1-2 , ' .

  1. B. .
  2. D. 䳿
  3. I. . ,
  4. II. , ;
  5. II. (䳺, ,
  6. II.
  7. III. 5. - Ͳ

abyssal [s'bissl] , ; bypabbsal[, Hips'bis (3) l] a

adjacent [s'dseissnt] ,

ash [aefl n

belt[Belt] ; ;

body[ 'Bodi] , ; solid (liquid, gaseous) bodies (, ) ; ; ; ;

common[ 'Komsn] ; ; syn general;ant uncommon

cool[Ku: l] v (); ; ; ant heat- ()

dimension[Di'men / (s) n] ; pi ; ; syn measurement, size

dust[DASt]

dyke[Daik]

extrusion[Iks'tru: 3 (9) n] ; ; ant intrusion; . ( )

fine[Fain] , ; ; -


; ; , ( ); ; fine-graded (fine-grained), ; fines pi ;

flow[ϳ] v ; ; ; ; flow of lava

fragmentary[ 'Fnegnuntan] ,

glass [gla: s] ; glassy[ 'Glorsi] , ;

gold[Gould]

inclined[M'klaind]

mica[ 'Maika]

permit[Pa'mit] v , ; syn allow, let; make possible

probably[ 'Probsbli] adv ; syn perhaps, maybe

shallow[ 'Jaelouj ; ; ant deep

sill[Sil] ,

stock[Stok] ,

vein[Vein] , ,


3. ) -Iff.

intrusive, extrusive, creative, descriptive

) , :

1. Igneous rocks are those which have crystallized from magma. Magma may rise through fissures to the surface of the Earth as lava.


Unit 5___ 115

In geology this process is called extrusion. Thus, ... rocks are formed either as lavas or as fragmentary rocks.

2. Igneous rocks on the other hand may be cooled among the
other rocks of the crust. The process is known as intrusion and such
rocks are called ...

3. In his Reminiscences of a Mining Engineer Academician Ter-
pigorev gave ^ description of the training of specialists at the Mining
Institute in St.Petersburg before the Revolution. Students 'specia
lization was based on ... courses and elementary practical training.

4. :

fragmentary rocks slowly-cooled rocks

intrusive igneous rocks at shallow depths

exposed igneous rocks adjacent rocks

coarse-grained minerals deep-seated rocks

of great scientific value enormous lateral pressure

of unequal hardness at a slow rate

different mineral particles rock fissures

bedded veins clay veins

flat veins numerous veins

steep veins smaller dimensions

coal fines glassy surface

inclined coal seams mode of occurrence

different sources of fuel volcanic ashes and dust

5.
:

intrusive and extrusiverocks; intrusive magma;large crystals; volcanicrocks; mountain zones; zonesof major deformation; mineralgrains; granitesand diorites;the group of intrusive or plutonicrocks; straight parallelwalls; gigantic crystals;several tons;slowly-cooled batholiths;thick laccoliths;other plutonites;coarse-grained pegmatites; lavaflow

6. .
:

Igneous Rocks

Igneous rocks have crystallized from solidified magma ..

Igneous rocks can be classified in a number of ways and one of them is based on mode of occurrence. They occur either as intrusive (below the surface) bodies or as extrusive masses solidified at the


116___ ___ Unit 5

. ' " V>.

Earth's surface. The terms "intrusive" and "extrusive" refer to the
place where rocks solidified,

The grain size of igneous rocks depends on their occurrence. The intrusive rocks generally cool more slowly than the extrusive rocks and crystallize to a larger grain size. The coarser-grained intrusive rocks with grain size of more than O.5 mm called plutonic or abyssal are referred ito as intrusive igneous rocks because they are intruded into older pre-existing rocks. Extrusive or volcanic rocks have even fitier grains, less than 0.05 nun and are glassy.

Exposed igneous rocks are most numerous in mountain zones
for two reasons. First, the mountain belts have been zones of major
deformation. Second, uplifts in mountain belts have permitted
plutonic masses to be formed.

