Dendrochronological and radiocarbon dating of the medieval stronghold in Ujście (Poland)

In 2008, the archaeological museum in Piła carried out excavations in the site No. 5 in Ujście upon the river Noteć (Poland), at the Rybacka Street and in the Old Market Square. In 12 archaeological excavations and 4 surveys abundant wooden structures were discovered, from which about 800 samples were taken, mainly of pine (Pinus sylvestris L.) and oakwood (Quercus sp.). The studies were aimed at absolute dating of wood with the dendrochronological method, the wiggle matching fitting curves method, as well as anatomical determination of wood. Absolute dating of the oakwood from the Rybacka Street allowed to distinguish the oldest fortifications of the stronghold from the ninth century, and also intensive introduction of wood in the years 980–1080 AD, whereas analysis of wood from the Old Market (survey IV) allowed to distinguish eight structural levels, from the 1530s until the 970s. On the basis of the pine wood 227-year-long local chronology 2U_02A was produced, dated with the wiggle-matching method for the period 860–1080 (±10) cal. AD. Most of the pine samples proved to represent wood introduced in the 990s and 1040s (±10) cal. AD, and also some repairs in the years 1000–1030 and 1050–1070 (±10) cal. AD.