|Length||440 metres (1,444 ft)|
Chartist Cave (or sometimes Chartist's or Chartists' Cave) is a culturally significant cave on Mynydd Llangynidr in southern Powys, Wales. The entrance is a broad arch formed of Twrch Sandstone ('Millstone Grit') which overlies the Carboniferous Limestone immediately beneath.
The cave is located at around 2.5km north-northeast of the village of Trefil at an elevation of about 550m at OS grid reference SO 127152 (51.8286 degrees North, 3.2672 degrees West). The entrance to Chartist Cave is high on the moors near the summit of Mynydd Llangynidr. The arched entrance is formed by a millstone grit cap from beneath which the underlying limestone has been eroded. The cave is also known by two Welsh names; Ogof Fawr (the 'Big Cave') and earlier as Tylles Fawr (the 'Great Hole'). The more commonly used modern name derives from 1839 when Chartist rebels used the cave to stockpile weapons in advance of their march on Newport in November of that year. There is a plaque at the entrance commemorating the actions of the Chartists.
Digging by the Severn Valley Caving Club in 1969 and 1970 led to the discovery of a passage dropping to a lower chamber with many passages leading off from it. The known length of the cave is 440m but it is believed to form a part of a much more extensive cave system under these moors. In the cave were found a clay pipe, a flat perforated stone, and both animal and human bones. The stone may have been of considerable antiquity, but the human bones were thought to be between fifty and one hundred years old.
- "Ordnance Survey map 141: Brecon". One inch series. Ordnance Survey. Missing or empty
- "Chartist's Cave". Caves of South Wales. Retrieved 28 April 2016.
- Royal Commission on the Ancient and Historical Monuments of Wales (1986). An Inventory of the Ancient Monuments in Brecknock (Brycheiniog): Later prehistoric monuments and unenclosed settlements to 1000 A.D. pp. 13–. ISBN 978-1-871184-19-8.
- "Site of Special Scientific Interest Citation". Countryside Council for Wales. Missing or empty