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Widecombe History Group Talk July 2007
The Archaeology of Quarrying and Mining on S. E. Dartmoor.
by Phil Newman
Phil is involved with surveying archaeological monuments of behalf of English Heritage.
Dartmoor is predominately granite.
He is looking at the history of the extraction from Dartmoor of granite, china clay, and tin primarily.
Around the edges of Dartmoor the rock is basically metamorphic aureole and it is these rocks that produced most of the copper, silver, lead and manganese that is also part of his research.
Reflecting on the uses of granite the earliest man made feature in granite is considered to be The Spinster’s Rock dating from 3000 B.C. early Neolithic.
The early periods, Bronze age and onwards man has used the native stone to construct house from hut circles (round houses), stone rows and standing stones, reeves, burial cists and tumuli, into the dark ages, 13th century longhouses, like Hutholes in this parish, churches and dwellings throughout the centuries.
This hard rock has also been useful for the making of troughs, millstones, poundstone, gate posts, crosses and monuments both large and small in fact a long list of artefacts have been made from the granite itself. It is in veins within the granite that minerals have been found and this has led on to mining.
Granite needed cutting and shaping one way this was done was by using a pitching tool. This cut straight edges on rocks, and a set of ‘two Feathers and a Tare’ which are tools used in conjunction with a row of holes drilled into a rock. Into each hole would be placed the two feathers and the tare placed between them, each hole would have the same and by hitting each tare in turn, gradually the pressure built up by these ‘wedges’ the stone would crack along the line of the holes. There is plenty of evidence of this method of cutting granite on the moors for people to see!
An even earlier method was to cut a row of grooves in the rock and place wooden wedges in them hit them to tighten them and by adding water which made the wood swell again the stone would crack along the line.
As quarrying developed and explosives became available deeper holes were drilled in the rock and gunpowder was used to blast off large amounts of stone at a time. Evidence of this can be found in many of the disused quarries.
Merrivale and Haytor are the best known quarries and though some documentation is available there are few on Haytor pre the 1829 print that shows cottages, school, perhaps a chapel and sheds within a hamlet. Further quarrying resulted in these buildings being demolished. Recent aerial views show up some of the evidence and the routes of part of the Haytor granite railway, this railway is unique in the country even the world. Running to Stover Canal and on to Teignmouth. Tin extraction from 12th to 18th centuries include the casiterite (tin oxide) of The Kelly Mine was mentioned.
The find of ingots of tin off Bigbury Bay a few years ago, tin from Dartmoor could point to the wealth of Lydford from tin and The Stanary Parliament of Crockern Tor were mentioned, as did the question, "did the ‘Judges Seat’ at Dunnabridge Pound come from Crockern Tor"? Another tale of the moors that still needs proving.
The veins of minerals (lodes) were mined, the alluvial gravel in the streams comes from these lodes, detached from the lodes carried down the streams. The tin was extracted sometimes by digging pits after which the lodes if promising were followed into the hills leading to mining and the mines themselves all adding to the archaeological evidence for the re-searcher to consider.
Tin can be separated from the gravels by washing in water and the tin, being denser sinks to the bottom.
Slides showing wheel-pits, sometimes these pits joined together forming open cast trenches ‘gurts’, leats, small reservoirs, dams, and the gurts at Challacombe all added to the interest of the talk. The mounds of waste thrown back as the digging process took place. There are still sites that need recording and in many cases still need finding.
The processes by which the stone was crushed by the stamps at the head of the mines, the associated stamp stone, or mortar stones, the crazing mills, buddle stones, blowing houses for smelting and the mould stones for the ingots make one realise that this industry was on Dartmoor for many centuries. Around the edges of Dartmoor between the 18th and 20th centuries tin, copper. silver and manganese were extracted and while water was used to power the machinery, water was a problem within the mines and adits were dug into the mines to drain off much of the water, some had to pumped out and eventually steam engines were developed for this purpose.
Various sites were mentioned in this area, Vitifer, Challacombe, Bagtor, Druid and Hemsworthy.
Rodney Cruze brought some samples of rock and ore found at Pitton Farm, some of this appeared to be tin ore as did some finer samples. It is a general rule that tin lodes run from East to West while Lead ore lodes run North to South
Some of these sites also show other activities including the rabbit farming at nearby warrens. All in all a very interesting talk.
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