Wilson cycle
The repeating sequence in which an ocean basin opens by continental rifting, widens, then shrinks and closes by subduction, ending in collision.
Continental rift: A elongated zone where a continent is stretching and fracturing, the first stage of ocean-basin formation. Stage one: rifting is how the cycle begins, before any oceanic crust exists.
Atlantic Ocean: The ocean opened by breakup of Pangaea since about 180 million years ago, still widening today. The type example of a mature, widening ocean in the middle of the cycle.
J. Tuzo Wilson: Canadian geophysicist who proposed transform faults, hotspots and the repeating ocean-opening-and-closing cycle. He described the cycle in 1966 and it now carries his name.
Accretionary orogen: Mountain belts built by adding island arcs, plateaus and terranes to a margin rather than by continent-continent collision. An alternative orogen type that does not fit the open-then-close template.
Orogeny: The process and episode of mountain-belt formation, usually at convergent or colliding plate boundaries. Every collision stage of the cycle leaves an orogenic belt as its signature.
Seafloor spreading: Creation of oceanic crust at mid-ocean ridges as plates diverge, widening the basin between them. Stage two: spreading makes a young narrow sea grow into a wide ocean.
Red Sea: A young oceanic basin formed where the Arabian plate rifted from Africa, only a few million years old. A cycle just past rifting: a nascent ocean in its narrow, infant stage.
Plate tectonics: The theory that Earth's outer shell moves as interacting rigid plates, unifying earthquakes, volcanism and mountain building. The cycle is the large-scale temporal pattern that plate tectonics explains.
Geosyncline theory: The pre-plate-tectonics idea that mountain belts form by subsidence and folding of thick sedimentary troughs. The rival explanation of mountain belts that Wilson's cycle displaced.
Suture: The geological boundary where two once-separated continental blocks are welded after an ocean closes. Sutures are the fossil scars marking completed Wilson cycles.