It's my turn again, after finding Kubilay's Aurora Crater.
That one took me longer than it should, the geology and vegetation pattern led me almost directly to the right spot once I started looking: Scattered deciduous forest, light dusting of snow on north slopes, seemingly semi-arid climate, and volcanism: Nevada, near the border with California. Mono Lake is not far from here, and that area has almost exactly the same features.
So here's a new one - and it's a single dune. :)
Yes, it's a small area. And there is a good reason for that. Have fun!
For any new players to Where on (Google) Earth, simply post a comment with latitude and longitude and write something about the (geologic/geographic/hydrographic) feature in the picture. If you win, you get to host the next one. Previous WoGEs are collected by Felix on his blog and a KML file.