I. Answer the following questions:

1. How do we learn things about lithosphere?

2. Where do scientists secure specimens?

3. What do specimens from the slopes of Mount Everest prove?

4. What depths have several well borings reached?

5. How can you determine the nature of the rocks?

6. Why can't we learn much about lithosphere through direct observation?

7. What do rocks constitute?

8. Into what large groups can we divide rocks?

9. What do all rocks contain?

10. What is the nature of igneous rocks?

11. What kinds of igneous rocks do you know?

12. How many active volcanoes do you know?

13. Are there any active volcanoes in our country?

14. What processes do igneous rocks undergo?

15. What happens to particles of eroded rocks?

16. Under the influence of what forces do igneous and sedimentary rocks change their qualities?

17. What is the difference between igneous and metamorphic rocks?

II. Find in the text equivalents to:

to deposit, almost, at one time, to make up, some, height, under, over.

III. From questions to the italicized words:

1. Mountain climbers have reached elevations of 27 000 feet on Mount Everest.

2. The forces of erosion carried away particles of eroded rocks.

3. Igneous rocks constitute the great bulk of the lithosphere.

4. They will study the materials on the walls of deepest mines.

IV. Translate into Russian. Pay attention to the verb "to have":

They have specimens.

They have to secure specimens.

They have secured specimens.

1. Many of the most important changes have taken place on the surface of the earth.

2. The earth has a diameter of approximately 8 000 miles.

3. Scientists have to secure many specimens before they can determine the nature of the rock.

4. The surface of the earth has low relief.

5. For centuries men have secured salt from the ocean.

6. Ships go round the earth in an east and west direction, but it is also possible to go round in a north and south direction. But that is much more difficult because we have to pass the very cold Arctic regions and only a few brave men have been able to penetrate into the heart of those cold lands.

7. The earth has an outer shell 40 to 50 miles in thickness, beneath which there is a mass of iron of iron and nickel.

8. They had to examine many specimens before they could determine the nature of this rock.

Part II

SUPPLEMENTARY READING

The earth and its natural elements

The Universe. The universe includes all material things; the earth is a part of the universe. Large bodies of the universe are stars. The sun is a star, but it is not the largest star. It appears large because it is the star nearest the earth. The distance from the earth to the sun is 93 000 000 miles. Light travels swiftly – 186 000 miles per second – and passes from the sun to the earth in 300 seconds.

Beyond the sun, the star nearest the earth is so far away that light from it takes 4 years to reach the earth. The light that we receive from the North Star left the North Star 47 years ago. Light from very distant stars requires more than 100 000 00 years to reach the earth.

The Solar System. The sun is the central body of that part of the universe called the solar system. The solar system consists of the sun, planets, moons or satellites, comets, meteors.

The sun has a diameter of 860 000 miles. It is many times greater in size, or volume, than all its planets combined.

Planets are bodies that revolve around the sun. The nine planets in order from the sun outward are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Jupiter is the largest planet. Its diameter is 86 000 miles, more than ten times the diameter of the earth. Saturn, Uranus and Neptune are also larger than the earth. Mercury, Venus, Mars and Pluto are smaller than the earth.

Satellites, or moons are smaller than their planets and revolve around them. The earth has one satellite, our moon, the largest satellite of the solar system. The moon is 2 000 miles in diameter and 240 000 miles distant from the earth. Mars has two moons, Jupiter – nine, Saturn – nine, Uranus –four and Neptune – two.

Comets are luminous heavenly bodies, often having a long tail. Comets follow an orbit about the sun.

Meteors, or shooting stars, are fragmentary solid bodies that become heated and visible as they pass through the earth's atmosphere.

The Earth. The earth forms an extremely small portion of the universe. It rotates on its axis from west to east, riving a succession of day and night every 24 hours. The earth revolves around the sun once in 365 1/4 days, or one year. The path followed by the earth in its annual movement around the sun is the earth's orbit. The plane that includes the path of the earth around the sun and that also passes through the center of the earth and the center of the sun is the plane of the earth's orbit.

