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 Is an intrusive rock body younger than the rock it intrudes?
 What is younger: a fault or the rock layers it cuts?

Task 5. Look at Figure 4.2. It shows formation of an angular unconformity. Look at
the figure and say: does an angular unconformity represent an extended period during
which deformation and erosion occurred? Talk about angular unconformity using the
figure and the information from the text.

Task 6. Look at Figure 4.3. This is an example how can a relative time scale for the
rocks and events in the area of the cross-section be established. Remember that this
method gives us no idea of how many years of Earth history are represented, for we have
no numerical dates. Nor do we know how this area compares to any other. Analyze the
figure.

Task 7. Find English equivalents for the following (see the text). Try to build up
your own sentences with them.
Дізнаватись; уявляти собі раніше; численні спроби; уточнювати (вказувати)
фактичну кількість років; точно визначити чисельні дати для гірських порід; бути цінним і
до сих пір широко використовуватись; важливе наукове досягнення; дуже просте правило;
чітко сформулювати принцип; залягати горизонтально; нахилений під гострим кутом;
логічний та зрозумілий (про принцип); допомагати визначити; представляти значні
геологічні події в історії Землі; бути відсутнім у геологічному літописі; шари, які
залягають полого (або горизонтально); важко визначити; земна поверхня, яка зазнала
ерозії у древні часи; відокремлювати старі метаморфічні або інтрузивні магматичні
породи від шарів (пластів) осадових порід молодшого віку; ерозія вищерозміщених
гірських порід.

Task 8. Build up an annotation to Text 1.

GRAMMAR FOCUS

Modal verbs (Part 1)
Task 1. Explain the use of modal verbs with different Infinitive forms and translate
the sentences:
1. To be detected the electron must have an interaction with the detector.
2. He cannot have made such a serious mistake in his experiment.
3. All the preparations for the experiments used in air navigation have to be small and
light in weight.
4. According to the law of conservation of energy, the energy spent in starting the body must
be equal to that when it is stopped.
5. Surface tension may be expressed in any unit of energy per unit of area.

Task 2. Explain the use of modal verbs and their equivalents in the following
sentences and translate them.

1. Within this time the maximum change in conductivity was to be observed.
2. However useful it may be, it cannot be employed to advantage unless it can be obtained
in adequate quantities and at reasonable price.
3. For other types of signals the carrier level may have to be increased.
4. In order to make the satellite a whole number of highly involved scientific and
engineering problems had to be solved.