The Loh Down On Science

Earth Reset

And now, for a story about our planet that’s a bit tilted.

This is Sandra Tsing Loh with the Loh Down on Science, asking: Could the planet tilt fifty degrees, then snap back into place?

Geophysicists at Harvard say yes!  Records in ancient rocks show this has happened at least five times over two billion years.

The phenomenon is called “oscillatory true polar wander.”

But something intrigued the scientists. How does Earth always pop back to normal?
     
They analyzed data on our planet’s lithosphere. That’s the crust and the underlying layer called the mantle. Then they created a computer simulation showing the lithosphere's movement over geologic time.

Turns out, tilts happened during times when the crust’s plates formed one massive supercontinent. The mantle then bulged up below it. The imbalance tilted the planet.

But the tipped crust was under stress. Like a stretched rubber band it eventually had to relax--and the imbalanced mass had to rebalance. Call it the Weeble effect.
 
Whoa! This sure gives plate tectonics a new slant!  Geology joke.


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