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Offa's Dyke: Plas Power Section is an early medieval linear earthwork that runs through Wales as part of the longer frontier work traditionally attributed to the 8th-century Kingdom of Mercia. This section of the dyke follows the local terrain across the Coal Measures bedrock that underlies the site, where mudstone, siltstone and sandstone layers alternate with bands of coal and ironstone. The construction of such extensive earthworks required substantial labour to cut through or build up material across the landscape, with the dyke's alignment responding to the natural topography and geology of the ground.
The Plas Power section forms part of a monument of national significance, protected by Cadw under reference DE139. The earthwork consists of a substantial bank and ditch, though its original height and proportions have been modified by centuries of erosion and agricultural use. The heavily worked Coal Measures geology of the area would have presented particular challenges to those constructing the dyke, as the variable strata and harder bands of ferricrete would have required determined effort to break through.
This section exemplifies how early medieval frontier works were adapted to local landscape conditions. The dyke's course through this Welsh terrain reflects both strategic considerations and the practical constraints imposed by the underlying geology, creating a monument whose form and preservation remain intimately connected to the landscape in which it was constructed.
Offa's Dyke: Plas Power Section is a scheduled monument protected by Cadw under reference DE139. View the official record →
Offa's Dyke: Plas Power Section is an early medieval linear earthwork that runs through Wales as part of the longer frontier work traditionally attributed to the 8th-century Kingdom of Mercia. It is designated a Scheduled Ancient Monument by Cadw under reference DE139.
Offa's Dyke: Plas Power Section dates from the early medieval period, and is classified as a linear earthwork. It is one of over 32,000 scheduled monuments protected across the UK.
Offa's Dyke: Plas Power Section is a Scheduled Ancient Monument, legally protected by Cadw — the body responsible for designating and safeguarding heritage sites in Wales. The official designation reference is DE139.
Several scheduled monuments lie within 10 km, including Wat's Dyke: Section extending from Pentre-Clawdd to Wynnstay Park (5.8 km), Offa's Dyke: Section SW from Tatham Bridge (6.1 km), Wynnstay Colliery Walker Fan House (6.3 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Offa's Dyke: Plas Power Section's history, each drawn from the record and mapped to the exact spot:
Every location is different. Not every section appears for every place, only what the historical record actually holds turns up in a report.
Offa's Dyke: Plas Power Section stands on Pennine Middle Coal Measures Formation And South Wales Middle Coal Measures Formation (Undifferentiated), bedrock that formed in the Moscovian. The rock here is mudstone, siltstone, sandstone, coal, ironstone and ferricrete.