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Looking for NCERT Class 11 Geography Chapter 4 Distribution of Oceans and Continents Solutions? This blog provides clear, well-explained answers to all the exercise questions from Chapter 4 of the Fundamentals of Physical Geography textbook. These easy explanations will help you prepare better for your exams. Whether you’re studying for a test or want to understand the chapter for class discussions, this guide will make everything easier to learn. You can also download a free PDF of the solutions to revise anytime you want.
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NCERT Solutions Class 11 Geography Fundamentals of Geography Chapter 4 Distribution of Oceans and Continents
These NCERT solutions for Class 11 Geography Fundamentals of Geography Chapter 4 Distribution of Oceans and Continents will help you prepare effectively for your exams. By studying the explanations thoroughly and regularly revising the key concepts, you can score well.
1. Multiple Choice Questions
(i) Who amongst the following was the first to consider the possibility of Europe, Africa and America having been located side by side?
(a) Alfred Wegener
(b) Antonio Pellegrini
(c) Abraham Ortelius
(d) Edmond Hess
(ii) Polar fleeing force relates to:
(a) Revolution of the Earth
(b) Gravitation
(c) Rotation of the earth
(d) Tides
(iii) Which one of the following is not a minor plate?
(a) Nazca
(b) Arabia
(c) Philippines
(d) Antarctica
(iv) Which one of the following facts was not considered by those while discussing the concept of sea floor spreading?
(a) Volcanic activity along the mid-oceanic ridges
(b) Stripes of normal and reverse magnetic field observed in rocks of ocean floor
(c) Distribution of fossils in different continents
(d) Age of rocks from the ocean floor
(v) Which one of the following is the type of plate boundary of the Indian plate along the Himalayan mountains?
(a) Ocean-continent convergence
(b) Divergent boundary
(c) Transform boundary
(d) Continent-continent convergence
Solutions:
(i) (c) Abraham Ortelius
(ii) (c) Rotation of the earth
(iii) (d) Antarctica
(iv) (c) Distribution of fossils in different continents
(v) (d) Continent-continent convergence
2. Answer the following questions in about 30 words
(i) What were the forces suggested by Wegener for the movement of the continents?
(ii) How are the convectional currents in the mantle initiated and maintained?
(iii) What is the major difference between the transform boundary and the convergent or divergent boundaries of plates?
(iv) What was the location of the Indian landmass during the formation of the Deccan Traps?
Solutions:
(i) Alfred Wegener suggested that two main forces caused the continents to move. One was the polar-fleeing force, caused by Earth’s rotation. The other was the tidal force, created by the gravitational pull of the Moon and the Sun.
(ii) Convection currents in the mantle start because of the heat coming from Earth’s core. This heat makes the mantle material rise and then sink as it cools near the surface. The continuous temperature difference keeps these currents moving inside the Earth.
(iii) At transform boundaries, tectonic plates slide past each other sideways and do not form or destroy crust. But at convergent boundaries, plates come together and one may sink. At divergent boundaries, plates move apart and a new crust is formed.
(iv) During the time the Deccan Traps were formed (about 60 million years ago), the Indian plate was located near the equator. It was moving northward, which later caused it to collide with the Eurasian plate and form the Himalayas.
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3. Answer the following questions in about 150 words
(i) What are the evidences in support of the continental drift theory?
(ii) Bring about the basic difference between the drift theory and Plate tectonics.
(iii) What were the major post-drift discoveries that rejuvenated the interest of scientists in the study of distribution of oceans and continents?
Solutions:
(i) Alfred Wegener’s continental drift theory suggested that all continents were once joined together in a supercontinent called Pangaea. Later, they slowly moved apart. He gave several proofs to support this idea. First, the shape of the continents like South America and Africa look like they fit together like pieces of a jigsaw puzzle. Second, fossils of the same animals and plants, like the reptile Mesosaurus, have been found in both Africa and South America, even though they are now far apart. This means those continents were once connected.
Third, similar rock formations and mountain ranges are found on continents now separated by oceans, which suggests they were once part of the same landmass. Lastly, glacial deposits found in now warm places like India, South Africa, and Australia show these areas were once close to the South Pole. All these clues together support Wegener’s idea that the continents have drifted over time.
Also Read:
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(ii) The Drift Theory, proposed by Alfred Wegener in 1912, suggested that all continents were once part of a single supercontinent called Pangaea, which later broke apart and drifted to their current locations. Wegener supported his theory using evidence like the matching coastlines of South America and Africa, similar fossils found on different continents, and geological similarities. However, he could not explain the force responsible for the movement, so the theory was not widely accepted at the time.
In contrast, the Plate Tectonics Theory, developed in the 1960s, provided a more scientific explanation. It states that the Earth’s outer shell, the lithosphere, is divided into large slabs called tectonic plates. These plates move slowly over the semi-molten asthenosphere due to convection currents in the mantle. This theory explains not only the movement of continents but also the causes of earthquakes, volcanoes, and mountain formation. In short, drift theory explains what moved, while plate tectonics explains how and why it moved.
(iii) After Wegener’s theory was introduced, scientists later made discoveries that helped them understand how continents and oceans change over time. One major discovery was mapping of the ocean floor, which showed mid-ocean ridges (long underwater mountain chains) and deep ocean trenches. These features could not be explained before. Then came the seafloor spreading theory by Harry Hess. He said that new ocean crust forms at the ridges and moves away, pushing continents apart. Scientists also found magnetic patterns on the ocean floor. These were symmetrical stripes of normal and reversed magnetic fields on both sides of the ridges. This showed that new crust was being added regularly.
Another important discovery was radiometric dating, which proved that rocks near the ridges were younger than those farther away. All these findings proved that the ocean floor was not still, it was moving. This led to the development of the plate tectonics theory, which fully explained how continents and oceans shift over time.
Download NCERT Solutions Class 11 Geography Fundamentals of Geography Chapter 4 Distribution of Oceans and Continents
Download NCERT Solutions for Class 11 Geography Fundamentals of Geography Chapter 4 Distribution of Oceans and Continents to prepare well for your exams. These solutions explain all the questions and important concepts in simple language, making it easier for you to understand and score better in your exams.
Download NCERT Solutions of Class 11 Fundamentals of Geography here:
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