A bad year for earthquakes
At least 20,000 people died in six serious earthquakes in 1999, and many more were left injured and homeless. The worst of these earthquakes was in northwest Turkey in August, when more than 16,000 people died in the densely-populated area around Izmit. In October California was ‘lucky’ because a major earthquake occurred in the Mojave Desert rather than near Los Angles, 160 km away.
All this does not mean that earthquakes are becoming more frequent or more powerful than in the past. The difference is that more people are at risk as the world population grows. Rich countries have been able to cut the death toll from earthquakes by developing anti-quake technology and building ‘flexible’ buildings that sway during tremors. This has not happened in poorer countries, where poor-quality buildings and rapidly-growing populations have increased the danger.
The devastation caused by the Turkish earthquake was much worse than it need have been. Scientists had warned that the country’s industrial region, as well as thousands of homes, had been built in the area of highest seismic risk.
The number of potential earthquake victims has also been increased by the migration of people from rural areas to towns, where they tend to be much more crowded together. This is a particular problem in high-risk areas like the Pacific rim.
Limestone in Europe
Limestone landscapes are distinctive and widespread. The rock occurs in a number of different forms and, depending on the historical and present-day climate, it will give rise to a variety of landforms. Across Europe the various types of limestone produce spectacular scenery. The termkarst, which comes from a region in Slovenia, is often used to describe such landscapes. They are found through Slovenia, Croatia, Bosnia-Herzogovina, Montenegro and Albania.
Mountain limestones occur throughout the Alps, extending westward to France. Beyond the Alps limestone is found in the Grands-Causses region of the Massif Central, where the Tarn and Lot rivers have cut steep gorges.
Limestone also forms the underlying geology of many Mediterranean islands. Throughout southern Europe these rocks owe their origin to deposition in the ancient Tethys Sea, of which the Mediterranean is a small remnant. They have been lifted by tectonic forces and eroded by water and ice to produce the steep slopes,, gorges and caves associated with the rock.
Limestone also occurs in northern Europe, where it is the product of deposition in much more ancient seas. In the English Pennines limestone was formed some 350 million years ago in the Carboniferous period. Around Ingleton and Malham in Yorkshire we can see, on a micro scale, the karst features typical of those in eastern Europe.
Vulcanism
A volcano is an opening in the earth’s crust through which molten rock, usually called magma while underground and lava aboveground, pours forth. Because the emerging material accumulates near the orifice, most volcanoes in the course of time build up mountains with a characteristic conical shape that steepens toward the top, with a small depression or crater at the summit. Lava escapes almost continuously from a few volcanoes, but the majority are active only at intervals.
Volcanic Eruptions
A volcanic eruption is one of the most awesome spectacles in all nature. Usually earthquakes provide a warning a few hours or a few days beforehand – minor shocks probably caused by the movement of gases and liquids underground. An explosion or a series of explosions begins the eruption, sending a great cloud billowing upward from the crater. In the cloud are various gases, dust, fragments of solid material blown from the crater and the upper part of the volcano’s orifice, and larger solid fragments representing molten rock blown to bits and hurled upward by the violence of the explosions.
Gas continues to issue in great quantities, and explosions recur at intervals. The cloud may persist for days or weeks with its lower part glowing red at night. Activity gradually slackens, and presently a tongue of white-hot lava spills over the edge of the crater or pours out of a fissure on the mountain slope. Other flows may follow the first, and explosive activity may continue with diminished intensity. Slowly the volcano becomes quiescent, until only a small steam cloud above the crater suggests its activity.
Not all eruptions by any means follow this particular pattern. Volcanoes are notoriously individualistic, each one having some quirks of behavior not shared by others. In one group of volcanoes the explosive type of activity is dominant, little or no fluid lava appearing during eruptions. Cones of these volcanoes, built entirely of fragmental material ejected in a solid or nearly solid state, are very steep sided; examples are found in the West Indies, in Japan, and in the Philippines. Other volcanoes, like those of Hawaii, have eruptions characterized by quiet lava flows with little explosive activity. Mountains built by these volcanoes are broad and gently sloping, quite different from the usual volcanic structure. The most common kind of volcano is neither wholly of the “explosive” type nor wholly of the “quiet” type, but has eruptions in which both lava flows and gas explosions occur.
The chief factors that determine whether an eruption will tend to be a largely quiet lava flow or tend to be explosive are the viscosity of the magma and the amount of gas it contains. (The greater the viscosity of a liquid, the less freely it flows: honey is more viscous than water.) Magma is a complex mixture of the oxides of various metals with silica and usually has an abundance of gas dissolved in it under pressure. Like most molten silicates it is extremely viscous, and with rare exceptions lava creeps downhill slowly, like thick syrup or tar. The viscosity depends upon chemical composition; magmas with high percentages of silica are the most viscous. The presence of gas also affects viscosity; magmas with little gas are the most viscous. If the magma feeding a volcano happens to be rich in both gas and silica, the eruption will be explosive. A magma with modest gas and silica contents results in a quiet eruption.
The gaseous products of volcanic activity include water vapor, carbon dioxide, nitrogen, hydrogen, and various sulfur compounds. The most prominent constituent is water vapor. Some of it comes from groundwater heated by magma, some comes form the combination of hydrogen in the magma with atmospheric oxygen, and some was formerly incorporated in rocks deep in the crust and is carried upward by the magma to be released at the surface. Much of the water vapor condenses when it escapes to give rise to the torrential rains that often accompany eruptions.
