Question

Before the present theory of plate tectonics, scientists used the hypothesis of continental drift to propose that Earth's continents are in motion. Which of the following were initially used to support the hypothesis of continental drift? I. the matching shapes of continent edges II. similar fossils on different continents III. matching rock types on different continents IV. evidence in the rock record for climate change
answers

Question 1 options:

II and III only


I and IV only


II, III, and IV only


I, II, III, and IV

Answer 1

The answer is d all of them

Answer 2

Answer:

Option (4)

Explanation:

The continental drift refers to the movement of the continents over the earth's surface from one place to another. It was first discovered by Alfred Wegener. He forwarded some pieces of evidence in support of this theory but he was unable to explain the main mechanism behind the continental motion.

Some of this evidence includes-

• The continental margin perfectly matches with one another suggesting that the continents were once connected together.
• The occurrence of similar fossil assemblages in different continents also suggested that the continents were once all together.
• Similar rock sequences were also found in distant continents.
• Some of the rocks deposited at different places also suggested the type of climate it existed during its time of deposition. For example, the till deposits indicate glacial deposits which have formed due to the drifting of the glaciers over the landmasses. This indicates that during that time the earth was experiencing a much colder type of climate, such as the ice age.

So, all the above evidence suggested that the earth was once comprised of a single landmass, known as the supercontinent 'Pangaea', which got separated and formed the present scenario.

Later, the concept of 'Plate tectonic theory' came that was able to explain the reason for the movement of the plate. The convection current generates in the mantle, that forces the plates to move. These currents are formed due to the heat supplied from the interior of the earth.

Thus, the correct answer is option (4)- that is I, II, III, and IV.