Llyn Padarn

Also within

Gwynedd County

Geology & landscape

Geological Period: Cambrian, Precambrian · Rock Type: Slate

Landscape processes: Glacial, Volcanic / Igneous

Birds & fish recorded

Fish

Description

Description This site is notified for its biological and geological interest. It is one of only three remaining natural localities in Wales for the Arctic charr Salvelinus alpinus L., a glacial relict fish species, and is a classic geological site of national importance. The Welsh populations of charr represent a distinct race S. alpinus perisii and the Padarn population is genetically different from those in Llyn Cwellyn and Llyn Bodlyn. The same race also inhabited the adjacent Llyn Peris before the hydro-electric scheme destroyed its habitat and new breeding sites were established elsewhere. Spawning in Llyn Padarn occurs locally in shallow, marginal waters, notably along Afon y Bala. The geological site, a section of the northern lake shore, is the only locality in the type area of the Cambrian System where the relationship between the Cambrian rocks of the Slate Belt and ancient Precambrian, Arvonian volcanic rocks can be adequately demonstrated. The complex interdigitation of volcanic and sedimentary facies is well displayed, but the interpretation of this site was the subject of bitter controversy in the time of the pioneer geologists. The site is of prime significance not only because it is here that the base of the Cambrian System in its type area is to be found, but also because it is one of Britain’s most historic geological localities. It has important research and educational value. Llyn Padarn also has some aquatic plant interest, notably floating water-plantain Luronium natans and small quillwort Isoetes echinospora. Otters and small numbers of wildfowl frequent the lake and the outflow, Afon Rhythallt, is one of the most important spawning sites for salmon and sea-trout in north Gwynedd.

Species mentioned