Shifting Sands

The average citizen would tend to associate Alaska with igloos, glaciers and icebergs. But sand dunes? C'mon. That's the Sahara.

The fact is that Alaska has extensive areas covered by sand dunes. Most of these have been created since the last glacial period (the Wisconsin) about twenty-five thousand years ago.

Granted, glaciers and sand dunes don't often go together, but in this case they do. Many of us in interior Alaska live on ground called loess (pronounced luss). This is rock flour that has been ground up by glaciers and transported by the wind to form the topsoil on most of our hills.

But strong winds can also pick up larger fragments and carry them downwind where they are deposited and eventually build up a considerable mass. This is how Alaska's sand dunes are formed. Most of them are found in the northwest part of the state, deriving from "storm winds" that have swept the area since the last glaciation. Residents of the Delta area are all too familiar with the fact that this process is still going on.

Riverbed sand is the most common source of Alaska's sand dunes, and after it is picked up, the sand is dropped when the storm runs out of steam. Commonly, this occurs in northwest Alaska from winds blowing from the southeast to the northwest.

A good example is provided by the "Great Kobuk Sand Dunes" about 80 miles east of Kotzebue. Here it is evident that the wind transportation has come from the southeast, and the vegetation surrounding the dune is gradually being overcome to the northwest and trying to reestablish itself to the southeast.