Page 95 - Science class 4

11 Formation, Erosion and

Conservation of Soil

l Soil l How is Soil formed?

Inside l Layers of Soil l Life in Soil
Inside
the l Types of Soil
the
Chapter
Chapter
1. Gravel 2. Sandy 3. Clayey 4. Loamy
l Soil Erosion l Conservation of Soil

SOIL

Soil is composed of organic and inorganic matter. The
organic matter consists of decayed plants and animals.

The inorganic matter consists of particles of rocks and
mineral salts. Soil is considered as a natural resource. It

is as important as air and water for our survival. We

need soil for growing crops, building houses and for
making pots and toys.

Plants get water and nutrients from the soil. Animals

and human beings depend on plants either directly or
indirectly for their food. So, there is lifeless without soil.

HOW IS SOIL FORMED ?
Soil is formed from rocks that are broken into very

small pieces. Rocks get heated up by the Sun. They
get cooled at night. Repeated heating and cooling

break them into smaller pieces. Flowing water
causes these rock pieces to bang against each
other. This further breaks the rocks into much

smaller pieces. These tiny pieces of rock get carried
away to far off places by water or wind. Gradually

they turn into powder-like substance called soil.
This powder, together with the remains of dead
animals and plants, make up the soil that we have

today.

Layer in the soil