Английский язык в сфере профессиональной коммуникации. Геология. Учебное пособие

VIII. Перескажите текст по плану, используя слова, данные в скобках:

1.The origin of sedimentary rocks (secondary, to form, pre-existent rocks).

2.The materials composing sedimentary rocks (to lay down under water, to be derived by disintegration and decomposition of pre-existing rocks).

3.The principal agents which take part in shifting the materials composing sedimentary rocks (moving water, to form aqueous sediments, mechanical action of wind, eolian sediments, ice).

4.Kinds of sediments, (mechanically, chemically and organically formed sediments).

5.Characteristic features of sedimentary rocks, (layered structure, bedding plane, fossils, ripple marks, cross-bedding).

IX. Прочтите тест без словаря и выполните тесты:

The sedimentary rocks have been formed at the surface of earth, either by accumulation and cementation of fragments of rooks, minerals and organisms, or as precipitates (осадки) from sea water and surface solutions.

The process of natural cementation is very slow.

Most sedimentary rocks form distinct layers or strata. The beds are separated from each other by bedding planes, which generally result from many factors during the period of deposition of sediments.

Sedimentary rooks are classified and named on the basis of their size that is the size and shape of their constituent particles; and on their composition, that is, the kinds of materials that compose the particles and the cementing substances.

Two general subdivisions of sedimentary rocks may be recognized:

a. Clastic sedimentary rocks. They are composed mainly of fragments of rocks and minerals which have been transported to the site (место) of deposition and cemented there.

Organic and chemical sedimentary rocks. They are composed mainly of the cemented shells (ракушки) of organisms, or of precipitates from aqueous solutions, such as sea water.

X. Определите, какой из заголовков соответствует содержанию прочитанного текста:

1.Texture of sedimentary rocks.

2.Sedimentary rocks.

3.Composition of sedimentary rocks.

XI. Укажите номера предложений, в которых содержатся ответы на вопросы:

1.How have sedimentary rocks been formed?

2.On what factors is classification of sedimentary rocks based?

3.What general subdivisions of sedimentary rocks are recognized?

4.What is the composition of clastic sedimentary rocks?

5.What is the composition of organic and chemical sedimentary rocks?

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XII. Кратко передайте содержание текста на английском языке.

XIII. Прочитайте текст:

Sedimentary rocks have been formed by decomposition of sediments by water, wind or glacial ice and later have solidified into rock.

Three quarters of the land surface of our planet consist of sedimentary rocks, that is why they are highly important.

Economically they are of great interest, because they contain mineral fuels, such as coal, oil and gas, and some of the most valuable mineral resources, such as sedimentary iron ores.

The most characteristic feature of sedimentary rocks is their layered structure. Each layer is called a bed or a stratum. In thickness the beds range from less than an inch to many feet.

Each bed, as a rule, is separated from the bed below and the bed above it by a stratification (bedding) plane. The stratification can be distinguished (различать) by differences of adjacent beds (соседние пласты) in colour, composition, texture and thickness.

XIV. Ответьте на вопросы:

1.What is the importance of sedimentary rocks?

2.What mineral resources do sedimentary rocks contain?

3.What is the structure of sedimentary rocks?

4.How can the stratification in sedimentary rocks be distinguished?

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UNIT 7. CONSOLIDATION OF SEDIMENTS INTO SOLID ROCKS

III. Прочитайте и переведите текст:

Sediments, at the time, when they are laid down, are in general loose, incoherent and highly porous ones. They are consolidated into solid rock under the influence of many factors. One of these factors is the long-continued and heavy pressure exerted by masses which may be thousand feet in thickness.

Another important cause of consolidating sediments into solid firm rock is the deposition of mineral matter from percolating waters in the spaces, between the grains, which cement them together. The most common cementing substances deposited from solution in the rock pores are silica, calcium carbonate and iron oxide, but the finer clay-like substances mechanically deposited with the coarsermaterials may also act as cement. The interstices between the grains may become almost entirely filled with cement, while sediments are converted into very firm solid rock.

The interior heat of the earth rising into such masses of sediments may aid in some degree to consolidate them be quickening the chemical and mechanical activity of the percolating waters which deposit the cement.

