Continent drift theory

1. Chapter 3
The Origin of Ocean
Basins
©2003 Jones and Bartlett Publishers
2
The Origin of Ocean Basins
Mr. Toradmal Agastirishi B.
Asst. Professor .
Department of Geography
Dada Patil Mahavidyalaya, karjat, Dist- Ahmednagar

2. 70.8 %
29.2 %

3. Land Hemisphere
Water Hemisphere

6. All previous hypotheses and theory dealing with the origin of ocean basins have
rejected after the postulation of
Continental Drift Theory
Sea Floor - Spreading Plate Tectonic theory

8. INTRODUCTION
Prof. Alfred Wegener was German
meteorologist. He propounded his
continent drift in 1912 but it could
not come in light till 1922 when
he elaborated his concept in book
entitled “ Die Entstehung der
Kontinente and Ozeane “
( The origin of continents and
Oceans ) which was translated in
English in 1924.

9. Basic Premise of Theory
 Wegener believed in Three Layers System of earth .
1. Sial – Outer layer
2. Sima – Intermediate layer
3. Nife – Lower layer

10. According to Wegener sial was represented the continental
masses whereas the ocean crust was represented by sima.
Continents or sial were floating on sima.
Basic Premise of Theory

11. Basic Premise of Theory
 PANGAEA ( SUPERCONTINENT )
Wegener assumed , on the basis
of evidences of Palaeo-climatology,
Paleontology, palaeobotany, Geology
and Geophysics, that all the
landmasses were united together in the
form of one landmass which he named
Pangaea which was surround by a
huge water body, known as Panthalasa.

12. Super-Continent PANGAEA
PANTHALASAPANTHALASA

13. Super-Continent
PANGAEA = Gondwanaland + Laurasia
Super- continent Pangaea was broken into two parts in
Triassic period (200 million years ago )
LAURASIA –
The northern part of Pangaea
comprised N. America,
Greenland, Europe and N . Asia.
GONDWANALAND –
The southern part of Pangaea
comprised S. America, Africa
Antarctica, Australia, and
Peninsular of India.
TETHYS- These two parts were
separated by a long shallow sea
called the Tethys

36. Continents Drifting

37. Force Responsible
for the Continent Drift
According to Wegener after breaking Pangaea drift in two directions
Equator ward movement –
The equator ward movement was
caused by gravitational
differential of force and force of
buoyancy.
West ward movement –
The west ward movement of
continents was caused by the
Tidal force of the Sun and the
Moon

38. Evidences
in Support of the Theory
1. GEOGRAPHICAL SIMILARITY ( Jig-Saw-Fit )
2. GEOLOGICAL EVIDENCES
3. PALAEONTOLOGICAL EVIDENCES
4. GEODETIC EVIDENCES
5. BIOLOGICAL EVIDENCES
6. PALAEOCLIMATIC EVIDENCES

39. GEOGRAPHICAL SIMILARITY
( Jig-Saw-Fit )
South
America
Africa
According to Wegener there is
geographical similarity along
both the coasts of Atlantic
Ocean. The eastern coast of S.
America can be fitted into the
western coast of Gulf of Africa
Wegener called it “ Jig=saw-Fit
“

40. GEOLOGICAL SIMILARITY

41. GEOLOGICAL SIMILARITY
Geological evidences
denote that the
Caledonian and
Hercynian mountain
systems of the western
and eastern costal area
of the Atlantic are
similar.
The
Appalachians Mt.
System of N. America
are same with the Mt.
systems of Ireland,
Wales and NW Europe.

42. PALAEONTOLOGICAL
EVIDENCES
Distribution of Fossils
There is marked
similarity in the fossils
and vegetation
remains found on the
eastern coasts of S.
America and western
coasts of Africa.

43. GEODETIC EVIDENCES
It has been reported form geodetic evidences that
Greenland is drifting westward at the rate of 20 cm /year,
after 1960s Sea-floor spreading have confirmed the
movement of Greenland.

44. BIOLOGICAL EVIDENCES
 The Lemmings (small size animal) of the northern
part of Scandinavia have a tendency to run westward ,
when their population is increased but they were fall
in the sea water due to absence of any land
This behavior of lemmings proved the fact
that the landmasses were united in the ancient time.
 The distribution of Glossopteris flora in India, S.
Africa, Australia, Antarctica, Falkland islands etc.
proves the fact that all the landmasses were
previously united in the form of Pangaea .

45. PALAEOCLIMATIC
EVIDENCES
Ancient Glaciations

46. PALAEOCLIMATIC
EVIDENCES
Ancient Glaciations
The evidences of
Carboniferous Glaciations of
Brazil, Falkland, S. Africa,
peninsular India, Australia,
and Antarctica further prove
the unification of all
landmasses in one landmass
(Pangaea) during
Carboniferous period.

47. Criticism of the Theory
1. The force applied by Wegener ( Differential Gravitational
force and Buoyancy and Tidal force of the Sun and Moon )
are not sufficient to drift the continents so apart, and
continents would need Tidal force to be 10,000 million
times as powerful as it is at present , if it had it would
stop the earth’s rotation within year.
2. Both the coasts of the Atlantic Ocean can’t be completely
refitted. Thus ,the concept of “ Jig-Saw-Fit “ can’t be
validated.

48. Criticism of the Theory
3. Wegener has not the elaborated the directions and
chronology sequence of the displacement of the continents.
4. He did not described the situation of pre – Carboniferous
time. Thought most points of Wegener ‘s Theory was
rejected but its central theme ( Displacement of continents )
was retrained .

49. Continental Drifting and Origin of Ocean Basins
The disruption, rifting and displacement (Drifting) of continents began from
Carboniferous Period to Pliocene Period. According to Wegener that all the
landmasses were united together in the form of one landmass which he named
Pangaea (About 200 million years) which was surround by a huge water body,
known as Panthalasa.
Formation of Tethys Sea
Super- continent Pangaea was broken into two parts in Triassic period (200
million years ago ).
LAURASIA – The northern part of Pangaea comprised N. America, Greenland,
Europe and N . Asia and
GONDWANALAND – The southern part of Pangaea comprised S. America,
Africa Antarctica, Australia, and Peninsular of India. These two parts were
separated and space was filled up with water body was called Tethys Sea.

50. Formation of Atlantic Ocean
During Cretaceous period Gondwanaland broke up and Indian peninsula,
Madagascar, Australia and Antarctica away from each other due to the impact
of tidal force of the Sun and Moon.
Similarly , North away from Europe and South America away from
Africa and moved westward at different rate while Africa moved toward east
and ‘S’ shape of Atlantic Ocean could be possible.
Formation of Indian Ocean
In Cretaceous period Gondwanaland broke up and Indian peninsula,
Madagascar, Australia and Antarctica away from each other due to the impact
of tidal force of the Sun and Moon.
Due to the northward movement of Indian peninsula , eastward movement of
Australia and southward movement of Antarctica Indian Ocean was formed.

51. Formation of Pacific Ocean
The size and shape of the Panthalasa was reduced due to the movement of
continent from all sides toward Panthalasa. Thus the reaming portion of
Panthalasa became the Pacific Ocean.
Formation of Arctic Ocean
Arctic Ocean was formed due to the outward movement of continental
blocks from north pole.
According to continental Drift theory it may be point out that
Ocean basin were formed because of drifting of continents from
Carboniferous period to Pliocene period when present pattern of ocean
basin was attained.