Rhinogydd

The Rhinogydd are formed of hard sedimentary rocks of Cambrian age which occur as a major anticlinal structure known to geologists as the Harlech Dome.

This structure which originated during the Caledonian Orogeny (mountain-building period) extends from Cadair Idris in the south to Blaenau Ffestiniog in the north.

The formation also contains and is overlain by some siltstones and mudstones which form a broken zone of softer scenery around the periphery of the area's rugged core.

The most popular walking route in this area begins at the Roman Steps at 52°51′16.76″N 4°0′18.43″W / 52.8546556°N 4.0051194°W / 52.8546556; -4.0051194, which leads from Cwm Bychan through Bwlch Tyddiad and around Rhinog Fawr.

Despite the name, these steps are not Roman and are in fact the well preserved remains of a medieval packhorse trail leading from Chester to Harlech Castle.

Rhinog Fach and Y Llethr from the slopes of Rhinog Fawr
Panorama of the Rhinogau from the summit of Y Garn with the River Mawddach estuary at far left and Diffwys , Crib y Rhiw , Y Llethr , Rhinog Fach and Rhinog Fawr from left to right