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Twyn Garreg Wen Cairn is a prehistoric round cairn in Wales, protected by Cadw under reference BR276. The monument sits upon Lower Devonian bedrock comprising interbedded sandstone and conglomerate, geological formations laid down during the Early Devonian period. This solid foundation of sedimentary rock would have provided a stable base for the cairn's construction, and the local stone sources likely contributed material for the monument itself.
Round cairns of this type were built across Wales during the Bronze Age and earlier periods, typically serving as burial monuments or ceremonial markers. The construction method involved heaping stone, often quarried or gathered from the surrounding landscape, into a mounded form. The specific geology at Twyn Garreg Wen, with readily available sandstone and conglomerate, made the site practicable for monument builders seeking suitable materials.
Today the cairn survives as a landscape feature testament to prehistoric settlement and ritual practice in Wales. Its location and construction reflect ancient communities' knowledge of their local environment, selecting sites where natural geology could be practically exploited. The monument remains under the stewardship of Cadw, Wales's historic monuments service, ensuring its preservation for future study and public appreciation.
Twyn Garreg Wen Cairn is a scheduled monument protected by Cadw under reference BR276. View the official record →
Twyn Garreg Wen Cairn is a prehistoric round cairn in Wales, protected by Cadw under reference BR276.
Twyn Garreg Wen 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 Garreg Wen 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 BR276.
Several scheduled monuments lie within 10 km, including Four Round Cairns on Mynydd-y-Glog (8 km), Two Round Cairns on the Summit of Mynydd-y-Glog (8.1 km), Round Cairn and Ring Cairn South of Twyn-y-Glog (8.4 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Twyn Garreg Wen 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 Garreg Wen Cairn stands on Lower Devonian Rocks (Undifferentiated), bedrock that formed in the Early Devonian. The rock here is sandstone and conglomerate, interbedded.