The abandoned, flooded, slate quarries in this complex in the Nantlle Valley are rewilding. On their adjacent slate tips, the greening is slow, beginning with lichens and mosses. The greening may take centuries, as this landscape would have done after the end of the ice age. The quarries have extraordinary stories too, of both the life working here and the innovative technologies they had to use.Slate heaps cover half the mountainside. They are slowly being colonised. In this close-up of part of a tip, by lichens, then mosses, ferns, succulents and grasses, all gradually getting a foothold. Some of these organisms seem to be competing, even growing on top of a rival. How many centuries until these mountainous tips green over?Some of the technology used to keep these ultra-deep quarries operating. On the left, the huge beam engine that pumped water night and day to stop the quarry floor from flooding. On the right, one of the great hauling ramps for cable-dragging tonnages of slate. This quarry flooded once the engine was switched off. One scuba club has (only with permission of the owners) specialist deep-dived here, down through hundreds of feet of water to the strange world of the quarry floor, which even has surviving quarry-buildings. There is a good view too of how some of the birches and oaks have managed to root and thrive in fissures in the exposed slate around the flanks of the quarry.