Which pair of forces did Wegener suggest as the cause of continental drift?
- A.Ridge push and slab pull
- B.Pole-fleeing force and tidal force
- C.Isostasy and gravity
- D.Convection currents and radioactivity
Correct answer
Explanation
The correct answer is B, the pole-fleeing force and the tidal force. Wegener attributed the horizontal movement of the continents to the pole-fleeing force, which arises from the rotation of the earth and the bulge of the equator, and to the tidal force, which arises from the attraction of the moon and the sun. Both were quickly shown to be far too feeble to shift a continent, and this remains the chief criticism of his theory. Option A, ridge push and slab pull, are forces named in modern plate tectonics, not by Wegener. Option C, isostasy and gravity, explain the vertical balance of crustal blocks, not horizontal drift. Option D, convection currents driven by radioactive heat, was Arthur Holmes's contribution of the nineteen thirties and is the force plate tectonics actually relies upon.
Read the full article: Continental Drift and Plate Tectonics: Exam Notes
Practice Questions
View allThe theory of continental drift was propounded by:
- A.Alfred Wegener
- B.Harry Hess
- C.Arthur Holmes
- D.Charles Lyell
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Wegener, a German meteorologist and climatologist, put forward the continental drift theory in 1912 and developed it in his book The Origin of Continents and Oceans; he argued that all the continents once formed a single landmass, Pangaea, which broke up about two hundred million years ago.
Read the full explanation →In Wegener's theory, the single great ocean that surrounded the supercontinent Pangaea was called:
- A.Tethys
- B.Panthalassa
- C.Laurasia
- D.Gondwana
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Wegener held that about two hundred and fifty million years ago all the land of the earth lay together as one mass, Pangaea, and that one enormous ocean, Panthalassa, surrounded it.
Read the full explanation →The Tethys Sea separated which two landmasses after the break-up of Pangaea?
- A.Laurasia and Gondwanaland
- B.Africa and South America
- C.India and Australia
- D.Antarctica and Australia
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When Pangaea began to break about two hundred million years ago, it parted into a northern mass called Laurasia or Angaraland and a southern mass called Gondwanaland, and the long narrow Tethys Sea lay between the two.
Read the full explanation →The concept of sea floor spreading was given by:
- A.Alfred Wegener
- B.Harry Hess
- C.Alfred Lothar Nazca
- D.Edward Suess
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After the detailed mapping of the ocean floor during and after the Second World War revealed mid-oceanic ridges, deep trenches and a surprisingly thin cover of sediment, Hess proposed in 1961 that molten material rises along the ridge, forms new ocean floor and pushes the older floor away on both…
Read the full explanation →The Himalaya was formed by which type of plate boundary?
- A.Divergent boundary
- B.Transform boundary
- C.Convergent boundary of continent and continent
- D.Convergent boundary of ocean and ocean
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The Indian plate moved northwards and met the Eurasian plate. Both carry light continental crust, so neither could sink far into the mantle; instead the sediments of the Tethys Sea lying between them were compressed, folded and thrust upwards to form the Himalaya, and the collision is still going on…
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