Archaeological Excavation of a Potential Bale Site

By September 23, 20132013

A potential lead bale site at SE 05939 99141 was found in 2012 and was excavated as a joint project in the summer of 2013 by the Swaledale and Arkengarthdale Archaeology Group (SWAAG) and the Northern Mine Research Society (NMRS) under the supervision of professional archaeologist, Tony Liddell of Vindomora Solutions and funded by NMRS.

On 24 July 2013, a geophysical survey was undertaken of the site by Dr Robert Vernon, who identified features consistent with bale technology. The results of this survey were used to guide the selection of the areas to be excavated. The excavation centred on an area where there was the highest concentration of slag and charcoal, together with an adjacent natural gulley filled with charcoal and some outlying areas where slag had been located by preliminary fieldwork. The remains of a sandstone wall covered with a deep mixture of slag and soil were identified as the probable centre of metallurgical activity. Slags were widespread throughout the site and together with the presence of large amounts of charcoal led to the tentative conclusion that this had been a slag reworking site.

Post excavation studies gave calibrated radiocarbon dates for charcoal from sealed contexts as Cal AD 1410, Cal AD 1430 and Cal AD 1330/1340/1400. Eleven out of twelve samples of charcoal were shown to be hazel; pollen types were mainly from grass/sedge vegetation together with dung fungus spores and a little tree and heather pollen. Slag melting points were measured on 4 samples and showed initial softening between 960oC and 1,100oC, and full melting at 1,100oC to 1,140oC. Experiments on surface topsoil and and the underlying clay showed that temperatures in excess of 950oC were unlikely to be present below about 19mm and therefore, a permanently burnt clay subsurface would not be encountered. These tests showed that the heat-affected clay would be converted to soil after repeated wetting and freezing.

The wider context of neighbouring bale sites on Fremington Edge and local mineworkings was also discussed.

Richard Smith, Timothy Laurie, Alan Mills and Rob Vernon

A full report can be found in British Mining No 98, 2014, pp. 2-33.

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