Page 114 - SST Class 07

long history of the earth. Himalaya contains We have already learnt about the four major
deposits of sedimentary rocks once laid down in domains of the earth— lithosphere, hydrosphere,
a shallow sea in that region. While some of the atmosphere and biosphere in previous classes.
changes are due to naturals processes, others are Let us refresh our knowledge about these four
caused by human activities. domains.

Human environment has also undergone Lithosphere
changes in space and time. Human dwellings Lithos in Greek means ‘stone’. The sphere of
have changed from a hut to skyscrapers. Villages rocks or stone refers to the rocky crust of the
have developed into towns, cities and mega earth extending upto 100 km in depth.
cities. Political institutions have changed from an Obviously, it does not cover the whole of the
autocratic set up to a democratic set up. earth. This is also the life zone beyond which life
Religions have also changed. Buddhism, Jainism cannot survive.
and Islam are relatively new when compared to This life sustaining zone is composed of rocks
Hinduism. Means of transport and communica- rich in silica and aluminum, called sial layer. The
tions have also changed in the course of time. basins that support the oceans are composed of
NATURAL ENVIRONMENT silica and magnesium called sima. The sial and
The natural sima form the crustal part of the earth. In this
environment part, rocks are found in solid state in great
Abiotic
includes both Environment variety. Since rocks are aggregates of minerals,
biotic compo- they also help to support life. The rocks of the
nents (plants and crust come from the interior of the earth and are
Total
animals) and Environ- distributed and deposited in layers. They have
ment
abiotic compo- varying responses to internal forces of the earth.
Human Biotic
nents (air, water Environment Environment In the process of rock formation, both the inter-
and soil). nal and external elements take part. This is the
most essential feature of our total environment.
Total Environment Crust

Solar Energy Mantle
Core

Atmosphere Hydrosphere

Biosphere
(Living systems)

Hydrosphere

The hydrosphere is the liquid water component
Lithosphere
Heat Heat of the earth. The hydrosphere includes water
storage areas such as, seas, lakes, ponds, rivers,
and streams.
Four Domains of the Earth

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