UNIT 3
TEXT
ROCKS
GRAMMAR REVISION INFINITIVE, PARTICIPLE, GERUND.
Ex.1.Read the following international words and word combinations and give their Russian
equivalents.
magma, granite, quartzite, intrusive, texture, reservoir, lava, basalt, volcano, to erode,
pore, to metamorphose, aggregates of minerals, accumulation and cementation of fragments,
physical characteristics, typical metamorphic agent
Ex.2.Give all the possible derivatives of the following words. Translate them into Russian.
Hard; to differ; to solve; to compose; deposit; divide; form; inhabit; to vary; origin; to
depend; measure; change.
Ex.3.State the part of speech of the underlined words. Translate the sentences.
1. Glacial deposits have almost no relation to the character and the structure of the
underlying rocks.
2. Glaciers deposit their loads on almost any surface, on land, in fresh water, or in the sea.
3. The change in fossil forms results from the change in conditions.
4. This results in a general blowing of the air from the poles towards the equator.
5. An earthquake is any vibration of the earth’s surface due to natural causes.
6. The formation of clay minerals is the direct result of weathering (выветривание).
7. The rotation of the earth causes day and night change.
8. The rise of temperature causes snow to melt.
9. The possibility that some of the material lying on the lunar surface is chemically
unchanged since the formation of the planet remains high.
10. These rocks are made up in part or entirely of the remains of animals and plants.
11. Running water can never lower very large areas of the land below sea level.
12. The lower limit of wave action varies.
13. Roads and railroads often follow both banks of a river, since the land there is fairly level.
14. The work of the atmosphere is to level the land surface.
15. Variations in the temperature of the atmosphere effect great changes in rocks.
16. Temperature changes are usually of more effect in the case of igneous rocks than in that
of sedimentary rocks.
Ex.4.Translate the following sentences into Russian. Pay attention to the Infinitives.
e.g. 1).To divide rocks into classes we should know the modes of their origin.
Чтобы подразделить породы на классы, нам следует знать характер их залегания.
2).Rivers carry their debris and deposit it at the estuary to be dealt with later on the sea.
Реки несут с собой обломочный материал и откладывают его в устье, а затем эти
обломки поступают в распоряжение моря.
1. To trace the evolution of the earth and its inhabitants we must study geology as well
as other sciences which are concerned with the physical processes on and within the
earth.
2. To understand the origin and classification of rocks we must learn something about
the various minerals composing them.
3. Fragments of rocks, minerals and organisms accumulate at the earth surface to form
sedimentary rocks.
4. To begin the study of the earth we have to know something about its dimension,
shape, and outer zones.
5. To understand the meaning of the word “petroleum” we must know its origin.
6. To be classed as hard rocks must resist abrasion or scratching.
7. Some heavy elements unite readily with oxygen to make oxides and with silicon to
make silicates.
Ex.5.Translate the following into English.
1. Для того чтобы подняться на поверхность……
2. Для того чтобы исследовать породу………
3. Для того чтобы понять происхождение земли ……..
4. Для того чтобы классифицировать эти породы…….
5. Для того чтобы изучить состав породы………
6. Для того чтобы отличить эти минералы……..
7. Для того чтобы увидеть отдельные зерна песка…….
8. Для того чтобы пробить себе путь……..
Ex.6.Translate the following sentences into English.
1. Для того чтобы различить образцы пород,
микроскопом.
2. Для того чтобы рассмотреть
увеличительное стекло.
минералы,
нужно рассмотреть их под
слагающие
породу,
3. Он провел ряд исследований, чтобы понять происхождение породы.
4. Чтобы начать изучение земли, необходимо знать ее размеры и форму.
он
взял
5. Чтобы понять происхождение и классификацию пород, важно знать состав
минералов, из которых они состоят.
Ex.7.Translate the following sentences into Russian. Pay attention to the Verbals (неличные
формы глагола) underlined.
1. When solidifying magma turns into an igneous rock.
При затвердевании магма превращается в изверженную породу.
2. Magma forces its way through strata thus causing the overlying rock layers to be
domed.
Магма пробивается сквозь пласты пород, тем самым выгибая эти вышележащие
слои в куполообразные формы.
3. On reaching the surface molten material solidifies into an extrusive igneous rock.
Достигая поверхности, расплавленное вещество затвердевает и превращается в
эффузивную магматическую породу.