Glaciers
In a cold climate with abundant snowfall, the snow of winter may not completely melt or evaporate during the following summer, and so a deposit of snow accumulates from year to year. Partial melting and continual increase in pressure cause the lower part of a snow deposit to change gradually into ice. If the ice is sufficiently thick, gravity forces it to move slowly downhill. A moving mass of ice formed in this manner is called a glacier. Approximately 10 percent of the earth’s land area is covered by glacial ice at the present time.
Today’s glaciers are of two principal types:
Valley glaciers – found, for instance, in the Alps, on the Alaskan coast, in the western United States – are patches and tongues of dirty ice lying in mountain valleys. These glaciers move slowly down their valleys, melting copiously at their lower ends; the combination of downward movement and melting keeps their ends in approximately the same position from year to year. Movement in the faster valley glaciers (a few feet per day) is sufficient to keep their lower ends well below timberline.
Glaciers of another type cover most of Greenland and Antarctica: huge masses of ice thousands of feet thick and thousands of square miles in area, engulfing hills as well as valleys, and appropriately called continental glaciers or ice caps. These, too, move downhill, but the “hill” is the slope of their upper surfaces. An ice cap has the shape of a broad dome, its surface sloping outward from a thick central portion of greatest snow accumulation: its motion is radially outward in all directions from its center. The icebergs of the polar seas are fragments that have broken off the edges of ice caps. Similar sheets of ice extended across Canada and northern Eurasia in relatively recent geological history.
Apparently a glacier moves by internal fracture and healing in the crystals of solid ice as well as by sliding along its bed. Like a stream, a glacier carries along rock fragments which serve as tools in cutting its bed. Some fragments are the debris of weathering that drop on the glacier from its sides; others are torn from its bed when melted water freezes in rock cervices. Fragments at the bottom surface of the glacier, held firmly in the grip of the ice and dragged slowly along its bed, gouge and polish the bedrock and are themselves flattened and scratched. Smoothed and striated rock surfaces and deposits of debris containing boulders with flattened sides are common near the ends of valley glaciers. Where such evidence of the grinding and polishing of ice erosion is found far from present-day glaciers, we have reason to infer that glaciation was present there in the past.
Valley glaciers form in valleys carved originally by streams. A mountain stream cuts like a knife vertically downward, letting slope wash, slumping, and minor tributaries shape its valley walls; by contrast, a glacier is a blunt erosional instrument which grinds down simultaneously all parts of its valley floor and far up the sides as well. Effects of this erosion are best seen in valleys that have been glaciated in the past but in which glaciers have dwindled greatly or disappeared. Typically such valleys have U-shaped cross sections with very steep sides, instead of the V shapes produced by stream erosion. Their heads are round, steep-walled amphitheaters called cirques, in contrast to the small gullies at the heads of stream valleys. Tributary streams often drop into a formerly glaciated valley over high cliffs because a large glacier carves out its channel much more actively than a small one does. A tributary valley left stranded high above its main valley is called a hanging valley and is often the scene of a spectacular waterfall.
Divides between cirques and between adjacent U-shaped valleys tend to be sharp ridges because of the steepness of the valley walls. In general, since valley glaciers produce deep gorges, steep slopes, and knifelike ridges, their effect is to make mountain topography extremely rugged. The earth’s most spectacular mountain scenery is in regions (the Alps, the Rockies, the Himalayas) where valley glaciers were large and numerous several thousand years ago.
The influence of ice caps on landscapes is very different from that of valley glaciers. We cannot, of course, observe directly the effect of existing ice caps on the buried landscapes of Greenland and Antarctica, but larger ice caps that once covered much of Northern Europe and North America have left clear records of their erosional activity, which we can easily see from the rounded hills and valleys, the abundant lakes and swamps so characteristic of these regions. Like a gigantic piece of sandpaper, an ice cap rounds off sharp corners, wears down hills, and fills depressions with debris, leaving innumerable shallow basins which form lakes when the ice recedes.
Glacial erosion is locally very impressive, particularly in high mountains. The amount of debris and the size of the boulders that a glacier can carry are often startling. But in general, on a worldwide basis, the erosional work accomplished by glaciers is small. Only rarely have they eroded rock surfaces deeply, and the amount of material transported long distances is insignificant compared with that carried by streams. Most glaciers of today are but feeble descendants of mighty ancestors, but even these ancestors succeeded only in modifying landscapes already shaped by running water.
Minerals
Rocks are aggregates of substances called minerals, which as a rule are crystalline solids with fairly definite compositions and structures. Some rocks, for instance limestone, consist of a single mineral only, but the majority consist of several minerals in varying proportions. The different minerals in a coarse-grained rock like granite are apparent to the eye; in fine-grained rock, the separate minerals can be discerned with the help of a microscope.
What Minerals Are
It is not difficult to understand why certain substances occur as minerals and why others do not. We expect to find the more chemically inactive elements, such as gold, platinum, and sulfur, in the free state, whereas chemically active elements, such as sodium, calcium, and chlorine, are always found in combination as compounds. Compounds readily soluble in water, such as sodium chloride, sodium carbonate, and potassium nitrate, form deposits in desert regions but are rare elsewhere. Substances that tend to react with oxygen occur only well below the surface away from the oxygen of the atmosphere. Unstable compounds like phosphorus pentoxide are necessarily absent from the earth’s crust.
Silicates are by far the most abundant minerals; mica, feldspar, and topaz are familiar examples. Carbonates are another important class, its most conspicuous representative being the carbonate of calcium called calcite. Oxides and hydrated oxides include such common materials as hematite (ferric oxide), the chief ore of iron, and bauxite (hydrated aluminium oxide), the chief ore of aluminium. Various metals are obtained from deposits of sulfide minerals, such as galena (lead sulfide and sphalerite (zinc sulfide). Elements that occur free, or native, were mentioned above. Less frequent as minerals are sulfates, phosphates, and chlorides.
