Read the text. For Questions 1-6, choose the right paragraph A-E. One question is extra. Fill in the table.

1.How long has the gravimetric method been used?
2.What information do geologists analyse to decide what type of material is under the ground?
3.What instrument is used to make gravity measurements?
4. What are the advantages of the method?
5. When was the method first used?
6. What influences the gravitational field?

A. The primary goal of studying detailed gravity data is to provide a better understanding of the subsurface geology. The gravity method is a cheap, non-destructive remote method.The equipment for gravity measurements is small and portable. It is called a gravimeter.
B. It is a well-known fact that mining of natural resources often damages the environment. It is better to make measurements of gravity fields before mining in order to reduce the negative influence of excavation works.
C. How do geologists understand where to mine for oil, gas and other minerals? There is a wide range in density among rock types. The success of the gravity method depends on different earth materials having different densities that produce variations in the measured gravitational field.
D. These variations can then be interpreted by computer methods to determine the depth, geometry and density that causes the gravity field variations. This is how geologists can predict the type of material beneath our feet.
E. By the beginning of the 1930s, it became obvious that the gravimetric method was very effective in searching for minerals, oil, gas and coal. Due to this method oil fields were discovered in the Middle Volga, in the Arctic region, in Western Siberia and Sakhalin.

	A	B	C	D	E
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