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Cefn Mawr cairn is a prehistoric round cairn located in Wales and protected by Cadw under reference GM581. The monument sits upon bedrock of the South Wales Upper Coal Measures Formation, a geological sequence laid down during the Westphalian period and composed of mudstone, siltstone, sandstone, coal, ironstone and ferricrete. This solid foundation of mixed sedimentary strata provided the geological base upon which the cairn's builders constructed their monument in antiquity.
Round cairns of this type typically date to the Bronze Age and served as burial monuments for prominent members of prehistoric communities. The construction would have involved the deliberate accumulation of stone to form a visible mound over a grave or graves, creating a lasting marker of the deceased within the landscape. Such monuments functioned both as repositories for the dead and as enduring territorial markers visible across the surrounding terrain.
The survival of Cefn Mawr cairn today reflects the durability of its stone construction, though like many such monuments it has been subject to erosion and damage over millennia. The ironstone and ferricrete components within the underlying Coal Measures geology would have been available locally for building material, allowing the monument's constructors to draw upon resources present in the immediate landscape. The cairn remains an important archaeological monument testifying to Bronze Age burial practices and settlement patterns in Wales.
Cefn Mawr cairn is a scheduled monument protected by Cadw under reference GM581. View the official record →
Cefn Mawr cairn is a prehistoric round cairn located in Wales and protected by Cadw under reference GM581.
Cefn Mawr cairn dates from the prehistoric period, and is classified as a round cairn. It is one of over 32,000 scheduled monuments protected across the UK.
Cefn Mawr cairn 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 GM581.
Several scheduled monuments lie within 10 km, including Cae'r Mynydd Ventilation Furnace and Mine (6.1 km), Maesteg blast furnaces (7.1 km), Cwmafan copper works flue (7.8 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Cefn Mawr cairn'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.
Cefn Mawr cairn 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.