Maarg Manthan · Topic 3.3

Continental Drift Theory of Alfred Wegener

Geography › Geomorphic Movements and Plate Tectonics · Topic 3.3

The continental drift theory, proposed by the German meteorologist Alfred Wegener in 1912, says that all continents were once joined in a single supercontinent, Pangaea, surrounded by the ocean Panthalassa, which broke up from about 200 million years ago into Laurasia and Gondwanaland and then into the present continents. Evidence came from fit, rocks, fossils and glaciation.

5 min read · UPSC Prelims · Geography · Geomorphic Movements and Plate Tectonics

At a Glance

Proposed by Alfred Wegener, 1912
Supercontinent Pangaea, in the ocean Panthalassa
Breakup Laurasia in the north and Gondwanaland in the south
Forces proposed Pole-fleeing force and tidal force
Weakness Forces were too weak to move continents
Exam link UPSC Prelims, Geography: Geomorphic Movements and Plate Tectonics

Where Does It Fit?

This is the third topic of the category on geomorphic movements and plate tectonics. The previous topic covered surface processes, and this one begins the story of how continents move. The next topic covers seafloor spreading, which supplied the missing mechanism. Previous topic: Exogenic Movements, Denudation and Weathering. Next topic: Seafloor Spreading and Paleomagnetism.

What Is the Continental Drift Theory?

In short: Wegener argued that the continents were once one landmass that broke apart and drifted to their present positions.

The idea that the continents fit together like a jigsaw had been noticed by earlier thinkers, but the German meteorologist Alfred Wegener put it forward as a full theory in 1912 and published it in his book on the origin of continents and oceans in 1915. According to him, all the continents formed a single huge landmass called Pangaea, meaning all earth, which was surrounded by a vast ocean called Panthalassa, meaning all water. About 200 million years ago Pangaea began to split. It first broke into two large landmasses: Laurasia in the north, which included North America, Europe and most of Asia, and Gondwanaland in the south, which included South America, Africa, India, Australia and Antarctica. The Tethys Sea lay between them. These then fragmented and drifted into their present positions. The ocean floor and the continents therefore were not fixed, which was a radical idea at the time.

What Evidence Did Wegener Give?

Evidence	Observation
Jigsaw fit	The coasts of South America and Africa fit closely, especially along the edge of the continental shelf
Rocks of the same age	Rock belts of 2,000 million years in Brazil match those of West Africa; the Appalachian mountains match the Caledonian mountains of Scotland and Scandinavia
Fossils	The same land fossils on widely separated continents, such as Mesosaurus, a freshwater reptile, in South America and southern Africa, and the seed fern Glossopteris across the southern continents including India
Glaciation	Tillite deposits of the same age in India, South Africa, Australia, South America and Antarctica show a common ice age
Placer deposits	Gold-bearing rocks of Ghana match the source of gold placers in Brazil
Climate	Coal in Antarctica shows that warm, wet forests once grew near the pole

The evidence from the Gondwana rocks of India, which hold coal and the fossils of Glossopteris, is a key proof that the Indian peninsula was part of Gondwanaland, a theme developed in Movement of the Indian Plate.

What Forces Did Wegener Propose?

Wegener suggested that the continents moved because of two forces. The first was the pole-fleeing force, a force that arises from the rotation of the Earth and its equatorial bulge and drives continents toward the equator. The second was the tidal force, the pull of the Moon and the Sun, which he suggested dragged the continents westward. The westward drift was used to explain why the Americas moved away from Europe and Africa and why the Himalayas and Alps formed through the northward movement of Gondwana and the closure of the Tethys.

Why Was the Theory Rejected at First?

Physicists showed that the forces proposed by Wegener were far too weak to move continents through the solid rock of the ocean floor. Tidal forces could not drag continents westward, and the pole-fleeing force was extremely small. Wegener could not explain how continents could plough through oceanic crust. Although the evidence of fit and fossils was convincing, the lack of a mechanism meant that most geologists did not accept the theory during his lifetime, and he died in 1930 on an expedition to Greenland. As an analytical point, this is a good example of how an idea backed by evidence can be set aside until a mechanism emerges, and in this case the mechanism arrived three decades later in the discovery of seafloor spreading.

