Wilson Cycle

The Wilson cycle is the long-term sequence by which an ocean basin opens and then closes over hundreds of millions of years, named for J. Tuzo Wilson. It runs through stages: continental rifting and a young ocean basin (the East African Rift, then the Red Sea), a mature spreading basin with passive margins (the Atlantic today), the start of subduction and basin closure (the Pacific shrinking), final collision that consumes the ocean (the Mediterranean), and continental suturing that builds a mountain belt (the Himalaya from the closed Tethys). Each opening generates oceanic crust at a ridge; each closing destroys it at a trench, sometimes leaving ophiolites stranded on land.