1. When examining a fragment of rock or a handful of soil more closely we find that it is a
mixture of different substances.
2. Many different factors have to be considered when selecting a site for drilling.
3. In examining rocks a geologist distinguishes two major groups.
4. It is important when exploring a new area, to determine whether the organic matter has
been heated enough to produce oil.
5. It’s often very difficult to identify a mineral simply by looking at it.
6. When determining hardness, mineralogists usually scratch the rock.
7. When conducting geological exploration in the field, a geologist should be able to identify
the principal minerals with a naked eye.
8. While studying the west coast of Africa and the east coast of South America, Alfred
Wegener noticed the extraordinary way these coasts mirrowed each other.
Ex.8.Translate the following sentences into Russian. Pay attention to the construction
«Nominative +Infinitive”.
e.g.
1). Rocks are known to be divided into three great classes.
Известно, что породы делятся на три большие группы.
2). Earth appears to have undergone cyclic changes.
По-видимому, Земля претерпевает циклические изменения.
Quarts, feldspar, mica, garnet, dolomite, and some others are known to constitute an
important group of rock-forming minerals.
1. In many regions great thickness of strata is found to have been tilted, so that they now
lie in inclined positions.
2. The earth is considered to have undergone great changes during its existence.
3. Some properties of minerals are likely to be associated with their internal structure.
4. The Earth seems to have been formed at least 4.55 billion years ago out of a cloud of
cosmic dust.
5. The Himalayas are believed to be still rising by a measurable amount today.
6. The properties of minerals appear to be closely associated with their internal structure.
7. The word “geology” is not likely to be used in its present sense before the 17th century.
8. About half of the world’s oil reserves has been estimated by the geologists to occur in
carbonates.
9. Igneous ricks are sure to be the most dense rocks.
WORDS TO THE TEXT “ROCKS”.
плавить(ся), таять
1.melt v.
Snow melts when the sun shines.
The sugar melted in the tea.
извергать(ся), выбрасывать
2.erupt v.
When a volcano erupts it throws out a lot of hot,
melted rock called lava, as well as ash and steam.
3.solidify
твердеть, застывать, кристаллизоваться
v.
Water solidifies by reduction of temperature.
4.igneous
магматический, изверженный
adj.
In geology, igneous rocks are rocks that were once
so hot that they were liquid.
эффузивный
5.extrusive adj.
These hills are the extrusive edges of strata.
6.grade
классифицировать, сортировать
v.
I’ve graded their work from 1 to 10.
The species were graded by size.
7.coarse-grained
Ant. fine-grained
8.subsequently
adj.
крупнозернистый
course-grained minerals
впоследствии, позднее, позже
The Queen visited the new museum and
subsequently attended a banquet in the Town Hall.
9.expose
обнажать(ся), выходить на поверхность;
v.
подвергать
The rocks are exposed at low tide.
Thousands of people were exposed to radiation
when the nuclear reactor exploded.
10.precipitate n.
осадок
The atmospherical precipitates are rain and snow.
осаждать(ся), выпадать (об осадках)
precipitate v.
Particles may precipitate in crystalline form as a fine
powder.
куча, кипа, пачка (геол.)
11.pile n.
a pile of stones, a pile of papers, a pile of rocks
нарушать, приводить в беспорядок
12.disturb v.
to disturb the order of deposition
образование складок
13.folding n.
Folding is a geological process.
опрокидывать(ся), переворачивать(ся)
14.overturn v.
The car hit a tree and overturned.
15. constituent
adj.
образующий, составляющий часть целого
Atoms are constituent parts of molecules.
16.clastic
adj.
обломочный, кластический
The word “clastic” is derived from Greek klastos”,
meaning “broken in pieces”.
17.limestone
n.
известняк
Limestone is used as building material and in the
making of cement.
18.sandstone n.
песчаник
Sandstone is a sedimentary rock consisting of sand
or quarts grains cemented together. It is often used
for building houses and walls.
глина
19.clay n.
Clay can be shaped and baked to make things such
as pots and bricks, and ceramics.
20.subject to
v.
подвергать чему-либо
This metal should not be subjected to too high
temperatures.
21.marble
n.
мрамор
The staircase of this palace is made of
marble.
A marble statue.
