Results of a one-dimensional model for the closing of the ocean between Laurentia and Gondwana, initially of width 4340 km. Forces acting are shown with arrows: SP = Slab Pull; TS = Trench Suction. The Laurentia plate is shown as green, with the continental region hatched, Gondwana as the magenta hatched region, and the ocean plates as blue. The red lines are subduction zones.