Back to Homepage
Wales Underground
Homepage Take a look at maps Links View this page in Welsh

Great Orme
Copper Mines


History & Archeology





History and Archeology

Since excavations began in 1987, over 100,000 tonnes of waste from the 18th and 19th century mining has been removed. This revealed entrances into the most extensive mines of our ancient world. Four miles of tunnels have been surveyed that date from between 1860 BC and 600 BC. Some are large enough to walk through while others are so small that very young children must have mined them. A large cavern, about 13 metres high, 23 metres wide and 15 metres in depth was mined over 3,500 years ago.

Bronze Age miners used volcanic stones, usually of Dolerite or Diorite, from the beach as hammers and over 2,500 of these have been found (ranging from 2 to 29 kilos in weight). Loose and broken rock was then scrapped away with a piece of animal bone. Of the 30,000 bones found in the mine about 80% are from cattle with the remainder from sheep, goats, deer and wild boar. Sometimes the miners lit fires against the rock which would crack after it was allowed to cool. Charcoal remains of coppiced trees indicate that forest management was practised to supply the mine with wood.

On the surface the copper ore was crushed and washed before smelted in a clay kiln at a temperature of 1,100 degrees centigrade, reached by pumping air through burning charcoal with leather bellows. It has been estimated that up to 1,769 tonnes of copper metal was extracted from the Great Orme mine during the Bronze Age. Some of this copper was used for ornamental purposes but on its own is too soft for tools and weapons. Mixed with 10% tin, copper gives bronze; a tougher metal that can be poured into moulds and hardened by hammering with stone. Axes were probably the most commonly made bronze objects and the amount of metal extracted would have permitted the manufacture of over 10 million of them. It is quite possible that the Great Orme was producing such a surplus of copper that it might even have been exported outside of Britain. Perhaps the most remarkable aspect of this bronze production is that the tin must have come from Cornwall, involving a round trip of over 500 miles.

Interestingly, there is no evidence of either Iron Age or Roman activity in the mines. Mining, did, however, take place between 1692 AD and 1881 AD when thousands of tonnes of waste rubble was duped over the surface of the site covering the old tunnel entrances. Shafts were sunk and steam-driven engines used to pump out water from the very deepest. The heyday of the mines was from the 1830s to the 1850s when 300 to 400 local men were employed on a part-time basis. Iron drills and gunpowder made mining more efficient and small steam engines introduced in the 1830ís made the hauling much easier. However, at no time were the miners raised or lowered to work, but had to climb the 120 to 160 metres at the beginning and end of their shifts. Ore worth £250,000 was therefore produced in 15 years. However, the duty on imported copper was abolished in 1848 and large scale mining was starting in Australia, North America and Chile making British mine uneconomic. When mining ceased the shafts were covered over with timber and rubble effectively sealing them for over a hundred years.

It was not until 1976 that an amateur archaeologist discovered two ancient galleries and radiocarbon dating of charcoal found in them indicted a date of between 1300 and 1020 BC showing that the mines had indeed been worked during the Bronze Age. Little more was done until 1987 when the local Council thought of landscaping the area for a car park. During the surveying three major shafts were opened up and a complex network of early workings discovered. It was realised how important the site was. In 1990 Tony Hammond established Great Orme Mines Ltd to excavate and open the site to the public. Visitors were first allowed in 1991 although excavation work continues even today.


Geology >>