Archaeomagnetism, the application of paleomagnetic methods to archaeological materials, is interdisciplinary not only in its methods but also in its impact. Well-dated archaeological materials are a critical data source for geomagnetic secular variation models [1–6], which are used to explore the dynamic structure of Earth’s core [7, 8], the rates of cosmogenic isotope production in the atmosphere [9–11] and the possible effect of geomagnetism on climate [11–13]. Precise documentation of the ancient field also helps contextualize geomagnetic observations from the modern era, such as the evolution of the South Atlantic Anomaly [14, 15] and the ongoing decline in the field’s intensity [16–18].

Albert Einstein once called the behavior of the magnetic field one of the great mysteries of physics, but understanding and possibly predicting its changes has taken on a new urgency for scientists. The field has lost around 10 percent of its strength since measurements began less than 200 years ago, leading some researchers to question whether we are on the way to a flip in polarity, which would be preceded by a loss of our precious shield against cosmic radiation.