Some of the original stones can be seen in the path surface, each with its two holes into which pins were driven to hold the tramway plates. The tramway up the Nedd Fechan gorge now gives ready access to walkers. An early factory was built by Messrs Frederick and Jenner at Dinas Bridge and a works was later established at Pont Walby near Glyn-neath. ![]() In both cases tramways were forced through difficult terrain to these mine entrances to permit horse-drawn drams to take away the rock to the brick works. The silica rock was worked through a series of adits – horizontal mine passages driven into the side of the hill – both behind Craig-y-ddinas and on either side of the Nedd Fechan upstream of Pontneddfechan. Only bricks made from more or less pure silica could stand the intense temperatures without shattering. The burgeoning industries of industrial South Wales needed large numbers of heat-resistant bricks to line the furnaces in which copper and iron-smelting took place. It is the purity of these rocks – almost 100% silica (SiO2) – that made them a target for miners from the 18th to the 20th century. In the steep walls of the gorges of the Nedd Fechan, the Afon Mellte and the Sychryd are exposed beds of a very hard and pure sandstone which have come to be known as ‘the silica rock’. It is in fact the lowermost of a whole family of such beds which collectively are termed the ‘Millstone Grit’ – a gritstone is simply a sandstone formed from coarse angular grains of quartz or ‘silica’. But then this is a very special sort of sandstone. The area around Pontneddfechan at the head of the Vale of Neath is one of very few in the world where sandstone has been extensively worked in underground mines.
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