For 13 years, I lived on the flanks of Mynydd Parys and it is, therefore, an important part of my life and that of my children, who grew up in its landscape and learned all about geology there.
This post is simply a photographic drift along the mine and its various features, mostly from the vantage point of a drone, which affords a much clearer understanding of the area than from the ground, where many things are very difficult to see or comprehend.
The opencast and underground workings have been exploited since the Bronze Age (many stone hammers from the period remain underground, with carbon dating of sediments confirming it), the ores emplaced some half a billion years ago as the Iapetus Ocean closed. Parys was then a back-arc basin setting above a subduction zone, giving rise to 'black smoker' hydrothermal systems. Parys is a classic 'kuroko' type deposit of metalliferous ores, meaning it is a massive sulphide deposit lain down horizontally on the sea floor. Over geological time, the Parys deposit became tilted at a fairly steep angle. Look carefully around the mountain, notably in the central stump of rock within the Great Opencast, and you'll see countless thin quartzy veins bearing tiny crystals of metal (it would be appreciated if you didn't smash rocks or remove crystals, if you visit).
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| Courtesy of GeologyLearn.blogspot, showing the geological setting leading to a back-arc basin, within which the Parys deposits formed as a hydrothermal 'black smoker'. |
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| A black smoker (left) and the basic mechanism behind them (right). Courtesy geo.libretexts |
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| Position of the closing Iapetus Ocean, with what would become the British Isles lying in the southern hemisphere. Courtesy newgeology.us |
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| Mynydd Parys, in a very low drone view resembling one of the most commonly-captured ground-based views of the Great Opencast area and windmill ruin, beyond. |
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| The classic view of the Great Opencast, taken from the 'eye' vantage point. |
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| Aerial view of most of Mynydd Parys, seen from the NE in 2005. |
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| The summit of Mynydd Parys, with the remains of the once 5-sailed 'mill' that in fact added some power to a steam-powered dewatering pump. It was the only 5-sailed 'mill' on Anglesey, though it lasted only for about 50 years. It was stabilized by repointing and having one timber floor reinstated in the early 2010s. |
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| Parys 'mill' from directly above. |
October 2026. More coming verrrrry soon...