Unfortunately the study of minerals requires the learning of a special list of names, some of them apparently duplicates of other names. As an example, the mineral whose formula is CaCO3 is given the name calcite instead of the chemical name calcium carbonate. For this seeming redundancy there are two reasons:
The formula CaCO3 describes not only the composition of calcite but also that of aragonite, a less common mineral with a different crystal form, hardness, density, and so on; the chemical name calcium carbonate alone does not distinguish between calcite and aragonite.
Calcite often contains small quantities of MgCO3 and FeCO3 , and its composition is not precisely represented by the formula CaCO3 because the iron and magnesium carbonates form an integral part of the calcite structure with Fe and Mg atoms replacing some of the Ca atoms in the crystal lattice.
Many other mineral formulas besides that of calcite apply to two or more distinct substances, and most minerals show a similar slight variability in composition. Hence chemical names are seldom really applicable, and the student of minerals finds necessary a new nomenclature.
Luckily, for present purposes we need only a few additions to our vocabulary. More than 2,000 different minerals are known, but most of these are rare. Even among the commoner minerals, the greater number occur abundantly only in occasional veins, pockets, and layers. The number of minerals that are important constituents of ordinary rocks is surprisingly small, so small that acquaintance with less than a dozen is adequate for an introduction to geology.
Mineral Properties
Common minerals are not only limited in number but are also easily recognizable with some experience, often by appearance alone. To distinguish the rarer minerals microscopic examination and chemical tests may be necessary, but for the minerals that compose ordinary rocks such simple physical properties as density, color, hardness, and crystal form make identification relatively straightforward.
In describing the important rock-forming minerals, two properties need special attention: crystal form and cleavage. Most minerals are crystalline solids, which means that their tiny particles (atoms, ions, or atom groups) are arranged in lattice structures with definite geometric patterns. When a mineral grain develops in a position where its growth is not hindered by neighboring crystals, as in an open cavity, its inner structure expresses itself by the formation of perfect crystals, with smooth faces meeting each other at sharp angles. Every mineral has crystals of a distinctive shape so that well-formed crystals make recognition of a mineral easy; unfortunately good crystals are rare, since mineral grains usually interfere with one another’s growth.
Even when well-developed crystals are not present, however, the characteristic lattice structure of a mineral may reveal itself in the property called cleavage. This is the tendency of a substance to split along certain planes, which are determined by the arrangement of particles in its lattice. When a mineral grain is struck with a hammer, its cleavage planes are revealed as the preferred directions of breaking; even without actual breaking, the existence of cleavage in a mineral is usually shown by flat, parallel faces and minute parallel cracks. The flat surfaces of mica flakes, for instance, and the ability of mica to peel off in thin sheets show that this mineral has almost perfect cleavage. Some minerals (for example, quartz) have practically no cleavage; when struck they shatter, like glass, along random curved surfaces. The ability to recognize different kinds and degrees of cleavage is an important aid in distinguishing minerals.
The Earth’s Interior
The average density of the earth as a whole is twice that of the crust. Evidently the earth cannot be hollow (as was once thought) or even like the crust but must consist of extremely dense materials. What are they likely to be? Are they solid or liquid? Is the interior a uniform mass or does it have a structure of some sort? Is it hot or cold? Answers exist for these questions which, though based on indirect arguments and leaving many details unsettled, nevertheless fit together into a reasonably complete picture of the inside of our planet.
Interior Structure
Earthquake P and S waves do not travel in straight lines within the earth. There are two reasons for this. The first is that the speeds of both kinds of waves increase with depth, so that their paths are somewhat curved owing to refraction. The second reason is more spectacular: there are layers of materials having different properties within the earth. When an earthquake wave traveling in one layer reaches the boundary, or discontinuity, that separates it from another layer in which its speed is different, refraction also occurs. Now, however, the refracted wave shows an abrupt change in direction, unlike the more gradual change due to speed variations within each layer.
Let us suppose that an earthquake occurs somewhere. We consult the various seismological observatories and find that most though not all of them have recorded P waves from this event. Curiously, the stations that did not detect any P waves all lie along a band from 103° to 143° (11,400 to 15,900 km) distant from the earthquake. We would find, if we consulted the records of other earthquakes, that no matter where they took place, similar shadow zones existed. This is the clue that confirmed an early suspicion that the earth's interior is made up of concentric layers.
The earth is divided into a central core and a surrounding mantle. P waves leaving the earthquake are able to go directly through the mantle only to a limited region slightly larger than a hemisphere. Those P waves that impinge upon the core are bent sharply toward the center of the earth, and, when they emerge, they are 4,500 km or more away from those P waves that just barely cleared the core. From an accurate analysis of the available data, it was found that the mantle is 2,900 km (1,800 mi) thick, which means that the core has a radius of 3,470 km (2,160 mi), over half the earth's total radius. However, the core constitutes less than 20 percent of the earth's volume.
Supporting the above finding and giving further important information about the nature of the core is the behaviour of the S waves, which require a solid medium for their passage. The transverse motion involved in such waves requires that each particle of the medium in which they occur drag with it adjacent particles, which is impossible in a liquid where each particle is not firmly attached to its neighbours. The back-and-forth motion involved in P waves, on the other hand, simply requires that each particle exert a push on the next one, which can happen as easily in a liquid as in a solid. Since it is found that S waves cannot get through the core at all, the conclusion follows that the core is a liquid. A liquid core not only accounts for the absence of S waves but also for the marked changes in the velocity of P waves when they enter and leave the core.
