this post was submitted on 22 Aug 2025
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xkcd #3132: Coastline Similarity

Title text:

Hey! A bunch of the early Cretaceous fossils on each coast seem to have been plagiarized, too!

Transcript:

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Source: https://xkcd.com/3132/

explainxkcd for #3132

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[–] frog@feddit.uk 7 points 1 month ago (2 children)

When there was only one land mass, is there any scientific theories if that would change the rotation of the earth on its axis or around the sun?

[–] mineralfellow@lemmy.world 8 points 1 month ago (1 children)

It would not. The mass of the Earth doesn't change, and angular momentum is conserved.

[–] frog@feddit.uk 2 points 1 month ago (2 children)

I was curious since mass would seem lopsided. I guess not enough. Thanks for answering.

[–] deltapi@lemmy.world 4 points 1 month ago

My layman's understanding is that the water mostly makes up for it, and that more wobble comes from the moon than any inconsistency in land-mass distribution

[–] WalrusDragonOnABike@reddthat.com 4 points 1 month ago (1 children)

The crust of the earth is relatively thinner than the skin of an apple from my understanding. So I wouldn't expect anything happening on the crust to have a huge impact on that kind of behavior. Granted, even small changes could be noticable.

[–] frog@feddit.uk 3 points 1 month ago

That's a great point. When it comes to the Earth's mass, the surface is barely a factor.

[–] emergencyfood@sh.itjust.works 3 points 1 month ago

No, but the climate was probably cooler and drier than today. In fact the interior regions of the supercontinent might have been too dry to support most life-forms.