Thursday, 20 August 2009

Landscape of Lead

The mineral riches of the Mendip Hills were well known in Europe, and it didn’t take the Romans long to reach Somerset and start mining. As early as 49AD their engineers were digging up lead and smelting it to extract the silver, and their activities over several hundred years have left a lasting impression on the landscape around the village of Charterhouse.

Uphill to the east, Ubley Warren looks as though a giant’s child played with it long ago, before the grass grew over the furrows, pits and nodules. Below the road, a dry, flat-bottomed valley twists between more odd-looking hillocks; the nature lover may wonder why the valley floor is bereft of bracken and other plants. Only grass seems to grow here.

This is Velvet Bottom, a destination to inspire even the most reluctant young walker. Today this odd valley is a nature reserve managed by the Somerset Wildlife Trust, but its formation and character are anything but natural. When the Romans came here lead ore was so plentiful and so close to the surface of the ground that it could be dug out of shallow trenches. Water was diverted from local streams into so-called ‘buddle pits’ in the valley floor, where the ore was separated from other impurities.

There was a Roman mining town in the vicinity of Charterhouse, commemorated in the Townfield nearby. Archaeological investigations by Sir Richard Colt Hoare at the end of the eighteenth century revealed little, but recent aerial photography has shown the distinctive pattern of a town, with a main street and houses laid out on either side. A circular structure in the next field seems to have been an amphitheatre, although it takes quite an effort to imagine this quiet landscape filled with the cries of Romans at sport.

It’s equally hard to picture the traffic that must have been moving constantly to and from this remote outpost of Rome, via the main road that ran south east to join the Fosse Way. In fact the mines were intermittently busy for centuries after the Roman legions departed, with extensive activity in the seventeenth and eighteenth centuries. In 1844 Cornish tin miners arrived, hoping to exploit the lead deposits further by digging deeper; when their efforts proved worthless they turned their attention to the spoil heaps of previous generations, resmelting the slag and leaving the newer mounds we can see today.

So today’s landscape owes its character to Roman mining and a typically Victorian thoroughness in reprocessing. The hillsides above the road are pockmarked with pits and the sealed entrances to mineshafts, the grass tinted yellow by the presence in the soil of lead, cadmium and other metals.

In the valley itself the land is so poisoned that most plants struggle to grow, giving the impression of a river of grass flowing between banks of bracken. On either side are constant reminders of the industrial past, from the general unevenness of rough or ‘gruffy’ ground and worked-out mineral veins known as ‘rakes’ to the heaps of shiny black slag that looks like glassy coal. On these inhospitable mounds you can see plant colonies taking root and spreading, mostly grasses and alpines that have somehow adapted to life with few nutrients and an overabundance of lead and zinc.

Some rare species, such as alpine penny cress, are found only in this kind of metal-rich environment, while others appreciate the lack of competition from less tolerant plants like bracken and willow herb.

Local guide Adrian Boots, an expert in the ecology of the Mendips, admires the varied habitats around Charterhouse. While the rabbit-grazed limestone grassland of Ubley Warren supports numerous reptiles, adders included, and Velvet Bottom provides an unlikely refuge for rare alpines, a short walk leads to the rich ancient woodland of Long Wood.

Adrian leads foraging parties in search of wild food and so perhaps is biased towards the wild garlic and fungi of the woodland. He is understandably wary of lead.

“Velvet Bottom,” he says, “Is definitely one place I wouldn’t take them, but it is amazing. Quite a unique landscape.”

The woods, he adds, are part of the story too. Cut down for fuel by generations of miners, they have now grown back to cover the largest area in two thousand years.

When I first visited with my young children they shared Adrian’s enthusiasm for this enchanted place, playing happily for hours among humps and hollows that could only have been made by fairies. At the time I was happily ignorant of the potential hazards: I would certainly brave the adders again, and potential mine shaft accidents, but it might not be the best place for a picnic.

Extracted from an article in The Bristol Magazine

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