Historic Landscape Characterisation
Merthyr Tydfil

012 Cyfarthfa Iron Works

HLCA 012 Cyfarthfa Iron Works Iron Works and nearby interrelated features: including industrial transport and water management features; historic, technological and artistic associations; site of former ironmaster's residence.

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(Photo: GGAT Merthyr 012)

Cyfarthfa iron Works and Associated Features character area: important early ironworks with surviving remains.


Cyfartha Iron Works were founded in 1765, and by 1806 had become the largest in the world, thanks to its having been the first in the area to change to the production of bar iron and adoption of other technologically advanced processes in the late 18th century. The fortunes of the works were more mixed in the latter half of the 19th century, in spite of a change to steel production. It is a nationally and internationally important landscape characterised by surviving industrial features such as the Charging Bank and Blast Furnaces, Pont-y-Cafnau Iron Bridge, Cyfartha Cinder Tips, and the limestone quarry and associated tram road.

Historical background

The historic landscape area of Cyfarthfa Iron Works and associated features is the site of the ironworks founded in 1765 by Anthony Bacon, a native of Cumberland, and his partner William Brownrigg. The works initially operated a single furnace and concentrated on the production of pig iron. Following Bacon's retirement in 1783, Richard Crawshay gained control of the Cyfarthfa Works. Thereafter the works remained in the Crawshay family, passing from Richard Crawshay, who died in 1810 to William Crawshay I, who directed operation from his London office, while the day to day management, including the great expansion of the works fell to William Crawshay II, and was responsible for the building of Cyfarthfa Castle in 1825 (see HLCA 013).

The works at Cyfarthfa was the first in the area to change to the production of bar iron, which ultimately lead to Cyfarthfa becoming the largest Ironworks in the world by 1806. Instrumental in adopting Cort's puddling process soon after it was patented in 1784 were William Crawshay in partnership with George Watkin, foundry manager, perhaps most notable for his involvement in the design of several of the area's early cast-iron bridges, including the surviving Pont-y-Cafnau. Cyfarthfa was forced to buy in supplies of pig iron from both Dowlais and Plymouth for refining to maintain its production of bar iron.

The layout of the works at the time is detailed in a view drawn c. 1800 by William Pamplin; this shows four furnaces and associated charging houses and casting sheds used in the production of pig iron, and the 48ft diameter waterwheel which powered the bellow's. Immediately to the north is a large building with numerous chimneys housed the puddling furnaces and rolling mills. The early 19th century layout of the works and its associated features appears on OS maps and surveyors drawings of the period. Also detailed are tramroads leading to the Glamorganshire Canal.

The works benefited from the upsurge in railway construction during the 1830s and 1840s, and in 1833 a new mill was built as a result, however shrinking export markets, among other difficulties were to effect the second half of the 19th century. Robert Thompson Crawshay could see no future in the iron industry by 1864 and only with great reluctance renegotiated the Cyfarthfa lease. Though production reached a peak in 1871, the period was marked by boom-bust and labour relations problems. One strike in particular begun in April 1874 over wage reductions lasted over a year, while the furnaces remained out of blast until 1879 and death of Robert Thompson Crawshay.

The ironworks was shown in detail on the OS maps of 1875 and 1878 located either side of the river Taff connected by two tramroad bridges, in addition to Pont-y-Cafnau. Notable features extant at the time, apart from the blast furnaces, were casting sheds, a smithy, and a coke yard (similar to that illustrated by Pamplin in 1800) with extensive coke ovens to the rear of the charging bank and the Tai-mawr leat to the northwest of the works.

The conversion to steel began shortly afterwards with the construction of four new iron clad furnaces, and steel production started in 1884 under Robert Thompson Crawshay's three sons, trading under the name of Crawshay Brothers (Cyfarthfa) Ltd. Cylindrical iron clad furnaces were erected before the former ironworks blast furnaces. An important feature of the period was the linear slag tip leading northwest along the west bank of the Taff Fawr dating to c. 1884. Other changes included a new range of coke ovens with alterations to the configuration of the coke yard. In 1902, an ailing Cyfarthfa works was acquired by GKN. In spite of additional investment, the works proved unprofitable and production ceased in 1910, with a brief reprieve during the First World War.

The associated Cinder Tips Area to the south was part of the Dynevor Estate leased to the Crawshays. It was depicted in its early stages during the first quarter of the 19th century, linked to the ironworks by tramroad, part of a more extensive transport network also characteristic of adjacent areas, HLCAs 066, 069 and 070). Over the intervening period the area was extensively tipped over: the cinder tip eventually extending as far as Georgetown, and in the process of being extended south to Cwm Pant Bach. A separate area of cinder tips was also located to the south of Cwm Pant Bach, just north of Ynysfach Ironworks. Small allotments characterised the fringes of the area, while an engine house was located just north of the Cinder Tips Area. By 1905 though the Cinder Tips remained largely unchanged; the engine house was now disused, while the tip area to the north of the Ynysfach ironworks appeared to be largely covered by small, regular allotments.

An old ironstone level (Ynysfach Pit) was located in the same general area. By 1919, the allotments to the west side of Llwyn Celyn Lane have been tipped over.

The area to the northeast of the ironworks and Pont-y-Cafnau contains the Gurnos Limestone Quarry, associated scheduled Tramroad and limekiln, near Pont-y-Cefn, and the scheduled Cyfarthfa Feeder Canal. The need for both water and limestone at the Cyfarthfa Ironworks necessitated the construction of a combined packhorse or plateway bridge and aqueduct, Pont-y-Cafnau, during the 1770s this would have been of wood; sketches by JMW Turner in 1797 depict the elevated wooden aqueduct, which formerly fed a great water wheel known to have been in use from 1796. A lease of 1771 secured the right to quarry limestone from the Gurnos Quarry and the Gurnos Tramroad had been built by 1792-3. The present Pont-y-Cafnau Iron Bridge, depicted in a painting of c. 1819/20 by Penry Williams, is thought to date from this period, or shortly after, c. 1793. The layout of the features of the area is detailed by 1875 OS map which also depicted the Cyfarthfa Feeder Canal and the leat approaching from a weir (possibly that built in 1766-77) on the Taff Fechan to the north via Pont-y-Cafnau.


For further information please contact the Glamorgan-Gwent Archaeological Trust at this address. Link to the Countryside Council for Wales website at www.ccw.gov.uk or Cadw at www.cadw.wales.gov.uk