Text How is oil located underground?

Men have developed certain fairly good methods to look for and find oil. But first, how does oil get into the ground to begin with?

Scientists think that petroleum was formed from plants and animals that lived ages ago in and around warm seas that covered much of the earth. As the plants and animals died, they piled up on the sea bottom. In time, millions of tons of sand and mud covered them. Under pressure, the mud and sand changed to rock. The plants and animals turned to a dark liquid trapped in the pores of the rock.

So when men go looking for oil, they know that it is most likely to be found in rocks that used to be the bottoms of old seas. However, oil does not collect in all these rocks. It collects in places called “traps”. An oil trap consists of porous rock between layers of nonporous rock. The oil collects in tiny spaces in the rock.

The oil hunter searches for oil traps in several ways, using scientific instruments. These instruments do not actually show whether there is oil, they only help the oil hunter locate what may be an oil trap.

One of the instruments is a gravity meter. Heavy rocks pull harder, or have a greater force of gravity, than light rocks. The gravity meter gives clues to underground formations by measuring the “pull” of buried rocks.

A magnetometer, which measures variations in the earth’s magnetic field, may also be used to gain information on underground rock formations. But the most widely used method for searching for oil is to make a small earthquake by setting off a charge of dynamite. When the earth’s shivers, which travel faster through some types of rock than they do through others, are timed and measured.

But there is still no guarantee after all these measurements that oil will actually be found in any particular spot!

Ex.1 Think and answer.

1 What is petroleum formed from?

2 Where did ancient plants and animals live?

3 How did mud and sand change into rock?

4 Where is oil likely to be found?

5 What are traps?

6 Can an oil hunter locate oil trap?

7 How does a gravity meter work?

8 What is a magnetometer?

9 What methods are used in oil hunting?

10 Are there any guarantee that oil will actually be found in any particular spot?

Text How were the oceans formed?

There are many things about our own earth that still remain a mystery to us, and one of them is how the oceans were formed.

Actually, we do not even know for sure how old the oceans are. It seems certain that oceans did not exist in they first came into being as clouds of vapor which turned into water as the earth grew cool. Estimates have been made of the ocean’s age based on the amount of mineral salt in the ocean today. These estimates range between 500,000,000 and 1,000,000,000 years.

Scientists are pretty sure that most of the earth’s land was covered by the sea at one time in the past. Some areas of the earth have been under water several times. But we do not know if any part of the deep ocean ever was land, or whether any land existing today was once beneath the deep ocean.

There is a great deal of evidence to show that certain parts of the land were once the bottom of shallow seas. For example, most of the limestone, sandstone, and shale found on land were deposited sediments. The chalk that is found in England, Texas, and Kansas was deposited on the bed of a sea. It is made up of the shells of tiny creatures that sank to the ocean bed to form what we call chalk.

Today, the waters of all the oceans cover nearly three-quarters of the surface of the earth. While there are many great ocean areas where man has not yet explored the bottom or taken soundings, we have a good, rough idea of what the bottom is like. There are sections that are like mountains ranges, and there are plateaus and plains. But the ocean bottom is not as varied as the surface of the continents.

Ex.1 Think and answer.

1 Do we know for sure how the oceans were formed?

2 Do we know for sure how old the oceans are?

3 What do we know for certain?

4 How could the scientists estimate the ocean’s age?

5 How can we prove that certain parts of the land were once under the water?

6 Can we prove that any part of ocean ever was land?

7 How does chalk form?

8 How much of the earth’s surface is now occupied by the oceans?

9 How can the bottom of the great oceans be studied?

10 How does the relief of the ocean bottom look like?

Text London fogs

Because of its geographical position in a deep river valley London is occasionally enveloped by unusually thick fog. The worst of these fogs began on 4^th December, 1952 and there was a similar one in December, 1963. All traffic was forced to a standstill as visibility fell to nil. The streets near the centre of London were jammed with buses crawling along at two miles per hour. Before long all had stopped. Drivers abandoned buses and cars. People who usually travelled by road decided to take the underground with the result that the entrances had to be closed to prevent crushing. People caught in the fog literally felt their way with one hand along the walls of buildings, holding the other out before them to avoid colliding with other people. At Covent Garden a performance had to be abandoned after the first act because so much fog had penetrated into the house that the audience could no longer see the singers clearly. It was a terrible fog and caused the death of some 4,000 people in London.

As a matter of fact this deadly kind of fog is called by Londoners “smog”. It is the kind of fog you get only in towns – particularly in the industrial areas. It is a mixture of smoke and fog together and it is dangerous and deadly especially for people who are suffering from any kind of respiratory troubles. In the big towns and cities you get very much smoke, it is concentrated because it doesn’t come from household chimneys only, but from all factories too. This is the stuff that does most of the damage because it contains so much different chemicals which, when we breathe in add as irritants to the whole of the respiratory system. Even the ordinary fog is pretty nasty.