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Clawdd Mawr, Mynydd Caerau is an early medieval linear earthwork located in Wales and protected by Cadw as a monument of national importance. The earthwork comprises a substantial bank and ditch that would have served as a territorial boundary or defensive line during the early medieval period, when such linear monuments became common features of the landscape across Britain and Wales. The monument's construction exploited the local geology, with its bank built from material excavated from the adjacent ditch; the underlying bedrock of mudstone, siltstone and sandstone from the South Wales Upper Coal Measures Formation would have provided stable ground for such engineering works.
The location on Mynydd Caerau, on the Coal Measures geology that characterises much of South Wales, suggests the earthwork was positioned to control or demarcate territory in a landscape already utilised for its mineral resources. The ferricrete and ironstone deposits present in the bedrock geology were exploited in the medieval and later periods, reflecting the area's long history of industrial use. Clawdd Mawr remains a significant archaeological survival, preserving evidence of early medieval land organisation and territorial control in South Wales.
Clawdd Mawr, Mynydd Caerau is a scheduled monument protected by Cadw under reference GM231. View the official record →
Clawdd Mawr, Mynydd Caerau is an early medieval linear earthwork located in Wales and protected by Cadw as a monument of national importance. It is designated a Scheduled Ancient Monument by Cadw under reference GM231.
Clawdd Mawr, Mynydd Caerau 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.
Clawdd Mawr, Mynydd Caerau 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 GM231.
Several scheduled monuments lie within 10 km, including Garth Hill Platform House (5.3 km), Llangynwyd Castle (7.5 km), Plas-y-Betws relict garden (8.2 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Clawdd Mawr, Mynydd Caerau'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.
Clawdd Mawr, Mynydd Caerau stands on South Wales Upper Coal Measures Formation, bedrock that formed in the Westphalian. The rock here is mudstone, siltstone, sandstone, coal, ironstone and ferricrete.