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Presented byMohit kumar
PankajArun kumar
Ankit srivastava
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ORIGIN
OFTH
EEA
RTH
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Contents
Big
bang
theo
ry/ex
pans
ion
Orig
in of
galax
ies
Orig
in of
solar
syste
m
•Neb
ula hy
poth
esis
•Co
llision
or en
coun
ter hy
poth
esis
•Pla
nete
simal
hypo
thes
is
Orig
in of
the e
arth
oCr
ust, m
antle
and c
ore f
ormati
on
oAtm
osph
ere f
ormati
on
oLit
hosp
here
form
ation
oHyd
rosp
here
form
ation
Ea
rth hi
story
– Geo
logica
l time s
cale
•Pre
cambri
an Ti
me
•Pa
leozo
ic Era
•Mes
ozoic
Era
•Ce
nozo
ic Era
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BIG
BAN
G TH
EORY
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BIG BANGEXPANSION
APPROXIMATELY 13.7 BILLION YEARS AGO The whole universe was compressed into the confines of anatomic nucleus. Known as a singularity, this is the momentbefore creation when space and time did not exist. According to the prevailing cosmological models thatexplain our universe, an ineffable explosion, trillions ofdegrees in temperature on any measurement scale, that wasinfinitely dense, created not only fundamental subatomicParticles and thus matter and energy but space and timeitself. These events was occurred are termed as Big bang.
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ORIGIN OF GALAXIES
Gravity makes hydrogen and helium gas coalesce to form giant clouds that will became galaxies, smaller clumps of gas collapse to form the first stars.
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ORIGIN OF SOLAR SYSTEM There are three theories regarding the origin
of the solar system:-Nebula hypothesisCollision or encounter hyothesisPlanetesimal hypothesis
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NEBULA HYPOTHESIS` Planets and their satellites
were formed at same time as the sun. Space was filled by a rotating cloud (nebula) of hot gas and dust, as it cooled began to contract
Note: It is most acceptable theory, as
its modification has been made.
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Drawbacks of nebula hypothesis• The mass of material in each ring would be too
small to provide the gravitational attraction needed to cause the ring to condense into a planet.
• As the nebula contracted, the largest part of the angular momentum would remain associated with the main mass that condensed to form the Sun, which disagrees with the observed distribution of angular momentum in the solar system.
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COLLISION OR ENCOUNTER HYPOTHESIS
It assumed that the Sun was formed before the planets.
The gravitational attraction of a closely passing star or the blast of a nearby supernova explosion drew out a filament of solar material that condensed to form the planets.
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Drawbacks of collision hypothesis
The solar material would have been so hot that it would dissipate explosively into space rather than condense slowly to form the planets.
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PLANETESIMAL HYPOTHESIS The discredited theory that the close passage
of a star to the sun caused many small bodies (planetesimals) to be drawn from the sun, eventually coalescing to form the planets.
The planets and satellites of the solar system were formed by
gravitational aggregati- on of planetesimals.
ORIGIN OF THE EARTH
There are several formation process took place resulting in the origin of the earth:-
• Crust, mantle and core formation.• Atmosphere formation• Hydrosphere formation• Lithosphere formation
The Age of the Earth
4.6 billion years old =4,600,000,000
Image courtesy of NASA, http://en.wikipedia.org/wiki/Image:The_Earth_seen_from_Apollo_17.jpg#file
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EARTH HISTORYGEOLOGICALTIME SCALE
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The earth’s 4.6 billion year history is divided into major units of time:
Cenozoic Era Mesozoic Era Paleozoic Era
Precambrian Time
Image created by Jason Brechko for Lake George Association (Lake George, NY)http://www.lakegeorgeassociation.org/geology_facts.htm
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Precambrian Time• 4.6 billion years before present to
544 million years before present• Longest era with a sparse fossil
record• Origin of earth’s crust, first
atmosphere, and first seas• Earliest fossils of cyanobacteria use
photosynthesis to produce oxygen• Ozone layer in the atmosphere is
formed from oxygen
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Image courtesy of http://www.sharkbay.wa.gov.au/tourism/what_to_see_and_do/images/stromatolites_lge.jpg
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Paleozoic era • 544 million years before present to
245 million years before present• Marine communities flourish• Early fishes develop• Origin of amphibians, insects &
reptiles• Recurring ice ages/ Appalachians
mountains form• Spore-bearing plants dominate
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Images courtesy of: http://discover.edventures.com/images/termlib/p/paleozoic/support.gif, http://en.wikipedia.org/wiki/Trilobites
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Paleozoic era (continued)…
• 286 - 248 million years before present: Supercontinent of Pangea forms
• 248 million years before present: MASS EXTINCTION-90 % of all known families lost!
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
c
Image courtesy of http://www.ig.utexas.edu/research/projects/plates/teaching_ideas.htm?PHPSESSID=def1b9
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Mesozoic Era
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
• 245 million years before present - 65 million years before present
• The age of the dinosaurs!• Gymnosperms dominate land plant/
origin of angiosperms - flowering plants• Origin of mammals & birds• 145 million years before present -
asteroid impact? MASS EXTINCTION • Pangea begins to separate/ Rocky
mountains form
Image courtesy of http://nascarulz.tripod.com/dinomain.html
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65 million years before present….• ASTEROID IMPACT!• Mass extinction of
ALL dinosaurs and many marine organisms
• End of the Mesozoic era
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Image courtesy of NASA: http://www.nasaexplores.com/show2_912a.php?id=01-074&gl=912
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Cenozoic Era• 65 million years before present -
today• Present era we live in• Continued evolution and
adaptations of flowering plants, insects, birds, mammals
• Mammals dominant• Major crustal movements &
mountain building (Alps & Himalayan mountains form)
Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
Image courtesy of: http://www.karencarr.com/gallery_Cenozoic_arch.html
And during the Cenozoic era…
• The most primitive hominid (human ancestor) evolves - approximately 4.4million years before present
• The first modern humans (homo sapiens) evolved approximately 100,000 years before present
Image courtesy of: http://www.wilderdom.com/images/evolution/8.jpg
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THANK Y
OU
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