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Continental Drift Theory – Evidence, Wegener’s Theory

By BYJU'S Exam Prep

Updated on: November 14th, 2023

Continental drift theory deals with the distribution of the oceans and the continents. For millions of years, all the land of Earth was joined together in a supercontinent, which is known as Pangaea. But about 200 million years ago, the land started to drift apart and broke into two pieces. According to the continental drift theory, these large two pieces continued to break apart into smaller continents that are seen today, and scientists called it movement ‘continental drift’.

The major objective of the continental drift theory lies in analyzing the major climatic change that occurred in the geologic past. This frames to be an essential segment of the syllabus for IAS exam. Continental drift theory notes would cover all the related facts and information related to the theory. It would surely help the candidates to cover this topic in the Geography section and make their preparation rock-solid.

What is Continental Drift Theory?

German meteorologist Prof. Alfred Wegener proposed that around 250 million years before the present there was one single vast continent called ‘Pangea’ surrounded by oceans on all sides called Panthalassa. He further suggested in the continental drift theory that the Pangea split into two parts around 200 million years before the present Laurentia or Angaraland and Gondwanaland. After that the continents further broke down and moved to the current position by drifting, he called this drifting continental drift.

In the continental region of tropical zones, evidence of glaciation was found in the past, and in the continental region of colder zones, evidence of tropical climate was found. There were only two possibilities either the climate have changed, or the continents have changed their positions. Wegener ruled out climate change that requires changes in earth’s axial alignments, orientation, rotation, and movements, and rather suggested movements or drifting of continents.

Objectives of Continental Drift Theory

German meteorologist Prof. Alfred Wegener proposed the theory of continental drift in 1912. The first continental portion of the earth was called ‘Pangea’, and the oceanic part was called ‘Panthalassa’. Later, a sea called Tethys divided Pangea into two parts, namely Laurentia (Laurasia) or Angaraland to the north and Gondwanaland to the south of Tethys.

  • In 1922 the meteorologist Alfred Wegener illustrated this concept in a book titled ‘Die Entstehung de Kontinente and Ozeane’. The book was translated English language in 1924.
  • The foremost aim of Wegener for propounding the continental drift theory was to illustrate the major climatic change which occurred in the geological past, such as Carboniferous glaciation.
  • There could be two major illustrations that could be the illustration of the reason for climate change [1] the continents that remained at their places and were stationary while the climatic zones altered their locations from one region to another. [2] If the climatic zones were fixed and do not alter their locations, the drift would have been witnessed in the continents. Wegener assented to the second option.

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Continental Drift Theory- Basic Premise

Alfred Wegener acted in accordance with the idea of Earth comprising three layers, the outermost layer was made up of ‘sial’, the middle one of sima, and the underneath layer of nife. In accordance with the theory proposed by Wegener the outermost layer known as the sial was confined to the mainlands only while the sima represents and displays the crust of the ocean. The sima did not lay any resistance to the sialic masses also known as continents floating on the sima.

  • Wegener put forth the argument in the continental drift theory that states all the mainlands were associated together to form one landmass. The same was named as Pangaea. The water body is named Panthalassa which surrounds the landmasses known as Pangea.
  • Around 200 million years ago the continental segment of the Earth Pangea initiated breaking up and this resulted in the formation of two large masses of continents Lauria and Gondwanaland forming the Northern and Southern segments.
  • Later, Gondwanaland and Laurasia continued to break into several smaller landmasses and splitted mainlands moved away from each other and henceforth the present location of the continents and ocean basins became possible.

Evidence of Continental Drift Theory

The pieces of evidence for the continental drift theory have been presented here. The study of this evidence will lead us in attaining proper knowledge of the continental Drift theory. Walk through the point illustrated here to attain complete knowledge of continental drift to be able to answer the questions appropriately in the UPSC prelims and mains exam.