Ex.9.Read the text and do the following tasks:
1. Give examples of each class of rocks.
2. Find the construction “Nominative + Infinitive”.
3. Find English equivalents to the following.
По-разному; характер происхождения; пробиться в другую породу; в любом случае; в
основном; в виде лавы; глубинные массы; водные растворы; другими словами; снизу
вверх; представляют большой интерес.
ROCKS
Rocks are aggregates of minerals. They form the solid crust of the earth. Different kinds of
rocks contain different minerals, have different physical properties, and were formed in different
ways. Geologists group the rocks of the earth’s crust into three types according to their mode of
origin: igneous, sedimentary and metamorphic.
Deep in the earth’s crust, temperatures are high enough to melt rock into magma. Magma
sometimes erupts to the surface as lava, or it may force its way into other solid rock
underground. In either case, when magma cools, it solidifies, forming igneous rocks, such as
granite and basalt.
Two subdivisions of the igneous rocks are recognized. The lavas and solid fragments
erupted from volcanoes are called extrusive rocks. They are composed in large part of
microscopic mineral crystals and glass. In a few places igneous rocks can be seen to grade into
rocks composed of much larger crystals. These coarse-grained igneous rocks are called
intrusive rocks , and are widespread at the earth’s surface, but have not been observed in
process of formation. The intrusive rocks were not thrown up to the surface like lavas, but
solidified deep underground. Subsequently, the roof rock that covered many of these buried
masses was eroded away, thus exposing the intrusive rock at the surface.
The sedimentary rocks have been formed at the surface of the earth, either by accumulation
and cementation of fragments of rocks, minerals, and organisms, or as precipitates from sea
water, and other water solutions.
Most sedimentary rocks form distinct layers or strata. In any pile of sedimentary strata that
has not been disturbed by folding or overturning since accumulation, the youngest stratum is at
the top and the oldest at the base. In other words, the order of deposition is from the bottom
upward. Sedimentary rocks are classified and named on the basis of their texture, that is, the
size and shape of their constituent particles; and on their composition, that is, the kinds of
minerals that compose the particles and cements. Two general subdivisions may be recognized:
clastic sedimentary rocks and organic and chemical sedimentary rocks.
It should be noted that sedimentary rocks are of great interest to petroleum geologists
because most oil and gas accumulations occur in these rocks due to their most important
physical characteristics: porosity and permeability. The greater the porosity of a formation, the
more petroleum it is able to hold. A rock is permeable when its pores are connected --- that is,
oil, gas, and water can flow through it by moving from one pore to another. Thus to be
commercially productive a petroleum reservoir must be both porous and permeable. Limestone,
sandstone, and clay are considered to be typical sedimentary rocks.
Metamorphic rocks are rocks ---either igneous, sedimentary, or other metamorphic rocks--that have been buried deep in the earth where they are subjected to high temperatures and
pressures. The term comes from the Greek “meta”, the change, and “morphe”, form or shape.
When undergoing the metamorphic process, physical and chemical properties of the original
rock are found to change, thus altering rock composition and appearance. To form a
metamorphic rock metamorphic agents (heat, pressure, various gases and vapors) interact with
the parent rock. So, for example, limestone can be metamorphosed into marble, and sandstone
into quartzite.
Ex.10. Pick up pairs of a) synonyms and b) antonyms
a) solid, like, type, bed, deep, size, sufficient, as, hold, little, layer, hard, high, various, make
up, dimension, enough, kind, compose, different, profound, few, keep, tall,
b) different, high, coarse-grained, upward, permeable, solid, extrusive, downward, deep,
low, top, same, fine-grained, shallow, low, bottom, impervious, intrusive.
Ex.11. Translate the following word combinations.
1. way
2. high
- the best way to learn the language; ways and means of examining rocks;
in the same way; in different ways; the only way out; the shortest way to
the station
- waves up to 40 meters high; high in the mountains; at high speed; goods
of high quality; a highly-qualified specialist; highly-educated person
3. recognize
- to recognize somebody; to recognize three groups of rocks
4. solution
- water saline solution; the best solution of the problem
5. pile
- a pile of rocks; a pile of books
6. order
- the order of deposition; in order to do something; to keep documents in
order
- the bottom of the sea; the bottom of the page; the order of deposition is
from the bottom upward; the well bottom
7. bottom
8. subject
- the subject of discussion; school subject; the subject of a thesis; to
subject substances to intense heat; a metal subject to corrosion
Ex.12.Say which word doesn’t match.
