Before revision: Movements in the earth 's crust, and the closure of the Iapetus Ocean, transformed these sediments into crystalline schists that lie underneath the base of the mountain range, which local erosion and uplift then brought to the surface.
After revision: Movements in the Earth 's crust, and the closure of the Iapetus Ocean, transformed these sediments into crystalline schists that lie underneath the base of the mountain range, which local erosion and uplift then brought to the surface.