TL-dating applied to building archaeology: The case of the medieval church Notre-Dame-Sous-Terre (Mont-Saint-Michel, France)

The recent application of thermoluminescence (TL) dating to young building materials is being increasingly developed for use in the field of buildings archaeology. Ensuring the accuracy of the dating method is of the utmost importance in order to achieve results which are pertinent enough to have archaeological significance. This paper deals with an archaeological building study of the first church built on the Mont-Saint-Michel (France) and improvements made to the TL-protocol in Bordeaux. The aim is to achieve precise dates for the material under analysis and therefore, a better understanding of the evolution of the building. For this study, 14 bricks have been sampled from eight different masonries and submitted for TL dating analysis. With the exception of one sample which appears to be non-contemporaneous to the others, the date results range from 900 ± 80 to 1020 ± 60 AD. The results were then averaged according to the two phases established by the archaeological building study. The first two stages of the primitive church both date from the 10th century.