 The oldest sub-aerial rocks in modern-day Iceland are from 16.5 Ma.Although most scientists believe Iceland is capable of being an island because it is both in contact with a mantle plume, and being actively split apart by the Mid-Atlantic Ridge, some other convincing seismological and geophysical evidence calls the previously discussed mantle plume/hotspot assumption into question.Some geologists believe there is not enough definitive evidence to suggest a mantle plume exists beneath Iceland because sea floor heat flow through the lithosphere surrounding Iceland does not deviate from normal oceanic lithosphere heat flow that is uninfluenced by a plume.