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Caerffili Mountain Shaft Mounds is a post-medieval and modern monument comprising subsidence features created by coal extraction. Located in Wales, the site sits above the Pennine Middle Coal Measures Formation and South Wales Middle Coal Measures Formation, geological sequences of Moscovian age comprising mudstone, siltstone, sandstone, coal, ironstone and ferricrete. These strata provided valuable mineral resources that were worked from the surface downwards through shafts, leaving distinctive earthwork mounds where spoil and subsidence accumulated at ground level.
The mounds represent the industrial heritage of coal mining expansion that transformed the Welsh landscape from the late seventeenth century onwards. As miners extracted seams from below, the ground above collapsed in characteristic patterns, creating the topographic depressions and raised areas now visible across the site. The ferricrete beds interspersed within the coal measures would have hardened the overlying strata, affecting the stability and pattern of subsidence witnessed here.
The monument is recorded and protected under Cadw reference GM454, recognising its value as evidence of Wales's industrial past and the geological processes that shaped both the landscape and its economic development.
Caerffili Mountain Shaft Mounds is a scheduled monument protected by Cadw under reference GM454. View the official record →
Caerffili Mountain Shaft Mounds is a post-medieval and modern monument comprising subsidence features created by coal extraction. It is designated a Scheduled Ancient Monument by Cadw under reference GM454.
Caerffili Mountain Shaft Mounds dates from the post medieval/modern period, and is classified as a shaft mounds. It is one of over 32,000 scheduled monuments protected across the UK.
Caerffili Mountain Shaft Mounds 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 GM454.
Several scheduled monuments lie within 10 km, including Melingriffith Water Pump (5.2 km), Cooking Mound East of Taff Terrace (5.4 km), Cross in Llandaff Cathedral (7 km).
This page is just one thread. A full Aubrey report pulls together 13 strands of Caerffili Mountain Shaft Mounds'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.
Caerffili Mountain Shaft Mounds stands on Pennine Middle Coal Measures Formation And South Wales Middle Coal Measures Formation (Undifferentiated), bedrock that formed in the Moscovian. The rock here is mudstone, siltstone, sandstone, coal, ironstone and ferricrete.