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Pen-Twyn Earthwork is a prehistoric hillfort located in Wales, protected by Cadw as a scheduled monument under reference MM064. The site occupies ground underlain by Lower Devonian rocks of sandstone and conglomerate, which would have provided the stone for construction and fortification of the hillfort's defences. These Early Devonian deposits, exposed across the landscape, created a naturally robust foundation and ready supply of building material for the Iron Age or Bronze Age builders who constructed the earthwork.
Hillforts of this type typically comprised banks and ditches designed to enclose hilltop settlements or communal gathering places, combining practical defence with displays of communal labour and authority. At Pen-Twyn, the underlying geology of harder, interbedded sandstone and conglomerate would have influenced where ditches could be dug most effectively and how the earthen banks were formed and stabilised.
The monument remains an important record of prehistoric settlement patterns and territorial organisation in Wales. Its protected status under Cadw reflects its significance as evidence of Iron Age or Bronze Age communities and their engineering capabilities on this particular stretch of Welsh landscape.
Pen-Twyn Earthwork is a scheduled monument protected by Cadw under reference MM064. View the official record →
Pen-Twyn Earthwork is a prehistoric hillfort located in Wales, protected by Cadw as a scheduled monument under reference MM064.
Pen-Twyn Earthwork dates from the prehistoric period, and is classified as a hillfort. It is one of over 32,000 scheduled monuments protected across the UK.
Pen-Twyn Earthwork 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 MM064.
Several scheduled monuments lie within 10 km, including Pen y Clawdd Castle Mound (3.1 km), Remains of St Michael's Chapel and Skirrid Fawr Defended Enclosure (5 km), St. James's Churchyard Cross, Llanvetherine (7.3 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Pen-Twyn Earthwork'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.
Pen-Twyn Earthwork stands on Lower Devonian Rocks (Undifferentiated), bedrock that formed in the Early Devonian. The rock here is sandstone and conglomerate, interbedded.