Page 153 - SST Class 07

large water body, such as a sea, ocean or lake.
The place where the river joins another water
body is called the mouth. The area drained by
the river and its tributaries is called the river
basin.

The running water in the river carries out its work
in three ways :
1. It erodes the rocks over which it flows.
2. It transports the eroded materials.
3. It deposits the materials which it has trans-
Salto Angel Falls
ported.

The erosional work of the river results in the
widening and deepening of the river valley. Such
a valley is called a V-shaped Valley. In hilly areas,
the river moves swiftly. Thus, there is more
erosion and transportation of the sediments and
practically no deposition.

Victoria Falls
When the river leaves the mountains and enters
the plains, the flow is no longer swift. The floor of
the river valley widens due to continuous erosion
along its banks. The river twists and turns to form
large bends or loops. These are called meanders.
Now, the river erodes, transports and deposits
the sediments.
Rain on the River
Due to continuous erosion and deposition, the
When the water of the river falls almost vertically
meandering loops become almost circular and
down a steep valley side, a waterfall is formed.
come very close to each other. In due course of
They are important because they can be used to
time, the river is able to cut the strip of land
generate hydroelectricity. The steep sloping
between the two loops and takes a straight
segment of the swift-flowing river is called a
course. The circular loop that is left behind,
rapid.
completely cut-off from the main channel, forms
Jog or Gersoppa Falls on the Sharavati river in
an ox-bow lake.
Karnataka is the highest (about 260 m) waterfall
During floods, the river generally overflows its
in India. The highest waterfall in the world in the
banks. The fine alluvial soil brought by the river
Salto Angel Falls (975 m) in Venezuela in South
is deposited on the floor of valley. This fertile part
America and the Victoria Falls in Africa are also
is called flood plain. In the flood plain, the coarse
famous.
materials are deposited along the banks of the

Social Science-7 153