Page 111 - SST Class 07

Vertical Movement or fissures in the earth’s
surface. The faulting can be
Vertical movements result in a rise or fall of the
horizontal or vertical, or
earth’s crust. These are continent-building
movements and cause a large scale uplift (rising) both types can occur
simultaneously.
and subsidence (sinking). Faulting
A plateau is formed at the place of an uplift, while Landforms and Human Activity
a valley is formed at the place of a subsidence. In addition to various earth movements, humans
also cause a change in the landforms on a large
Horizontal Movement
scale. Cutting down of trees; construction of
When the tectonic plates compress against each roads, buildings, dams and canals; mining; and
other, it results in folding ; and when the tectonic the use of explosives for construction or warfare
plates cause tension, faulting occurs. are some of human activities which cause a

Folding : Folding occurs when two plates collide. change in the earth. Man has become so powerful
The rocks often bend than break. This collision that he has disturbed the ecological balance by his
results in up-folds called anticlines and down-folds activities. Human activities are
called synclines . The causing irreparable harm to the
anticlines cause environment. Time is ripe when
mountains, such as we should become aware of
Himalayas in India and this problem and save the earth
Andes in America, from such changes.
while synclines result in A dam
Folding
valleys. Just Think!

Faulting : When tectonic plates move away from
each other, a tension is caused resulting in cracks How have human activities greatly changed the
earth’s surface and harmed the environment?

v The endogenic forces work within the earth and the exogenic forces outside it.
v Earth movements can occur suddenly or gradually.

v A volcano occurs when the magma erupts out of a fissure on the earth’s crust.
v An earthquake occurs due to tectonic movements.
v The earth’s surface undergoes a change by weathering and erosion.
v Tectonic movements can be vertical or horizontal.

v Human activity has greatly changed the earth’s surface and harmed the environment.
v The faulting can be horizontal or vertical, or both types can occur simultaneously.

A. Tick (3) the right option :
1. An exogenic force works ______________ the earth.
(a) within (b) outside (c) none of these

Changing Earth and Landforms
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