The Earth's magnetic history last month was pulled back to 3.7Gya - like, 760My after 4.46 Gy; before even the cratons. This field removed xenon from our atmosphere. Now Prof. Tarduno at Rochester have the Vendian magnetism, which coincides with the Ediacara menagerie.
The Vendian started 635Mya. For 26My in this span the field was weaker than it has ever been.
This would have held whatever xenon was left (most was already gone by 2.5Gy) but stripped away hydrogen - just like over Venus. There would have been an oxygen pulse, so strong this injected into the (evaporating) oceans.
It follows that landmass was less before the Vendian, than after. Which I think might actually check out. Although "land" in those days probably also meant "snow".
Luckily the field spun up again, saving us from Venus' fate. Tarduno elsewhere says this started 565Mya. Cambrian won't start until 541Mya.
Anyone seeking to check further on Tarduno's thesis should ponder... deuterium. Did we have a lower deuterium-ratio, before the Vendian than afterward? Compare hydrates laid down during "Cryogenian", versus now...?
I still don't know why the dynamo abruptly cranked into a standstill and why it started again; nor, why then. I'm not seeing any abrupt Velikovskyian tacks in other planets. Unless... it's Theia. Chunks interfering?
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