Critically examine plate tectonics and explain its relation to the evolution of major landform features on the surface of the earth. ~ Civil Services Self Study

Question:

Critically examine plate tectonics and explain its relation to the evolution of major landform features on the surface of the earth. ( 64th BPSC, 2019)

Answer:

Plate tectonics theory is a modern theory given by Mckenzie, Parker, and Morgan in 1967 that explains the current position of continents and ocean and it also explains the evolution of major landforms such as mountains, ridges, plateaus, volcanic landforms, etc. As per the theory, the earth's crust is divided into many large and small plates and it moves horizontally and vertically over the asthenosphere.

Critical examination of plate tectonics theory:

The force of plate movements:

As per the theory, it was assumed that the force of plate movement is convection current operation in the mantle.
It is not clear how the convection current is operating in the mantle. As per physics law, there must be friction between the moving plates and the asthenosphere. The theory does not explain these facts and it also did not explain the balance between the plate and asthenosphere.
As we know that the mantle has two parts i.e asthenosphere( in semiliquid form) and the lower mantle in solid form. The asthenosphere is a very thin layer of about 180 km. We also know that lithospheric plate thickness varies from 15 to 200 km. The theory did not answer how the asthenosphere is balancing the lithospheric plate.

Regarding Mountains development:

In the case of fold mountains;

As per the theory, fold mountains originated in the convergence boundaries of the two plates; that is true. For example, the Himalayas, Andes, Rockies mountains, etc evolved on the convergence boundary.
The theory also helps in the understanding of the creation of blocks and volcanic mountains.

So we can say, plate tectonics theory is able to explain the evolution of mountains correctly, but again it did not explain the things that balance the mountains.

Earthquake and seismic activities:

Plate tectonic provide partial information about the seismic and earthquake activities. As per the theory, the epicenter of the earthquake is generally found in the boundary line of the plate; but in reality, it is uncertain to predict the epicenter of an earthquake; it can be anywhere on the earth's surface.

Regarding Volcanic eruption:

Plate tectonic theory is correctly able to explain the volcanic activities at the mid-oceanic ridge and pacific ring of fire. But it is not able to explain the phenomenon of volcanoes' hots spots. For example, it is unclear the mechanism of the formation of the Deccan trap during the Indian plate movement.

For the above reasons, we can say that the plate tectonics theory explains the origin of many landforms correctly, but we cannot say that it is a perfect theory, because it is not able to answer many things correctly.

Try to solve the following questions:

What is plate tectonics? how do plate movements transform the earth's crust? ( 25 Marks, 66th BPSC geography Optional Paper)
Bring about the basic difference between the drift theory and Plate tectonics. (UPPSC)
Critically examine plate tectonics and explain its relation to the evolution of major landform features on the surface of the earth. ( BPSC, 2019)
Describe the concept of plate tectonics and explain the effects of the collision of two similar and two dissimilar plates. ( UPPSC 2020)
State the concept of plate tectonics. How does it help in explaining the formation of the Himalayas and the Appalachian Mountains? (UPSC 2014, 250 words, 20 marks)

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