What are waterfalls?

 

Landforms

Rivers, lakes and streams are natural bodies of water that
are found across the world. When it rains or when snow on
mountains melts, the water flows down the slopes, forming
streams. Several streams join together to form a river. Small
rivers drain into larger rivers. The water in rivers keeps flowing
until it reaches the sea, though a few rivers hit very dry desert
land and dry up.

 What are waterfalls?
Sometimes the surface over which a river
flows drops suddenly. Then the water flows
over to form a waterfall. There are different
kinds of waterfalls. A cascade waterfall flows
down a series of natural rock steps. There
are no steps in a free-falling waterfall. In a
fan waterfall, the water spreads out as it falls
down. Angel Falls in Venezuela is the highest
free-falling waterfall in the world. The water
falls 807 metres (2,648 feet) without any
interruption. Often, the sunlight falling over
a waterfall creates a rainbow.
 Do rivers flood?
 Yes, they do. Rivers often overflow their
banks and flood the land around them. This
can happen when there has been a lot of rain
or a lot of snow has melted in the mountain
where the river starts its journey. Floods are
often very destructive. They can damage
crops and houses and kill people. But in the
long run they can also do some good. They
bring fresh soil down the river and spread it
on the flooded land. Egyptian farmers have
been dependent on the annual flooding of
the Nile for thousands of years. The Amazon
and the Ganges rivers regularly bring fertile
soil to the agricultural areas downstream.
 How are lakes formed?
 Sometimes, rainwater collects in big
hollows in the ground to form lakes. These
hollows can be formed by the movement
of the plates that make up the Earth’s crust,
or by moving glaciers. Lakes are also formed
by landslides that leave huge depressions in
the ground. Most lakes and rivers contain
freshwater. In places containing a large
amount of salt, lake water can be salty.


1. Which is the largest freshwater lake in the world?
Lake Superior, one of the Great Lakes of North America, is the
largest freshwater lake in the world. This lake is over 560 kilometres
(350 miles) long and about 257 kilometres (160 miles) wide.

2. What is the Sahara known for?
The Sahara is the largest hot desert in the world. Located in Africa, it spreads across Mauritania,
Morocco, Mali, Algeria, Tunisia, Niger, Libya, Chad, Egypt, Sudan and Eritrea.

3. Which is the longest river?
The Nile is the longest river on Earth. It flows for 6,695 kilometres (4,184 miles).

4. Why is Lake Baikal special?
Lake Baikal in southern Siberia is the deepest lake in the world, with a maximum depth
of 1,637 metres (5,371 feet). It has been around for almost 30 million years.