Extensive Survey on Radiocarbon Dating of Organic Inclusions in Medieval Mortars in the Czech Republic

Abstract

Dating organic inclusions in mortars such as charcoals is a useful alternative or complementary method to dating mortars themselves, helping to estimate the building age. To assess the limitations of this dating approach, organic inclusions were searched for in surface mortar layers of six early to late medieval buildings in the Czech Republic with relatively well-known age. Altogether, 123 samples were found. About 80% were successfully radiocarbon (14C) dated. However, only 66% originated from wood relatively young when used in lime burning. To judge which samples are relevant to the actual building date, sufficient statistics is crucial. We recommend dating at least 5–10 samples, i.e., collecting 6–12 samples, for a site with uncomplicated building history, or per building phase. Otherwise, unrealistically old or young dates might be obtained. With the recommended statistics, inclusion-based dating provides building ages with uncertainty of 50–100 years.

HORIZONTAL WATERMILL CHRONOLOGIES BASED ON 14C DATING OF ORGANICS IN MORTARS: A CASE STUDY FROM JARASH, JORDAN

“…This method has been successfully applied to the dating of lime mortars and plasters with macrocharcoal inclusions from the study area (Lichtenberger et al 2015; Philippsen and Olsen 2020; Daugbjerg et al 2021, 2022; Passchier et al 2021; Boyer 2022). The method has also been employed in dating construction materials from other Jordanian archaeological sites (Al-Bashaireh 2013; 2017) and globally (Berger 1992; Van Strydonck et al 1992; Vega et al 2013; Ponce-Antón et al 2020; Regev et al 2020; Daugbjerg et al 2022; Brabcová et al 2023). The effectiveness of 14 C dating and the correct interpretation of the results is influenced by OM particle size, the number of OM fractions present and their sources.…”

Characterization of Historic Lime Mortars from the Arch of San Martin to Identify the Construction Phases of the City Wall of Burgos (Spain)

“…absolute dating of the lime mortars is mainly used. In radiocarbon dating of mortars, the charcoal embedded in the mortar (e.g., [19][20][21][22][23][24][25][26][27]) or the lime binder (e.g., [28][29][30][31][32][33][34]) are used. Nevertheless, the use of charcoal fragments should be used with caution due to the effects of old wood [35].…”