Tar Tunnel

Miners struck a gushing spring of natural bitumen, a black treacle-like substance, when digging a canal tunnel for the Coalport Canal in 1787, or else digging a level in search of coal. After digging around 3000 ft into the hill the canal project was abandoned in favour of bitumen extraction. A wagonway was constructed in the tunnel to remove coal from the mines in before or during 1796. The tunnel was a great curiosity in the eighteenth century and bitumen still oozes gently from the brick walls today. Bitumen's chief commercial use at the time was to treat and weatherproof ropes and caulk wooden ships, but small amounts were processed and bottled as 'Betton's British Oil', a panacea…

The tunnel is around 1km long. The first 18 meters of the tunnel have a double layer of brick lining with single brick lining continuing out to 300 meters. There is then a 420 meter long unlined section after which the tunnel narrows to around 0.9 meters diameter and the brick lining returns. A secondary tunnel leaves the main bore at 361 meters.