Page 17 - READING COMPANION TO ENGLISH EXAMS

1.3 ROCK FORMATION

The Rock Cycle

Rock is a naturally occurring mass of one or more minerals formed in the Earth’s crust and on its surface by
temperature, pressure, time, and environmental changes. Based on the processes that resulted in their formation,
rocks are conventionally classified into three major classes: igneous, sedimentary, and metamorphic. These
three classes are then further subdivided into groups and types diversely depending on various factors, the most
significant of which are chemical, mineralogical, and textural characteristics. Igneous rocks—derived from the
Latin word for fire—solidify from magma, a molten mixture of rock-forming minerals and substances evaporating,
such as gases and steam. This type of rock forms at high temperatures since its constituent minerals crystallise
from molten material. Another one, sedimentary rocks, are created by depositing mineral or organic particles
on the Earth’s surface with the help of running water, wind, ice, or living organisms. Rivers, oceans, winds, and
rain runoff can carry the particles washed off eroding rocks and transport them to a new location. Once enough
particles removed from the rocks collect and settle in a new location, the lowest layers can compact and cement
together to create solid rock. Meanwhile, the accumulated residue creates layers, which can be distinguished
by colour, particle size, cement type, or internal arrangement. The third type, metamorphic rocks, are formed by
the alteration of pre-existent rocks in return for changing environmental conditions, such as temperature change,
pressure, mechanical stress, and chemical component addition or subtraction.

a Match the highlighted words and phrases in the passage to the definitions below.
1. : one of the parts of something that combine to form the whole
2. : the outside or top layer of something
3. : a very small piece of something
4. : to come or develop from something
5. : to be carried away from someone or something by the action of water or another liquid
6. : in several very different ways
7. : being present in a place at or from an earlier time
8. : to press something tightly together
9. : in a way that is normal and ordinary, and perhaps not very interesting
10. : to be a characteristic that makes two people, animals, or things different
b Rewrite the sentences below considering the original meaning of each sentence and using the
words in parentheses.
1. Rocks have quite different characteristics because of their mineral components, the ways in which they are
composed, and the processes that have influenced them since formation. (constituent)

2. Having formed billions of years ago at depths between 150 and 250 kilometres in the Earth’s mantle
under extreme temperature and pressure, diamonds are found only rarely, which makes them commonly
valuable. (conventionally)

3. What makes granite different from all other rocks is that it is one of the most common rocks we come
across daily, such as in kitchen countertops, house floor tiles, etc. (diversely)

4. Since different mineral interactions can result in various formations, the abundance and diversity of
minerals in the Earth’s crust explain why numerous rock types have existed. (surface)

5. Not only were the rocks formed by the particles taken from existing substances, but environmental factors
also contributed to the rock formation process and their properties. (wash off)

16
Ortaöğretim Genel Müdürlüğü Öğretim Programları ve Ders Kitapları Daire Başkanlığı