Furnace Fields: Iron Age and Roman Metalworking between York and the Humber
An archaeological investigation associated with a proposed renewable energy development at Thornton in the East Riding of Yorkshire (UK) revealed extensive evidence for middle Iron Age to early Roman industrial activity. Amongst over 200kg of archaeometallurgical residue finds was a single intact furnace bottom which weighed 155kg and is of national significance. Almost all the residues were produced during iron smelting in non-slag tapping, slagpit, furnaces, employing a wood pit-packing. This technology is typical of the early and middle Iron Age. Detailed analysis suggested that the smelting employed a very rich bog iron ore, with a moderate phosphate content, that would probably have produced phosphoric iron. The large size of the intact furnace bottom suggests a process in which blooms might have been produced sequentially, rather than just a single iron bloom. The large size also indicates a process requiring considerable resources such as iron ore and charcoal, perhaps suggestive of a communal effort. Similarly sized furnaces are known from the early and middle Iron Age in south and south-west England but are unknown from the Midlands and the North. The low-lying valley of the River Foulness has been known as an important source of bog iron and 19 Iron Age smelting sites have previously been discovered. The site at Thornton is potentially part of a larger, regional tradition of iron working in the lowlands of East Yorkshire.