The earth's axis is inclined 23 1/2° from the perpendicular to the plane of the earth's orbit. The axis always points to the same part of the heaven, the north end toward the North Star.

The related position of the earth and sun, and the movements of the earth, cause the change of seasons. The vertical ray of the sun annually migrates north and south between the Tropic of Cancer and the Tropic of Capricorn. Long days and the steep rays of .summer bring warm weather; short days and the slanting rays of winter bring cold weather.

Shape and Size of the Earth. The earth is spherical in shape, but not a perfect sphere. The polar diameter of the earth is 26 miles shorter than the equatorial diameter. Because the earth is so nearly a sphere in shape, all parts of the earth's surface are about the same distance from the earth's center, and a body on the earth's surface weighs approximately the same in different parts of the earth.

Latitude and Longitude. Latitude and longitude make it possible to locate a place with absolute accuracy.

Latitude is distance north or south of the Equator, measured in degrees, minutes and seconds of a circle. The highest latitude that any place on the earth may have is 90°. The North Pole and South Pole have the highest latitude, 90° from the Equator. Latitude, or distance from the Equator, is a chief factor determining climate. Regions within 30° of the Equator lie in low latitudes, regions between 30° and 60° north or south of the Equator are in middle latitudes, while regions between 60° and the poles are in high latitudes.

Longitude is distance east or west of the prime meridian, measured in degrees, minutes and seconds of a circle. The prime meridian passes from pole to pole through Greenwich, London, and its longitude is 0°. The greatest longitude a place on the earth may have is 180°, on the meridian opposite the prime meridian. If one knows the latitude and longitude of a place, he can readily locate the place on a globe or on a map.

Change in time on the earth corresponds to change of longitude, a change of 15° in longitude corresponding to a change of 1 hour in time.

The Earth and Parts. The earth consists of the lithosphere, the hydrosphere and the atmosphere.

The lithosphere or rock sphere, one-fourth of which forms land and three-fourths ocean bottom.

The hydrosphere, or water sphere, covers three-fourths of the outer surface of the lithosphere.

The atmosphere, or air sphere, several hundred miles thick, completely envelops the lithosphere and hydrosphere.

Distribution of Land and Water. Of the 197 000 000 square miles of the earth's surface, 29 per cent consists of land, while oceans, and seas cover the remaining 71 per cent. The land areas consist of seven continents and numerous islands. The water area consists of five oceans and many gulfs, bays and seas.

The Oceans. Five large oceans and their gulfs, bays and seas make up the world ocean, or hydrosphere. Although the ocean averages more than 2 miles in depth, in proportion to the diameter of the earth it forms only a thin film of water on the outside of the lithosphere. The ocean is one continuous body of water broken into irregular parts by continents and islands.

The portion of the earth's crust, or lithosphere, covered by waters consists of the shallow continental shelf, bordering continental shores to a depth of 600 feet; the continental slope, extending from the continental shelf to the true ocean basin at a depth of 10 000 feet or more; the deep ocean basin, occupying three-fourths of the ocean bed, or more than one-half the surface of the earth.

Land Forms. The land area consists of plains, plateaus, hill lands and mountains.

Plains are lowlands of the earth. Plains bordering the ocean are coastal plains. Plains lying far from the ocean are interior plains. Plains may slope upward from the ocean far into the continent and gradually reach an elevation of several thousand feet above sea level.

Plateaus are highlands whose broad summit areas stand above adjoining plaint, or extend among mountains.

Mountains are highlands having small summit areas. Mountains rise higher than adjacent plains or plateaus. Mountains may be classified as young mountains and old mountains.

Young mountains have great heights, steep slope and barren surface, especially at high altitudes. The Rocky Mountains, the Alps are young mountains. Old mountains have less altitude and more gentle slopes, and are often covered to the top with vegetation. The Urals are old mountains.

