Researchers had long suspected the Earth had another layer at its core, but because its composition is so similar to the layer surrounding it, the innermost inner core was hard to spot.

The Earth has a layered structure made up of the core, the mantle and the crust. Different elements are present in different parts of the Earth’s structure. The crust is made from enormous ...

Whether convection in the Earth's mantle extends through its entire ... tended to support whole-mantle convection. The potential compositional boundary was typically put at 660 km depth ...

They believe the D" layer may be a unique composition leftover from this colossal impact, potentially holding clues to Earth's formation. The paper is published in the journal National Science Review.