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133 points kristianp | 1 comments | | HN request time: 0.201s | source
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kevinkeller ◴[] No.42161353[source]
I love this type of articles where we can reconstruct what happened so long ago just based on careful observations.

Some other instances I've come across:

* The K-Pg extinction event that wiped off dinosaurs had the impact it did because the asteroid happened to impact a shallow water region. This kicked up a lot of sulfur (in gypsum) that further affected global climate: https://en.wikipedia.org/wiki/Chicxulub_crater#Effects

* Earth likely had rings ~466M years ago. We deduced this by looking at impact craters from that time period, and seeing that they all lie near the equator (accounting for continental drift): https://www.sciencedirect.com/science/article/pii/S0012821X2...

* Earth's rotation period was probably frozen at 21h, ~600M years ago, likely due to interaction between lunar and solar tides. This resonance could have been broken by ice ages (!!!). Amazing to think that global climate affects earth's rotation: https://en.wikipedia.org/wiki/Earth%27s_rotation#Resonant_st...

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1. thangalin ◴[] No.42161612[source]
> reconstruct what happened so long ago just based on careful observations.

Me too! My book is filled with them. Like how minerals in lava, affected by Earth's magnetic field, lock into place while cooling, which provides us with yet another cross-check for radiometric dating. See page 23:

https://impacts.to/downloads/lowres/impacts.pdf