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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 between 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

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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. а) Найдите в правой колонке руссжше эквиваленты следующих слов в сочетаний слов:

10. Переведите сочетания слов, обращая внимание на место причастия прошедшего времени по отношению к определяемому существительному:

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11. Н айдите предлож ения, • которы х им ею тся прич астия прош едш его времени. О пределите их ф ункцию . П ереведите предлож ения:

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 (фарфор).

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.З а м е н и тоепр ед е ли т ел ьпрноеид а то ч ноепре дл о же нопиер ед ел и те л ь

ны мп р и ч а с т ноыбмо р о т.о м

Образец: 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 magma may 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, andesite, 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. Н айдите в тексте Л и вы пиш ите: 1) причастия прош едш его времени в ф у нкци и лев о го оп ред ел ен ия вм есте с су щ естви тел ь н ы м и , к отор ы е он и определяю т; 2) причастия прош едш его врем ени, вх одящ ие в определитель ны й причастий оборот; 3) прич астия прош едш его врем ени, исп оль зуем ы е для образования глагольных ф орм группыPerfect;4) причастия прош едш его времени, используемы е для образования страдательного залога.

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17. Суммируйте содержание текст» А, используя слон в скобках.

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.Расскажите об изверженных породах. (См. рнс. 2, с. 118.) В своем рассказе дайте ответы на следующие вопросы:

1.What does Fig2. 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.W hat minerals does each group of rocks represent?

ГРАММАТИКА1. Степени

сравнения прилагательных и наречий

Односложные и некоторые двусложные прилагательные и наречия образуют сравнительную степень прибавлением к своей основе суффикса -ег, а превосходную степень — при-бавлением суффикса est- . Многосложные и большинство дву-сложных прилагательных образуют сравнительную степень при помощи слова more более, а превосходную — при помо-щи словаmost

самый, наиболее.

Перед прилагательными в превосходной степени употребляется определенный артикль.

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1. М есто наречий в предложении

Наречия неопределенного времениalways всегда, often

часто, seldom редко, already уже, usually обычно, som etim es

иногда, soon скоро, never никогда и т.д. ставятся перед смысловым глаголом или после первого вспомогательного глагола в сложных глагольных формах:

Наречия, выполняющие в предложениях функцию - об стоятельства места и времени, стоят либо в начале предложения перед подлежащим, либо в конце предложения:

Наречия, определяющие прилагательное, причастие или другое наречие, обозначают признак или степень качества и всегда стоят перед словом, к которому относятся:

a chemically pure substanceхимическичистоевещество;

a highly developed industryвысокоразвитаяпромышленность.

3. Наречияна -1у

От многих прилагательных можно образовать наречия, прибавив к ним суффикс -ly: nice — nicely, great — greatly, careful — carefully, definite — definitely, excellent — excellentlyи

Др.

Некоторые наречия, образованные от прилагательных с помощью суффикса -1у, отличаются по значению от соответствующих прилагательных:

to consist of quartz, orthoclase and micato be determined by at least four variable geologically relatedparameters

20. Прочитайте следующие слом и сочетания слов 1-2 раза про себя, затем вслух и постарайтесь запомнить их.

товатый, тонкослоистый; syn flaky

marble [ 'ma:bl] л мрамор

mention ['теп/(э)п] v упоминать, ссылаться; л упоминание

at least по крайней мере

to give an opportunity (of) давать возможность (кому-л., чему-л.) In such a way таким образом

21. а) Определите по словообразовательным элементам (суффиксам и префиксам), какой частью речи являются следующие слова. Переведите их:

know n— unknown; differ — different — difference; found — founder — foundation; m ean — m eaning; difficult — difficulty

б) П ер ев ед интаер у сск ияйзы кп р и л а га т ел ьснсуы фе ф и к сом-a b le : changeable, understandable, valuable, variable, breakable

•) Заполните пропуски прилагательными, образованными от выделенных глаголов или существительных:

1. Under the action of pressure and high temperature rocks change their composition and structure. One may say that the structure and composition of rocks are ....