1. Form, make up, contain, shape.
2. Different, kind, various, unlike.
3. Property, characteristic, type, feature.
4. Solid, dense, hard, clastic.
5. Source rock, parent rock, mother rock, reservoir rock.
6. Cover, layer, bed, stratum.
7. Divide, link, disconnect, classify.
8. To change, to alter, to transform, to act.
9. General, common, only, usual.
10. To subject, to expose, to submit, to disturb.
Ex.13. Translate the following sentences into Russian.
1. Rocks composed almost entirely of fine-grained silica are common, but they are unlikely
to form large masses.
2. Basalt is the world’s most abundant solidified lava.
3. Granite, characterized by a granular texture, has feldspar and quartz as its two most
abundant minerals, and therefore most granite is light colored.
4. Clastic sedimentary rocks are those composed of broken fragments of pre-existing
minerals, rock particles or precipitates that have been cemented together.
5. The materials erupted from volcanoes include solids, liquids and gases.
6. Naturally enough, as soon as the lava reaches the surface it cools rapidly and the fluid
tends to solidify. In some cases the solidification occurs only at the surface and
subsequently a stream of lava flows along beneath the hardened crust.
7. The conditions to which the rocks are subjected determine the kind of metamorphic
changes that occur.
8. Since any rock may be metamorphosed in one or several different ways, there are
different kinds of metamorphic rocks.
9. When melted rocks are erupted to form extrusive rocks.
10. In many limestones it is easy to see the remains of small organisms without using the
microscope.
11. Folding takes place when a force horizontal to the surface of the earth make rock strata
bend.
12. Although intrusive rocks were always originally formed deep underground, they are now
widely exposed because of earth movements and erosion processes.
13. The folding of rocks, after erosion has worked at the surface, originally makes the
surface more uneven than it was before.
14. It is indeed, only through the removal of the products of weathering that fresh surfaces
are exposed to the further action of weathering processes.
15. Nearly all the great mountains of the world have been formed by the folding of layers of
the earth’s crust.
16. Limestone is quantitatively much less important than shale and sandstone among
sedimentary rocks of the world, but it is the chief non-clastic type. Kinds of limestone,
graded on the basis of composition and texture, are almost without number, and each
represents somewhat different conditions of making.
17. There are very few areas in the British Isles which have not been disturbed in some way
or another by human activities.
18. Rocks are constantly subjected to a wide range of chemical and metamorphic changes,
all of which affect their strength.
19. In many regions the earth’s surface has been disturbed by folding more than once along
the same axes.
20. If magma when forcing its way upward has sufficient heat and pressure it reaches the
surface to become an extrusive igneous rock.
21. With progressing regional metamorphism, the constituent rock minerals often grow more
coarse-grained.
22. Chemically formed rocks are those derived when mineral matter that has been in
solution becomes insoluble and is precipitated.
23. The great piles of sediments are the inevitable result of long continued operation of the
slow process we observe today.
24. Rocks are aggregates of minerals. The wide variations in appearance and physical
properties they exhibit depend on the amounts and kinds of different minerals they
contain, and on how the grains of these minerals are arranged.
25. Sometimes thick piles of layers can be overturned by rapid vibrations such as those that
result from earthquake.
Ex.14. Give the terms to the following definitions.
1. Any mass or aggregate of one or more kinds of mineral or organic matter, forming
the solid crust of the earth.
2. A sedimentary rock composed mainly of sand grains cemented together in varying
degrees.
3. Rocks formed by solidification of molten matter within the earth’s crust.
4. Fine-grained igneous rocks formed at the surface of the earth.
5. Rocks formed by consolidation of sediments.
6. The size and shape of rock constituent particles.
7. A rock which pores are connected.
8. Rocks derived from pre-existing rocks by mineralogical, chemical, and structural
alterations due to high pressure and heat.
9. Agents of metamorphism.
10. A hard crystalline metamorphic form of limestone, typically white, which may be
polished and is used in sculpture and architecture.
