Radiocarbon measurements on river wood deposits collected in August 2019, Mackenzie River, Canada

1) Large wood samples from 6 regions in the Mackenzie delta area (Aklavik, Inuvik, Coast, Mackenzie River, Arctic Red River, Peel River), with a range of different sites sampled in each region.
2) Samples of wood were collected from the outermost part of wood pieces.
3) Cellulose was extracted and the %C, stable carbon isotope composition (d13C, permil) and radiocarbon activity (Fraction Modern, F14C) were measured on the cellulose. Quality assurance on the geochemical measurements was via analytical standards and blank tests made during the sample analyses.
4) Radiocarbon measurements were converted to estimates of age - providing constraint on the age of the earliest growth rings - using OxCal 4.4 to provide a lower and upper bound age.
5) Wood age modelled using OxCal 4.4, reporting the 95% confidence range of lower and upper ages. For samples with F14C<1, IntCal20 was used. For samples with F14C>1, Bomb21NH1 calibration curve was used.