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Offa's Dyke: Tan-y-Graig Section is an early medieval linear earthwork in Wales, constructed as a defensive frontier between English and Welsh territories. Built during the later 8th century, the monument comprises an substantial bank with ditch, typical of the ambitious engineering works undertaken during this period to define territorial boundaries across difficult terrain.
The Tan-y-Graig section crosses bedrock composed of Dinantian limestone with subordinate sandstone and argillaceous rocks, characteristic of the Mississippian geological formations that underlie much of the Welsh borderland. The solid geology would have presented considerable challenges to the construction gangs who shaped the earthwork, explaining the variable height and profile of the surviving bank across this stretch.
The monument is protected as a scheduled ancient monument by Cadw under reference FL108. Like other sections of Offa's Dyke, this earthwork remains one of the most impressive archaeological remains of the early medieval period in Britain, demonstrating the administrative capacity and resources commanded by the Mercian kingdom under Offa's rule to undertake such large-scale linear construction projects across diverse landscapes.
Offa's Dyke: Tan-y-Graig Section is a scheduled monument protected by Cadw under reference FL108. View the official record →
Offa's Dyke: Tan-y-Graig Section is an early medieval linear earthwork in Wales, constructed as a defensive frontier between English and Welsh territories. It is designated a Scheduled Ancient Monument by Cadw under reference FL108.
Offa's Dyke: Tan-y-Graig 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: Tan-y-Graig 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 FL108.
Several scheduled monuments lie within 10 km, including Bron Fadog Enclosure (5.4 km), Round Barrow 135m SE of Lodge Farm (5.8 km), Cae Gwyn Cave (6.4 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Offa's Dyke: Tan-y-Graig 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: Tan-y-Graig Section stands on Dinantian Rocks (Undifferentiated), bedrock that formed in the Mississippian. The rock here is limestone with subordinate sandstone and argillaceous rocks.