GM425

Remains of Blast Furnaces, Cyfarthfa Ironworks  

14/05/1981  

Designated  

Merthyr Tydfil  

Park  

303805  

206879  

Industrial  

Blast Furnace  

Post Medieval/Modern  

The following provides a general description of the Scheduled Ancient Monument. The monument consists of the remains of Cyfarthfa Ironworks. Begun in 1765, in their heyday they were the biggest ironworks in the world. The scheduled remains on the western side of the River Taff, are divided into two areas: southern and northern. Southern area This area contains the remains of seven blast furnaces, the charging area, engine house, calcining kilns, melt house and boilers. Blast furnaces: The former blast furnaces form the northern part of the stone retaining wall. Originally seven, during the 1880s modernisation the sixth from the north was replaced by the great stone arch and the spaces between the furnaces were infilled with stonework to form a new charging ramp for Bessemer furnaces. The blast tunnel behind the furnaces enclosed by the charging ramp is open at the northern end and is also accessible from small tunnels associated with each furnace. It is almost as high as the furnaces themselves and roofed with arched brickwork. The furnaces are partly supported by iron cross-members from the rear wall. The smaller tunnels associated with each furnace are approx. 2m high, narrow, brick-lined and arched. Within the smaller tunnels the bases of the furnaces can be inspected. The white brick lining is visible at these points as is the rubble filled into the furnaces following their closure. Large diameter cast iron pipework associated with the blast is lying dislodged in a recess forming a continuation of the blast tunnel to the rear of the arched opening. Engine house and surround area: The ruin of the engine house appears as a huge upstanding area of collapsed masonry. To the north is another upstanding structure backing onto the rear retaining wall. The surrounding area is hummocky, probably concealing the collapsed remains of buildings together with waste heaps - this area was also the site of the melting house and boilers. Calcining kilns and charging area: There is access to the higher level above the furnaces from below along a stone embankment. The furnace tops are visible as pit-like depressions in the surface. A series of calcining kilns are located up on this charging area and material from these would have fed the blast furnaces. The rear boundary of the charging area is a stone retaining wall of a staggered form which has partly collapsed in places. To the south of this wall a railway arch is incorporated. Northern area This area, directly adjacent to the River Taff, is the location of other buildings associated with the ironworks - namely the brick kilns and a building which may be an early farm house. A substantial masonry wall around 5m high extends out to the river. Erosion by the river has revealed masonry remains and slag deposits. The monument is of national importance for its potential to enhance and illustrate our knowledge and understanding of the development of the iron industry in Wales. It retains significant archaeological potential, with the strong possibility of the presence of associated archaeological features and deposits. A blast furnace may be part of a larger cluster of industrial monuments and their importance can further enhanced by their group value. The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.