To resolve this, radiocarbon dating of these samples fromWaun Mawn was conducted in conjunction with optically stimulated luminescence (OSL)dating of sediment from within the packing deposits that were contemporaneous with themonoliths’erection, and fromfilled-in sockets (from after the monoliths’removal). OSL dat-ing determines the burial age of sediments, with the dating signals being reset by light expos-ure immediately prior to deposition (Smedley2018).