St Peter's Cave

St Peter’s Cave is a natural limestone opening in the base of Hardwick Cliff above the River Wye in Chepstow. It sits just below Bulwarks Camp and above the high-water mark, forming a scheduled monument. The cave lies within Llanelly Formation limestone formed about 344 million years ago during the Carboniferous period. Nearby rocks include Gully Oolite, Black Rock Limestone and Hunts Bay Oolite, all part of the same geological story. Triassic mudstones and conglomerates overlie the limestone across the area. The cave’s entrance faces south-east and opens directly onto the riverbank. The cave may hold the earliest evidence of human occupation in the lower Wye Valley. In the 1960s charcoal deposits were found inside, suggesting Upper Paleolithic activity. Reverend Cecil Cullingford explored the site in 1950 with Monmouth School pupils, recognising its archaeological potential. A scheduled monument since the 1960s, it was later measured at 21 metres long by Cadw. Earlier accounts from 1892 describe explorers reaching 46 to 64 metres before crawling became necessary. The cave’s history includes a 19th-century drowning and railway blasting that altered its chambers. Visitors reach the cave along the riverbank beneath Hardwick Cliff. The entrance is small and muddy, opening into a low chamber filled with silt and algae-covered walls. A pit lies about 22 metres inside under the railway line. Boulders mark the 9-metre point, and the floor rises towards a mud choke at 28 metres. The cave sits within a Special Area of Conservation for bat sites and woodlands, with nearby slopes managed to encourage tree growth. Access is rough and requires care, following a path beside the cliff to the riverside opening.