Ex.15.Arrange the words given below into three columns:
Igneous
Sedimentary
Metamorphic
Cemented, fine-grained, loose, hard, stratified, crystalline, altered, permeable, coarsegrained, unconsolidated, porous, impermeable, layered, glassy, metamorphosed, foliated,
deep-seated, dense.
Ex.16.Open the brackets choosing the proper English word.
Rocks are a naturally occurring solid (mixture, aggregate) of minerals and, sometimes,
organic materials. Rocks are classified by mineral and chemical (composition, structure), the
texture of the (constituent, consisting) particles and also by the processes that formed them.
Rocks can be (arranged, classified) into three main groups which are igneous rock,
sedimentary rocks, and metamorphic rocks. These three main groups of rocks are classified
by geologists on the basis of their mode of (occurrence, origin).
Igneous rock (derives, originates) from the cooling and (solidification, cementation) of
molten rock. Igneous rocks are formed either underground or above ground. Underground
the (molten, solidified) rock is called magma. As the magma cools slowly it becomes
(intrusive, extrusive) igneous rocks. On the other hand, igneous rocks are also formed when
volcanoes (erupt, expose), causing the magma to (rise, raise) (upward, downward) to the
surface. Magma above the earth is called (fluid, lava). (Intrusive, extrusive) igneous rocks
are formed as the lava cools above the ground.
Sedimentary rocks are rocks which are formed when layers of (cement, sediment)—clay,
sand, gravel, and minerals—(deposit, precipitate) to the bottom of the ocean and then
compact and (cement, solidify).
Ex.17.Translate the following sentences into English.
1. Магматические породы образовались в результате остывания расплавленного
вещества, называемого магмой.
2. Различают два типа магматических пород: а) интрузивные, которые
образовались в результате остывания магмы в значительных глубинах, в
условиях больших давлений и высоких температур; б) эффузивные породы,
которые образовались в результате остывания лавы, вылившейся на
поверхность земли.
3. Классификация магматических пород основана на условиях их образования и
минералогическом составе.
4. Минералогический состав магматических пород
зависит от химического состава магмы.
в значительной степени
5. Поднимаясь на поверхность
и вытекая в виде лавовых потоков,
расплавленное вещество, в конце концов, остывает и превращается в
магматические породы путем отвердения.
6. Интрузивные магматические породы, глубоко под землей
путем затвердения, иногда обнажаются на поверхности.
образовавшиеся
7. Гранит и базальт типичные примеры магматических пород.
8. Породы, образующие земную кору, делятся на три основных класса, причем
такое деление основано на характере происхождения пород.
9. Некоторые
осадочные
породы
образовались
сцементирования обломков пород или организмов.
путем
скопления
и
10. Большинство осадочных пород залегает отчетливыми слоями.
11. В пачке осадочных пород, которая не была затронута процессами
складкообразования с момента накопления, самый молодой пласт находится
вверху, а самый древний—внизу. Иными словами, порядок отложения – снизу
вверх.
12. Осадочные породы представляют наибольший интерес для геологовнефтяников, что обусловлено их физическими свойствами: пористостью и
проницаемостью.
13. Наиболее распространенные осадочные породы—песчаник и глина.
14. Под метаморфизмом понимают любое изменение минералогического состава,
структуры или текстуры
изверженной, осадочной или метаморфической
породы.
15. Благодаря метаморфизму
изменяется.
первоначальный
характер
породы
заметно
16. Видоизмененные таким образом породы составляют метаморфическую группу
пород.
17. Различные факторы, такие как температура, давление, различные газы и пары,
влияют на образование метаморфических пород.
18. Метаморфические породы широко распространены в земной коре. Под
действием различных метаморфических агентов известняк превращается в
мрамор, а песчаник в кварцит.
Ex.18. Answer the questions.
1. What is a rock?
2. What is the classification of rocks based on?
3. What rocks are known as igneous?
4. In what way have igneous rocks been formed?
5. What subdivisions of igneous rocks are recognized?
6. What is the subdivision of igneous rocks based on?
7. Do intrusive and extrusive rocks differ greatly? Can they be told from each other with
naked eye?
8. What rocks are known as sedimentary?
9. What is the mode of occurrence of sedimentary rocks?
10. Into what groups are sedimentary rocks subdivided? What is the main principle of
these subdivisions?
