Backwell Environment Trust

 Location 

The evidence of mining in the past is widely spread across both reserves. The most obvious examples are two 17th century underground lead mines located about 150 metres above the Church Town entrance to JSWNR on the right hand side. (There is a information board situated next to the path).

The Remains of one of the Lead Mines Today

Geology

The geology of Jubilee Stone Wood is dominated by Carboniferous limestone which was laid down some 300 to 350 million years ago in a warm, shallow sea from the remains of countless marine animals.

One hundred and fifty million years later during the Jurassic Period, mineral rich water began to be forced up from the hot depths of the earth through the many faults and fissures in the limestone which today has resulted in the accumulation of numerous metal ores in the bedrock.

Whilst both copper and iron ores are present in the Carboniferous limestone of Backwell Hill, the most abundant minerals are ‘galena’ (lead sulphide) and ‘calamine’ (zinc carbonate). Historical records confirm that both these metals were being mined here during the 17th century and possibly even earlier as was the case at Goblin Combe. Zinc combined with copper is converted into brass which was a highly prized alloy during the period and was much in demand. In fact during this century, most of the calamine extracted from the west of England originated from this area which, in turn, led to the city of Bristol becoming a major centre for the industry.

Mining Methods

The mining of lead in the British Isles goes back to prehistoric times and was one of the factors that attracted the Romans to Britain in 43AD. Lead ore or ‘galena’ usually occurs in narrow, vertically orientated seams. When the miners located these outcrops at or near the surface they would have dug simple, open cast circular pits or grooves to extract the ore.

Some of the deposits of lead however were found to descend deeper into the bedrock and the miners would have ultimately reached a point where it would become too difficult to remove the rock by shovel whilst the steep walls of the pit would have become increasingly unstable. When this situation developed, the miners would have dug vertically down through the limestone bedrock opening up a small shaft where they could more easily follow the linear seam of galena.

The ore and waste material was removed from the pit by the use of a hand winch (referred to as a ‘jack roller’ or ‘windlass’) attached to a bucket (known as a ‘kibble’). When the miners reached the bottom of the seam or the limits of practical working they would follow the ore seam on the surface and start a new shaft adjacent to the last, repeating the process as far as it was practical to do so.