Пособие состоит из 16 уроков и трех дополнительных разделов. Каждый урок рассчитан на работу в течение 4-5 часов аудиторных занятий
жүктеу/скачать 2.09 Mb. Pdf көрінісі
|
| 7 Lesson 7 The Earth
7.1 Words and word combinations to the text sphere – сфера, шар spheroid – сфероид pole – полюс layer – оболочка atmosphere – атмосфера hydrosphere – гидросфера lithosphere – литосфера liquid – жидкий crust – земная кора mantle – мантия boundary – граница granite – гранит sedimentary rocks – осадочные породы silicate rocks – силикатные породы basalt – базальт density – плотность property - свойство radioactivity – радиоактивность lead – свинец uranium – уран to yield – давать approximately – приблизительно 7.2 Find Russian equivalents to the following word combinations to compare with масса Земли a tiny speck различные свойства the mass of earth период времени rigid shell дно (ложа) океана the ocean floor газообразное состояние the earth’s interior сравнивать с … different properties твердая оболочка length of time gaseous state liquid state solid state крошечная частица внутренняя часть Земли твёрдое состояние жидкое состояние 34 7.3 Read and translate the text The Earth Our planet on which we live, the earth seems to be a very large body. But compared with quite an ordinary star, like the sun the earth is only a tiny speck in the universe. The earth is not a true sphere but a spheroid flattened at the poles so that the axis on which it rotates is shorter by 27 miles than the equatorial diameter. The outer layers of the earth are the atmosphere, the hydrosphere, and the lithosphere. The atmosphere, the outermost layer, is the envelope of gases that surrounds the earth. The hydrosphere includes all the bodies of water on the earth in gaseous, liquid, and solid states. It makes up only 0.02 per cent of the mass of the earth. The three major parts of the earth are the crust, the mantle, and the core. The outermost more or less rigid shell covering the earth constitutes the earth’s crust. It includes the rocks of the continents as well as the rocks beneath the ocean floor. The lower boundary of the crust is 20 to 25 miles beneath the surface of the continents and only about 4 miles beneath the ocean. The continents are made up of a rock type known as granite covered by a thin layer of sedimentary rocks, and underlain by basalt, while the floor of all ocean basins is mostly underlain by basalt with a thin layer of sedimentary rocks above. The mantle composed of materials much denser than those making up the crust extends to a depth of 1800 miles, its density increasing with depth. It is believed to consist of dunite or some closely allied ultrabasic silicate rock. Figure The core of the earth seems to consist of two parts having different properties. The outer core, more than 1,000 miles thick below the mantle behaves like a liquid. The inner core, 18 times as dense as water, behaves like a solid, although its temperature may be as high as that at the surface of the sun. How old is the earth? The discovery of radioactivity around 1900 gave the scientists a new means of estimating the age of the earth. All naturally radioactive elements are known to change finally into lead. One gram of uranium will yield 1/7 000 000 000 of a gram of lead a year. Thus by measuring the amount of lead present in rocks containing uranium we can estimate how much radioactive change occurred and what length of time needed for this change. The oldest rock so far discovered has been dated at about 3.7 billion years old. We know the earth was formed earlier than that and astronomers believe it to have been approximately 4.5 billion years ego. жүктеу/скачать 2.09 Mb. Достарыңызбен бөлісу:
|