What Was the Lasting Contribution?

New data from the ocean floor in the 1950s and 1960s, including mapping of mid-ocean ridges and the study of paleomagnetism, revived the idea in a stronger form. The seafloor spreading theory, covered in Seafloor Spreading and Paleomagnetism, showed that the ocean floor, and not just the continents, is in motion. This led to the unifying theory of plate tectonics, in Plate Tectonics and Types of Plate Boundaries. Wegener’s central idea, that continents have moved, was proved correct, but the explanation is now that continents are carried along on plates, rather than ploughing through the ocean floor on their own.

Why Is This Topic Important?

Foundation Precursor to plate tectonics
Evidences Frequent Prelims theme
India Gondwana link

What Came Next?

The next topic describes seafloor spreading and paleomagnetism. Next topic: Seafloor Spreading and Paleomagnetism.

Key People and Terms

Pangaea Single supercontinent
Panthalassa Ocean around Pangaea
Laurasia Northern landmass
Gondwanaland Southern landmass
Tillite Rock formed from glacial deposits
Glossopteris Fossil seed fern of Gondwana

Exam Corner

Points to Remember

Proposed by Alfred Wegener in 1912.
Pangaea began to split about 200 million years ago.
Laurasia in the north, Gondwanaland in the south.
Forces: pole-fleeing and tidal.
Evidence included Glossopteris and tillite.

Do Not Confuse With

Pangaea and Panthalassa Land versus ocean
Laurasia and Gondwanaland North versus south
Continental drift and plate tectonics Continents moving alone versus carried on plates

Memory Hook

One land, one sea; two pieces, many parts; fit, fossils, ice and rock, but no force to push.

Mains Angle

Questions ask for evidence and limitations. These points add depth.

Evidence Fit, fossils, glaciation
Limitation No adequate mechanism
Legacy Led to seafloor spreading

A Question You May Face

An original practice question, not a past paper question.

“Critically examine Wegener’s theory of continental drift and the evidence for it.”

How to Answer

Theory Pangaea and its breakup.
Evidence Fit, fossils, rocks.
Criticism Forces too weak.
Legacy Plate tectonics.

GS Relevance

Prelims: Wegener, Pangaea, evidences, forces. GS Paper 1: geomorphology and plate tectonics.

Frequently Asked Questions

Who proposed the continental drift theory?

The continental drift theory was proposed by the German meteorologist Alfred Wegener in 1912 and described in his 1915 book. It states that the continents were once a single landmass, Pangaea, that split and drifted to their present positions.

What are Pangaea and Panthalassa?

Pangaea was the single supercontinent that included all the landmasses of the Earth, and Panthalassa was the vast ocean that surrounded it. Pangaea began to break up about 200 million years ago into Laurasia in the north and Gondwanaland in the south.

What is the evidence for continental drift?

The evidence includes the jigsaw fit of the coasts of South America and Africa, matching rock belts across the Atlantic, the same fossils such as Mesosaurus and Glossopteris on separated continents, tillite deposits of a common ice age, and coal in Antarctica.

What forces did Wegener suggest for drift?

Wegener suggested two forces: the pole-fleeing force, arising from the Earth's rotation and the equatorial bulge, and the tidal force, the pull of the Moon and the Sun. Scientists later found that both were far too weak to move the continents.

Why was the continental drift theory not accepted?

The theory was not accepted because Wegener could not give a force strong enough to move continents through the ocean floor. The lack of a convincing mechanism overshadowed the evidence, and acceptance came only after seafloor spreading and plate tectonics were developed.

PYQ Practice — Statement Analysis

1 Wegener proposed that the continents were once joined as a single mass called Pangaea.

True

He proposed it in 1912.

2 Gondwanaland included North America and Europe.

False

It included the southern continents and India.

3 Glossopteris fossils support the idea of continental drift.