Reasons for Designation
Iron has been produced in England from at least 500 BC. The iron industry, spurred on by a succession of technological developments, has played a major part in the history of the country, its production and overall importance peaking with the Industrial Revolution. Iron ores occur in a variety of forms across England, giving rise to several different extraction techniques and structures. Ore was originally smelted into iron in small, relatively low-temperature furnaces known as bloomeries. These were replaced from the 16th century by blast furnaces, which were larger and operated at a higher temperature to produce molten metal for cast iron. Cast iron is brittle, and to convert it into malleable wrought iron or steel it needs to be remelted. This was originally conducted in an open hearth in a finery forge, but technological developments, especially with steel production, gave rise to more sophisticated types of furnaces.
Crowborough Warren furnace survives well as prominent earthworks and below-ground remains. Despite the breach to the dam, the isolated setting has helped to ensure that the monument has survived largely undisturbed. The exposed elements of the furnace indicate that there is a good degree of survival and hence archaeological potential. Good documentation dating to 1574 exists means that it is closely datable and correspondingly significant. The site has group value with Crowborough forge, approximately 0.5km downstream.
Details
The monument includes a 16th or 17th century blast furnace, dam or pond bay and slag heaps surviving as earthworks and below-ground archaeological remains. It is situated in Old Furnace Wood at the foot of a stream valley in Ashdown Forest on the High Weald. The dam is a prominent earthwork, about 100m long and over 5m high, which is orientated WNW to ESE across the main stream. The stone foundations of the blast furnace have been identified to the north of the dam.
The dam has been breached since the 19th century, when a single-arch stone packhorse bridge was built across the stream. The breach may indicate the position of the former sluice. A spillway is situated at the western end, its channel rejoining the stream about 70m north of the dam. Further downstream are extensive slag heaps.
The site is thought to be that later occupied by John Baker, of Battle, noted in a list of 1574. It is marked as 'Old Furnace' on a map of 1747, by which time it was presumably no longer in use.
Crowborough Forge, a separate Scheduled monument, is situated approximately 0.5km downstream.
Further archaeological remains, such as pillow mounds, survive in the vicinity of this monument but are not included because they have not been formally assessed.
The foot bridge is excluded from the scheduling although the ground beneath is included.
Sources: NMR TQ43SE8. PastScape 407066.
Crossley, D. 1991. English Heritage Monuments Protection Programme. Industrial Monuments: The Iron and Steel Industries. Step 3 report. Version O (Site Assessment 56).
Hodgkinson, J. 2008. The Wealden Iron Industry. Stroud: Tempus Publishing. p135-6.
