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Carreg Hir Standing Stone, Pen-Rhiw-Tyn is a prehistoric standing stone located in Wales and protected by Cadw under reference GM170. The monument rises from bedrock of the South Wales Upper Coal Measures Formation, a geological sequence of Westphalian age comprising mudstone, siltstone, sandstone, coal, ironstone and ferricrete. This varied stratum would have been familiar to the prehistoric communities who erected the stone, its base anchored in the industrial-era geology of south Wales that has shaped the landscape for over three hundred million years.
The stone stands as evidence of human activity in the region during prehistoric times, when such upright stones served communal purposes—whether as territorial markers, ritual focal points or burial monuments. The specific geological context of this location, with its substantial coal and ironstone deposits, reflects the coal-bearing formations characteristic of the south Welsh valleys, though the monument itself considerably predates the industrial extraction of these resources.
Today Carreg Hir remains a physical connection to the prehistoric occupation of the Welsh landscape. Its protection under Cadw ensures the preservation of this standing stone and contributes to understanding prehistoric settlement patterns across south Wales.
Carreg Hir Standing Stone, Pen-Rhiw-Tyn is a scheduled monument protected by Cadw under reference GM170. View the official record →
Carreg Hir Standing Stone, Pen-Rhiw-Tyn is a prehistoric standing stone located in Wales and protected by Cadw under reference GM170.
Carreg Hir Standing Stone, Pen-Rhiw-Tyn dates from the prehistoric period, and is classified as a standing stone. It is one of over 32,000 scheduled monuments protected across the UK.
Carreg Hir Standing Stone, Pen-Rhiw-Tyn 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 GM170.
Several scheduled monuments lie within 10 km, including Ruins of St Baglan's Church (3.2 km), Plas Baglan (3.3 km), Cwm-Clais Castle Mound (4 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Carreg Hir Standing Stone, Pen-Rhiw-Tyn'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.
Carreg Hir Standing Stone, Pen-Rhiw-Tyn 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.