Archaeomagnetism

Abstract

The study of the magnetic properties of archaeological materials, archaeomagnetism, is particularly significant in geophysics as it enables secular variations in the direction and strength of the geomagnetic field over timesscale that are far longer than those for direct measurement (~400 years). In comparable magnetic studies of rocks, paleomagnetism, these secular variations are commonly averaged out during the processes by which rocks acquire their remanent magnetization. Conversely, archaeomagnetic records provide an additional dating tool for archaeologists. As a comparative dating tool, archaeomagnetism enables relative dating between nearby samples (100–200 km) within ~10–20 years. As a dating tool, it is mainly dependent on the validity of the ages used to compile the regional Master Curve. It is thus unique, as a scientific dating method, in that as more data are acquired, age “outliers” can be identified and their age reassessed. Consequently, the Master Curves are continually improving and, ultimately, could have the same precision as for relative dating. There are also interesting applications in using such observations in conservation studies and establishing past environmental conditions.