Plate Tectonics Vocabulary

  1. Inner core – the solid (metals) innermost layer of the earth. Composed primarily of Fe andNi.
  1. Outer core – The liquid inner layer, Fe & Ni
  1. Mantle – The largest layer of Earth. Molten rock that extends to a depth of about 3,000 km. Moves like a fluid. Divided into upper & lower.
  1. Crust – outermost layer of the earth that covers the mantle. Solid, rigid rock 5 – 100km. (75% sed). Oceanic (5 km dense basalt) Continental thicker (continents & islands).
  1. Lithosphere – The cool, solid, outer layer of the earth extending to a depth of about 100 km
  1. Asthenosphere – The hot, semi-liquid layer of the earth’s mantle below the lithosphere
  1. Tectonic Plate – Lithosphere(crust and rigid upper mantle) broken into smlg pieces that move around on top of the asthenosphere. The movement is responsible for geologic features of Earth.
  1. Continental Drift – Wegener’s hypothesis that all continents were once connected in a single large landmass that broke apart about 200 million years ago and drifted slowly to their current positions.
  1. Pangaea – large, ancient landmass that was composed of all the continents joined together
  1. Mid Ocean Ridge (MOR) – Huge underwater mountain ranges that form along cracks in the crust. Molten rock rises through the cracks and form new oceanic crust.
  2. Convection – circular flow of matter in currents in heated material
  1. Convection current – A circular pattern in which heated material rises then cools and sinks creating a continuous loop or cycle
  1. Theory of Plate tectonics – theory that Earth’s crust and upper mantle are broken into plates that float and move around on a plastic-like layer of the mantle.
  1. Divergent Boundary(spreading centers)– Area where 2 plate move away from each other.
  1. Rift Valley– As ridges continue to widen, gaps are formed to create rift valleys
  1. Magnetic Reversal – North pole becomes south pole and vice versa. Switch in directional polarity.
  1. Hot Spot – Heated rock rises in plumes or thin columns from the mantle usually in the middle of a plate, not the boundaries
  1. Transform boundary– occur where 2 plates slide past one another, they can move in the opposite direction or the same direction but at different rates of speed
  1. Convergent Boundary– Area where 2 plates move together.
  2. Subduction zone– the area where plates collide and the oceanic plate subducts, or goes down, beneath the less dense continental plate.
  3. Continental-Continental Convergence
  4. Oceanic-Oceanic Convergence w/subduction
  5. Oceanic-Continental Convergence w/subdution