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SAI INTERNATIONAL SCHOOL
STD VII SUBJECT - GEOGRAPHY
TOPIC-CH – 2-Inside our Earth(LESSON NOTES)

Sub-topic- Rock cycle

Notes- Importance of rocks-

ÿ Rocks and minerals are all around us! They help us to develop new technologies
and are used in our everyday lives.
ÿ Rocks are one of the best sources of fuel and power. For example, we derive coal,
petroleum and even natural gas from rocks.
ÿ Minerals are extracted from rocks. Many important minerals such as gold and
diamond are mined directly from rocks.
ÿ Salt can be extracted from rocks.
ÿ Rocks also serve as a source of water supply. Many springs and wells all over the
world get their sources from rocks.
ÿ Rocks and minerals are important for learning about earth materials, structure, and
systems.
ÿ Rocks are one of the beauties of nature and therefore can serve as tourist
attraction.
ÿ Construction material is obtained from rocks.

ROCK CYCLE

The rock cycle is the process by which rocks of one kind change into rocks of
[
another kind. Rocks are constantly changing in what is called the rock cycle. It
takes millions of years for rocks to change.
v Melted rock or magma is sent to the earth's surface by a volcano. It cools and
forms an igneous rock.

v Next the weather, or a river, and other events will slowly break up this rock into
small pieces of sediment.

v As sediment builds up and hardens over years, a sedimentary rock is formed.

v Slowly this sediment rock will get covered with other rocks and end up deep in the
Earth's crust.

v When the pressure and heat get high enough, the sedimentary rock will
metamorphose into a metamorphic rock and the cycle will start over again.

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