With the aim of reconstructing the intensity of the earth's magnetic field during the last six millennia, we sampled copper slag deposits from various archaeometallurgical sites in Israel and Jordan. This represents the first such study in the southern Levant. Hundreds of paleointensity results indicate that copper slag material, which shows similarities in magnetic characteristics with quenched basaltic glass, constitutes one of the most efficient archaeological recorders of the geomagnetic field. The results were obtained out of more than 70 slag samples from 30 archaeometallurgical sites, most of which are located in the large copper production regions of Timna and Faynan situated in the arid Arava/Arabah valley.
Paleointensity results from well dated archaeological contexts were used to track the secular variations of the geomagnetic field and to reconstruct their tendencies. Analyzing results from other sites has contributed in return to dating their context and enabled better understanding of many sites, some of which has substantial implication on our understanding of the dawn of metallurgy in the southern Levant.
Our results show highly fluctuated geomagnetic field behavior during the last six millennia, with relatively low field intensity during the 4th millennium B.C. and a conspicuous peak around 3,000 B.C. These trends agree with other paleointensity data obtained lately by other research groups. Establishing paleointensity variations curve enabled us to compare it with excellent paleomagnetic results from many poorly dated and disputed sites. Some of the sites in the Timna valley were re-dated, and others such as the disputed “Chalcolithic” furnace found at Site 39b was confirmed to date from the Chalcolithic period, making it one of the earliest smelting furnaces in the world.