The division of the earth into a core and mantle was first suggested in 1906 by R. D. Oldham to explain the presence of shadow zones. Later very sensitive seismographs came into use which detected faint traces of P waves in the shadow zones, which should not have been able to get there at all. In 1936 Inge Lehmann proposed that within the liquid core there is a smaller solid inner core that can bend some of the P waves passing through it so that they reach the shadow zones. Subsequent research confirmed this notion and the inner core is now believed to have a radius of 1,250 km (780 mi).
From observations first made on a 1909 earthquake it became clear that there is a distinct difference between the surface regions of the earth and the underlying mantle. The line of demarcation is known as the Mohorovicic discontinuity, after its discoverer. Under the oceans it is seldom much more than 5 km thick; under the continents it averages about 35 km, and it may reach 70 km under some mountain ranges!
Rocks
There is hardly any limit to the variety of rocks on the earth's surface. We find coarse-grained rocks and fine-grained rocks, light rocks and heavy rocks, soft rocks and hard rocks, rocks of all sizes, shapes, and colors. But close study reveals that there is order in this diversity, and a straightforward scheme for classifying rocks has been developed which simplifies the problem of understanding their origins and properties.
Rock Classification
At first glance, it is not obvious how rocks can be separated into definite categories. We might decide that a light-colored, coarse-grained rock like granite should belong in a different class from a dark, fine-grained volcanic rock like basalt, but we can find a whole series of rocks with properties transitional between the two, and so we cannot say just where one class ends and the other begins. The basic problem is to make distinctions that are not always clear-cut in nature.
Since rocks are composed of minerals, we might guess first that they could be classified on the basis of the kinds and amounts of minerals they contain. But we find that rocks of widely different structures and origins have nearly the same mineral composition, and so we would be grouping together rocks of obviously different types. A classification based on chemical composition encounters the same difficulty, since it places in the same pigeonhole rocks that have little else in common; it has the further disadvantage that chemical compositions are not evident in the field but require laboratory analysis. We might disregard composition and classify rocks according to their origin. This would be an excellent method if it could be applied to all rocks, but the sad fact is that we simply do not know how some rocks were formed and the origin of many others can be determined only after lengthy study.
Evidently we expect a classification of rocks to fulfil several different purposes. We should like it to summarize something about the origins of different rocks, about their compositions, and about their structures, and at the same time we should like to be able to apply it to rocks as we find them in the field. These objectives cannot all be satisfied at the same time. Our recourse is to adopt a compromise, a classification that will accomplish each purpose as well as possible without slighting the others. The particular compromise we shall use is not the only possible one, but it is justified by its simplicity and convenience.
A fundamental division of rocks into three main groups according to origin is agreed on by nearly all geologists:
1. Igneous rocks are those that have cooled from a molten state. Some of these can be observed in process of formation, for instance when molten lava cools on the side of a volcano. For others an igneous origin is inferred from their composition and structure. Two-thirds of crustal rocks are igneous, and the bedrock under the oceans and continents falls into this category.
2. Sedimentary rocks consist of materials derived from other rocks and deposited by water, wind, or glacial ice. Some consist of separate rock fragments cemented together; others contain material precipitated from solution in water. Although sedimentary rocks make up only about 8 percent of the crust, three-quarters of surface rocks are of this kind.
3. Metamorphic rocks are rocks that have been changed, or metamorphosed, by heat and pressure deep under the earth's surface. The changes produced may involve the formation of new minerals or simply the recrystallization of minerals already present.
Igneous Rocks
The structure of igneous rocks is characterized by random arrangement of grains, by ragged crystal borders, by intertwinings and embayments such as one might expect in a mass of crystals growing together and interfering with one another's development. In coarse-grained rocks like granite, this structure is visible to the naked eye; in fine-grained rocks it is revealed by the microscope. The principal constituents of these rocks are always minerals containing silicon: quartz, feldspar, mica, and the ferromagnesian group.
The siliceous liquids from which igneous rocks form are thick, viscous materials resembling melted glass both in properties and in composition. Sometimes, in fact, molten lava has the right composition and cool rapidly enough to form a natural glass – the black, shiny rock called obsidian. Usually, however, cooling is slow enough to allow crystalline minerals to form. If cooling is fairly rapid and if the molten material is highly viscous, the resulting rock may consist of minute crystals or partly of crystals and partly of glass. If cooling is extremely slow, mineral grains have an opportunity to grow large and a coarse-grained rock is formed. The grain size of an igneous rock, therefore, reveals something about its history and gives us one logical basis for classification.
Mineral composition provides a convenient means of further classification. Nearly all igneous rocks contain feldspar and one or more of the ferromagnesian minerals; many contain quartz as well. Thus a coarse-grained rock containing quartz, feldspar, and black mica is granite; a fine-grained rock with no quartz and with feldspar in excess of the dark constituents is andesite, and so on.
This classification is convenient for several reasons:
1 Grain size and usually mineral composition can be determined from inspection in the field. Except for a few fine-grained types, an igneous rock can be named without detailed laboratory study.
2. Even if a rock is too fine for its mineral content to be easily determined, its colour often shows its place in the table. Granite and rhyolite, which contain only a little ferromagnesian material, are nearly always light-coloured; gabbro and basalt, with abundant ferromagnesian minerals, are characterictically dark; diorite and andesite usually have intermediate shades. Granite and rhyolite are sometimes designated as felsic rocks (because of their large feldspar content) and gabbro and basalt as mafic rocks (because of their ferromagnesian content).
