No. 16: Summer 1981
The impressively strong magnetic anomalies discovered on the lunar surface remain enigmas. They appear to be superficial patches of highly magnetic material rather than deep-seated manifestations of basic lunar structure. Instead of being associated with gravity anomalies, the magnetic patches seem coincident with strange swirl-like markings on the moon's surface. The logical inference is that the swirls are surface patterns of highly magnetic substance -- but why the pecu-liar patterns and where did the strongly magnetic material come from?
(Hood, L.L.; "The Enigma of Lunar Magnetism," Eos, 62:161, 1981.)
Comment. The swirls were originally attributed to cometary impacts, but comets hardly seem likely carriers of highly magnetized materials.
Reference. The lunar magnetic swirls are cataloged at ALZ3 in The Moon and the Planets. For a description of this catalog, got to: here.