There is a stretch of stone-built causeway, circa 130 metres carrying Incline No.4 of the Glyncorrwg Railway, that was also known as Parsons' Folly (NPRN 34840), as it ascends from the Neath Valley to its Summit Level (NPRN 34843).

Source: Stephen Hughes and Paul Reynolds (1989) 'A Guide to the Industrial Archaeology of the Swansea Region' Association for Industrial Archaeology.

Claire Parry, RCAHMW, 17 October 2011.