11. Why are sedimentary rocks of prime importance for petroleum geologists?
12. What is referred to as metamorphism?
13. What kinds of rocks can be metamorphosed?
14. What agents are considered to be the most effective in altering the rock material?
15. Can you give examples of each class of rocks?
Ex.19.Read the text and do the following tasks:
a. Divide the text into paragraphs and give headings to the paragraphs.
b. Find key sentences of each paragraph.
c. Render the text using the found key sentences as a plan.
Igneous rocks derive their name from Latin word “ignis” meaning “fire”. The ancient people
thought that there were fires within the earth. They described volcanoes as burning mountains,
whereas we realize today that combustion is almost absent in volcanoes although there is
abundance of heat. We do not believe there are “fires” within the earth, yet we are practically
certain that the interior of the earth is very hot. We know that for the first mile the temperature
varies about one degree Fahr.for every 60 feet of added depth. It is practically certain that the
major part of the interior is solid at all times. But limited quantities of the earth’s crust at times
melt, cool again, and resolidify. Sometimes this molten rock comes up a long way to reach the
surface of the earth. But molten rock does not always rise far enough to reach the earth’s
surface. It may consolidate between walls of older rocks. Any rock which forms by consolidation
from a molten material is called an igneous rock. In this group there are two distinguishing
features. Firstly, the size of the crystals, which is an indication of the rate of cooling and hence
of the depth of formation. For instance, granite which has large crystals was cooled very slowly
and formed at great depth within the crust, while rhyolite which has no crystals, being like glass,
was cooled very rapidly and is a form of lava, emitted by a volcano directly onto the surface.
Thus we may divide the igneous rocks into those which crystallize within the earth and those
which solidify at the surface. The former is called intrusive rock and the latter is named extrusive
rock. Intrusive rocks are well-crystallized and generally coarse-grained, the crystals being large
enough to be recognized with naked eye. Extrusive rocks are commonly fine-grained, with
crystals too small to be distinguished without a magnifying glass. The second feature is the
chemical composition. Igneous rocks are described as acidic and basic, according to the
proportion of silica (quartz) in their make-up. Often a chemical analysis must be carried out to
determine the correct composition and name of the rock.
Ex.20.Read the text and say why metamorphic rocks are of little importance for oil hunters.
In examining rocks the geologists distinguish two major groups, sedimentary rocks being of
the utmost importance for petroleum geologists. But a third group of rocks is also recognized.
This is composed of rocks whose texture or mineral composition has been changed under the
action of heat, pressure and chemically active fluids with the possibility of admixture of another
rock. These rocks are known as metamorphic rocks. They are only of negative interest to the
geologist looking for oil since their presence indicate conditions which are impossible to the
preservation of large volumes of oil.
Metamorphism is referred to as the process, by which changes are brought about in rocks
within the earth’s crust by various metamorphic agencies. The end-product of metamorphism,
the metamorphic rock, is the result of the interaction of the metamorphic agencies and the
parent rock.
The most significant agency of all is probably dynamic metamorphism, which is produced by
actual movement or change in the shape of the rock formation. The action of solutions
accompanies this process and gives rise to talc, mica, and chlorite. Dynamic metamorphism
forms shists and gneisses; it seems to make highly effective all the other metamorphic
processes which are otherwise very slow and may be only potentially of importance.
Answer the following questions.
1. What is the subject of the text?
2. What is the purpose of the text?
3. What does the text start with?
4. What aspects related to metamorphism does the author consider in the text?
5. What conclusion can you make?
Ex.21.Translate the text in writing. Use a dictionary.
ATLANTIC ONCE A DEAD SEA
The Atlantic Ocean may once have been a shallow evaporating pan with water as salty
as that of the Dead Sea. A lifeless lake then only a few miles across, the Atlantic waters
deposited thick layers of salt on what are now the continental margins of West Africa and North
America.
This is the picture inferred from a seismic survey of the sea bottom of the coast of NorthWest Africa. Dr. P.A. Rona, of Columbia University, New York, has discovered that the thick
layers of sediment which have accumulated on the sea floor near the coast are punctuated by
several giant pyramids of salt, up to 25 miles thick at the base.
The sediment layers revealed by the seismic waves are buckled upwards, suggesting
they have been pierced through pyramids of salt pushing upwards from beneath.