Since the conversion of loose material into solid rock is usually a slow process, time is an important factor in this case.

The sediments from which different kinds of sedimentary rocks are formed are: gravel, sand, mud, silt and clay.

Gravel is composed of material from the size of a pea, the individual pieces are called pebbles. They may have a rounded appearance. Large loose fragments of gravel are called boulders.

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Sand is the material composed of particles smaller than gravel. It does not cohere when wet. The grains of sand may be rounded and angular, the main sandforming mineral being quartz.

Mud, silt and clay are sediments composed of very fine-grained particles. They cohere when wet. Kaolin is characteristic of many muds, silts and especially clays.

COMPOSITION OF SEDIMENTARY ROCKS

Sedimentary rocks are in general more simple in mineral composition than are most of the igneous ones. Fewer minerals of less complex chemical composition and as a rule of more stable character, make up the principal components of sedimentary rocks.

The most common minerals composing sedimentary rocks are quartz, kaolinite, feldspar, mica and the iron oxides together with those precipitated from solution, such as the carbonates (calcite, dolomite and siderite) and the sulphates (gypsum and anhydrite), as well as a few less commonly occurring ones.

EXERCISES

IV. Образуйте существительные от данных слов с помощью суффикса -ness и переведите их:

1.firm — прочный;

2.hard — твердый;

3.thick — мощный (толстый);

4.coarse — крупный;

5.fine — мелкий.

V. Найдите в списках А и В синонимы:

VII. Найдите русские эквиваленты английских словосочетаний:

VIII. Заполните пропуски соответствующим по смыслу глаголом:

IX. Поставьте вопросы к подчеркнутым членам предложения:

Masses of many thousand feet in thickness exert heavy pressure upon sediments.

X. Перескажите текст, отвечая на вопросы:

1.In what state are sediments at the time when they are laid down?

2.What factors influence sediments when they are consolidated into solid

rock?

3.What are the most common cementing substances deposited from solution in the rock pores?

4.What is the role of the interior heat of the earth in consolidating sediments into solid rock?

5.From what sediments are different kinds of sedimentary rocks formed?

6.What are the most common minerals composing sedimentary rocks?

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XI. Прочитайте текст без словаря и выполните тесты:

Sediments are converted into rocks by different processes, such as compaction (сжатие, уплотнение) of sediments and cementation.

Composition is very effective in the clay sediments, which under the pressure of the upper beds become shales (глинистые сланцы).

By means of cementation loose, incoherent sediments are converted into solid firm rocks. Cementation is the deposition of mineral matter in the spaces between the grains of a sediment. The most common cements are calcite, silica in the form of quartz and iron oxide.

The different kinds of sedimentary rocks are determined chiefly by the nature of the sediments form which they were formed.

The chief sediments are the sedimentary rocks derived form them are as follows:

a.gravel — conglomerate and breccia

b.sand — sandstone

c.clay (mud) — shale

d.calcareous(известковый) mud and sand — limestone, etc.

The rocks formed from muddy or clayey sediments are termed argillaceous (глинистый). Sandy rocks are called calcareous (известковый).

The texture of sedimentary rocks depends upon the relative size of the particles, which determines the fineness or the coarseness of grain, upon their shape and upon the amount (количество) and character of the cement which determines the firmness or friability (хрупкость) of the rock.

The size of grains varies widely. Thus conglomerates are coarse-grained rocks; sandstones are medium-grained (среднезернистый) and shales are fine-grained rocks.

The shape of the component grains depends on the amount of their transportation. They are usually more or less rounded, but sometimes are angular.

XII. Определите, какой из заголовков соответствует прочитанному тексту:

1.Conversion of Sediments into Rocks.

2.Composition of Sedimentary Rocks.

3.Processes Affecting Conversion of Sediments into Rocks.

XIII. Перескажите текст по плану:

1.Compaction and cementation of sediments.

2.Different kinds of sediments and the sedimentary rocks derived from them.

3.Factors influencing the texture of sedimentary rocks.

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XIV. Прочитайте тест и кратко передайте его содержание на английском языке:

Sedimentary rocks are formed on the surface of the Earth as a result of the action of water, air and organic remains.

