, .

  1. A) , .
  2. B. .
  3. I. . ,
  4. I.
  5. II. , ;
  6. II. (䳺, ,
  7. II.

: Conglomerateis formed from gravel.


Sandstone

Rock salt Mineral oil Shale

Peat and coal Igneous rocks

Sedimentary rocks Metamorphic rocks


through the sedimentation

of mineral substances, from sand, from clay minerals, from organic remains, from particles of pre-existing rocks, by the accumulation of plant

remains, from magma, from either igneous or sedimentary

rocks.


20. 䳺
:

1. There (To be) three main groups of rocks, namely, sedimen
tary, igneous and metamorphic rocks.

2. These rocks (To make up) the crust of the Earth.

3. Sedimentary rocks (To be divided) into: mechanical sediments -
gravel, sand, sandstone, shale, etc; chemical sediments - rock salt,
gypsum, ironstones, etc; organic sediments - peat, coal, etc.

4. The particles of consolidated rocks (To be cemented) firmly to
one another.

5. Gypsum (To be formed) through sedimentation of mineral
substances that (To be dissolved) in water.

6. It is quite obvious that the textures of igneous rocks (To vary) accord
ing to the depth at which rocks (To be formed) many years ago.

7. Exposed igneous rocks (To be formed) at various depths.

21. ,
either either ... or.

either ; either ... or ... ;

1. Metamorphic rocks have been derived either from igneous or
from sedimentary rocks.

2. Sediments are formed either at the surface or near the sur
face of the Earth by the action of heat, water and the remains of
organisms.


Unit 4_______________________________________________ 97

3. Mechanical sediments can be either consolidated or uncon-
solidated.

4. Igneous rocks are formed as extrusive or as intrusive masses
solidified either at the surface of the Earth's crust or deep under
ground.

5. Either of these rocks are very important because they are of
ten rich in mineral deposits.

22. ,
. ( 䳺-.)

to consist (of), to be used as fuel, to be dissolved, substance, fuel, as is known, by the action of, to be formed, the Earth's crust, sedimentation

1. ,
.

2. 䳺 ,
, .

3. , '
. ֳ .

4. .

23. ) ,
䳺 . .



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