the Wilson cycle

• First proposed in 1966. 
• Continents show a cyclic history:

  1. Rifting 
  2. Drifting 
  3. Closure 
  4. Collision
  5. Followed by rifting again 
• 1: 

  Continental rifting is where the mantle rises creating tension of the lithosphere causing thinning. This creates a rift in the continental lithosphere forming a divergent plate boundary. 

   
• 2: 

  Ocean forming basins with a central ridge, they have a passive margin on each side, the ocean gets bigger and wider until subduction begins at margins. 

   
• 3: 

  Closure is due to subduction at convergent plate boundaries - closing the ocean. 

  Island arcs form with trenches. 
• 4:

  Collision 

   
• Supercontinents form every 500 million years.