We know that true polar wander (TPW) can occasionally tilt whole planets and moons relative to their axes, but it's not entirely clear just how often this has happened to Earth.

Bacteria fossils trapped in the rock, forming chains of the mineral magnetite, offer some of the most convincing evidence yet of true polar wander in the Late Cretaceous – and it may help settle a scientific debate that's been going on for decades.

True polar wander is when the geographic poles shift substantially, so the outer wrapping of Earth tilts over.

"True polar wander would look like the Earth tipping on its side, and what's actually happening is that the whole rocky shell of the planet – the solid mantle and crust – is rotating around the liquid outer core.".