Tearing of continents is less traumatic than it would seem to humans, who imagine the continents as one plate and think of how lumber resists being torn, metal bends and twists before tearing, and a rope of fibers resists while the fibers snap one by one. Continents are in fact an overlay of many plates, and faults are where most of the plates have fractured in the same place. The continents are attached because some of the plates have not fractured. This concept should not be that hard to grasp if one considers that many land faults have a slip-slide relationship of the plates, which are moving in different directions past each other. This motion would not be possible if the plates were not, in fact, separate.
Thus, ripping apart of continents is no more traumatic than subducting or slip-sliding. The land along the edges generally retains its altitude, as this was determined by the thickness of the plates, thus its boyancy on the sea of lava. Solid land is composed to a great degree from the lighter elements, which rose to the top during the early cooling of planet Earth, and thus formed the floating crust.