Normand Chalkstone (France): geology and historical uses from quarries to monuments

Several important monuments in Normandy were constructed from antiquity onwards with Normandy chalkstone (coccolithic limestone). These demonstrate the role of this stone in the development of traditional architecture, especially in the Medieval Age and, so, this work aims to propose the nomination of the chalkstone from Normandy as Global Heritage Stone Resource. Stratigraphic, petrographic and geochemical analyses allow identifying three main varieties of Normandy chalkstone used as a building stone: dedolomitized chalkstone, calcarenite and glauconite-quartz chalkstone, all Cenomanian to Coniacian in age. These varieties of chalkstones were quarried in underground galleries totalling over 15 km in length, mainly in the Caumont, Vernon and Fécamp quarries. Technological data are in accordance to their usual applications for building and indoor works of the Historical Monuments in Normandy. Archaeological research has reported the historical and extensive utilization of the chalkstone for specific works (walling, foundations, openings, sculptures) during Roman times and after the 10th century, in relation with three constructive techniques of historical value.