The largest bodies of igneous rocks are called batholiths (Fig. 2).
Batholiths cooled very slowly. This slow cooling permitted large min
eral grains to form. It is not surprising that batholiths are composed
mainly of granitic rocks with large crystals called plutons. As is
known, granites and diorites belong, to the group of intrusive or
plutonic rocks formed by solidification of igneous mass under the
Earth's crust. Granites sometimes form smaller masses called stocks,
when the occurrence has an irregular ihipe; but smaller dimensions
than the batholiths.

Laccoliths and sills, which are very similar, are intruded be-
tween sedimentary rocks. Sills are thin and they may be horizontal,
inclined or vertical. Laccoliths are thicker bodies and in some cases
they form mountains.

Dykes are also intrusive bodies. They ranges in JhicJmeSs from a few inches to several thousand feet. Dykes, are gerjraify much longer than they are wide. Most dykes occupy cracks and have strai & nt parallel walls. These bodies cool much more rapidly and are commonly fine-grained. For example, granite may occur 4n dykes that cut older rocks.

Pegmatites (Quartz, orthoclase and mica) also belong to the
group of plutonic or intrusive rocks. They occur in numerous veins
which usually cut through other plutonites, most often granite, or
adjacent rocks.

Extrusive, igneous rocks have been formed from lava flows which come from fissures to the surface and form fields of volcanic rocks such as rhyolite, andesite, basalt, as well as volcanic ashes and dust, tuff, etc. As a rule, these rocks of volcanic on | in cool rapidly and are fine-grained. It is interesting to note that basalt is the most


Unit 5




Satellite Cone

Laccolith \

Volcano


Fig. 2. Igneous rocks

abundant of all lavatypes.lt is the principal rock type of the ocean

Igneous rocks are rich in minerals that are important economically or have great scientific value. Igneous rocks and their veins are rich in iron, gold, zinc, nickel and other ferrous metals.

7. , . ϳ .

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.

4. The grain size of igneous rocks depends on mode of occur
rence.

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.

8. :

1. Have igneous rocks crystallized from magma or have they been formed by sedimentation?


118___ Unit 5

2. Which types of igneous rocks do you know?

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

4. Can you give an example of intrusive or plutonic rocks?

5. Are diorites intrusive or extrusive formations?

6. What do you know about batholiths?

7. Do pegmatites belong to the group of plutonic or volcanic rocks?

8. How do pegmatites occur?

9. What minerals are igneous rocks rich in?

9. )
:

1. adjacent layers )

2. abyssal rocks )

3. dimensions of crystals )

4. valuable minerals ) ()

5. shape and size of grains ) ()

6. mode of occurrence e)

7. coarse-grained )

8. uplifts )

9. zones of major deformation )

) :

1. a) irregular shape

2. ) at a certain depth

3. ) economically important

4. ) solidified masses

5. ) scientific value

6. e) to cool slowly

7. ) existing types of rocks

8. ) fine-grained

9. ) fragmentary rocks

10. ) numerous cracks or fissures

10. ,
:

accelerated process weathered fragments of rocks

crystallized magma generally applied method

successfully improved design unconsolidated and consolidated rocks \

weakly deformed minerals unfrozen ground

rapidly cooled rocks detailed studies of the Earth's crust

utilized equipment dissolved minerals

minerals dissolved by the consolidated rocks

action of water rocks consolidated by some substances

rocks formed by solidification stratified sediments

rocks exposed on the Earth's exposed rocks

surface transformations caused by new

conditions ...


Unit 5___ 119

11. , - 䳺
. . :

1. Igneous rocks form a large group of minerals which are eco
nomically important.

2. The igneous rocks formed by cooling occur either as intrusive
or extrusive rocks.

3. Orthoclase is particularly used in great quantities as raw mate
rial in the production of porcelain ().

4. The clayey mass obtained by the decomposition of orthoclase is usually
white and is called kaolin. The product obtained is used in industry.