3. Grain size usually gives an indication not only of the rate of cooling but also of the environment in which a rock was cooled. Sufficiently rapid cooling to give fine-grained rocks occurs most commonly when molten lava reaches the earth's surface from a volcano and spreads out in a thin flow exposed to the atmosphere. Since fine grain size usually betrays volcanic origin, rhyolite, andesite, and basalt are often called volcanic or extrusive rocks.
Coarse-grained rocks, on the other hand, have cooled sufficiently slowly for large crystals to have formed, which must have occurred well beneath the earth’s surface. Such rocks are now exposed to view only because erosion has carried away the material that once covered them Since these rocks do not reach the surface as liquids but are intruded into spaces occupied by the other rocks, they are often called intrusive rocks.
Sedimentary Rocks
Sediments laid down by water, wind, or ice are consolidated into rock by the weight of overlying deposits and by the gradual cementing of their grains with material deposited from underground water. The resulting rocks are usually characterized by the presence of distinct, somewhat rounded grains that have not grown together like the crystals of igneous rocks. A few sedimentary rocks, however, consist of intergrown mineral grains formed by precipitation from solution in water. Since sediments are normally deposited in layers, the majority of sedimentary rocks have a banded appearance owing to slight differences in colour or grain size from one layer to the next. Sedimentary rocks may often be recognized at a glance by the presence of fossil – remains of plants or animals interred with the sediments as they were laid down.
UNIT VIII
| GRAMMAR FOCUS |
THE SYSTEM OF TENSES
Task 1. Study the following table and get ready to practice the use of the Present Simple and Present Continuous.
| Formation | Present Simple | Present Continuous | |
| Statement | Констатация факта  V, Vs (3л.ед.ч.) Mr. A speaks good English |    Процесс  am is + Ving are Mr. A is speaking English now. | |
| Question | Do Does + S + V Does Mr. A speak English? |  am is + S + Ving are IsMr. A speaking English now? | |
| Negative |  ... do not (don’t) +V ... does not (doesn’t) + V Mr. A doesn’t speak French. | ... am not (‘m not) + Ving ... is not (isn’t) + Ving ... are not (aren’t) + Ving Mr. A isn’t speaking French now. | |
| Use | ·  habits He doesn’t do the written work · permanent situations He studies at the University · general truths The earth revolves round the sun. | · actions happening now The students are watching a DVD now. · temporary situations She is working at the museum until the end of the month. · annoying habits She is always talking at the lessons. | |
| Typical words and phrases | always – usually often – sometimes – rarely never every Month/week each Monday/week once/twice a week | now right now at the moment today this week/month |
Task 2. Circle the correct word or phrase.
1. I read/ am reading a newspaper at least once a weak.
2. Does Gary ever talk/ Is Gary ever talking about his expedition to the Amazon jungle?
3. Each water molecule contains/ is containing two hydrogen atoms and one oxygen atom.
4. The earth is forming/ forms an extremely small portion of the universe.
5. When one passes/ is passing from place to place on the surface of the earth the appearance of heaven changes/ is changing constantly.
6. Geology studies agencies and processes which continually alter/ are altering the earth’s surface.
7. Now science exercises/ is exercising a decisive influence on technology, creating new problems for it.
8. Holiday travel becomes/ is becoming more and more popular with every day.
9. Woodland of Great Britain are occupying/ occupy 7 percent of the surface.
10. The earth constantly rotates/ is rotating on its axis from west to east.
Task 3. Complete using the correct Present Simple or Present Continuous form of the verbs in brackets.
1. Alan _____ (study) to be a geographer but I don’t think he ____ (enjoy) it.
2. Energy _____ (occur) in several forms.
3. The amount of energy used in agriculture _____ (increase) from year to year.
4. Nowadays human activity even in the far north of Russia, North America and Greenland _____ (damage) nature.
5. The planet _____ (get) warmer causing the ice in Antarctica to melt.
6. The Rocky Mountains still _____ (rise) as the pressure between the two plates _____ (continue).
7. Rivers _____ (get) their water from rainfall and melting snow.
Task 4. Study the following table and get ready to practice the use of the Present Perfect and the Present Perfect Continuous.
| Formation | Present Simple | Present Perfect Continuous | |||
| Statement | Завершенность   have Has + V3 They have just returned from the expedition | Частичная завершенность + процесс
has + been + Ving I’ve been learning English for three years. | |||
| Question | Have Has + S + V3 ? Have they returned from the expedition? | Have Has + S + been + Ving Have you been learning English? | |||
| Negative |  ... have not (haven’t) + V3 ... has not (hasn’t) + V3 They haven’t returned from ... . |  ... haven’t been + Ving ... hasn’t been + Ving I haven’t been learning English. | |||
| Use | · completed actions at a time in the past which is not mentioned They have returned from the expedition · completed actions where the important thing is the result now They have brought many specimens from the expedition. | · actions continuing up to now or just before now. (the time spent on the action is important) I’ve been learning English for three years. | |||
| Typical words land phrases | for – since – just – already yet – ever – never – so far | for – since - just |
haveTask 5. Complete using the correct Present Perfect or Present Perfect Continuous form of the verbs in brackets.
