Holocene history of the Great Kobuk Sand Dunes, Northwestern Alaska

Located just north of the Arctic Circle, the Great Kobuk Sand Dunes (GKSD) are an inland dune field that is closely surrounded by boreal forest. The history of the GKSD tells us about changes in aridity, a climatic parameter whose history is poorly understood at high latitudes. Vegetated dunes in several states of geomorphic preservation surround the active dune field today, evidencing a complex history of Holocene activity. Small lakes in the forest bordering the dunes accumulate wind-blown sand. We use 14C-dated, lake-sediment cores to reconstruct a continuous history of sand influx over the last 8000 yr. The validity of this record is supported by limiting ages obtained from stratigraphic sections within the dune field. The extent of the GKSD underwent a fluctuating shrinkage coincident with Neoglaciation. This downsizing trend was interrupted by periods of increased sand deposition into lakes occurring 4800–4200, 3300–2600, 1300–700, and 300–100 calendar years ago. Aridity in the Kobuk valley during the Holocene probably was controlled by the frequency of North Pacific storms entering the region in late summer. Our results describe the first continuous history of changing moisture balance for central Beringia during the Holocene and comprise a baseline against which future records of climatic and ecological change in this region can be compared.