The entire outermost part of Earth may be wandering over the planet's whirling molten core, new research suggests.
Knowing whether the Earth's outer layers are roaming in this manner is key to understanding the big picture of how the planet's surface is evolving overall, scientists added.
At various times in Earth's history, the planet's solid exterior — its crust and mantle layers — has apparently drifted over the planet's spinning core. To picture this, imagine that a peach's flesh somehow became detached from a peach's pit and was free to move about over it.
This movement of the Earth's outer layers is known as "true polar wander." It differs from the motion of the individual tectonic plates making up Earth's crust, known as tectonic drift, or the motions of Earth's magnetic pole, called apparent polar wander.
'Hot spot' landmarks
Past research suggested the Earth experienced true polar wander during the early Cretaceous period that lasted from 100 million to 120 million years ago. Determining when, in which direction and at what rate true polar wander is taking place depends on having stable landmarks against which one can observe the motion of Earth's outer shell, much like one can tell a cloud is moving by seeing if its position has changed relative to its surroundings.
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