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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