Plate Tectonics

Plate Tectonics

The Basics of Plate Tectonics

  • Plate tectonics is the theory explaining how the Earth’s crust, or lithosphere, is divided into large pieces called tectonic plates.

  • These tectonic plates move over the semi-fluid layer of the Earth’s interior called the asthenosphere.

  • There are several major plates such as the Pacific Plate and the African Plate, and several smaller ones, including the Philippine Plate and the Juan de Fuca Plate.

Plate Movements and Interactions

  • The plates can move towards each other (convergent boundary), away from each other (divergent boundary), or slide past each other (transform boundary).

  • These movements are driven by convection currents in the semi-fluid asthenosphere beneath the plates. The heat for these currents comes from the decay of radioactive elements in the Earth’s mantle and core.

  • Convergent boundaries can form subduction zones (where one plate is forced under another) or mountain ranges (where two plates collide and push up).

  • Divergent boundaries create mid-ocean ridges where new crust is formed from magma pushing up from the mantle. This can lead to the creation of new sea floor in a process known as sea floor spreading.

  • Transform boundaries cause earthquakes due to the friction that occurs when two plates slide past each other.

Impacts of Plate Tectonics on the Earth

  • The movement and collision of tectonic plates are responsible for earthquakes, volcanic activity, the creation of mountain ranges, and trench formation.

  • Over geological time, plate tectonics have significantly influenced the shape and location of continents in a process called continental drift.

  • An understanding of plate tectonics is also essential in identifying geological hazards and the locations of economic resources such as oil and minerals.

Tectonic Plates and the Rock Cycle

  • Plate tectonics plays an important role in the rock cycle. Magma from the Earth’s mantle solidifies to form igneous rocks at divergent boundaries, and existing rocks are melted or metamorphosed by the intense heat and pressure at convergent boundaries.

  • The weathering and erosion of rocks at the Earth’s surface, followed by deposition and compaction, can lead to the formation of sedimentary rocks.

  • Over time, all these processes interact to continually recycle and change the rocks at the Earth’s surface.