Anglesey has an amazing array of geological sites and historic monuments scattered across its landscape. The island has more rocks of different ages than any other area of a similar size in the United Kingdom.
Rocks have shaped the landscape, affected where people chose to live and provided the raw materials for industries such as copper mining at Parys Mountain, Amlwch and brick making at Borth Wen, as well as providing the stone for local buildings. Anglesey is part of the coastal plain stretching into the Irish sea from the mountains of Snowdonia. It became an island around 3500BC when water levels rose, flooding the river valleys and forming the Menai Strait.
290 square miles in area, it is formed mainly of pre-cambrian rocks 600 million years old with deposits of shale and limestone still prominent around the headland at Penmon. The southeast coast consists of carboniferous limestone with fossils over 300 million years old. Following the last ice age the glaciers melted and deposited a topsoil of boulder clay, responsible for the island’s rich, fertile soils which gradually eroded over time to form the landscape you see today.
In the north east the fascinating landscape of Parys Mountain dominates the skyline. Once a copper mine there is now little evidence of its industrious past – only gorse and moor grass, surrounded by pools and lakes remain.
Copper was mined at Parys Mountain during the Roman period and possibly much earlier. In the 1760s full scale mining began, to satisfy demand for copper; this was used to produce guns, metal plating for ships and coinage. At its peak, it was the largest copper mine in the world, employing around 1,500 men, women and children. The end of the Napoleonic wars brought with it a reduction in the demand for copper and a subsequent decline in the mine’s fortunes.
Copper was not the only source of wealth. Limestone was quarried along the coast from Penmon Point near Beaumaris and by-products of the smelting industry were sulphur, lead, silver and zinc.