Ancient slag suggest that the magnetic field of the Earth is more variable than scientists ever imagined.
The geomagnetic field is the result of the movement of the molten iron in the core. The strength of the field and its structure is constantly changing, but slowly. Paleomagnetisty believe that secular variations do not exceed 16%. But the new data obtained in a copper smelter, located near drevnegipetskimi mines in southern Israel, suggest that the strength of the magnetic field could grow by 40-100%, and then return to the "normal" state in less than twenty years.
If the metal is frozen very quickly, it is possible to determine the features of the magnetic field at a given time. Usually paleomagnetisty study for this volcanic glass. Luis Silva of the University of Leeds (UK) and his colleagues replaced him slag left after copper smelting — in fact, the same lava flow, but on a smaller scale.
Analysis of slag from Timna possible to discover, among other things, traces of wheat grain, figs, grapes, and even human hair. All this has enabled the work to date the foundry overseas II and I century BC. e.
The samples were then combined with the already studied slag mines Khirbat en-Nahas, in the north-east of the Jordan. In total, in the hands of scientists were data for 1050-870 years. BC. e.
Some samples melted and rapidly cooled, and then compared with the intact slag. It turned out that in the area of 990 and then 900 years. BC. e. strength of the magnetic field change is 5-10 times faster than scientists used to seeing, and 2.5 times higher than the current rates.
However, there is a suspicion that this is some feature of the Middle East, but not the entire Earth. It is possible that just somewhere under Israeli special magnetized portion of the molten iron turned somehow special.