70 per cent of the earth’s surface is composed of sedimentary rocks.

Sedimentary rocks may be either loose or cemented. For example, sand is a loose sedimentary rock but it may consolidate into sandstone; gravel may become a conglomerate with the help of the cementing substances.

Loose sedimentary rocks are highly porous. Their porosity varies with the type of rock. For example, the porosity of sand varies from 28 to 40 per cent; in clays it is more that 50 — 55 per cent. Some hard sedimentary rocks, such as limestones, are also porous, but their porosity is much lower.

Many sedimentary rocks are stratified. The layers are distinguished from each other by composition, size, colour and density in the structure of their mineral grains.

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Limestone. This is the most important and widely distributed of the carbonate rocks. It is composed of calcium carbonate of varying degrees of purity, the more common impurities being magnesia, silica, clay, iron. Limestones vary in colour according to the character and amount of impurities present. When it is pure, the rock is white. However, the various shades of grey to black are the most common colours, and many other colours are known.

Limestones are found in beds of all thicknesses up to 100 feet or more. They weather chiefly through solution, the soluble calcium carbonate being removed and the insoluble material (clayey and siliceous impurities) left in place to form residual soils.

When limestones have been exposed to heat and pressure in the earth crust, they become crystalline and are then marbles.

If sufficiently thick bedded, limestones are widely used for building purposes. Clay. Clay resembles shale chemically and mineralogically and in most cases is

of sedimentary origin. The typical clays are unconsolidated, but all gradations are found between these and hard shales, the intermediate forms being known as clay shales.

Flint. Flint, known also as chert and hornstone and referred to as a variety of quartz, is a hard dark-grey to black rock, breaking with conchoidal fracture, and composed of amorphous or chalcedonic silica Chert occurs chiefly as nodules, layers, or lenses in chalk and limestone and is especially common in many of the dolomitic limestones.

Dolomite. Dolomite is similar in colour, texture, and other physical characters to limestone, except that it is slightly harder and somewhat more resistant because it is less soluble. It is not always an original rock, but sometimes has been derived from straight calcic limestones by the substitution of magnesium carbonate for a part of the calcium carbonate — a process known as dolomitization.

EXERCISES

IV. Отвечая на следующие вопросы, составьте короткие сообщения о главных видах осадочных пород:

a. Sandstones

1.What component minerals do sandstones contain?

2.What are the common colours of sandstones?

3.What is the practical importance of sandstones? b. Shales

1.What is the composition of shales?

2.What structure do shales possess?

3.Into what rocks can shales grade? c. Limestones

1.What is the composition of limestones?

2.What factors does the colour limestones depend upon?

3.Under what conditions do limestones become marbles?

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V. Переведите текст со словарем:

SEDIMENTARY ROCKS

The original source of these rocks is largely igneous rocks, which by their disintegration form boulders, gravel, sand, clay and soluble compounds. These materials, large and small, having been transported by gravity, rivers, waves, ocean currents, winds or glaciers, are consolidated to form sedimentary rocks.

The most characteristic feature about the structure of sedimentary rocks is that they are stratified, that is they consist of layers called strata which nay vary in thickness from a fraction of an inch to many feet. One stratum is separated from another by a different type of a sediment, for example, strata of sandstone may be separated by thin layers of shale or fine sand or carbonaceous (plant) matter. Consolidation of the loose particles may have resulted from pressure of the overlying beds or of earth movement such as mountain building, or it may have come about by the deposition of some cementing material such as calcium carbonate, iron oxide or silica around each particle, thus binding the whole mass together. Sedimentary rocks are classed in three groups: mechanically formed, chemically formed and organic.

MECHANICALLY-FORMED ROCKS

Most sedimentary rooks have been laid down by water, and so most of the particles in a sedimentary rock will be of about the same size, as water assorts the particles according to size. A strong current is capable of carrying large particles, and of rolling boulders along the bottom. But as the strength of the currant diminished the larger particles of rock are dropped. For example, when a river empties into the seas the coarser sand is deposited at the mouth, while the finer mud may be carried some distance before it settles to the bottom.

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