How did the salt get there? From the theory of continental drift, it is known that up to
about 200 million years ago the land mass of North America abutted on to Europe and North
Africa. The continents were prised apart by volcanic activity along what is known now the
underwater mountain range known as the Mid-Atlantic Ridge.
In the early stages of this process the Atlantic Ocean would have been a shallow
stretch of water, perhaps closed off from the other oceans of the world in these circumstances
the surface waters might have evaporated as fast as new water could flow in, and a layer of salt
up to a mile thick would have been deposited.
After several million years, when the neighboring continents had drifted further apart,
the north Atlantic joined up with the south Atlantic into a full-fledged deep water ocean.
Sediments of organic and mineral debris piled up on top of the salt layer until the pressure of
overlying material was sufficient to sand pyramids of salt punching up through the mile or so of
sediments to the surface of the sea floor.
Dr.Rona has geological evidence to believe that the salt layer was deposited about 150
million years ago.
The salt domes in the Gulf of Mexico may have a similar origin, and may even have deposited
from seas contiguous with the early north Atlantic. When salt domes push through petroliferous
sediments they form excellent traps in which oil accumulates; the salt domes of the Gulf coast
provide millions of barrels of oil yearly.
The structure discovered by Dr.Rona resemble salt domes in their seismic reflections, but this
will need to be checked.
(“THE TIMES”, LONDON)
Ex. 22. Render the text in English:
В геологии горными породами называются природные минеральные агрегаты.
Горные породы состоят из одного или нескольких минералов. Наука, которая занимается
изучением горных пород, называется петрографией. В настоящее время известно около
1000 видов различных горных пород. В петрографии принята классификация горных
пород по их происхождению. По этой классификации все горные породы делятся на 3
большие группы: магматические, осадочные и метаморфические. 90% земной коры по
объему составляют магматические и метаморфические породы и только 10% составляют
осадочные породы.
Минералы и горные породы, образующиеся из магмы, называются
магматическими. К ним относятся гранит, базальт и некоторые другие. Образование
магматических горных пород можно наблюдать в районах действующих вулканов, где
магма изливается на земную поверхность. Такая магма, достигшая земной поверхности,
называется лавой. При отвердевании лава образует эффузивные (излившиеся) горные
породы. Горные породы, образовавшиеся из магмы, которая затвердела на глубине,
называются интрузивными (или плутоническими, глубинными).
Осадочные и магматические породы образуют две основные группы горных пород
в литосфере. Но когда такие породы находятся в условиях большого давления и высокой
температуры, они изменяются и превращаются, в метаморфические породы. Процесс
изменения горных пород под действием тепла, давления, жидких и газообразных веществ
называется метаморфизмом.
Осадочные горные породы образуются в самой верхней части земной коры при
невысокой температуре и давлении. Осадочные породы делятся на три главных типа:
обломочные, органогенные и хемогенные.
Как образуются обломочные горные породы? Под действием тепла и холода, воды
и воздуха горные породи постоянно разрушаются и делятся на части, или обломки. Реки
и ветер переносят этот обломочный материал в другие места. Самое большое
количество обломочного материала оседает в океанах и морях. Постепенно под
давлением новых слоев он превращается в твёрдую осадочную породу. Так, например,
песок превращается в песчаник, глина - в глинистый сланец и т.д. Песок, песчаник, глина
- это обломочные породы.
Второй тип осадочных пород - органогенные породы. Органогенными называются
горные породы, которые состоят из органических остатков животных и растений. Это
такие породы, как мел, уголь, известняк и другие.
Третий тип осадочных пород - хемогенные. породы. Эти породы образуются в
результате выпадения веществ в осадок из водных растворов. Это такие породы, как
каменная соль (NaCl), гипс и другие.
Осадочные породы имеют большое практическое значение в нефтяной геологии.
Ex.23.Agree or disagree with the following statements and give your reasoning.
1.
Classification of rocks is based on their composition.
2.
Igneous rocks are the best reservoir rocks.
3.
Sedimentary rocks are formed at the surface of the earth.
4.
Metamorphism is the change of texture and composition of metamorphic rocks.
5.
Sedimentary rocks are of great interest for petroleum geologists.
Ex.24. Give summary of the text “Rocks” from ex.9.
Ex.25. Speak on:
1. Classification of rocks.
2. Igneous rocks.
3. Sedimentary rocks.
4. Metamorphic rocks.