The Clydach Gorge − through which this busy road passes – became a major focus of industrial activity in the 18th and 19th centuries when South Wales came to the fore in the production of coal and iron.


The Challenge

Construction of a new 8 km length of dual carriageway here presented a major engineering challenge. The route through the spectacular Clydach Gorge is very narrow in places and the existing road had to be kept open while the new one is built on the same line.

Like the road construction, the archaeological works have to be accommodated within the same landscape and operational constraints. The main cultural heritage interest lies in the industrial period when the Clydach Gorge was a centre for activity from the 17th century onwards. Within the gorge examples of iron working, coal mining, quarrying and successive transport systems throughout the industrial period are preserved.

The importance of this landscape is highlighted by its proximity to the Blaenavon World Heritage Site, while much of the route lies within the Brecon Beacons National Park.

Excavating a stone structure on the heads of valley project Trial Trenching on the heads of valley project Excavation work on the A465 heads of valley project

Our Approach

Wessex Archaeology has been involved in many road construction projects over the past 30 years, but in terms of topography and access this was one of the most difficult. Wessex Archaeology has worked closely with consultant’s RPS and alongside Costain, who are building the new road, to ensure that all elements of the archaeological work run smoothly within the timeframe of the construction programme.

The archaeological investigations will extend over approximately three years, most undertaken immediately in advance of construction in 2015 but some scheduled intermittently through in to 2018. These comprise building recording, geophysical survey, trial trench evaluation, excavation and a series of watching briefs, followed by assessment and publication of the results, in both academic and popular form. 

5 historic buildings recorded prior to demolition

One of the earliest tramroads recovered

64 19th-century Methodist graves excavated

Our Results

A leat (water supply) system was recorded which possibly dates to the late 17th century and relates directly to the earliest definitively located iron-making site in the valley of the River Clydach – the Llanelly Furnace, which belongs to the first phase of iron making in South Wales.

Investigation of several late 18th−early 19th-century tramroads provided evidence for the construction methods as well as an indication of the degree of preservation of these important routes that were used for transporting iron, coal and limestone along the Clydach Gorge.

Four historic buildings were surveyed, revealing a variety of vernacular architecture typical of the region. This included the remains of three modest, late 18th-century stone dwellings, occupied by workers in the local stone quarries and iron industries.

Historic building recording and subsequent excavation of a Primitive Methodist chapel showed the construction methods of a typical Welsh valleys chapel. The excavation of the associated cemetery uncovered 64 graves, the individuals from which were carefully removed and have been subsequently reburied during a formal ceremony at a nearby church.