Ben-Yosef, and 7 co-authors, reported in 2008 that paleointensity and archaeointensity studies since the 1950s have produced numerous geomagnetic intensity data for the last seven millennia. As a consequence of different experiments and materials, there is a complex and internally inconsistent picture of the geomagnetic field behavior. In this study we present data using a recently developed experimental design on a heretofore unexploited recording medium: copper slag deposits. Our results, based on hundreds of specimens from various archaeometallurgical sites of the Southern Levant, demonstrate the applicability of copper slag material for archaeointensity studies. In addition to frequently exhibiting good experimental behavior, slag has further advantages such as dense multilayer deposits and in cases embedded charcoals, which open the door to data sets with excellent age control and resolution. The data presented here augment the high quality database from the Middle East and support previously observed periods of rapid change of the intensity of the geomagnetic field.
In this paper the authors have demonstrated the suitability of copper slag material in archaeointensity research. Using this medium together with a sophisticated experimental protocol (the ‘‘IZZI’’) the authors obtained consistent archaeointensity results from the last seven millennia. Their results show good agreement with the recently published data sets from Syria, and augment the existing record of the geomagnetic field intensity. Their data support trends in the field intensity changes, such as the relatively low prior to 5,000 years ago and the conspicuous peak around 3000 years ago. They also support the existence of several short episodes of rapid change of the geomagnetic field intensity.
The recently accumulated high-quality data show that the global model [Korte and Constable, 2005a] underestimates the variability of the geomagnetic field. Slag material has further potential for archaeointensity research. Applying a pre-experiment selection procedure may well increase the success rate, and using embedded charcoal for direct dating will increase the dating precision. In many localities, slag accumulated in multilayer mounds that can provide samples for high resolution investigation of specific periods of interest, such as the peak in the Iron Age or episodes of rapid intensity changes. Copper production sites can be found in many parts of the Old World, as well as certain locations in the New World, covering different and complementary time ranges since the invention of copper industry, approximately 7,000 years ago. Using this material for archaeointensity reconstruction will open another door toward better understanding of the Earth’s magnetic field in the late Holocene.
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