Download 3rd Science - Army Goodwill School

ARMY GOODWILL SCHOOL BONIYAR
HANDOUTS
SUBJECT: SCIENCE
CLASS: 3RD
TOPIC : ROCKS AND SOIL
Introduction :We already know that our earth is made up of rocks. Rocks are made
of two or more minerals. Rocks differ in their size, shape, color, texture, origin and use.
Soil in the topmost layer of the earth’s surface. Soli is formed over a long period of
time. Soil is important to us in many ways.
Rocks and its types :Each rock is made of two or more minerals. Rocks can be
divided in three types on the basis of how they are formed.
(a)
(b)
(c)
Rocks under water. E.g. Sandstone, limestone.
Rocks deep inside the earth. E.g. Marble, state.
Rocks near the earth’s surface. E.g. Basalt, granite.
Rocks are mostly used for construction purposes. Our famous buildings like Taj
Mahal is made of Marble and Red Fort is made of sandstone.
Soil :- Soil is the topmost layer of earth’s surface. It consists of a mixture of particles of
broken rocks, minerals and decaying plants and animals.
Soil is formed over a long period of time due to weathering of rocks and minerals.
Contents of Soil :- Soil contains pieces of broken rocks, minerals, decaying plants and
animals (humus), air and water.
Types of Soil :Soil varies in color and composition. There are three types of soil
sandy, clayey and loam.
(a)
Sandy soil - it is composed of beg sand particles. It does not hold much
water.
(b)
Clayey soil - it is composed of very fine particles. It holds a lot of water.
(c)
Loam soil – loam is a mixture of sand and clay. It can hold both air and
water. It is ideal for growth of plants.
Uses of soil :(a)
(b)
(c)
(d)
Soil is important to us in many ways:-
Soil provides water and minerals to plants for growth.
Soil prevents floods by absorbing rain water.
Soil is the habitat of many tiny creatures like snails, earthworms, etc.
Soil provides us many useful minerals like diamond, graphite.
Conclusion :- This chapter tells us about the different types of rocks and their uses and
what is soil, its types and uses.