GeologyRocks

Little is known about the process of growth of Earth's inner core. Because it is slowly cooling, many expected that the inner core would be very homogeneous and clean. It was even suggested that Earth's inner core may be a single crystal of iron, however, this is at odds with the observed degree of messiness inside the inner core. Seismologists have revealed that the inner core is in fact rather messy and has some large scale structures such that seismic waves pass through it more rapidly in some directions than in others.