A new study has revealed that mounds of stone – remnants of the ancient lead mining operations in the Yorkshire Dales, in the UK – are under threat. The heaps of refuse are themselves being mined to produce aggregate, used to surface and upgrade tracks.

Robert White, Senior Historic Environment Officer at the Yorkshire Dales National Park Authority (YDNPA), explained to reporters that the National Park is scattered with such spoil heaps that attest to the presence of former mineral extraction and processing sites – especially those of the lead industry, most of which date from the 18th and 19th century.

White added that the removal of former lead mining wastes, most often uncontrolled, severely damages the historic integrity of these many unrecorded mining landscapes. Archaeologists need access to the various types, colours and sizes of the waste materials – the physical evidence – in order to be able to interpret and analyse the minerals, the periods of activity and processes involved in post-extraction operations. Moreover, many of these unrecorded heaps, containing discarded tools and other artefacts, cover previous phases of mining activity.

“The reuse of former lead mining waste as aggregate happens frequently on shooting estates – but mine spoil is a finite and diminishing resource and the considerable loss of it in recent years raises both conservation and environmental issues.”

To counter this, the YDNPA is asking landowners to help in the preservation efforts that aim to protect the vital information about the history of the mining industry as well as the geology of the National Park.

In addition to causing severe damage to the historical environment of the Yorkshire dales, this detrimental activity poses a serious threat to the environment, explained White. Many of these heaps as well as dressing floors were located near to water courses as the process of dressing lead ore requires washing. Now, the unregulated removal of heaps can lead to the contamination of these same water courses by heavy metals and other toxic materials, contained until now within the stable, undisturbed heaps.

Developers and landowners are reminded to notify the YDNPA before disturbing spoil heaps and possibly causing damage to both the archaeological and ecological potential.