major deformation h. взбросы

Match the Russian terms with the English equivalents.

1.затвердевшие массы 2.обломочные породы a.irregular shape b.at a certain depth
3. медленно остывать c. solidified masses
4. мелкозернистый d. to cool slowly
5. неправильная форма e. existing types of rocks
6. многочисленные трещины f. fine-grained
7. на определенной глубине g. fragmentary rocks
8. существующие типы пород h. numerous cracks or fissures

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?

LISTENING COMPREHENSION

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.

Igneous Rocks- Intrusive

category

formation

classification examples
plutonic   ………….     great masses …………….. …..fusion lower ……. ……… slow …………. ……… mineral crystals …………… rocks   relatively ……… …… stripes or ………….. cool at …….. ……… and faster have smaller …………  

acid,

………………

………………

 

 

………, basic, ………………

 

 

…………….   microgranite ,   …………..    
         

4.4. Listen to the lecture once more. Look at the diagram and describe the features produced by intrusive rocks, using the given definitions: (R.P – 5.5)

1. batholith a. saucer-shaped intrusion between rock strata
2. stock b. a lens-shaped intrusion that domes overlying strata
3. boss c. a sheet of igneous rock intruded horizontally between rock layers

4. dike d. wall of igneous rock injected up through vertical crack in preexisting rocks
5. sill e. small circular-surfaced intrusion
6. laccolith f. a small irregular surface area
7. lopolith g. huge deep-seated dome-shaped intrusion

You will hear a short conversation. At the end of it, you will be asked several questions. The conversation will be spoken twice. After you hear a question, read the four selections and choose the one that is the best answer to the sentence the speaker asked. Answer all questions according to what is stated/implied in the conversation.

1. Where does this conversation take place?

A. museum

B. exhibition

C. geological College

D. class

2. What is another term for igneous rocks?

A. hot spots

B. lava rocks

C. fiery rocks

D. molten rocks

3. What is the main topic of the conversation?

A. rocks and minerals

B. igneous rocks

C. sedimentary rocks

D. metamorphic rocks

4. What is the formation process of magma?

A. melting, cooling and solidifying

B. cooling, melting and solidifying

C. rising, melting and cooling

D. melting, rising and cooling

5. What are silicates?

A. silicon and oxygen and aluminum

B. silicon and oxygen and a metal

C. silicon and oxygen and silicate

D. silicon and oxygen and mafiс mineral

6. What does quartz consist of?

A. silicate and a metal

B. silicate without a metal

C. silicate without oxygen

D. silicon and oxygen


7. What are the two people?

A. a teacher and a student

B. geologists

C. a guide and a visitor

D. husband and wife

DISCUSSION TASK 1

Image a volcano and describe the development of it. You can use examples of different volcano eruptions (for example, St. Helen).

TASK 2

Here are 6 shapes of volcanoes: (R.P .-5.2)

1. loose-packed volcano

2. stratovolcano

3. caldera

4. rift volcano

5. spring hilltop

6. shield volcano Describe one of them.

Fig. 28 Shapes of volcanoes

TASK 3

Look at the Volcano-cross-section (R.P – 5.1) and state what are the

characteristic features.



WORDLIST

PRONUNCIATION


6.2 TERMS  
ash пепел, шлак, зола
balloon (outward) вздуваться, подниматься
basic (volcano) основной (базитовый) вулкан
chamber камера
cinder шлак, пепел
conduit канал
cone конус (вулкана)
cross section поперечный разрез
dissolved gas(es) растворенный газ
emit извергать
expanding bubbles расширяющиеся пузыри
extinct потухший, угасший
fissure трещина, разрыв
flank склон (горы)
hemisphere полушарие
inverted (cone) перевернутый (конус)
lava лава
linear линейный
mound купол, куполовидная постройка
outlet выходное отверстие
pressurized находящийся под давлением, сжатый
reservoir резервуар
shield щит
side (vent) боковой (кратер)
subsidiary (cone) побочный (конус)
to blast взрываться
to relieve понижать давление
to tower возвышаться
trench океанская впадина
tor скалистая вершина холма
vent жерло вулкана
weakness слабое место, непрочность

 


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