Hill lands resemble low mountains because of their steep slopes. The foothills of mountains are hill lands.

The Atmosphere. The atmosphere is a mixture of gases, enveloping land and water areas and extending outward from the earth for several hundred miles. The temperature of the lower atmosphere, or troposphere, grows colder with an increase of altitude to a height of about 7 miles. In the upper part of the atmosphere called stratosphere, temperature changes slightly. The zone between the troposphere and the stratosphere is the tropopause.

Pure, dry air in the lower atmosphere consists of 21 per cent oxygen, 78 per cent nitrogen, nearly one per cent argon and three-hundredths of 1 per cent carbon dioxide. Dust particles and water vapor are also present in the lower atmosphere. Water vapor may form 1 to 5 per cent of the volume of the atmosphere. The life of people and animals depends on oxygen which they obtain when they breathe. Plants need carbon, which they obtain through green leaves from the carbon dioxide in the air. Nitrogen and argon are not so important to life as oxygen and carbon dioxide.

The force of gravity holds the atmosphere to the earth. At sea level, air exerts an average pressure of 15 pounds per square inch. This is equal to the weight of a column of mercury 30 inches high or a column of water 34 feet high. Differences in air pressure are the chief cause of winds.

Weather. Weather is the condition of atmosphere with respect to heat or cold, wetness or dryness, calm or storm, clearness or cloudiness, during a short period of time.

In middle latitudes, as in the United States, Central Europe and Central Asia, changes of weather are frequent, with a wide range between summer and winter. In low latitudes as in the Amazon Basin of South America, changes of weather are slight, with a small range between summer and winter. In high latitudes, changes of weather are frequent, with colder winters and cooler summers than in middle latitudes.

Climate. Climate is the aggregate, or sum total, of weather during a long period of years.

Climatic conditions vary with latitude, distance from the sea, altitude above sea level, direction of wind and other factors. A climatic region includes those areas of the earth that possess similar climatic conditions.

Elements of Weather and Climate. Elements of climate and weather are: temperature, pressure, winds, precipitation, humidity, cloudiness and sunshine. Temperature is condition of the atmosphere with reference to heat. Pressure is weight of atmosphere, and at sea level is 15 pounds per square inch.

Winds are moving air, varying from gentle breezes to terrific winds that uproot trees and destroy buildings.

Precipitation is moisture condensed from the air as rain, snow, sleet or hail.

Humidity is the condition of atmosphere with reference to its water-vapor content. Humidity is low in the desert of Sahara, high in the tropical forests of the Congo Basin.

Cloudiness and sunshine denote the percentage of daytime that the sun shines.

The various climatic regions of the world possess different combinations of the six elements of weather and climate, and different parts of one region may vary considerably in the combination of the six elements.

The six elements of weather and climate operate everywhere, but we are most aware of temperature, precipitation and winds. Temperature and precipitation largely determine native and cultivated vegetation. In regions of warm temperature and abundant rainfall, tropical forests thrive; in regions of cool temperature and abundant rainfall, temperate forests; in regions of warm temperature with distinct wet and dry seasons, tropical grasslands or savannas; in regions of cool temperature and moderate rainfall, steppes and prairies.

An annual rainfall of less than 10 inches results in deserts, whether in warm or cold regions.

Insolation. Heat or energy radiated from the sun is solar radiation. Solar radiation that reaches the earth is insolation. The sun radiates energy in all directions, but only 1/2 000 000 000 th part reaches the earth, 93 000 000 miles away. Yet this small fraction of the sun's energy is the significant factor controlling the earth's weather and climate. The sun determines temperature; temperature, in turn, influences pressure, winds, humidity and precipitation.

Insolation is not evenly received over the earth’s surface. The vertical rays of the sun strike the earth's surface at an angle of 90° and concentrate on a small area. Oblique rays are slanting rays, spreading over a greater surface as they become more oblique. The tangent rays of sunrise and sunset merely graze the earth's surface. The vertical rays and very steep rays pass a shorter distance trough atmosphere than the more oblique rays and therefore lose less of the sun's energy.