1. Mapping _____ (make) great advances in the last years.
2. Men _____ (use) maps for thousands of years.
3. The passion for literature _____ (become) a national feature of the Icelanders.
4. Life _____ (originate) in the areas growing from small molecules of amino acids and nucleotides.
5. Meteorologists _____ (look for) reliable ways of forcasting the weather.
6. Men _____ (give) different names to different parts of the sea.
7. Oil and natural gas _____ (to transform) countries such as Saudi Arabia, Libya and the UAE.
8. The last 100 years _____ (be) a time when huge cities _____ (grow).
9. Many plant and animal species _____ (lose) their habitat and _____ (become) extinct because of deforestation.
Task 6. Study the following table and get ready to practice the use of the Past Simple, Past Continuous and Past Perfect.
| Formation | Past Simple | Past Continuous | Past Perfect | ||||||
| Statement | Констатация факта в прошлом  V2
It rained much last summer. |  Процесс в прошлом
were + Ving It was raining all day long yesterday. |    Завершенность к прошлому моменту  had + V3 The rain had stopped when they arrived | ||||||
| Question | Did + S + V ? Did it rain much ...? | Was Were + S + Ving Was it raining all day... | Had + S + V3 ? Had the rain stopped when...? | ||||||
| Negative | did not (didn’t) + V It didn’t rain much .... |  was not (wasn’t) +Ving were not (weren’t) + +Ving It wasn’t raining ... . | Had not (hadn’t) + V3 The rain hadn’t stopped when ... . | ||||||
| Use | ·  completed actions in the past, general truths about the past · repeated actions in the past used to + V I used to read many books in geography when at school. · Succession of actions | · actions happening at a moment in the past · two actions in progress at the same time | · actions and states before a moment in the past · finished actions and states where the important thing is the result at a moment in the past | ||||||
| Typical words and phrases | yesterday last week/summer/ year in January/2001 an hour/a week/a year ago | at that moment at one/two o’clock while from 6 to 9 o’clock | by by the time before after just when |
Ved V2
wasTask 7. Complete using the correct form of the verbs in brackets.
1. In 1920 scientists _____ (invent) instruments that _____ (measure) the depth of water.
2. The famous navigator J. Cook _____ (study) astronomy with great enthusiasm.
3. Some of the world’s oldest civilizations _____ (begin) in the river valleys of North Africa and the Middle East.
4. Before modern industry _____ (begin) in Northern Europe, a good climate and plentiful natural resources _____ (encourage) human settlement and development.
5. The Rocky Mountains _____ (form) where the Pacific Plate _____ (press) against the North American plate.
6. By 1900 the people _____ (cut down) 80 percent of the forests on Prince Edward Island and diseases _____ (destroy) much of what _____ (remain).
7. Galileo _____ (discover) the four satellites of Jupiter over three centuries ago.
8. When the earth _____ (reach) the size of the planet Mars it _____ (have) primitive continental platforms and ocean basins.
9. Beginning from its early formative stage the earth _____ (change) constantly.
10. The scientists _____ (learn) that the oldest rocks in our country _____ (form) 1600-1800 million years B.C.
11. During the last 2.6 million years the climate on the Earth _____ (change constantly).
12. 20000 people _____ (die) in six serious earthquakes in Turkey in 1999. Scientists _____ (warn) that the country’s industrial region and homes had been built in the area of highest seismic risk.
Task 8. Study the following table and get ready to practice the use of the Tenses expressing Future time.
| Formation | Future Simple | Be going to | Present Continuous | |||||||||||||
| Statement | Констатация факта в прошлом
Will + V The new airport will be the biggest in Europe. | The new airport is going to be the biggest in Europe |
|
Am
is + Ving
Are
We are driving to Berlin this weekend.
facts about the future · decisions made now · predictions · offers and requests 
Remember! With offers which are questions, we use shall with I and we. Shall I drive you to the airport? Task 9. Circle the correct word or phrase.
1. I’m becoming/ going to become an explorer when I grow up.
2. One day, people are living/ will live on Mars in special buildings.
3. This year, more than a million tourists shall/ will visit our local area.
4. If we do not/ will not take action to protect the earth’s atmosphere, it is going to/ will soon become unable to protect us.
5. According to the “closed universe” theory the universe contracts/ will contract eventually.
6. No matter how high a mountain, erosion is wearing away/ will wear away eventually it.
7.Wherever there are minerals worth extracting mining will occur/ is occurring.
8. By 2030 more than 60% of people are going to/ will live in cities.
9. The increase of greenhouse gases in the forthcoming 30 or 40 years is affecting/ will affectthe inhabitants of the planet.
Task 10. Complete using will or be going to.
If the destruction of the forest continues at the same rate there (1) _____ (be) nothing left in the nearest future. What (2) _____ (happen) if more of the Amazon forest is cut down? According to climatologists, two things are likely to happen: there (3) _____ (be) serious effects of the world’s climate, and the air that we breathe (4) _____ (lose) some of its oxygen.
If we lose the tropical forest, the air (5) _____ (contain) much less oxygen and much more carbon dioxide. It (6) _____ (become) difficult to breathe. With more carbon dioxide in the air, the temperature (7) _____ (rise), the icecaps at the North and South Poles (8) _____ (melt), the sea level (9) _____ (rise) and hundreds of coastal cities (10) _____ (be flooded). All scientists agree that if we destroy the Amazon forest it (11) _____ (be) environmental suicide – life on earth (12) _____ (become) difficult, even impossible.
Task 11. Read the following text putting the verbs in brackets into the correct form. Get ready to discuss its main points. Make an outline of the text and render its contents.
Charles Robert Darwin
The famous naturalist and thinker, Charles Darwin, (to be born) on February the 12th, 1809. The family (to live) near Shrewsbury, not far from the river Severn. Charles’ father was a well-known physician, a son of scientist Erasmus Darwin. Charles’ father (to hope) that his son also (to become) a Fellow of Royal Society.
As a boy Charles always (to walk) in the fields, shooting or rathunting. He was observing nature and comparing his observations with everything he (to read) in natural science books.
