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Digging Into the Past
In 2007, Lisa Tauxe, Scripps professor of geophysics and director of the Scripps Paleomagnetic Laboratory, trekked across Israel and Jordan in search of history. Tauxe and UCSD colleague Thomas Levy were collecting archeological artifacts from ancient copper mines that can be used to examine the magnetic field over the last 6,000 years.
Tauxe and members of her research team analyzed copper-mining slag, a by-product left behind from the melting of copper ore, collected from a variety of archeological sites in the magnetically neutral paleomagnetic lab at Scripps. The lab, which contains a small, windowless room packed with magnetometers and samples from around the world, is lined with special field-canceling wallpaper to prevent the present day magnetic field from influencing the analysis.
The study revealed that the field peaked in intensity about 2,000 to 3,000 years ago and has been weakening ever since.
Tauxe's deposits were formed from fast-cooling melts used in copper mining operations in the southern Levant region, the modern day border region of Jordan and Israel. The new find has been a boon to geoscientists offering them a valuable new source of material to extract field strength information as well as a way to settle archaeological debates on the age of specific artifacts from this time period.
Next page: Putting the Pieces Together