paleomagnetic

The story

1. Proto-Indo-European*kʷelh₁-der.?
2. Ancient Greekπάλαι (pálai)
3. Ancient Greekπᾰλαιός (pălaiós)
4. Englishpaleo-
5. Old Frenchmagnete
6. Ancient GreekΜάγνης (Mágnēs)
7. Ancient Greekμᾰ́γνης (mắgnēs)
8. Latinmagnēs
9. Middle Englishmagnete
10. Englishmagnet
11. Englishmagnetic
12. English todaypaleomagnetic

From paleo- + magnetic.