At sixteen Charles (to go) to Edinburgh University to become a doctor. He had no vocation for it but he was interested greatly in the natural history. During the hours of low tide he (to collect) various sea animals on the shore and (to study) them. Even while he was a student he (to make) two minor discoveries.
After two years of Edinburgh Charles still (to take) no interest whatsoever in his future profession so his father sent him to Cambridge to work for his degree so that he (may become) a parson (священник).
In the spring of 1831 Charles took his degree but refused to become a parson. Two of his professors (to encourage) him to make a special study of geology and in August of the same year he went to the Welsh mountains with a geological expedition.
Some time later he (to hear) that H.M.S.Beagle (to be to set off) on a trip to South America for a cartographical survey of the coast and wanted a naturalist. His biology professor’s advice was to go.
The expedition was away almost five years. The Beagle (to make) a very thorough study of the waters off the east and west coasts of South America and of the adjacent islands. The Beagle also (to visit). New Zealand, Australia and the Coral Islands in the Indian Ocean and on the way home Brazil and the Azores. His work on the geology of these countries and that of coral islands (to become) the subject of volumes that he (to publish) on his return.
Like most people in those days he (to think) that each species (to exist) thousands of years and never (to change). But during his travels he (to see) that different species of plants and animals, found in different parts of the earth in some ways (to be) similar.
It was when he was trying to explain the wild life of the Galapagos islands that he hit upon a solution: plants and animals (to change) to suit their surroundings.
In 1859 Darwin (to finish) his book “The Origin of Species by Means of Natural Selection”. It (to cause) a sensation. So did his later book “The Descent of Man”. The clergy, politicians, even some scientists came to agree with him. Darwin continued his research until his sudden death in 1882. He (to be buried) in Westminster Abbey, near I. Newton’s grave.
Ex. 12. Complete the sentences with the best form of the verbs in brackets.
People (1) ____ (to observe) the Moon since old days. The Moon (2) ____ (to be) a spherical heavenly body, much smaller than the Earth. It (3) ____ (to rotate) on its axis in a period which it (4) ____ (to take) it to orbit the Earth. As a result the same side of the Moon is visible from the Earth. The Moon (5) ____ (to appear) bright but it is not self luminous like the stars. It (6) _____ (to reflect) light and is really an opaque body. The Earth (7) ____ (to pull) the Moon and the Moon (8) ____ (to pull) the Earth according to the law of universal gravity.
Besides this natural satellite the Earth (9) ____ (to have) a large number of artificial ones. Indeed, several minor satellites (10) ____ (to rotate) around the Earth just now, which (11) ____ (to manifest) the power of human knowledge. Their distances from the Earth and the rates of movement (12) ____ (to differ). A great number of them (13) ____ (to flow) in space since the 60s of the 20th century.
There (15) ____ (to be) a universal law (16) ____ (to explain) the make-up and the movement of all heavenly bodies. There (17) ____ (to be) also major and minor laws which (18) ____ (to grasp) the whole scope of differences between these bodies.
Task 13. Look at this timetable for the Earth Sciences department at a university. The time now is 6 o’clock on the Wednesday evening. Say what has already happened and what is going to happen.
| Monday | Tuesday | Wednesday | Thursday | Friday | |
| 09.00 | Prof. Jones (L) Energy | Prof. Jones (S) Energy | Mr. Roberts (L) Properties of the earth | Mr. Roberts (L) The moving earth | Mr. Roberts (S) The earth in space |
| 10.00 | Mr. Smith (L) Earth materials | Prof. Jones (T) Energy | Mr. Roberts (L) The earth in space | Prof. Jones (S) Matter | Mr. Smith (T) Soil |
| 11.00 | Mr. Smith (L) Minerals | Mr. Smith (L) Rocks | Mr. Smith (T) Soil | Mr. Roberts (S) The earth as a planet | Prof. Jones (S) Matter |
| 14.00 | Mr. Smith (S) Earth materials | Mr. Smith (T) Minerals | Mr. Smith (T) Rocks |
L= lecture; S = seminar; T= tutorial
Task 14. Think how you would say it in English.
1. Человек столетиями добывал соль из океана.
2. Ученые Туркменистана составили атлас грязевых вулканов.
3. Туман на море всегда представлял опасность при навигации.
4. Миллионы звезд постоянно движутся в космосе.
5. Земля совершает полный оборот вокруг Солнца за 365 ¼ дня.
6. Погода изменилась к лучшему.
7. Географы пользуются большим разнообразием инструментов для выполнения своей работы.
8. За последние 600 лет вулканические извержения унесли жизни 200000 человек.
9. В настоящее время большое число людей уезжает из больших городов в сельскую местность.
10. География возникла в результате описания первых исследователей того, что они увидели во время своих путешествий.
11. К чему приведет вмешательство человека в естественные процессы окружающей среды?
12. Новые технологии и подходы помогут более эффективно и экономно использовать природные богатства
PASSIVE VOICE
Task 1. Study the following table.
| Compare | Active Voice | Passive Voice |
| The Sun attracts the planets. Форма глагола attracts показывает, что подлежащее (the Sun) совершает действие. (Солнце притягивает планеты.) | The planets are attracted by the Sun. Форма глагола are attracted показывает, что подлежащее (the planets) подвергается действию со стороны другого лица. (Планеты притягиваются солнцем.) | |
| Form | be + V3 (Past Participle) | |
| Use | · when we don’t know who does smth. The Belarusian State University was founded in 1921. · when we don’t need to say who does smth. The book was translated last year. |
The most widely used forms of the verbs in the Passive Voice.
