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Rivers
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake,
a sea, or another river. Rivers are mostly formed when the glaciers high up in the
mountains melt in the summer heat and flow into the sea. Glaciers are huge pieces of
moving sheets of ice rather like
frozen rivers. Such rivers have
water throughout the year and
they are called perennial rivers.
The Ganga, Yamuna and their
tributaries are perennial rivers.

The River Ganga flows out of
Gaumukh, the holy cave of the
Himalayas by the mel ng of the
Gangotri glacier. The Yamuna on
the other hand is formed by the
mel ng of snow of the Yamunotri
glacier. Some rivers are rain-fed. The Krishna, Godavari and Kaveri rivers of the Deccan
plateau receive water from the rains. The Luni on the other hand is a seasonal river of
the deserts of Rajasthan. It flows only during the monsoon months.

Oceans and seas
An ocean is one of the major conven onal division of the World, which occupies two-
thirds of Earth's surface. An ocean is a huge water body. Water is abundant in oceans
and seas. There are five oceans in the world- Pacific, Atlan c, Indian, Arc c and
Antarc c.

A sea is also a large water body, but smaller than an ocean. Inspite of presence of
water in abundance, ocean and sea water is not fit for drinking because it is salty.
Water flowing through rivers, on its course, picks up small amounts of mineral salts
from the rocks and soil of the riverbeds. When this water flows into the oceans and
seas, it makes them salty.

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