Which of the following ridges has the fastest rate of sea floor spreading?
- A.Arctic Ridge
- B.Mid-Atlantic Ridge
- C.East Pacific Rise
- D.Carlsberg Ridge
Correct answer
Explanation
The correct answer is C, the East Pacific Rise. Near Easter Island in the South Pacific the rise spreads at more than fifteen centimetres a year, the highest rate measured, while the Arctic Ridge in option A has the slowest rate of less than two and a half centimetres a year. Option B, the Mid-Atlantic Ridge, spreads at about two and a half centimetres a year, which is why the Atlantic has widened slowly and steadily since Pangaea broke up, and Iceland sits astride it. Option D, the Carlsberg Ridge, lies in the Indian Ocean between the Arabian Sea and the African coast and spreads at a moderate rate. For the examination remember only the two extremes: the Arctic Ridge is the slowest and the East Pacific Rise the fastest.
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 →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
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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.
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…
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