Plate Tectonics

What are plate tectonics?

Plate tectonics is the theory that Earth’s outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core. The plates act like a hard and rigid shell compared to Earth’s mantle. This strong outer layer is called the lithosphere.

plate tectonics

The earth’s lithosphere is composed of seven or eight major plates and many minor plates. The lithosphere is a rigid outermost shell of earth and is broken up into tectonic plates. When these plates meet, their relative motion determines the type of boundary like convergent, divergent or transform.

Volcanic activity, earthquakes, mountain-building and oceanic trench formation occur along these plate boundaries. The relative movement of the plates typically ranges from zero to 100 mm annually.

Plate Tectonics Causes:

Plate tectonics affects humans in several important ways.

  • It causes earthquakes
  • It causes volcanism
  • It induces recycling of elements within the biosphere and between the geosphere and biosphere
  • It causes mountain-building

Types of plate boundaries:

Plate Boundaries mainly consists of three types (fourth is a mixed type), formed in the manner the plates shift in relative to each other. These are collectively referred to surface phenomena’s of different types. Plate boundaries are of different types, namely:

Transform boundaries:

These boundaries happen where two lithospheric plates move apart, or maybe further precisely, collide away from one other despite the transform faults, where plates are neither created nor destroyed.

Divergent boundaries:

These boundaries happen when both plates move apart from one other.

Convergent boundaries:

These boundaries happen where both plates move towards one other to form a zone of subduction or a continental collision.

Transform boundaries:

These boundaries happen when natural or human-made structures that cross a transform boundary are offset—split into pieces and carried in opposite directions.

Plate boundary zones:

These boundaries happen where the effects of the interactions are unclear, and the boundaries, usually occurring along a broad belt.

Stay tuned with Byju’s to learn more about plate tectonics, earthquakes and much more.


Practise This Question

A man is watching two trains, one leaving and the other coming in with equal speed of 4 m/s. If they sound their whistles, each of frequency 240 Hz, the number of beats heard by the man (velocity of sound in air is 320 m/s) will be equal to