 The Cistercian monks, known to have been skilled metallurgists, also had a blast furnace (the only medieval example yet identified in Britain) for the smelting of iron ore into cast iron.The iron ore left in the slag at Laskill has been identified by Gerry McDonnell (archeometallurgist of the University of Bradford) as more refined than anything else at the time, suggesting a much more efficient blast furnace technology than otherwise existed – perhaps as advanced as a modern blast furnace.The destruction of the abbey at Rievaulx by King Henry VIII during the Reformation put an end to this blast furnace and its advanced technology.