When the inhabitants of ancient Mesopotamia inscribed the names of their kings into bricks, they probably did not imagine that this custom would become the key to solving a rare natural phenomenon.
The inscriptions on Mesopotamian bricks depicting kings when fired have proven to be a valuable source of information for modern researchers. According to a recent study published in the Proceedings of the National Academy of Sciences, traces of magnetic fields found on these artifacts indicate variability in the Earth's geomagnetic field over the past 3,000 years.
The study of bricks with the names of kings was made possible thanks to the unique approach of Professor Mark Altavila from University College London. The researcher focused on the so-called "Levantine Iron Age geomagnetic anomaly" - a period about 3,000 years ago in the Middle East.
After studying 32 Mesopotamian clay bricks, each decorated with the name of one of the 12 kings, Altavil and his colleagues made a surprising discovery. The iron oxide grains in the bricks retain the direction and strength of the magnetic field, allowing scientists to recreate its changes over centuries.
The measurements indicate fluctuations in the geomagnetic field over a 500-year period that began more than 3,000 years ago. Particularly interesting was the reign of King Nebuchadnezzar II, who, as you know, ruled the great Babylonian kingdom.
Five bricks dating back to the time of Nebuchadnezzar II showed an unusual increase in magnetic field strength. This discovery supports the hypothesis that the Earth's geomagnetic field can undergo rapid and significant changes.
The study confirms one of the competing timelines of the region's history. Dating methods like these will now help answer unanswered questions and also better understand the nature of the Earth's geomagnetic field.
Professor Altaweel concludes: “The geomagnetic field is one of the most mysterious phenomena in the geosciences.” And it seems that even ancient bricks may be the key to deciphering its secrets.