Wilson Cycle

What is the Wilson Cycle?

Alfred Wegener Recognized that the continents had once been joined in one large land mass. J. Tuzo Wilson concluded that the continents had been joined and separated several times throughout the history of the earth and that the process of opening and closing ocean basins is cyclic.  Hence, the Wilson Cycle. This cycle was postulated to explain the numerous parallel mountain chains on the different continents.  Fundamentally it revolves around the opening and closing of the Atlantic Ocean.

The Appalachian Mountains are the principle evidence--they have the characteristics of a collisional mountain range, but were formed before the breakup of Wegener's Pangaea. Therefore, the continents must have been separated before Pangaea, and the Appalachian Mountains were formed as Pangaea was assembled.

Here is how it works:
 

  1. A continents is broken apart by continental rifting.
  2. The ocean widens
  3. The oceanic crust gets old and subduction begins
  4. The ocean is closed up as the continents (what was once one continent) collide and a collisional mountain range is formed
  5. The continents are joined for a time.
  6. Mantle upwelling begins a new cycle of continental rifting (to one side of the mountain range)