Ancient Monuments

History on the Ground

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Blaen-Cwmbach Earthwork

A Scheduled Monument in Tonna, Neath Port Talbot (Castell-nedd Port Talbot)

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Latitude: 51.675 / 51°40'30"N

Longitude: -3.7463 / 3°44'46"W

OS Eastings: 279345

OS Northings: 198805

OS Grid: SS793988

Mapcode National: GBR H5.5NDM

Mapcode Global: VH5GP.05T8

Entry Name: Blaen-Cwmbach Earthwork

Scheduled Date:

Source: Cadw

Source ID: 394

Cadw Legacy ID: GM277

Schedule Class: Monument

Category: Enclosure

Period: Prehistoric

County: Neath Port Talbot (Castell-nedd Port Talbot)

Community: Tonna

Traditional County: Glamorgan


The monument is a small earthwork situated near the north-west corner of the Roman marching camp (GM258) on the ridge east of Tonna, Neath. It comprises an earth and stone bank about 9m wide and 1.5m high with a ditch on the south east side forming in plan the quadrant of a circle about 50m radius. There is a gap about 7.5m wide with a corresponding causeway across the ditch about 30m from the north end. The monument is probably an unfinished or slighted enclosure dating to the Iron Age (800BC to 43AD).

The monument is of national importance for its potential to enhance our knowledge of later prehistoric defensive organisation and settlement. The site forms an important element within the wider later prehistoric context and within the surrounding landscape. Its significance is further enhanced by its location within the later Roman encampment.

Source: Cadw

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