Source, character and weathering style of building stone in Culzean Castle & Country Park, Ayrshire

This report describes an assessment of the source, character and weathering style of the building stone that has been used in Culzean Castle and other historic structures that lie within Culzean Castle & Country Park (CCCP), in Ayrshire. The assessment was conducted by the Building Stones team of the British Geological Survey (BGS) on behalf of National Trust for Scotland (NTS). The project was funded by Historic Scotland, and the work has been conducted under the Memorandum of Agreement (2011-2016) between Historic Scotland and Natural Environment Research Council (NERC; as represented by BGS). The main building stone in CCCP structures is sandstone sourced locally from the Swanshaw Sandstone Formation. Descriptions of the quarries that are thought to have supplied the stone, and a brief assessment of the potential for obtaining new supplies of the same stone from these and other quarries, are presented in section 2 of this report. The results of a brief review of historical records of local quarrying activity and building history in CCCP are tabulated in an appendix and presented in section 3 as a ‘timeline’. The geological character of Swanshaw sandstone is described in section 4, and the main causes of weathering in sandstone are reviewed briefly in section 5. The character of weathering in the stonework of CCCP buildings, and some of the factors that are likely to be causing accelerated stone decay, are described in section 6. Recommendations for ‘best practice’ procedure in the long-term repair and maintenance of stonework in CCCP are presented in section 7. Key conclusions are summarised in section 8.