Ancient Alaskan sand dunes

Sand dunes in Alaska (USA)? Were parts of Alaska akin to the Sahara or were these dunes once coastal dunes? But 55 kilometers above the Arctic Circle?

Situated in Kobuk Valley National Park, the Great Kobuk Sand Dunes rise unexpectedly out of the sea of trees along the southern bank of the Kobuk River. These dunes – the largest active sand dunes in the Arctic – along with the smaller Little Kobuk Sand Dunes and Hunt River Sand Dunes create more than 75 square kilometers of towering sand. There are smaller patches of dune all along the Tanana River up to the Canadian border, and just across the border there is an enormous dune field. Some of the dunes in the Great Kobuk Sand Dunes rise over 30 meters high and these are the largest active sand dunes in arctic North America.

Kobuk Valley’s sand dunes are a relic of the last Ice Age. 28,000 years ago, the Earth cooled and glaciers began to form high in the mountains surrounding the valley. Over time, the slow, grinding advance and retreat of the glaciers ground the rocks beneath them into a fine sand which was blown by the wind into the sheltered, ice free Kobuk Valley.

In a 1990 paper, Peter Lea and Chris Waythomas mapped out the active and inactive sand bodies in Alaska[1]. Sand is just about everywhere, but most of the dunes are now covered with trees and shrubs. Large sand deposits remain on Alaska’s North Slope, the Seward Peninsula and all through Southwest and Interior Alaska (where the Taylor Highway dune is located).

In a study of the Nogahabara dunes, scientists including Mann wrote that one of the active dunes’ values is continuing to host plants like the Asiatic sand sedge (Carex kobomugi) that are relics from the time of the Bering Land Bridge[2].

Sand deposits everywhere in Alaska harken back to a time thousands of years ago when big winds blasted fine particles of glacier-ground mountain a long way. It must have been an unpleasant time to be walking around Alaska, but scientists like Mann are fascinated with what it left behind.

[1] Lea and Waythomas: Late-pleistocene eolian sand sheets in Alaska in Earth and Oceanographic Science Faculty Work – 1990
[2] Mann et al: Holocene history of the Great Kobuk Sand Dunes, Northwestern Alaska in Quaternary Science Reviews - 2002