The northern end of the ridge falls away to a broad upland vale containing the Afon Pyrddin and beyond which is the Brecon Beacons National Park.
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Saint Illtyd's Walk, a recreational walking trail follows a public bridleway to pass over Hirfynydd between Crynant and Resolven.
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All the strata are tilted in a generally southerly direction towards the axis of the South Wales Coalfield syncline though there is significant local variation, due in part to the proximity of the eastern slopes of the hill to the Neath Disturbance.
From there it climbs steeply up through forestry to Sarn Helen which here runs along Hirfynydd and then steeply down to Resolven in the Vale of Neath.