Rhiw-for-fawr
Also within
Climate exposure
This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.
Coastal habitats are exposed to sea-level rise and storm erosion. Where hard sea defences sit behind them, there's nowhere landward to retreat to — a squeeze that keeps compressing the habitat no matter how well it's managed.
Geology & landscape
Geological Period: Cambrian, Ordovician
Landscape processes: Coastal
Description
Description Rhiw-for-fawr is notified for its geological interest and lies 1km east of Criccieth. It comprises a south-facing cutting, separated from the sea by the Barmouth to Pwllheli railway line. Northwards, away from the coast, it includes the southern side of Rhiw-for-fawr, a hill which rises to about 43m. This is a site of international importance, showing the passage from the Ffestiniog Beds, through the Dolgelly Beds (Merioneth Series) into the Tyn-llan and Moel-y-gest beds (Tremadoc Series). The site is the historical type locality for the Cambrian-Ordovician boundary in Britain and has been a candidate international stratotype for that boundary, that is for the base of the Tremadoc Series. The site is unique in its complete illustration of the sequence at these stratigraphical levels, and several horizons in the Dolgelly Beds yield zonally-important assemblages of trilobites. The lowest Tremadoc horizons contain an abundance of early-zonal subspecies of the dendroid graptolite Dictyonema, whilst higher beds yield an abundant trilobite fauna. One of Britain’s most historic and important geological localities.