presentation on continental drift theory · he propounded his concept on continental drift in the...
TRANSCRIPT
Presentation on
Continental Drift Theory
Mr. S. S. Jadhav
Dept. of Geography,
M. J. College, Jalgaon
Email:[email protected]
Mob No:- 9763267396
The World
Introduction
In 1915 Wegener Published a book “The Origin of Continents and
Oceans”
Alfred L. Wegener
In 1912 Wegener published the first version & died defending his theory
Aim of the Theory
Professor Alfred Wegner of Germany was primarily a meterologist.
He propounded his concept on continental drift in the year 1912.
But it could not come in light till 1922.
Wegeners displacement hypothesis
was based on the works and findings of a scientists such as geologists,
palaeo-climatologists, Palaeontologists, geophysicists and others.
The main objective of wegener behind his „displacement hypothesis‟
was to explain the global climatic changes which are reported to have
taken place during the past earth history.
Assumption / Hypothesis
1. If the continents remained stationary at their places throughout
geological history of the earth, the climatic zones might have shifted
from one region to another region and thus a particular region might
have experienced varying climatic conditions from time to time.
OR
1. If land surface was stable, the climatic zones would have been
displaced.
2. If the climatic zones remained stationary the landmasses might
have been displaced and drifted. OR
2. If the climatic zones were stable, the land surface would have
displaced.
But wegener did not accept the stability of land surface.
Wegener opted for the second alternative as he rejected the view of
the permanency of continents and ocean basins
from one region to another region and thus a
particular region might have experienced
varying climatic conditions from time to time.
Basic Premise of the Theory
Wegener belived in three layers system of the earth:-
Outer layer-Sial
Intermediate layer-Sima
Lower layer- Nife
According to wegener sial was considered to be limited to the
continental masses alone where as the ocean crust was represented by
the upper part of sima.
Continents of sialic masses were floating on sima without any
resistance offered by sima.
Pangaea & Panthalassa If According to the theory of ‘Continental Drift’ there as only one
continent and one ocean about 250 million years ago.
Pangaea:- all the landmasses were united together in the
form of one landmass, which he named pangaea in
Carboniferous period.
Meaning: All Land
@ Wegener named this continent- Pangaea.
@ pangaea was supercontinent, which
Contained all our present continents.
# pangaea covered an area of about 150
Million sq.km. it spread equally between
The two hemispheres.
Panthalassa- Universal Ocean
Pangaea
Panthalassa
Tethys Sea:Pangaea
Panthalassa
Pangaea
Laurasia:- North Continent,
North America,
Europe
Asia
Formed Northern Part of Pangaea
Gondwanalad:- South Continent,
South America,
Peninsular India , Australia & AntarcticaRepresented the southern part of the
pangaea.
The Theory of Continental Drift
Evidences in Support of the Theory
Geographical (Jig Saw Fitting)
Geological
Climate
Fossils and Vegetation
Geodetic Evidences
Glaciations
Elevation of Everest
Satellite Images
Evidences
Found evidence for PANGAEA and proposed the theory of continental drift.
Continental Drift (p95 red book, 182 in Sciencesaurus)
• Theory that continents were
once part of a single
landmass that broke apart
and have moved to their
present locations.
• can drift apart from one
another and have done so in
the past
For more information about what the continents looked like throughout the Earth’s
History go to:
htttp://www.ucmp.berkeley.edu/geology/anim1.html
Pangaea
Pangaea is the name given to the single
landmass that was present 200 million
years ago
Can you name the continents in Pangaea?
http://kids.earth.nasa.gov/archive/pangaea/Pangaea_game.html
PANGAEAthe large landmass that included all of Earth’s
present day continents
Continents
“fit together”
like puzzle
pieces
WEGENER’S EVIDENCE
Support for Continental Drift
1. SHAPE OF THE CONTINENTSContinents fit together like puzzle pieces
WEGENER’S EVIDENCE
Fossil Evidence•fossils are remains of living things that lived long ago.•similar fossils have been discovered in matching coastlines on different continents.
WEGENER’S EVIDENCE
WEGENER’S EVIDENCE
• Mountains
– Some mountain ranges on different continents
seem to match.
• Ex: ranges in Canada match Norway and Sweden
• Ex: Appalachian Mtn. match UK mtn
WEGENER’S EVIDENCE
• Climatic evidence such as glaciers in
areas that are now close to the Equator
Satellites used to
measure the
movement of
continents
• Laser Geodynamics
Satellite (LAGEOS)
Evidence of Continental Drift
The Plates Move…
So what now?
Which way?
• 50 million years
CONTINENTAL DRIFT IN DOUBT
Why didn’t people believe in continental drift?
• People couldn’t image how the earth could be millions of years old
• People couldn’t image a force great enough to move the continents
BUT by the 1960’s evidence would prove continental drift is TRUE and…. The story continues (as does all good science!)
