The rapid spin of the early Earth could have influenced the way that the planet solidified.

Some 4.5 billion years ago, Earth was extremely hot, covered by a molten magma ocean, and completed a full rotation in a few hours. Christian Maas and Ulrich Hansen of the University of Münster in Germany calculate that the fast rotation could have influenced how crystals settled from the magma ocean and shaped Earth's interior. They used a three-dimensional model of the formation of silicate crystals in magma, and found that a fast rotation rate created a crystal layer that settled deeper beneath the poles than under the equator.

This could have played a key part in how Earth's mantle layer eventually solidified out of the magma ocean, say the authors.

J. Geophys. Res. Solid Earth http://dx.doi.org/10.1002/2015JB0121053 (2015)