Look at the Nantlle valley from the road and you see a green bowl with a ragged grey edge, as if someone had bitten the mountain. It is a place where the quarrying went down instead of along. The pits here are enormous, cut deep below the level of the lakes, with sheer sides, and the biggest of them, the Dorothea, became a flooded hole of cold green water. On the skyline, tips of waste slate lean against each other like broken plates. This is part of the slate landscape of north-west Wales that UNESCO listed in 2021, and the quarries here are among the oldest in the area, producing roofing slate from the eighteenth century and earlier.
The quarrymen lived in the villages of Talysarn, Penygroes and Nantlle, in long rows of terraced houses with a chapel on each corner. They worked in gangs, were paid by the amount of good slate they produced, and in the evening they sang, argued about theology and ran eisteddfodau, the Welsh poetry and music competitions. Welsh is still the first language in the valley, and the villages have a quiet, inward-looking air. Caernarfon, ten kilometres west, has the huge castle that Edward I began in 1283 and is the market town for the area.
Riding the Nantlle valley is gentler than the roads in Snowdonia to the east, though the scenery is no less striking. The road runs along the valley floor between lakes and old workings, with mountains on one side, including the long jagged Nantlle Ridge, and the sea on the other. Beyond Penygroes the land flattens towards Caernarfon, and from there the Llŷn peninsula opens up to the west, with empty lanes, sea cliffs and views of Bardsey Island. Rain is common, and cloud sits on the tops, but when it clears, the light across the sea is superb. Watch for sheep and loose stones on the lanes.
Penygroes has a few shops and a petrol station, but Caernarfon is the better choice for fuel, supermarkets and cafes. In the town you can get a pie and a pint, or a cup of tea on the harbour front, with the castle behind. Park carefully at the quarry viewpoints, because the edges are unfenced in places and the drops are serious. A calm evening, with the lakes still and the tips glowing, is a perfect time to be here.