Page 9 - Reading Success B6

Crude oil is a liquid that is mostly composed of hydrogen and carbon that
occurs naturally. While it can be found above ground in oil seeps, it is normally

found beneath the earth’s surface. Crude oil is required to produce the fuel we use
in cars, trucks, trains, boats, and airplanes. However, it is also used in a wide

variety of other products such as asphalt for roads, lubricants for all kinds of
machines, plastics for toys, bottles, food wrappers, and computers.

It is believed that crude oil was formed from very small plants and animals that

lived in ancient seas and oceans a very long time ago. When these plants or
animals died they sunk to the bottom of the ocean and mixed with mud, sand, and

clay. This mixture of mud and organic (once living) material is rich in hydrogen
and carbon, which are the primary elements of crude oil. As the years go by more

and more mud and other sediments are deposited on the ocean floor. After
millions of years this combination of mud and organic material is buried many feet

below the earth’s surface.

As one goes deeper into the earth the temperature increases. The pressure
increases as well due to the weight of all the rocks and mud above. The increased

pressure and temperature causes the organic material to become crude oil. If the
temperature is further increased the crude oil can become natural gas.

Main Idea

What is the main idea of this story?

a. the uses of crude oil

b. how crude oil is mined
c. the uses and formation of crude oil

d. how crude oil was discovered

12_Reading Success B 6