Insolation varies with the length of day. At the equinox when the noonday sun shines vertically on the Equator and the days and nights are everywhere twelve hours in length, insolation is greatest at the Equator and gradually decreases poleward as the sun's rays become more oblique and extend for a longer distance through the atmosphere. In northern summer, insolation increases in latitudes north of the Equator, because of the longer days and steeper rays; at the same time, in southern winter, in latitudes south of the Equator, insolation decreases, because of the shorter days and more oblique rays.

In equatorial and tropical regions where the noonday sun is always high in the sky and days vary slightly in length, temperatures remain high and uniform throughout the year. In middle latitudes, however, where, in summer, the noonday sun is high and the day long, and, in winter, the noonday sun is low and the day short, annual changes of temperature are great. At 40° latitude, north or south of the Equator, the length of day varies from 9 hours in winter to 15 hours in summer, and the noonday sun varies in altitude from 26 1/2° in winter to 73 1/2° in summer.

Air is heated by the processes of: absorption, radiation, conduction, compression and mixing.

As the sun's rays pass through the atmosphere, the air is warmed somewhat by absorbing the sun's energy directly.

Land and water radiate their heat, and air is warmed by radiation. Air in contact with the earth heats by conduction, and the heat is transferred from one body to another.

As cold upper air settles toward the earth, it is under increased pressure, which produces heat by compression.

Warm south winds mingling with cooler north winds warm the air by mixing.

Warm light air pushed upward by cooler, heavier air is a convection current, which also transfers heat by mixing.

Air is cooled by the processes of radiation, conduction, mixing and expansion.

Air cools if it radiates heat more rapidly than it receives heat. At night air cools because insolation ceases and radiation continues.

By conduction, heat passes from the air to the cooler earth below and to the cooler air above.

Mixing warmer air with colder air both cools the warmer air and warms the cooler air. Convection encourages mixing.

When warm, light air is pushed upward by cooler, heavier air, the upward-moving air, under less pressure, expands and cools.

Effect of Land and Water on Temperature. Continents and islands of various sizes break the water surface of the earth. Land surfaces differ in size, altitude, nature of soil and kind of vegetation. Water heats and cools more slowly than land, because:

1) water has higher specific heat than land; 2) water reflects the sun's rays more readily than land; 3) the evaporation of water uses much heat; 4) movement brings cooler water to the surface to be heated; 5) the sun's rays penetrate water to greater depths than they penetrate land.

Four times as much heat is required to raise the temperature of a given volume of water 1°, as a like amount of land 1°. The smooth water surface reflects a larger proportion of the sun's rays than does the rugged land surface. There is evaporation from moist land, but the amount of water evaporated from the land is slight compared with the amount evaporated from the ocean: Ocean waters move as tides, waves and currents; land surfaces are stationary and receive the full effect of the sun's rays. The sun's heat may penetrate ocean waters for more than 60 feet; it penetrates land not much more than 4 feet.

Differences in the heating and cooling of land and water directly influence climate. In summer, when land is hotter than the ocean, see breezes bring coolness to the land. In winter, when land is cooler than the ocean, winds from the sea bring milder temperatures. Far from the sea summers are hotter and winters colder than near the sea. Regions near the ocean have marine climate; those far inland continental climate.

Isotherms usually extend east-west, but temperature differences of land and ocean often cause isotherms to curve northward and southward.

Range of temperature is the difference between maximum, of highest, and minimum, or lowest, temperatures. We have daily, monthly and annual ranges of temperature.

Temperature determines the length of the growing season. In equatorial regions, where frost never occurs, the growing season continues throughout the year. In intermediate climates the growing season varies from 275 days near the tropics to less than 90 days near the Arctic Circle, Cotton requires a growing season of 200 days or more; corn 150 days or more; wheat 90 days or more.