engleski

Radiocarbon dating of burial and seed samples from the Sokol fortress in Konavle near Dubrovnik, Croatia

The area around the fortress Sokol in Konavle near Dubrovnik, Croatia, was inhabited as early as the prehistoric period. The fortress, which was built on a huge natural rock formation, was very important in Roman times, and it was also a significant control point on Justinian's limes (Byzantine Empire, 6th cent.), having a transitional role from the Balkan hinterland to the Adriatic Sea. In the medieval period, the fort was under several patrons, which frequently changed. In the late Middle Ages, it came under the rule of the Dubrovnik Republic, which held the fort until 1672, when it was abandoned. Archaeological excavations carried out in 2012 and 2013 revealed various phases of the site with many burials around the fortress ; unfortunately, the burial sites did not contain goods apart from one burial with a coin that can not be evaluated due to corrosion. The tombs are primarily constructed of stones and bricks (tegulae) and rarely without grave construction. According to stratigraphy and other finds, the approximate/relative dating was possible, so a comprehensive radiocarbon dating was performed. For radiocarbon dating the AMS (Accelerator Mass Spectrometry) technique was used. All samples were pretreated by ABA method and collagen was extracted from bones. Samples were then combusted to CO2 that was subsequently reduced to carbon (graphite). 14C activity was measured at the AMS Radiocarbon Facility at the University of Georgia (UGAMS), Atlanta, GA, USA. delta13C was also measured at UGAMS by isotope ratio mass spectrometer and then used for 13C-normalization of conventional radiocarbon ages (expressed in years Before Present, BP). Calibration of conventional 14C ages was performed using Oxcal4.2 software and IntCal13 calibration curves. 27 human bones revealed that the burials can be dated from early Roman to late Modern times. Out of the total number of samples, 25 bones were dated to the range between 1860 ± 24 BP and 576 ± 23 BP (90 cal AD – 1408 cal AD), one sample to 342 ± 20 BP (16th century) and one to 68 ± 21 BP (19th century). The delta13C of bone collagen ranged from -18.7‰ to -20.8‰ VPDB. Although the site is of a military character, not only men but also many women and children were buried there. This demonstrates that there was a settlement around the fort that is often called the town of Sokol in archival data. The huge time span of the burials also bears witness to the continuity of the residential area around the fort. Beside the burials, seeds of carbonized almond were also found in the prehistoric mixed layer that was formed after a large earthquake at the end of prehistoric period. The seeds were probably stored in a house. Two samples were dated to the Iron Age: 2480 ± 25 BP (756-543 cal BC) and 2520 ± 25 BP (787-567 cal BC). Large span of calibrated ages is due to the flatness of the calibration curve for period 750 – 400 cal BC. There is a museum at the top of the fortress and restored buildings. The area around the fortress is currently in the process of being converted into an archaeological park.

14C; dating; Sokol; Konavle

poster P60