1. weathering
The rocks break into small
pieces like it is called
weathering. As this action
continues, the size of the
rocks reduces and makes
way for soil formation.
2. As a result of weathering, rocks
disintegrate and becomes small
pieces and when the organic content
mix with this, in course of time, soil is
formed. For the formation of one
inch of soil, it takes about a thousand
or more years.
3. Weathering is mainly of
three types
•Mechanical weathering
•Chemical weathering
•Biological weathering
4. Mechanical weathering
Changes in
temperature and the
freezing of the water in
the cracks of the rocks
cause mechanical
weathering.
5. Changes in temperature
Rocks expand due to the heat of the
sun. the different minerals in the
rocks expand in different
magnitudes, on these rocks if
suddenly rain falls or at night
6. Freezing of water in the
cracks in rocks
• During the day, the heat of the sun causes the
snow to melt and water fills the cracks in the
rocks. At night when the temperature drops to
below freezing point, the water in these cracks
freezes and becomes ice.
7. Exfoliation
During the day, the rocks become
heated and expand with the rays
of the sun and at night the
temperature decreases, they
contract, this alternate expansion
and contraction causes the other
surface of the rocks to break into
layers. This kind of peeling away
of rock layers is called exfoliation.
8. Chemical weathering
• When the rain falls on
the rocks chemical
action takes place
between the minerals in
the rocks and the rain
water. As a result of this,
there can be
disintegration of the
rocks. This is called
chemical weathering.
9. Biological weathering
The roots of the trees
penetrate into the cracks
of the rocks and small
creatures make their
homes in these spaces.
These also cause the
disintegration of rocks.
This is called biological
weathering.
