They don’t know what causes earth’s magfield. A geologist once 75 years ago said it is the iron core, and that sounded good so a billion science textbooks have said that ever since.
Yeah, heh, funny how that works. :’)
http://www.freerepublic.com/focus/chat/1039487/posts
http://edition.cnn.com/2002/TECH/space/03/20/north.pole/index.html
http://www.physorg.com/news62919573.html
http://science-frontiers.com/sf006/sf006p07.htm
http://www.newscientist.com/news/news.jsp?id=ns99992814
http://www-spc.igpp.ucla.edu/personnel/russell/papers/ura_mag.html
[dead links]
http://www.press-citizen.com/apps/pbcs.dll/article?AID=/20051201/NEWS01/512010301/1079