250 Million Years Ago—Iapetus Ocean Closes. Pangea forms as the continents collide. The Appalachians are part of a larger zone of continental collision that includes the Marathon and Ouachita mountains in the s More
Continents collide where subduction completely closes an ocean. The buoyant continental crust lifts up a broad region known as a collisional mountain range.
150 Million Years Ago—Thick Sedimentary Layers. Continents collide but continue to converge.