Geosonnet 31

Gyrations of a topsy-turvy world
Could spur migration of the cryosphere
No snowball Earth, just poles and tropics whorled
The data which support this are unclear.
Precambrian magnetic fields suggest
That tropics, poles exchanged with frightful speed.
Magnetic hysteresis is the test
Anorthosite and feldspar crystals need.
A shaky witness cross-examination
The steep magnetic field begins to fray
Faced with a single crystal refutation
The polar history has gone away.
   The Ediacaran poles didn't roam.
   Emerging life was blessed with stable home.

Geology 43 132

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