Plate Tectonic Theory

Plate tectonic theory was proposed in 1967. Plate tectonic theory is the theory that explains how the tectonic plates were broken or flowed, what the reason is, and what the relationship is between the current earthquakes and volcanoes.

This theory is not of one scientist, Morgan, Parker, Mekenzy, and Stone put forward different concepts, and the concept created by combining all those concepts is called plate tectonic theory. This theory states that there are seven major tectonic plates in the world today and fourteen/twenty-two smaller tectonic plates. The Pacific Plate is different because it is entirely under the sea. Tectonic plates come in many shapes. Continental tectonic plates are made of granite (light) and oceanic tectonic plates are made of basalt (heavier).

On the basis of the theory of plate tectonics, the formation of some valley mountains is explained.

Plate Tectonic Theory

Continental and oceanic plate collision.

  • Because the oceanic plate is heavy, it is destroyed by subduction and its debris.
  • Mountains are formed in the valley. e.g. 1. Rocky Mountains (Pacific Ocean and North America) 2. Andes Mountains (South Pacific Ocean and South America)

The edges of the plate are divided into three parts

  • Ruined Coast
  • Constructive edge
  • Protective edge

Ruined Coast

When two plates collide and one plate is heavier and the other plate is lighter. The heavy plate moves towards the Earth’s womb and the light plate floats on it and is destroyed.

The Ruined Coast is likely affected by plate tectonic activity, which refers to the movement and interaction of large plates that make up the Earth’s crust.

The Ruined Coast may be located near a plate boundary where two plates are converging or moving apart. If two plates are converging, it can cause the formation of mountains or other geological features, while if two plates are moving apart, it can create rift valleys or mid-ocean ridges.

The Ruined Coast may also be affected by subduction, where one tectonic plate moves underneath another plate. This can cause earthquakes and the formation of volcanic mountains.

Constructive edge

When two plates move in opposite directions, the magma in the mantle rises and cools to form a new plate. These events are caused by ocean currents.

In plate tectonics, a constructive edge or constructive plate boundary is a type of boundary where two plates move away from each other, creating new oceanic crust and widening the distance between them. This process is called seafloor spreading.

At a constructive edge, magma rises up from the mantle to fill the gap created by the moving plates. This magma solidifies and forms new oceanic crust. Over time, this process can create vast ocean basins and separate continents.

The most famous example of a constructive edge is the Mid-Atlantic Ridge, which runs down the center of the Atlantic Ocean. Here, the North American Plate and the Eurasian Plate are moving away from each other, creating new oceanic crust in the process.

Other examples of constructive edges include the East Pacific Rise, the South Atlantic Ridge, and the Juan de Fuca Ridge. These boundaries are important in the study of plate tectonics, as they help scientists understand how the Earth’s crust is created and how continents have moved over time.

Protective edge

When two plates move around each other it creates transforms (segments).

The term “protective edge” is not a commonly used term in plate tectonics. However, there are several features in plate tectonics that can be considered as protective edges in certain contexts.

For example, subduction zones can be considered as protective edges because they are regions where one tectonic plate is forced underneath another plate, which can prevent the spreading of potential destructive forces such as earthquakes and volcanic eruptions.

Additionally, mountain ranges can act as protective edges by absorbing and deflecting seismic waves, thus reducing the impact of earthquakes on adjacent regions. The Himalayas, for example, are considered a protective edge for the Indian subcontinent.

It’s worth noting that while these features can provide some protection, they can also create new hazards in other ways. For example, subduction zones can lead to the formation of volcanic arcs, which can be highly active and dangerous. Mountain ranges can also create landslides and rockfall hazards in addition to seismic hazards.

Boundary Between Two Land Plots

1. Divergent boundaries

A new crust is formed when the tectonic plates move in different directions, some cracks occur in the middle part and lava comes out and a new crust is formed.

The Mid-Atlantic ridge is elongating at 2.5 cm/yr.

