Fig. 9 . Composition of the Earth’s crust. 1 – basalt, 2 – intrusion; 3 – mantle; 4 – crystalline rock; 5 – granite; 6 – sedimentary rock.
1. What does the Earth consist of?
A. shells
B. beds
C. layers
D. parts
2. The globe surrounded by a gaseous envelope is called
A. hydrosphere
B. asthenosphere
C. lithosphere
D. atmosphere
3. The atmosphere consists of
A. nitrogen and carbon
B. oxygen and nitrogen
C. carbon and oxygen
D. hydrogen and oxygen
4. The ocean basin makes up approximately _______ of the Earth.
A. one third
B. three fourths
C. two thirds
D. one fourth
5. One third of the Earth’s surface consists of
A. land and water
B. isles and islands
C. continents and mountains
D. continents and islands
6. Continental crust is of _________ composition.
A. basaltic
B. granitic
C. dolomitic
D. limestone
7. Crust is composed of
A. skin
B. layer
C. shell
D. ball
8. Moho is a zone between
A. outer core and inner core
B. crust and atmosphere
C. mantle and outer core
D. crust and mantle
9. The mantle is rich in
A. iron
B. silica
C. magnesium
D. basalt
10. The asthenosphere is a
A. weak sphere
B. rigid sphere
C. ductile sphere
D. finite sphere
11. The lithosphere is divided into how many plates?
A. six
B. five
C. nine
D. seven
12. Where is the transition zone located?
A. above the upper mantle
B. above the lower mantle
C. near the lithosphere
D. above the core
13. What letter stands for the core-mantle boundary?
A. A
B. B
C. D
D. C
14. Why does the core represent 31% of the Earth’s mass?
A. density
B. gravity
C. weight
D. mass
Read the text once more and fill in the chart with the necessary information. Then label the diagram and give an explanation what each item means.
THE EARTH
| Part | Division | Volume Composition Depth | Other terms |
3.1.3. Using this diagram, answer the following questions as briefly as possible. Use the information from the text « The Earth» and describe the diagram.( Paul Nixon & Alferdo Bezzi “English for Geologists”)
1. Does the Moho separate the mantle and the crust?
2. Is the lithosphere topped by a relatively lightweight crust?
3. Does the crust vary in thickness?
4. Where is the crust thinnest?
5. Does the lithosphere include the uppermost part of the mantle and crust?
6. Is the asthenosphere rigid?
3.2 DETAILED READING - Earth’s size and shape Read the text and then complete the task. Fill in the gaps.
Instruments including artificial satellites have helped scientists work out the Earth’s size, shape and other features. We know ours is one of the smallest, lightest planets of the solar system. Four others far exceed its mass and volume. But no planet has a greater density (5.5 times that of water). Careful measurements prove the ball-like Earth is not in fact a sphere. It measures 24,901.5 mi. (40 074 km) around the equator, but only 24,859.7 mi. (40 008 km) around the poles. So our planet bugles slightly at the equator and is slightly flattened at the poles.
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Centrifugal force created by the Earth’s spin produced this shape, an oblate spheroid. Even that description oversimplifies, for the Earth is very slightly pear-shaped.
Scientists accordingly use the term “geoid“ (earth shaped) to describe the Earth’s hypothetical, mean-sea-level surface-ignoring wrinkles formed by mountain chains and ocean floors. Geoid measurement involves taking sea-level gravity readings by gravimeter and studying “kinks” in orbits of artificial satellites. Both reveal so-called gravity anomalies reflecting local differences in mass in the Earth’s crust and mantle. Such differences account for vast but slight dips and bumps in the geoid’s surface. Gravity anomalies also reinforce the theory of isostasy – a state of balance in the Earth’s crust where continents of light material float on a denser substance into which deep continental “roots” project like the underwater mass of floating icebergs. (Lambert “The Field Guide to Geology” 1988, Cambridge University Press)
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