Utilization of δ¹³C, δ¹⁵N, and δ³⁴S Analyses to Understand¹⁴C Dating Anomalies within a Late Viking Age Community in Northeast Iceland

Abstract

Previous stable isotope studies of modern and archaeological faunal samples from sites around Lake Mývatn, within the Mývatnssveit region of northeast Iceland, revealed that an overlap existed between the δ 15 N ranges of terrestrial herbivores and freshwater fish, while freshwater biota displayed δ 13 C values that were comparable with marine resources. Therefore, within this specific ecosystem, the separation of terrestrial herbivores, freshwater fish, and marine fish as components of human diet is complicated when only δ 13 C and δ 15 N are measured. δ 34 S measurements carried out within a previous study on animal bones from Skútustaðir, an early Viking age settlement on the south side of Lake Mývatn, showed that a clear offset existed between animals deriving their dietary resources from terrestrial, freshwater, and marine reservoirs. The present study focuses on δ 13 C, δ 15 N, and δ 34 S analyses and radiocarbon dating of human bone collagen from remains excavated from a churchyard at Hofstaðir, 5 km west of Lake Mývatn. The results demonstrate that a wide range of δ 34 S values exist within individuals, a pattern that must be the result of consumption of varying proportions of terrestrial-, freshwater-, and marine-based resources. For that proportion of the population with 14 C ages that apparently predate the well-established first human settlement of Iceland (landnám) circa AD 871 ± 2, this has enabled us to explain the reason for these anomalously old ages in terms of marine and/or freshwater 14 C reservoir effects.

Best practice methodology for 14C calibration of marine and mixed terrestrial/marine samples

“…A further example of calibration of human remains influenced by a marine diet comes from our recent research on the farmstead of Hofstaðir in north-east Iceland (Sayle et al 2014). The farmstead lies on the River Laxá, 5 km west of Lake Mývatn, and has been documented as an area of major archaeological importance with respect to the settlement of Viking communities in Iceland (Friðriksson and Vésteinsson, 1997;Vésteinsson, 1998;Lucas and McGovern, 2007;McGovern et al, 2007;Lucas, 2009).…”

Stable Isotopes, Chronology, and Bayesian Models for the Viking Archaeology of North-East Iceland

“…This new information, it was surmised, would be invaluable in better understanding human diet, and so these data were used to interpret the diet of people buried within a cemetery associated with an early chapel at Hofstaðir, which lay <10 km north-west of Skútustaðir, and ∼5 km west from the shores of Lake Mývatn, along the River Laxá (Sayle et al 2014) (Figure 3). The chapel at Hofstaðir is believed to have three phases of development, with the youngest turf construction post-dating AD 1477.…”

“…In addition, the stratigraphy at the site indicates that the intensity of burial in the cemetery was much greater in the earlier phases (Gestsdóttir 2006;Gestsdóttir and Isaksen 2011). The 'raw' radiocarbon dates from nine individuals in the cemetery demonstrated the possibility for a large reservoir offset (Sayle et al 2014). Three of the nine (SK016, SK061, and SK066) had radiocarbon dates that, when calibrated using the terrestrial curve of Reimer et al (2013) placed their deaths pre-landnám (Table 1: Calibrated date).…”

“…This paper reviews the results of a long-term research project that ultimately used light stable isotope analyses and Bayesian mixing models to better model the chronology for a presumed Viking Age cemetery at Hofstaðir, near Lake Mývatn in north-east Iceland (Sayle et al 2013(Sayle et al , 2014(Sayle et al , 2016a(Sayle et al , 2016b. Each step of the project was informed by the previous results and the new questions that were often raised.…”

Dating Archaeological Cultures by Their Moats? A Case Study from the Early Bronze Age Settlement Fidvár near Vráble, SW Slovakia

“…In addition, clam shells and fish bones as found at Fidvàr (unpublished data) and other Early Bronze Age sites (Hlavatá 2015) raise the question as to the extent of a reservoir effect (Sayle et al 2014;Shishlina et al 2014). For the transition from the Hatvan to the Únětice culture observed in SW Slovakia, no absolute age control exists (Bátora et al , 2012.…”