This PPT takes a brief dig at the genesis of the Continental Drift Theory. It covers the causes and the evidences of the theory.

1. Continental Drift
Theory
-By Deekshitha S

2. Continental Drift Theory
● Alfred Wegener was the first person to
propose the theory of Continental Drift.
● Continental Drift is the movement of
earth’s continents relative to each other,
thus appearing to drift across the ocean
bed.
● Continental Drift theory is the theory
that once all the continents were joined
in a super-continent which scientists call
the Pangaea.
Alfred Wegener

3. Pangaea
Before After

4. Pangaea
● Wegener’s theory of continental drift states that the existing continents of the earth
were once glued together forming a super landmass.
● Over time, the landmass broke and drifted away and is still drifting to this day. In his
proposal, he stated that the super content, which he named Pangaea, meaning ‘’all
earth” once existed.
● As a result of movement of the supercontinent, Pangaea split into two super
landmasses namely Laurasia and Gondwanaland.
● aurasia, makes up the northern continents of today. Gondwanaland makes up the
southern continents of today.

5. Causes of Continental Drift
● The causes of continental drift are perfectly explained by the plate tectonic theory.
The earth’s outer shell is composed of plates that move a little bit every year. Heat
coming from the interior of the earth triggers this movement to occur through
convection currents inside the mantle.
● Almost all plate movement occurs in boundaries which lie between different plates.
When plates drift away from each other, there is formation of new crust at divergent
boundaries. On the other hand, tectonic movement destroys crust during interaction
of the plates.
● Continental drift has impacted the universe in many ways. It has affected the global
climate, the world’s geographical positions and the evolution of animals.Continental
drift also comes along with grave effects such as Volcanoes, Earthquakes, and
Tsunamis.

6. Examples of Continental Drift

7. Wegener’s Evidence
Geologic
Evidence in the layers
of rocks across
continents
Fossil
Evidence in the places
certain fossils are
found
Climate
Evidence in the
changing climates
during the past
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8. Geologic Evidence
● Rocks of the same age and type and
displaying the same formations are
found in south-east Brazil and South
Africa.
● The trends of the mountains in the
eastern USA and north-west Europe are
similar when placed in their old
positions.
● Similar glacial deposits are found in
Antarctica, South America and India,
now thousands of km apart.

9. Fossil Evidence
There are many examples of fossils found on
separate continents and nowhere else,
suggesting the continents were once joined. If
Continental Drift had not occurred, the
alternative explanations would be:
● The species evolved independently on
separate continents - contradicting
Darwin’s theory of evolution.
● They swam to the other continent/s in
breeding pairs to establish a second
population.

10. Climate Evidence
● Glacial deposits at current equator.
● Fossilized palm trees in Greenland.
● South Africa today has a warm climate.
Yet its rocks were deeply scratched by
ice sheets that once covered the area.
● Greenland had once been near equator
and had slowly moved to the Arctic
Circle.
● South Africa, once closer to the South
Pole, had moved slowly north to a
warmer region.

11. Other Circumstantial Evidence
The Jigsaw Fit
The similarity in outline of the coastlines of eastern South America and
West Africa had been noted for some time. The best fit is obtained if the
coastlines are matched at a depth of 1,000 metres below current sea
level.
The Tectonic Fit
Fragments of an old fold mountain belt between 450 and 400 million years
ago are found on widely separated continents today. Pieces of the
Caledonian fold mountain belt are found in Greenland, Canada, Ireland,
England, Scotland and Scandinavia. When these land masses are re-
assembled the mountain belt forms a continuous linear feature.

12. Thank You