Came across a (https://www.youtube.com/watch?v=g6thUIR3_rI) which describes Earth’s magnetic field having switched hundreds if not thousands of times during Earth’s 4.5 billion years.
So, how do we know thats a fact? What are scientists looking at that helped them determine this?
In: 2148
The ocean crust is a good one.
So Yknow how a long long time ago there was no Atlantic Ocean, and South America and Africa were touching?
Well, we know roughly how fast the Atlantic Ocean has grown, and as it grows more magma from the earths core rises up in the center and becomes new ocean crust.
Well, the magnetic field influences how the ferromagnetic Elements in the crust form crystals when solidifying from magma to rock.
So, using magnetometers we can “see” striped patterns where one stripe formed while the earths magnetic field was one way, and the other formed while the magnetic field was reversed. And by looking at how wide those stripes are and estimating how long each stripe took to form based on how quickly new crust is forming, we can estimate how much time there was between reversals based on those stripes.
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