The Afon Prysor was born when the melting ice liberated water to spring afresh through the ice-sculpted landscape, and the exuberant juvenile waters scoured their path to the ocean via a gorge that they carved on their course. Thus was Ceunant Llenyrch [Llenyrch Gorge] created. That was ten thousand years ago, as the Ice Age was concluding. The abounding rains that swept in from the Atlantic and the spray from the Rhaeadr Dhu [Black waterfall] Prysor's cascade, created an environment lush for ferns, which have thrived ever since among the trees of the narrow gorge, which at one place is a mere thirty three feet across. Its precipitous sides are not friendly to humans, and so as the rain forest dwindled in extent due to man's exactions Coed Llenyrch [Llenyrch Wood] remained unsullied.Experts suspect that there are places in Ceunant's narrow defile that have never known the footfall of humans. But who is to know?
Ceunant Llenyrch is one out of eight reserves of ancient Celtic rain forest that form the oak woods of the ancient county of Merionydd [pronounced Merionyth.] Only three are available for access to visitors, as the narrow gorges of the other five are too dangerous for tourists to tread. But Llenyrch has been joined to Coed Felinrhyd, a large woodland owned by the National Trust to create a single site that unites Celtic forests into a larger unity. The result is a 755 acre forest in the south of the Snowdonia National Park. Coed [wood] Felinrhyd is accessible to walkers and is very popular.
The uniqueness of the Celtic rainforest habitat lies not in its wildflowers, which are not abundant, but in its ferns, mosses, lichens and liverworts. The shady and wet environment is a dream for ferns, and over two hundred species of lichens, and about the same number of mosses. Some are rare, and recently one thought to have been extinct in Britain since the 1800s was rediscovered clinging to safety in Coed Llynyrch. The wood is also rich in epiphytes, plants that cling to trees and derive their nutrients from the air, rain, dust and plant debris.
Tree species are not unique, but there are some rare ones, such as the sessile oak. This, unlike the peduncular varieties of oak, has acorns with no stem that grow directly from the branches. Felled to near extinction to provide wood for industry and England's war fleets, it survives in isolated, inaccessible spots. There is the downy birch, not a common species.We find hazel and the ever-present rowan.
The woods, with all their mosses and epiphytes, have a Tolkien-like feel to them, and indeed, the great master of fantasy was deeply inspired by the Welsh myths of the Mabinogion, some of which were set in these ancient woodlands. The grave of the mythical king, Pryderi, slain in battle with the trickster god, Gwydion, a Celtic version of the Saxon Woden, was said to have been located in these forests, though no site has ever been identified as its whereabouts.