Scientists, focusing on the lead content of ancient ice cores, with high accuracy followed by political crises in the period from 1170 1216 for years. They were accompanied by a succession of UPS and downs in economic relations, led to changes in the pace of mining. To such conclusion the international group of glaciologists and historians, comparing the data of the atmospheric circulation with according to geo-archeological studies of glaciers in the Swiss Alps. Data from the study published in the journal Antiquity, they also devoted an editorial in Science.
Today the British village of Castleton — part of the national Park of the Peak district, which tourists visit for the limestone deposits, caves and ruins of a medieval castle. But 800 years ago this area was an industrial landscape and has been a generous lead contamination. Local farmers in large quantities mined and smelted lead and lead dust blown away by winds to a distance of 1,500 kilometers and settled on an Alpine glacier Colle of Gnifetti.
British historians and their American colleagues under the direction of Christopher Lovelock (Christopher P. Loveluck) the University of Nottingham suggested that the study of relict ice will allow you to establish the exact chronology of the production of lead and will help to associate it with historical events. Extraction of lead is accompanied by the production of silver, because these metals are often found in the same ore. Thanks to modern methods of mass spectrometry and paleoclimatic modeling contamination of ice lead can act as an indicator in the study of the medieval English economy.
In 2013, the glacier of Colle Gnifetti was a drilled well, from which was extracted 72-metre core. He kept precipitation accumulated over 2000 years and bearing traces of contamination from volcanic eruptions, dust storms in the Sahara and of human activity. To decode this information with minimal time-step, the team used a laser to cut layers of ice with a thickness of 120 microns. Each of these fragments were consistent with only a few days or weeks of snowfall throughout the core length. They analyzed samples (about 50,000 from each meter of core) — to contain about a dozen elements, including lead.
With the help of a program ClimateReanalyzerTM, which contains an extensive database of meteorological data allows you to visualize the weather changes, the researchers found, as lead dust carried by the trade winds Europe in the selected period of time. The model showed that during summer months the winds can blow lead dust into the glacier from the North-West of the UK. This helped to ensure the reliability of the methods chosen, as in the same period the lead was actively mined in Germany, and there was a possibility that the pollution will point to the economic development of another state.
Recorded spikes in the lead levels in the ice core coincides with the arrival of a new monarch to power: in such times, people minted silver coins that built cathedrals and castles. On the contrary, the sharp drop of concentrations was consistent with the political and economic crises — epidemics of plague, war, and overthrowing kings. For example, a sharp decline in lead content in 1170 falls at political event: the assassins of Henry the Young King killed the Archbishop of Canterbury. The king was excommunicated, the mining of lead and the payment of taxes was suspended. In the year 1193, on the contrary, there was sharp increase of lead content in the core. In that year Richard I the Lionheart was imprisoned by the Holy Roman Emperor Henry VI in prison in Germany, and served the British kingdoms were United to pay the ransom — production of lead increased.