Iron oxide baked into Mesopotamian bricks confirms ancient magnetic field anomaly

A brick dating to the reign of Nebuchadnezzar II (circa 604 to 562 B.C.), according to the inscription. This brick, which was looted and is now housed in the Slemani Museum in Iraq, and others helped researchers confirm an ancient magnetic field anomaly.

Ancient bricks from Mesopotamia have helped confirm a mysterious anomaly in Earth's magnetic field that occurred 3,000 years ago, a new study finds.

Brickmakers baked the bricks, which were imprinted with the names of Mesopotamian kings, between the third and first millennia B.C. Iron oxide grains within the clay recorded changes in Earth's magnetic field when the bricks were heated, enabling scientists to reconstruct changes in the magnetic field over time, the team reported in a study published in the journal PNAS on Monday (Dec. 18).