Magnetic Pole Reversals
The Earth is one big magnet. This is why when you use a compass, it points to the magnetic north.
But north didn’t always point northward. On average, it takes 250,000 years for Earth’s magnetic north to flip polarity.
As shown in rocks, magnetic pole reversals is one of the key gateways to recognizing the past.
On average, pole reversals occur every 200,000 to 300,000 years. We may be due for one soon.