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river. Thus, long ridges of low height are formed the roof of the caves remains, hence forming sea
along the banks. These are called natural levees. arches. The erosion further breaks the roof and
When the river reaches its mouth, it carries a only the walls remain. These wall-like features
large volume of water and alluvium. The excess are called stacks. Sea cliff is the steep rocky coast
load is deposited as sand bars in the wide river rising almost vertically above sea water. The sea
channel. This divides the main channel into waves deposit sediments along the shores form-
several channels, which are called distributaries. ing beaches.
In this stage, triangular-shaped land is formed WORK OF MOVING ICE
between the distributaries due to deposition of The snow which falls in high altitudes and high
sediments. This is called a delta. The Greek letter latitudes accumulates to form snowfields. The
D (Delta) was first used by the Greek historian snowfields are situated above the snowline.
Herodotus for the triangular depositional land on The river of snow and ice, which moves very
the mouth of the Nile river. The delta formed by slowly is called a glacier. Glaciers flow out from
the Ganga and the Brahmaputra rivers is the the snowfields. Like any other agent, the work of
largest in the world. a glacier is erosion, transportation and deposi-
WORK OF SEA WAVES tion. A glacier can modify and sometimes totally
The erosion and deposition by water in the form remove the existing landforms and substitute
of sea waves leads to the formation of coastal them with new and distinctly different ones.
landforms. Some coastal landforms are as follows :
g Sea Caves
g Sea Arches
g Stacks
g Sea Cliff
g Beaches
Stack
Glacier
Pure ice itself cannot do much work. When the
glacier passes through a valley, rock fragments
Sea Cave fall into moving ice from the mountain slopes. It
Sea Arch
Sea Arch
Sea Arch
also picks up rock pieces from the valley floor.
These rocks act as tools of erosion. These rocks
rub against the sides and the valley floor. This
creates a U-shaped valley with a flat bottom and
Sea Cave, Sea Arch and Stack
almost vertical sides.
Sea waves continuously strike at the rocks. This
The glacier carves out deep hollows along the
leads to cracks. The cracks become larger and
slope of a mountain. It develops an armchair-like
wider overtime. Thus, hollow like caves are
depression, called cirque. When glacial ice melts,
formed on the rocks. They are called sea caves.
the depression is filled up with water and forms a
As these cavities become bigger and bigger, only
lake. This lake is called tarn.
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