Fotos

Opened in 1867 the Pontsarn Viaduct crosses the Afon Taf Fechan, spanning 152 yards on it's seven arches rising 92 feet above the river. It was built to take the Brecon and Merthyr Tydfil Junction Railway over the river at the limestone gorge at Pontsarn, a few miles north of the iron town of Merthyr Tydfil, once the largest producing iron town in the world.

The Brecon and Merthyr had one of the longest and steepest climbs on any railway in the United Kingdom. A notorious climb of 1:37 over seven miles. Such was the gradient that it caused so many accidents that locals soon renamed the line as the Breckneck and Murder Railway.

The geology that the Afon Taf Fechan carves it way through is extremely interesting. Rising under the peaks of Pen-y-Fan and Corn Ddu in the Brecon Beacons it forms a valley in the old red sandstones that form the mountains. Then it meets the limestone outcrop at Pontsarn Gorge before entering the South Wales Coalfield at Merthyr Tydfil where it remains until the sea (Bristol Channel) at Cardiff.

It was the limestone, fast flowing water and abundance of woodland that brought the iron masters to the heads of the South Wales Valleys. The first ironworks were built in Merthyr Tydfil in 1767 at Dowlais. Three other large ironworks were soon to follow, Plymouth, Cyfarthfa and Penydarren. With the introduction of steam power Merthyr Tydfil was also able to produce huge quantities of coking coal and soon the ironworks were surrounded by coal mines.