"Biblical" urns told about unexpected changes in the Earth's magnetic field, writes PNAS edition.
Scientists have studied the traces of the Earth's magnetic field, which were "imprinted" in the clay of vessels created in biblical times. The study was led by archaeologist Eretsa Ben-Yosef of Tel Aviv University.
It was previously known that every 450 thousand - 1 million years, the north and south magnetic poles of the Earth change places. Evidence for this is found in the structure of ancient clays and volcanic rocks. For example, about 40 thousand years ago, the north arrow of the compass would point to the present-day south pole, and the south arrow to the north.
Israeli scientists have studied pottery that was recently discovered in the ancient Jewish city of Ramat Rachel. The ruins of this city were excavated back in the 60s of the last century.
In the 8th-2nd century BC, Ramat Rachel was one of the most active centers of trade in the Kingdom of Judah. The earthen vessels discovered during the excavations bear the date of their manufacture. This allowed geologists to study very accurately how the Earth's magnetic field has changed in the past.
Scientists explained that many rocks of the Earth, including clay, contain atoms of iron and granules of the rocks containing it, which make it possible to establish where the magnetic field of the planet was "turned" and what strength it had at the time of their formation. And if the clay is heated to a certain temperature, this information can be read using modern devices.
Therefore, knowing the date of manufacture of the earthen vessel, it is possible to establish what the Earth's magnetic field looked like in the distant past. Knowing this, Israeli scientists received a kind of "geomagnetic chronicle" describing how the planet's magnetic field changed from the 8th to the 2nd century BC.
And this time they managed to discover new information that had not been revealed earlier in the study of natural clays and rocks in the same part of the Middle East. In general, the strength of the magnetic field gradually decreased during that period, which is in line with theoretical predictions and other measurements. But at the end of the 6th century BC, there was an unexpected surge in the strength of the magnetic field, which is absent in the "natural" data. During this period, the field strength increased sharply, rising to a point twice the current strength of the Earth's magnetic shield.
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Also, the study of pottery made it possible to record an episode of a sharp drop in the Earth's magnetic field. This happened in 730-701 BC. Then, in just 30 years, the field strength fell by 27%.
Scientists note that the study of ancient pottery allows you to see how the Earths change places. And having such knowledge, they are sure, it is possible to predict where and when it will happen next time.
