CGP Plate Tectonics

• Core

  The centre of the Earth, split into inner core and outer core
• Inner core


  • Solid ball containing lots of iron and nickel
• Outer core


  • Liquid and also contains lots of iron and nickel
• Mantle

  The layer around the core, mostly made of silicate rocks
• Asthenosphere


  • The semi-molten layer of the mantle
• Crust


  The outermost layer of the Earth
• Lithosphere


  The rigid top part of the mantle and the crust together
• Types of crust

  • Continental
  • Oceanic
• Continental crust


  • Thicker (0-70 km) and less dense
• Oceanic crust


  • Thinner (~10 km thick)
• The core and mantle are very hot - the inner core is about 6000 °C and the mantle is around 1000-3500 °C
• The Earth's heat is the main source of internal energy, some from when the Earth formed and some from radioactive decay
• Tectonic plates


  Slabs that the Earth's lithosphere is divided into, which move in relation to each other
• Plate boundaries/margins


  The places where tectonic plates meet
• The theory that the Earth's lithosphere is made up of plates that move is called plate tectonics
• Slab pull


  The leading edge of a tectonic plate is denser and sinks, pulling the rest of the plate towards the boundary
• Convection currents


  Hotter, less dense rock rises, cooler, denser rock sinks, creating circulation that drives plate movement
• Sea-floor spreading


  As tectonic plates diverge, new crust is formed to fill the gap, causing the sea floor to get wider over time
• Sea-floor spreading creates mid-ocean ridges - ridges of higher terrain on either side of the gap
• A similar process of spreading occurs at land margins where plates are moving apart
• The photograph shows Hveravellir Iceland, located on the boundary between the North American and Eurasian plates
• The landscape is developing due to plate tectonics and the processes associated with it