A03_P07

¹⁴C dating of mortars from Monastery Hill in Tyniec, Poland

Michalska D¹, Krąpiec M², Gronowski M^3,4, Łyczak M^5,8, Bojęś-Białasik A⁶,  Kamińska M⁷

¹Institute of Geology, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Poznań, Poland, ²AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Mickiewicza Av. 30, 30-059 Krakow, Poland, ³Benedictine Abbey, Tyniec, Poland, ⁴Institute of History, University of Silesia, Katowice, Poland, ⁵Archaeological Company FRAMEA, ul. Na Kozłówce 4a/10, 31-664 Krakow, Poland, ⁶History of Architecture and Monument Preservation, Faculty of Architecture, Krakow University of Technology, ul. Kanonicza1, 31-002 Kraków, Poland, ⁷Institute of Art History of the Jagiellonian University , ul. Grodzka 53, 31-001 Krakow, Poland, ⁸Institute of Archeology, Department of Historical Sciences, Cardinal Stefan Wyszyński University, ul. Wóycickiego 1/3, 01-938 Warsaw, Poland

The Benedictine Abbey in Tyniec is the oldest existing monastery in Poland (11 cent. AD). The historic walls of the Monastery have survived to this day and crown the limestone hill on the Vistula River. The geological structure of the surrounding area is of great importance and is reflected in the composition of the mortars.

In vicinity of Tyniec one may observe outcrops of Upper Jurassic limestones represented by two facies: bedded limestones with cherts and massive limestones. Recently, it was discovered that the monks not only fortified the Tyniec hill but also partly built it up with loess. Additionally, a massive "stepped" stone platform was later built to strengthen the edge of the hill.

The mortars radiocarbon dating provides the first attempt to obtain the wide chronology of the extension of Tyniec walls. Petrographic analyzes were used to characterize the binder and aggregate from mortars, especially to identify the carbonaceous components like not totally burnt limestone fragments, lime lumps or secondary calcite. Mortars were analyzed using scanning electron microscope with electron dispersive spectrometer and polarizing light microscope. Different pretreatment and sample separation protocols were applied to illustrate the huge influence of mortar components and the local geological structure on the ¹⁴C measurement results.

In addition to the mortar analyzes, ¹⁴C measurements were also made for charcoal and wood samples from Tyniec Abbey. Radiocarbon dating was performed on the selected fractions using Accelerator Mass Spectrometry (AMS).