Steve It's not directly relevant but have you looked at Brannigan and Dearne's 'Romano-British Cavemen - cave use in Roman Britain' (Oxbow monograph 19, 1992)? Much of the information they present for the occupation and use of natural caves can be paralleled at alleged Roman mines such as Draethen and Llanymynech - perhaps we have been too quick to claim an association between Roman artefacts and Roman mining when what we really have is Roman domestic reuse of earlier (possibly much earlier) workings. Draethen for instance was certainly accessible during the Roman period but the evidence suggests it was used as a counterfeiter's den and not a working mine. But it would be very interesting for someone to revisit and reassess the workings there ... Good luck with the dissertation. John Pickin