The Iron Age Geomagnetic Field

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The interplay between archaeology and the study of the Earth's ancient magnetic field goes back to the late 19th century when physicists realized that ceramics and other archeological materials could retain a record of the ancient magnetic field. Ceramic materials were among the very first targets of modern experimental methods to determine the ancient field strength and the field known as "archaeomagnetism" remains vibrant today. Archaeologists are beginning to take advantage of the powerful constraints on ages of material for which full magnetic vectors are possible in regions with an accurate reference model and geomagnetists are taking advantage of the growing archeomagnetic data base which is producing more high quality data with better age constraints. However, partly owing to the experimental difficulties in recovering ancient magnetic field strength from geological and archaeological materials and partly because of a lack of well-dated materials for study, the archaeomagnetic data base remains heavily biased towards European data from the last millennia. This grant will support efforts to expand the global data set over the last four millennia, including new radiocarbon age control and new paleomagnetic and archaeomagnetic data from places that are currently under-sampled. The research supported here will have implications for numerical simulations of the geomagnetic field, and provide higher resolution age constraints for archaeological research. An accurate picture of paleointensity changes on a global scale (a goal to which this project contributes but does not solve by itself) is essential for understanding variations in the production of radiocarbon and the calibration of the radiocarbon time scale. Finally, this proposal will help support the continued development of online paleomagnetic teaching materials in the form of the Essentials of Paleomagnetism online textbook project of the PI (see http://magician.ucsd.edu/Essentials) and facilitate offering of online classes in paleomagnetism offered to graduate students the world over.