| Remember! | Tense | Form | Example | ||
| Present Simple | am (is, are) + V3 | The Crimea is noted for its subtropical climate. | |||
| Past Simple | was (were) + V3 | America was discovered by Christopher Columbus. | |||
| Future Simple | will be + V3 | Some specimens will be shown to the students. | |||
| Present Perfect | has (have) been + V3 | France has been noted for its well-balanced economic life. | |||
| Present Continuous | is (are) being + V3 | The air is being heated by the sun. | |||
| I. Remember! | |||||
| Translation | Examples | ||||
| · глагол быть + краткая форма причастия страдательного залога · глагол, оканчивающийся на -ся · неопределенно-личные предложения, в которых глагол- сказуемое в действительном залоге в 3 л. мн. ч. · краткая форма страдательного причастия · предложения с формальным подлежащим it переводятся неопределенно-личными предложениями или безличными | America was discovered by Christopher Columbus (была открыта) The Sun’s light is being reflected from the moon on the Earth (отражается) English is spoken in England. (говорят) The summits of the Crimean mountains are covered with steppe grasses (покрыты) It is known – известно It is said – говорят It was said – говорили It is reported – сообщается | ||||
| II. Remember! | |||||
| When the verb in a passive sentence is a phrasal verb, don’t forget to include the particle. They speak much about this discovery. → This discovery is much spoken about. | |||||
Task 2. Translate into Russian paying special attention to the passive form of the verbs.
1. It is known that most of the land area of the world is located in the Northern Hemisphere.
2. The achievements of our expedition to the North Pole were much spoken about.
3. Several methods have been used to determine the length of the postglacial time in Europe.
4. The tide in Devonshire comes very quickly, so that the people who are by chance among the rocks are being surrounded by the sea.
5. More than 40 mud volcanoes have been plotted on the geological map after geological studies.
6. The crust of the earth is constantly being affected by internal forces.
7. The Earth’s surface may be considered a huge chemical laboratory in which a quantitative rock analysis is being made.
8. The exploration of the northern most section of the island was interfered with by heavy ice conditions.
9. All the data of the experiment will be recorded.
10. Finland is a country where distinct regional contrasts are seldom met with.
Task 3. The words and phrases in bold in each sentence are wrong. Write the correct word or phrase.
1. James Cook appointed to lead the expedition to the Pacific.
2. In ancient times little knew about the shape of the Earth.
3. The first world maps made by the Greeks.
4. The earth’s upper mantle and warm currents have also studied.
5. Many power plants are building and more electricity is using.
6. The cosmic rays are studying with various types of space probes.
Task 4. Say it in English. Mind the passive forms of the verbs.
1. Карты составляются
2. Элементы территориальной структуры распределяются
3. Интернетом пользуются
4. Страны посещают
5. Открытия совершались
6. Новые земли освоены
7. Нефть добывают
8. Лесы вырубались
9. Численность животных сокращалась
10. Новые методы изучаются
Task 5. Use the correct passive or active form of the verbs in brackets.
Floods (l) _____ (cause) when a river (2) _____ (burst) its banks. This can happen if there (3) _____ (be) an unusual amount of rain, or if snow (4) _____ (melt) and the river (5) _____ (overflow). When a flood (6) _____ (take place) crops (7) _____ (destroy) and homes (8) _____ (damage).
Task 6. Rewrite the following passage in the passive.
Yesterday afternoon, a volcanic eruption destroyed an entire village. Mount Sirius, which experts thought was dormant, erupted at 3 pm. Tourists had seen smoke rising from the mouth of the volcano two days before. The police moved the villagers away from the area for their own safety. Tons of lava and rock came out of the volcano and wrecked houses, roads and trees. Although the blast physically injured only a few people, doctors are treating many for shock. The authorities are keeping the area surrounding Mount Sirius clear in case of further activity.
Task 7. Complete using the correct passive or active form of the verbs in brackets.
A: Did you visit many places when you were on holiday?
B: Well, on the first day we (1) _____ (take) on a tour of the historic monuments by our guide.
A: Oh. Did you go everywhere with him?
B: No, we also (2) _____ (go) to some places by ourselves.
A: How did you manage to travel to the other places?
B: We (3) _____ (advise) to hire a car, but we (4) _____ (choose) to travel on public transport because it is much cheaper.
A: How did you know which buses and trains to catch, though?
B: We (5) _____ (ask) at the tourist information centre and we (6) _____ (give) an excellent book which (7) _____ (tell) us everything we needed to know.
A: So, you enjoyed it then?
B: Oh, yes! We had a really great time!
Task 8. Read the following putting the verbs in brackets into the correct form. Be ready to speak on this topic.
Do you think Mars (1) _____ (colonise) by humans one day? The planet Mars (2) _____ (know) as “the red planet”. The soil there is red and its surface (3) _____ (cover) in volcanoes. Until recently, it (4) _____ (believe) that nothing could live on Mars, but during a recent space mission, tests (5) ______ (carry out), and now it (6) _____ (think) that life on Mars might be possible one day. During the space mission, special equipment (7) _____ (use) to examine the planet. No form of life (8) _____ (find) yet, and so far the planet (9) _____ (consider) unsuitable for inhabitation. However, we (10) _____ (tell) by scientists that, by 2020, humans (11) _____ (send) to Mars, and that one day, special cities (12) _____ (build) so that we can live there. It (13) _____ (hope) that by 2150, Mars will be a wonderful place to live. If a colony (14) _____ (build) on Mars, would you like to live there?
Task 9. Rewrite the paragraph, putting the verbs in the box in the correct active or passive form. You may have to use a verb more than once.
| to know, to reflect, to absorb, to arrive, to conserve, to occur, to be, to freeze, to transmit. |
The Greenhouse Effect