Complex sentence: In the hanging wall (the block above the fault), hotter material in deeper depth moves towards the surface; while the cooler material at shallower depth in the footwall (the block below the fault) moves to a deeper depth.
Split into simpler sentences: In the hanging wall (the block above the fault), hotter material in deeper depth moves towards the surface. While the cooler material at shallower depth in the footwall (the block below the fault) moves to a deeper depth.