Plate Tectonics

  • Plate tectonics is the theory that explains the structure and movement of the Earth’s crust. The Earth’s crust is divided into large pieces called tectonic plates.

  • There are two types of tectonic plates: oceanic and continental. Oceanic plates are denser and thinner than continental plates.

  • These plates are in constant motion, although at very slow pace – approximately a few centimetres per year. The movement is driven by the convection currents in the Earth’s mantle.

  • The boundaries where tectonic plates meet are known as plate boundaries. The interactions at these plate boundaries produce several geological events.

  • There are three main types of plate boundaries: divergent (where plates move apart), convergent (where plates move towards each other), and transform (where plates slide past each other).

  • Divergent boundaries occur when two tectonic plates move away from each other. This usually happens at the bottom of the ocean and leads to the formation of new crust through volcanic activity. Mid-Atlantic Ridge is an example of divergent boundary.

  • Convergent boundaries happen when two plates move towards each other. When an oceanic plate meets a continental plate, the denser oceanic plate is forced under the continental plate in a process called subduction. This can cause the formation of volcanic mountain ranges and deep-sea trenches. The Andes mountain range and Marianas Trench are examples.

  • At transform boundaries, plates slide past each other. These boundaries do not produce spectacular features like mountains or trenches but are associated with seismic activity including earthquakes. The San Andreas Fault in California is an example.

  • The theory of plate tectonics is supported by evidence such as similar fossil types found on different continents, the matching shapes of continents like South America and Africa, and through modern technology like GPS that can measure the movement of plates.

  • The understanding of plate tectonics plays a crucial role in predicting and understanding natural disasters such as earthquakes and volcanic eruptions.