Answer: The Earth’s lithosphere, which includes the crust and upper mantle, is made up of a series of pieces, or tectonic plates, that move slowly over time. A tectonic plate (also called a lithospheric plate) is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere. Different types of plate tectonic boundaries:

• Convergent boundaries: When two plates come together, it is known as a convergent boundary.
  • The impact of the colliding plates can cause the edges of one or both plates to buckle up into a mountain range or one of the plates may bend down into a deep seafloor trench.
  • A chain of volcanoes often forms parallel to convergent plate boundaries and powerful earthquakes are common along these boundaries.
  • The location where the sinking of a plate occurs is called a subduction zone. There are three ways in which convergence can occur. These are between an oceanic and continental plate, between two oceanic plates, and between two continental plates.
  • At convergent plate boundaries, oceanic crust is often forced down into the mantle where it begins to melt. Magma rises into and through the other plate, solidifying into granite, the rock that makes up the continents. Thus, at convergent boundaries, continental crust is created and oceanic crust is destroyed.
  • The Pacific Ring of Fire is an example of a convergent plate boundary.
• Divergent boundaries: It is formed when two tectonic plates move away from each other. A new crust is generated as the plates pull away from each other.
  • The sites where the plates move away from each other are called spreading sites.
  • Along these boundaries, earthquakes are common and magma (molten rock) rises from the Earth’s mantle to the surface, solidifying to create the new oceanic crust. For example, Mid-Atlantic Ridge.

• Transform boundaries: Two plates sliding past each other form a transform plate boundary.
  • Rocks that line the boundary are pulverized as the plates grind along, creating a linear fault valley or undersea canyon. Natural or human-made structures that cross a transform boundary are offset–split into pieces and carried in opposite directions.
  • Earthquakes are common along these faults.
  • In contrast to convergent and divergent boundaries, the crust is cracked and broken at transform margins but is not created or destroyed.
  • Ex: San Andreas fault zone, which extends underwater.

Even though plates move very slowly, their motion has a huge impact on our planet. Plate tectonics leads to the formation of oceans, continents, and mountains. It also helps us understand the reasons behind events like earthquakes and volcanoes.