Mountain ranges have formed, so Iceland is splitting in two(moving apart).

  • The boundary that forms the Red Sea between the Arabian tectonic plate and the African tectonic plate is a divergent type.

2. Convergent Boundaries

– Remains of the shell

– Earth plates slide under each other

– One tectonic plate slips under another tectonic plate.

– Narrows and troughs form when the oceanic plate subducts beneath the continental plate.

Volcanic mountains are formed when continental plates rise over oceanic plates.

e.g As the Naika tectonic plate subducts the South American tectonic plate, a trough is formed there, called the Japeru-Chile trough.

e.g – the Andes mountain range running parallel to the west coast of South America is formed.

Plate Tectonic Theory

If both the land plates are marine –

  • One tectonic plate passes under another tectonic plate thus forming a trough.
  • And volcanic mountains are formed on the rising tectonic plates.
  • Many times the volcano erupts from the mountains, forming islands or some chains of islands (island arcs).

e.g. the Hawaiian Islands are shown in the Pacific Ocean

e.g Mariana Trench – The world’s deepest trench in the Pacific Ocean.

If both land plates are continental

The tectonic plates don’t slide under each other because they have the same size and density, neither is heavier, and both are made of sial, so they don’t slide under each other, or overlap each other and they just push each other, so the land buckles. Then mountain ranges like the Himalayas were formed.

Transformer boundary

Transform boundaries are boundaries that flow in only one direction and, even if they flow in opposite directions, do not overlap or slide under each other but only rub against each other, such boundaries are called transform boundaries. Then no new crust is formed and no crust remains because there are no volcanoes, but there can be earthquakes.

  • These fractures form zig-zag boundaries
  • Most of the faults lie in the ocean.
  • If the tectonic plate is at sea level, i.e. if it is formed inside the sea, then it creates a rift.
  • And if tectonic faults occur on land, large valleys are formed.
  • Plate boundaries zone The boundaries between these broad bands of the crust are not fixed.

Proof of the theory of tectonic plates

  • The ocean floor is high and low, there are depressions on the ocean floor, mountains and valleys.
  • The Earth’s magnetic field has changed direction many times during Earth’s geological history. Volcanoes are responsible for the formation of the seabed.
  • This causes oceanic plates to move under each other to stay.
  • Submarine volcanic eruptions occur near oceanic troughs and most commonly along ocean ridges.

The interior of the earth

The core around the earth, the mantle around the core, and the mantle around the mantle are very important for the separation of the three inner tectonic plates which is diffraction.

How does tectonic plate deformation occur?

Precipitation currents are formed in the mantle, and the reason for the formation of the mantle is that there is a semi-liquid fluid, because the heat is high. The pressure is high, so the temperature increases and the rocks and minerals are found in molten form. And the upward pressure in the melt creates convection currents in Plate Tectonic Theory.

These currents tend to carry the lower part of the mantle up, and the colder part of the lithosphere above it is carried back into the mantle, heated again, and brought back up.

The upper cold part is taken back down, and it is maintained in a cycling motion, the direction is not fixed, and it can be important in different parts, in different directions.

These progressive currents carry with them the landmasses that float on them.

Importance of tectonic plates

  • Its job is not to allow the size of any ocean to increase or decrease.
  • Formation of soil and mineral deposits, due to tectonic plates
  • Continuous creation of new land
  • Continents formed on Earth
  • The size of volumes is increased

Formation of minerals

The minerals in the earth’s belly are continuously turned over and the currents cool down inside. Therefore, new minerals are formed on the surface and its important in Plate Tectonic Theory.

If it were not for tectonic plates, the earth would have been permanently watery because Pangea would not have formed.


  • When the tectonic plate is deformed, new land is created and thus biodiversity increases.
  • Biodiversity is more abundant on land than on sea
  • The former sea was bigger than today’s sea.
  • Continental land mass increased due to tectonic plate rifting.

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