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Offa's Dyke: Pentre-Bychan Hall Section is an early medieval linear earthwork forming part of the larger Offa's Dyke monument in Wales. This section extends 540 metres south from Bron-Wylfa, preserving substantial stretches of the distinctive bank-and-ditch construction characteristic of this Dark Age frontier work. The earthwork cuts across underlying bedrock of the Pennine and South Wales Middle Coal Measures Formation, a Moscovian-age sequence of mudstone, siltstone, sandstone and ironstone that would have presented a substantial obstacle to construction, lending the dyke's course added significance as a deliberately engineered boundary.
The monument is protected by Cadw under reference DE137. The geology of the site—with its bands of harder sandstone and ferricrete within softer mudstone—has influenced both the original positioning of the dyke and its modern survival. These resistant strata would have affected drainage and soil stability across the monument's route, factors relevant to understanding the engineering decisions made by early medieval builders.
This section represents one of the finest remaining stretches of a monument whose scale and ambition marked a significant phase of frontier fortification in early medieval Britain. The preservation of substantial earthworks here provides direct evidence of construction techniques and territorial strategies employed along this critical Welsh border.
Offa's Dyke: Pentre-Bychan Hall Section, extending 540m S from Bron-Wylfa is a scheduled monument protected by Cadw under reference DE137. View the official record →
Offa's Dyke: Pentre-Bychan Hall Section is an early medieval linear earthwork forming part of the larger Offa's Dyke monument in Wales. It is designated a Scheduled Ancient Monument by Cadw under reference DE137.
Offa's Dyke: Pentre-Bychan Hall Section, extending 540m S from Bron-Wylfa 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: Pentre-Bychan Hall Section, extending 540m S from Bron-Wylfa 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 DE137.
Several scheduled monuments lie within 10 km, including Wynnstay Colliery Winding Engine House (4.6 km), Offa's Dyke: Section N of Home Farm (4.7 km), Darland Wood Round Barrows (5.7 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Offa's Dyke: Pentre-Bychan Hall Section, extending 540m S from Bron-Wylfa'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: Pentre-Bychan Hall Section, extending 540m S from Bron-Wylfa 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.