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Twyn Bryn March is a prehistoric round cairn located in Wales and protected by Cadw as a scheduled monument under reference MM344. The site sits on bedrock of the Pennine Lower Coal Measures Formation and South Wales Lower Coal Measures Formation, comprising mudstone, siltstone, sandstone, coal, ironstone and ferricrete deposited during the Westphalian period. These sedimentary rocks would have exposed stone suitable for cairn construction, though the ironstone and ferricrete components are notably resistant and would have provided durable building material.
Round cairns of this type typically date to the Bronze Age and served as burial monuments, often containing inhumation or cremation remains. Such structures are common across upland Wales, where suitable stone was readily available in the landscape. The monument's survival as an upstanding feature indicates that the cairn accumulated sufficient stone to retain its form through millennia of weathering.
The site's location reflects Bronze Age settlement patterns in Wales, where communities established burial monuments on higher ground across the landscape. The presence of coal-bearing strata beneath Twyn Bryn March is characteristic of this region's geology, though the exact dimensions and preservation condition of the cairn would require archaeological survey to determine.
Twyn Bryn March round cairn is a scheduled monument protected by Cadw under reference MM344. View the official record →
Twyn Bryn March is a prehistoric round cairn located in Wales and protected by Cadw as a scheduled monument under reference MM344.
Twyn Bryn March round 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.
Twyn Bryn March round 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 MM344.
Several scheduled monuments lie within 10 km, including Cefn Man Moel cross-ridge dyke (7.4 km), Three Platform Houses on Cefn Brithdir (9.3 km), Gelligaer Common Roman Road (9.4 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Twyn Bryn March round 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.
Twyn Bryn March round cairn stands on Pennine Lower Coal Measures Formation And South Wales Lower Coal Measures Formation (Undifferentiated), bedrock that formed in the Westphalian. The rock here is mudstone, siltstone, sandstone, coal, ironstone and ferricrete.