Over several hundred million years the processes of plate tectonics propelled several landmasses to collide with this edge of North America, making mountains with each impact.
(the processes of plate tectonics; propelled; several landmasses; to collide with this edge of North America; T:Over several hundred million years)
the processes of plate tectonics
propelled
several landmasses to collide with this edge of North America T:Over several hundred million years