Radiocarbon (14C) ages were measured on 49 samples of macrofossils extracted from a sediment core extending back to roughly 30,000 calendar years before present (cal yr BP) from Salmon Lake, on Seward Peninsula, northwest Alaska. The 16.7-m-long core was collected in August 2022 by the Alfred Wegener Institute, Potsdam, Germany in collaboration with Northern Arizona University (NAU), Flagstaff, USA. The 14C ages were combined with age constrains from short-lived isotopes to generate an age-depth model (doi:10.1594/PANGAEA.984002) for the core using rBacon software. It serves as the timeline for sediment samples from the core, which have been used for a large suite of biological, geochemical and physical analyses.

Approximately 1 - 4 cm^3 of sediment were soaked in reagent-grade water and sieved at 150 µm to concentrate macrofossils. Plant and other macrofossils were picked under a light microscope. Most samples comprised a mix of terrestrial, aquatic and many unidentifiable plant fragments. Samples were pre-treated using weak acid.Samples were analyzed using the gas ion source interface of the MICADAS at the Northern Arizona University Arizona Climate and Ecosystems (ACE) Isotope Laboratory.