Discussing the age of the earth
Ex 1. Read the dialogue and reproduce it: a) abridged; b) in the form of a monologue.
Nick Kirilov, a geography student, and Prof. Smirnov, an experienced paleontologist are discussing some methods of determining the age of the earth.
| Nick K.: | To discuss all the methods of determining the age of the earth is beyond the province of this seminar. What are, to your mind, the most significant ones? |
| Prof. S.: | They are not very numerous. The most accurate and complete method is to study radioactive minerals. |
| Nick K.: | What is this method based on? |
| Prof. S.: | Such radioactive elements as uranium and radium disintegrate at a constant and determinable rate. That’s why it is possible to determine the age of rocks if we know the rate of disintegration. |
| Nick K.: | And what ratios have been used to form estimates of the age of rock masses that contain these metals? |
| Prof. S.: | It is known that uranium changes to lead. And it is possible to make an estimate of the age of certain rocks containing lead and uranium. |
| Nick K.: | As far as I know, scientists compare the rate of decomposition today with the total thickness of sedimentary rocks formed throughout all geologic time. |
| Prof. S.: | You are right. The rates of erosion of the land surface also have been used to determine the age of the rocks. But the results obtained vary greatly. |
| Nick K.: | To what conclusion did scientists come in estimating the age of the earth? |
| Prof. S.: | The scientists find that the length of the last three geologic eras as indicated by the radioactive record can be harmonized with the sedimentary record. The sedimentary records of the Proterozoic and Archeozoic eras are not well enough known to be used. So, we have only the incomplete radioactive data to determine the time represented by these very ancient eras. |
Ex 2. Do the translation making further use of it in your retelling.
Возраст земной коры уже определен, хотя возраст земли как планеты еще не известен. Определить возраст земной коры стало возможным, когда был изучен радиоактивный распад.
На скорость распада не действуют ни раскаленное состояние, ни охлаждение, ни огромное давление. При всех условиях один грамм урана выделяет ежегодно одно и то же количество свинца. Заключающийся в некоторых минералах уран распадается, а вместо него накапливается свинец. Чем меньше остается урана, тем больше становится свинца.
Значит, определяя в горной породе относительное количество урана и выделившегося из него свинца, можно определить ее возраст.
Ученые пришли к выводу, что древнейшие горные породы образовались за 1600-1800 миллионов лет до наших дней.
Listening Comprehension
Text “The Earth’s shape”
Part A. Pre-listening Activities
Task 1. Make sure that you know the following words and word phrases.
consider v – рассматривать
for scientific purposes – для научных целей
sufficient a – достаточный
accurate a – точный, правильный
adequate a – достаточный
oblate a – сплющенный или сжатый у полюсов
geoid n – геоид
bulge n – выпуклость
stick (out) v – выступать
arrow n – стрела, что-л., напоминающее по форме стрелу
transparency n – диапозитив
deviation n – отклонение
exaggerate v – преувеличивать
mirror v – отражать
dent n – выемка, вмятина
Task 2. Before listening answer the following questions.
1. Who was the first to declare that the earth was a sphere? (Parmenides)
2. When did he do that? (The fifth century B. C.)
3. How did Parmenides realize it? (Probably from listening to travellers).
4. Who used arguments showing that the earth is spherical? (Aristotle).
5. Is the earth a perfect sphere? (A spheroid flattened near the poles).
Part B. Listening Activities
Task 1. As you listen to the tape make brief notes to help you answer the following questions.
1. The lecturer says one word is not adequate to describe the earth shape. What is that word?
2. How many questions will be looked at in this lecture?
3. What term does the lecturer want you to note?
4. Who first computed the earth in terms of an oblate spheroid?
5. What terms does the lecture use to describe the “bits that stick out” and the “dents”?
6. Which, if any, of the three models is 100 % accurate?
Task 2. Listen to the tape once more and
A) fill in the gaps.
1. For most people the word “round” is … .
2. The sphere is not … for a great number of scientific purposes.
3. The … spheroid is actually the form the earth would have.
4. This oblate spheroid has become known as the … … .
5. It is called that after … .