Chapter 7: EARTH
Lithosphere is broken into
many small plates. These plates move around due to the
motion of magma inside the earth. This motion leads to
plates moving a few millimeters each year. The movement of
these plates causes changes on the surface of the earth.
The earth movements are divided on the basis of the forces
that cause them.
forces: acting in the interior of the earth.
E.g. Earthquakes, landslides, building mountains,
forces: acting on the surface of the earth.
E.g. Rivers, winds, glaciers, sea waves.
Work of a river:
river erodes the landscape due to the running water. When
a river tumbles over a very steep rock or down a river
valley it forms a waterfall. As the river enters a plain
it twists and turns to form large bends known as meanders.
Due to endless deposition and erosion the ends of the
meander loop come closer and closer and finally form an ox
bow lake which is cutoff from the river. If the river
overflows the banks it deposits fertile soil or other
elements along its banks called sediments. This leads to
formation of a flood plain.
the river closes to the sea its speed becomes slower and
the sediments it carried are deposited. This leads to a
breakup of the river into distributaries and each
distributary forms a mouth. The collection of sediments
from all mouths are called delta.
too carry sediments like rocks, sands which are deposited
on the path, these are called glacial
Even winds act as weathering agents, winds lifts and
carries sands from one place to another. When the wind
stops blowing the sands are deposited. Such sand deposits
on large areas are called loess.
Conditions favoring formation of Delta
- Active vertical and lateral erosion to provide sediments that shall be deposited at deltas.
- Preferrably sheltered and tideless coast.
- Sea adjoining delta should be shallow
- There should be no large rivers in the course to filter off the sediments.
- There should be no strong current flowing at right angles at the mouth of the river, washing away the sediments.
Estuaries are better than deltas for formation of ports as deltas see deposition of large quantities of silts thus preventing large ships from setting up anchor near ports.
Course of a river:
Upper course / Mountain course [stage of youth]: V-shaped valleys, gorges or canyons are formed. Rapids, cataracts or waterfalls also occur mostly in this stage but can also occur in lesser numbers in the next stages also.
Middle course / valley course [stage of maturity]:Interlocking spurs and meandering flow is seen. Also river cliffs and slip off slopes are common.
Lower or plain course [stage of old age]:Flood plains are seen at this stage and banks of the river are raised due to deposits forming leeves. Delta and ox bow lakes are also seen.
Land use patterns:
has 67% of its total land under forests, Canada has 52% of
its land under developmental use, India has 56% of its
area under cultivation and Australia has 56% of its area
Slavery or bonded labor
Better social amenities
Lack of food
Continuous trade and economic
Natural hazards / climate
Fragmentation of family owned
Table 1: Push
pull factors responsible for migration from villages to
Solar System and Planets:
to the sun but no atmosphere.
closest to the earth. Atmosphere has CO2 and poisonous
red planet or earth’s twin.
planet but not with any solid surface
planet with a ring.
highly tilted rotation axis.
cold and dark surface. Smaller than earth.
inner planets are rocky with less number of satellites
and outer planets are gaseous with many satellites.
It is a unique and representative ecosystem of terrestrial
and aquatic areas. These are recognized under the UNESCO's
man and biodiversity program. There are currently 18
reserves out of which 10 are recognized by UNESCO’s
world network of biosphere reserves viz. Nilgiri,
Nandadevi, Sunderban, Nokrek, Similipal, Panchmarhi,
Amarkantak, Agastyamala, Great Nicobar and Gulf of Mannar.
reserves have three areas:
here no human activity is permitted. No entry is allowed
except with permissions for special purposes only.
Buffer: here greater
variety of resource use strategies, research and
educational activities are permitted.
zone: it is an area of active cooperation between reserve
management and local people. Here economic activities are
permitted if they are in sync with conservation goals.
Fig 2: Biosphere
Fossil fuel formation:
oil, natural gas are the major fossil fuels in the
world. Coal formation goes through the following stages:
1 [peat]: partially decayed plant matter in swamps. It
has low heat content.
2 [lignite]: low cost, low sulphur and low heat content.
3 [bituminous]: Generally used as fuel due to high heat
4 [anthracite]: hard coal with low sulphur and high heat
and gas are found along geologically young tectonic belt
at plate boundaries where depositional basins are more
likely to occur.
obtained by converting biomass into alcohol to be used as
fuel. Jatropha and Pongamia are plants that can be used
to obtain bio-diesel.
obtained from sugarcane, sorghum can be used as a
substitute for petrol.
Q. In India, the problem of soil erosion is associated with which of the following?
Select the correct answer using the code given below. (UPSC CSAT 2014)
1 and 2 only
1 and 3 only
1, 2 and 3
Ans . B
Terrace Cultivation helps reduce soil erosion
Q.Lichens, which are capable of initiating ecological succession even on a bare rock, are actually a symbiotic association of (UPSC CSAT 2014)
algae and bacteria
algae and fungi
bacteria and fungi
fungi and mosses
Ans . B
In organisms called lichens, a chlorophyll-containing partner, which is an algae, and a fungus live together fungus provides shelter, water and minerals to the alga and, in return, the alga provides food which it prepares by photosynthesis
Q.With reference to two non-conventional energy sources called ‘coal bed methane’ and ‘shale gas’, consider the following ‘statements:
Coal bed methane is the pure methane gas extracted from coal seams, while shale gas is a mixture of propane and butane only that can be extracted from fine-grained sedimentary rocks.
In India abundant coal bed methane sources exist, but so far no shale gas sources have been found.
Which of the statements given above is/are correct? (UPSC CSAT 2014)
Both 1 and 2
Neither 1 nor 2
Ans . D
Shale gas contains methane along with "propane and butane".
Shale gas resources exist in India.
Q.In India, cluster bean (Guar) is traditionally used as a vegetable or animal feed, but recently the cultivation of this has assumed significance. Which one of the following statements is correct in this context? (UPSC CSAT 2014)
The oil extracted from seeds is used in the manufacture of biodegradable plastics
The gum made from its seeds is used in the extraction of shale gas
The leaf extract of this plant has the properties of anti-histamines
It is a source of high quality biodiesel
Ans . B
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