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Offa's Dyke: Brymbo Hill Section is an early medieval linear earthwork forming part of the substantial frontier defence constructed between England and Wales during the eighth century. This section of the dyke traverses terrain underlain by the Pennine and South Wales Middle Coal Measures Formation, a sequence of mudstone, siltstone and sandstone with bands of coal and ironstone deposited during the Moscovian period. The varied geology of this locality would have influenced the dyke's construction technique, with the builders exploiting the landscape's natural features and available materials to create the earthwork's characteristic steep banks and ditch.
The Brymbo Hill section demonstrates the dyke's engineering response to challenging topography, maintaining its linear course across upland terrain. The ironstone-rich bedrock would have affected soil stability and drainage across the work, considerations likely familiar to the early medieval engineers who adapted their construction methods to local geological conditions. The earthwork survives as a substantial landscape feature, preserving evidence of eighth-century territorial demarcation and labour investment on the Wales-England border.
The monument is protected by Cadw, the Welsh Historic Monuments service, under the reference DE109, ensuring its preservation for archaeological study and public access.
Offa's Dyke: Brymbo Hill Section is a scheduled monument protected by Cadw under reference DE109. View the official record →
Offa's Dyke: Brymbo Hill Section is an early medieval linear earthwork forming part of the substantial frontier defence constructed between England and Wales during the eighth century. It is designated a Scheduled Ancient Monument by Cadw under reference DE109.
Offa's Dyke: Brymbo Hill 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: Brymbo Hill 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 DE109.
Several scheduled monuments lie within 10 km, including Offa's Dyke: Sections N & S of Bryn yr Owen Colliery (6.9 km), Wat's Dyke: Section extending from Erddig Park to Middle Sontley (7.3 km), Offa's Dyke: Section S of Aberderfyn Road (7.4 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Offa's Dyke: Brymbo Hill 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: Brymbo Hill 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.