5. Quartz occurs in the form of small grains. Quartz crystals found in
the cracks and fractures of rocks are very hard and beautiful.

6. Pure quartz sands are used in the production of glass.

7. Actual observations of rocks exposed on the continent show
that shale represents 46 per cent of the total, sandstone about 32
per cent, and limestone about 22 per cent.

12.
.

: The igneous rocks which have crystallized from magma may rise through fissures to the surface of the Earth as lava. -> - The igneous rocks crystallized from magmamay rise to the surface of the Earth as lava.

1. The classification of igneous rocks which is given below is
based on texture and composition of minerals.

2. Igneous rocks were a hot molten mass which was known as
magma.

3. Observations have shown that the rock types which were pro
duced by molten volcanoes, include, for example, rhyolite, andes-
ite, basalt and other rocks.

4. Andesite which was first found in the Andes Mountains in
South America is the fine-grained rock, intermediate in composition
between granite and basalt.

5. Copper is second only to iron among the important metals
which are widely used in modern engineering.

13. : 1) 䳺
,
; 2) 䳺 ,
䳺 ; 3) ,
䳺 Perfect; 4) 䳺
, .


120___ UnitS

14. :

1. Abyssal rocks belong to the a) thatare economically important.

group of intrusive rocks

2. Uplifts in mountain belts 6) whichusually cut through

have permitted erosion to plutonites.

the depths

3. Granites and dioritcs occur ) becausethey are intruded into

as batholiths pre-existing rocks.

4. Pegmatites (quartz, orthoclase r) at whichplutonic masses are

and mica) occur in numerous formed, veins

5. Extrusive igneous rocks have ) wherethe changes in temperature

been formed as lavas are great.

6. Igneous rocks are rich in e) whichcome from fissures to

minerals the surface of the Earth's crust.

7. Physical weathering occurs ) whichare large irregular masses.

in the deserts and in high mountains

15.
:

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. As for the origin of intrusive rocks, they ...,

8. The grain size of igneous rocks may be different. For ex
ample ...

16. . , :

It seems to be wrong; I do not agree with yon; I do not think so; on the contrary; that's not quite so; as far as I know

1. Igneous rocks have been formed by sedimentation. Nothing is
written about different types of these rocks.

2. One can not explain the fact that exposed igneous rocks are
most numerous in mountain zones.

3. Granites and diorites belong to the group of extrusive rocks
and their mode of occurrence is unknown.

4. Plutonic or abyssal rocks are extrusive rocks with grain size
less than 0.5 mm.


Unit 5___ 121

17. ϳ , .

1. The formation of igneous rocks and their types, (To be formed,
to solidify, to cool, either ... or, magma, volcano, lava, fragmentary
rocks)

2. The grain size of igneous rocks and its dependence on the
mode of occurrence, (Grain size, plutonic or abyssal rocks, extrusive
and volcanic rocks)

3. The causes of exposed rocks formation in mountain zones.
(Various depths, zones of major deformation, uplifts, erosion)

4. Granites and diorites and their mode of occurrence, (intrusive
rock, to occur as ..., irregular mass, stocks, dykes, occurrences, at a
certain depth)
*

5. Pegmatites and their mode of occurrence, (Plutonic rocks, to
occur, vein, to cut through, as well as adjacent rocks)

18. . (. . 2, . 118.)
:

1. What does Fig. 2 show?

2. What type of rocks are represented there?

3. What intrusive and extrusive occurrences does the figure show?
What can you say about each occurrence?

4. What minerals does each group of rocks represent?

1.

 -, - - -est. - more, - - most, .

.



Unit 5


long longer the longest
heavy heavier the heaviest
difficult more difficult the most difficult
late later latest
early earlier earliest
clearly more clearly most clearly


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Sedimentary Rocks | | ) stratify stratification stratified | , . | ) , 䳺 . . | Weathering of Rocks | ) , . | ' . | Suspended particles - | (CROSSWORD) |

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