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Cross Ridge Dyke & Earthwork on Cefn Eglwysilan is a cross ridge dyke of unknown date, situated on the higher ground of Cefn Eglwysilan in Wales. The monument consists of an earthwork cutting across the ridge, a defensive or territorial feature typical of prehistoric and early medieval fortifications in upland Britain. The dyke exploits the natural topography of its Carboniferous bedrock, which comprises mudstones, siltstones and sandstones of the South Wales Upper Coal Measures Formation, weathered to form the moorland landscape in which it sits.
The monument remains unexcavated and its chronology undetermined, meaning it cannot yet be assigned with certainty to any particular period or culture. Cross ridge dykes of this type were constructed across Britain from the Bronze Age through to the medieval period, serving variously as boundaries, stock barriers or defensive lines. The specific geological setting here—on the exposed upland plateau above the coal-bearing strata—would have offered commanding views across the surrounding terrain.
The site is protected as a scheduled monument under Cadw reference GM452, reflecting its archaeological significance as a survival of earthwork construction in the Welsh uplands. Its preservation allows future research to contribute to understanding the landscape use and settlement patterns of the region across multiple periods of prehistory and history.
Cross Ridge Dyke & Earthwork on Cefn Eglwysilan is a scheduled monument protected by Cadw under reference GM452. View the official record →
Cross Ridge Dyke & Earthwork on Cefn Eglwysilan is a cross ridge dyke of unknown date, situated on the higher ground of Cefn Eglwysilan in Wales. It is designated a Scheduled Ancient Monument by Cadw under reference GM452.
Cross Ridge Dyke & Earthwork on Cefn Eglwysilan dates from the unknown period, and is classified as a cross ridge dyke. It is one of over 32,000 scheduled monuments protected across the UK.
Cross Ridge Dyke & Earthwork on Cefn Eglwysilan 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 GM452.
Several scheduled monuments lie within 10 km, including Five Round Barrows on Garth Hill (6.7 km), Caerffili Mountain Shaft Mounds (7.3 km), Rhiw Saeson Caerau (7.8 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Cross Ridge Dyke & Earthwork on Cefn Eglwysilan'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.
Cross Ridge Dyke & Earthwork on Cefn Eglwysilan 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.