Jig-Saw-Fit

The South America and Africa shorelines presented an astonishing and indisputable match. In 1964, after the death of Wegner, Bullard did a similar Jig-Saw-Fit but at a depth of 1,000- fathom lines under the earth. It proved to be quite perfect. Rocks of different continents on the two sides of the oceans had the same age and as well as similar composition: Eg. Brazilian coast and western Africa.

Tillite Deposit

Sedimentary deposits formed or brought by glaciers. Wegner said tillite deposits in different continents and different positions at present time, formed when all the continents were joint and located around the south pole

Placer Deposit

Sedimentary gold on Ghana coast without a source in proximity but the source being found coast in the Brazilian coast proves that the two continents were together.

Fossil Evidence

Fossil remains of Lemur are found in India, Madagascar, and Africa. This contiguous landmass was called Lemuria. Fossil remains of Mesosaurus (small reptile) found in southern Africa, as well as South America, also prove that the continents were together when animals moved to another continent.

Paleomagnetic Evidence

In different continents, the solidified magma of the past shows that magnetic field for the same time in a different direction, which is not possible. This phenomenon also explains if continents are places as Wegner proposed, then the magnetic field show the correct direction as per the past proposed direction.

Force for Drifting

After the evidence was presented by him, he stated about movements in the continental drift theory. Movements were in two directions. The first movement was in northward, and its cause was a gravitational and polar fleeing force. Laurentia moved and after that Gondwanaland moved in northward. The second movement was in westward, and north America, South America, Africa shifted towards west. The forces given as a cause are also the weakness of the theory. The continents do not move because of these forces.

  • In accordance with Wegener’s theory of continental drift, after the splitting of the landmasses, the continental portion of the Earth [pangaea] splited into two major directions [1] equatorward and [2] westward.
  • The gravitational differential force and force of buoyancy combined to lead to the equatorward movement of the landmasses.
  • The tidal force of the sun and the moon combined to lead to the westward drift of the continents. The theory stated that the attraction forces of the Sun and the Moon were responsible for drifting the blocks of the continents westwards or toward the interior segment of the Earth.

Evaluation of the Continental Drift Theory

The continental drift theory witnessed criticisms due to some loopholes. But on the other hand, this theory opened up new spectrums of comprehending the drifts of the continents and developing other theories. Check out the criticisms and contributions of Wegener’s theory of Continental drift.

Criticism faced by Continental Drift Theory

As stated by the continental drift theory the forces that are responsible for continental drift [differential gravitational force and the force of buoyancy and tidal force of the sun and moon] are inadequate for the continental drift process.

  • The modern theories disapprove of the concept stated in Weigner’s theory of continental drift of the continents or sialic masses floating over the sima layer of the Earth.
  • The “jig-saw fit” concept cannot be approved as the coasts of the Atlantic Ocean are unable to refit completely.
  • The theory lags the illustration of the pre-carboniferous times.
  • The vegetation can be found at other segments of the world, and there is a mandate of associating it with the past.

Contribution of Continental Drift Theory

Despite the fact that most points of Wegener’s continental drift theory were disapproved its central theme of horizontal displacement remained retained. In fact, Wegener’s continental drift theory resulted in the postulation of plate tectonic theory after 1960.

  1. This theory was the first comprehensive theory to talk about the drifting of continents.
  2. His contribution helped evolved the understanding of the direction of drift and the evidence supporting it.
  3. It finally led to the development of the theory of Seafloor Spreading and Plate Tectonics.

Continental Drift Theory UPSC

The continental drift theory is an essential and pivotal segment of the Geography section and the questions pertaining to this can be asked in the UPSC prelims and mains exam. Geography is an essential subject for both prelims and mains and the candidates must be covering all the essential topics of Geography including the Continental Drift Theory.

The candidates can get access to the continental theory UPSC notes to be able to cover the topic effectively and efficiently. The notes will aid the candidates to enhance their knowledge but will also help them during the revision time period. The candidates must follow the recommended books to be able to prepare effectively for the exam. Candidates can download the PDF file from the link to kickstart their preparation for the IAS exam.

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