Plate Tectonic Theory: Principles, Movements, Plate Tectonic Theory UPSC

By Balaji

Updated on: May 9th, 2023

Plate Tectonic Theory is a fundamental concept in the field of geology that explains the movement and formation of the Earth’s crustal plates. Plate Tectonic Theory was first given by Alfred Wegner in terms of continental drift. Alfred was a German Meteorologist. Plate tectonics is generally accepted as a scientific theory that states that the Earth’s Lithosphere is made up of tectonic plates, which have been moving since 3.4 billion years ago.

The Earth’s Lithosphere is the rigid outermost shell of the planet that consists of seven or eight major plates and is further divided into small plates known as ‘platelets’. The Plate Tectonic Theory has revolutionized the way scientists understand the Earth’s geological history and has provided insights into the formation of mountains, earthquakes, volcanoes, and other geological phenomena.

What is Plate Tectonic Theory?

Plate Tectonic Theory, which is also known as the Plate Tectonic Theory, is a scientific theory that deals with the dynamics of the outer shell of Earth’s Surface i.e. Lithosphere. According to this theory, the Earth is made up of a rigid layer known as the Lithosphere that is about 60 miles thick. The Lithosphere is broken down into large-size plates, regional-size plates, and several small ones known as ‘platelets’

Plate Tectonic Theory UPSC

The tectonic plates are composed of thick continental lithosphere and oceanic lithosphere that is topped by different kinds of crust. These tectonic plates can move because they have greater mechanical strength than the base of the lithosphere i.e. asthenosphere. The theory of Plate Tectonics was first introduced in 1967.

Principles of Plate Tectonic Theory

The Plate Tectonic Theory is one of the most important concepts in the field of geology and Earth sciences, yet it is Elegantly simple to understand.

  • The surface layer of Earth is 50 to 100 km thick, which is equivalent to 30 to 60 miles. These plates come together to form a layer known as the lithosphere.
  • The term ‘Lithosphere’ originated from Greek words meaning rocks.
  • The Lithosphere slides over a partially molten layer known as the ‘Asthenosphere’.
  • The Greek meaning of Asthenos is ‘weak’. The movement of tectonic plates is possible as the boundary of the lithosphere-asthenosphere acts as a layer of detachment.
  • As the tectonic plates in the lithosphere move across the Earth’s surface, they interact, collide, diverge, and converge with the other tectonic plates.
  • These plates are driven by forces whose concept is not understood yet. It may be driven by the convection of the Earth’s Surface or due to the pull of heavy metal pieces in the crust.
  • The collision of plate tectonics results in the formation of various hazards. Some of them are earthquakes, volcanic eruptions, and so on.

Movements of Tectonic Plates

The tectonic plates are never fixed. They always move across the surface of the asthenosphere horizontally. When these tectonic plates slide over each other or collide or move apart, it leads to earthquakes, volcanic eruptions, and other natural disasters.

  • The rate of movement of the tectonic plates varies considerably. For example, the arctic ridge has the slowest rate i.e. 2.5 cm per year or less.
  • On the other hand, the east Pacific rise in the West of Chile has the fastest rate i.e. 15 cm per year or more.
  • The rock below the rigid plates is believed to be moving in a circular motion. The rocks beneath the plates are highly mobile.
  • The material which is heated rises to the surface and starts to cool down and then sinks back into more depth. This results in the movement of the mantle.
  • Hence, the back-and-forth movements of the softened mantle are the force that drives the movements of tectonic plates.

Some Examples of Tectonic Plates

The tectonic plates are classified into various types. They are major plates, minor plates, and regional plates. Some examples of these plates are mentioned below.

  • Major Plates: The Earth’s surface is divided into seven major tectonic plates. They are Eurasia and the adjacent oceanic plate, Africa with the eastern Atlantic floor plate, the India-Australia-New Zealand plate, the Pacific plate, the South American plate, the North American plate, and the Antarctic (and the surrounding oceanic) plate.
  • Minor Plates: Some important minor plates are as follows: the Juan De Fuca plate found in the South-East of the North American Plate, the Fuji plate in the North-east of Australia, the Cocos plate between Central America and the Pacific plate, the Nazca plate between South America and Pacific plate, Philippine plate that is found between the Asiatic and Pacific plate, Caroline plate between the Philippine and Indian plate and so on.
  • Indian Plates: The Indian Plate includes the Australian continental portion and Peninsular India. The Kirthar Mountain in Pakistan follows the West, and the Rakim Yoma Mountains of Myanmar follow the East.

What are the Different Types of Tectonic Boundaries?

The movement of different types of tectonic plates causes the formation of tectonic boundaries. The tectonic boundaries are further classified into three types as follows

  • Convergent Boundary: A convergent boundary is a type of tectonic boundary that crashes into one another. They are often termed ‘destructive boundaries’ as they cause a lot of destruction.
  • Divergent Boundary: A divergent boundary is a type of tectonic boundary that is formed when the tectonic plates are pulled apart from each other. They are often termed as ‘constructive boundaries’.
  • Transform Boundary: When the tectonic plates move horizontally, sliding each other, a boundary is formed known as a transform boundary.

Plate Tectonic Theory UPSC

The Plate Tectonic Theory is a crucial topic in the UPSC exam, particularly in the Geology and Geography papers sections. Questions related to tectonic plate movement, the types of plate boundaries, and their associated landforms are frequently asked in the exam. Having a strong grasp of the Plate Tectonic Theory is crucial for aspirants to answer all the related questions with ease. To prepare effectively candidates can take the help of notes along with Geography Books for UPSC.

Plate Tectonic Theory UPSC Questions

Question: The theory of plate tectonics states that: a) The earth’s crust is divided into a single plate b) The earth’s crust is divided into multiple plates c) The earth’s crust is not divided d) The earth’s crust is only divided in the oceans

Answer: b) The earth’s crust is divided into multiple plates

Question: Which of the following is NOT a result of plate tectonics? a) Earthquakes b) Volcanoes c) Mountain building d) Hurricanes

Answer: d) Hurricanes

Question: Who proposed the Plate Tectonic Theory? a. Albert Einstein b. Isaac Newton c. Alfred Wegener d. Charles Darwin

Answer: c. Alfred Wegener

Question: Which of the following is NOT a piece of evidence for the Plate Tectonic Theory? a) Fossil distribution across continents b) Magnetic anomalies on the seafloor c) Formation of mid-ocean ridges d) Changes in Earth’s magnetic field

Answer: d) Changes in Earth’s magnetic field

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