Magnetic fields used to date Indian artifacts

You might be surprised what you can learn from a campfire. A campfire that has been cold for, say, 300 years.

Stacey Lengyel hopes she can tell, within 30 years or so, when it was used.

Lengyel, a research associate in anthropology at the Illinois State Museum, is the country's leading authority on archeomagnetic dating, a process built around two phenomena: when heated, magnetic particles reorient themselves to magnetic north; and over time, magnetic north is, literally, all over the map.