Contribution of 14C wiggle-matching to dendroarchaeology of coastal Birnirk and Thule sites in northern Alaska

Along the coast of Northern Alaska, wood remains from Birnirk and Thule archaeological sites are extremely well-preserved and have the potential to document climatic variations and cultural transformations in the early 2^nd millennium CE in northwest Alaska.

In this treeless coastal tundra, the primary wood resource is driftwood that come from the boreal forest carried by major interior rivers and ocean currents. While in northern Alaska, some Birnirk and Thule archaeological wood samples can be dated using the rare existing millennial tree ring master chronologies, many come from geographical areas where tree-ring master chronologies are too short (250-300 years). Here, we explore the potential of high-resolution wiggle-matching to accurately date tree-ring series that cannot be dated by conventional dendrochronology and develop preliminary tree-ring chronologies.

Figure 1: A. Location of existing tree-ring samples collections from Birnirk and Thule sites in Northern Alaska (black dots: sites discussed in the paper). © J. Taïeb; B. Architectural elements from Birnirk structure F-12 (north-east room) at Cape Espenberg. © C. Alix; C. Cross-section 12w51-22 from structure F-12 at Cape Espenberg. © J. Taïeb.

We present the wiggle-matching results based on 75 radiocarbon dates for eight archaeological timbers from the Piġniq, Rising Whale and Pingusugruk coastal sites in northern Alaska (Fig. 1). Wiggle-matching makes it possible to reduce the calendrical interval of these timbers’ last growth ring from centennial to decadal range and position 22 timbers in calendar time (Fig. 2). These results open new insights into tree-ring dating of others Birnirk and Thule architectural treering samples and analyzing climatic variations of the early 2nd millennium CE, in different regions of Alaska.

Figure 2: Results of ¹⁴C dating (n=75) in BP of 8 tree-ring series. Each tree-ring series is represented by a line and each ¹⁴C-dated single ring by a dot corresponding to its location in the tree-ring series (diagram inspired from Chochorowski et al., 2014). [Ping. = Pingusugruk, Piġ. = Piġniq]. © J. Taïeb.

Reference: Taïeb J., Daux V., Alix C., Hatté C., 2023. Contribution of 14C wiggle-matching to dendroarchaeology of coastal Birnirk and Thule sites in northern Alaska. Actes des rencontres internationales « Journées bois. Échanges interdisciplinaires sur le bois et les sociétés » organisées les 18-19 octobre 2021 à l’INHA, Paris, Archéologie, société et environnement, actes des « Journées Bois », volume 3 (1), 57-77.