There is an atmospheric phenomenon we call loess here in interior Alaska. It is fine airborne silt that forms surprisingly quick deposits on everything even when there is no wind. The same day you wash your car, you will find a layer of gritty dust on it, hard stuff that can scratch paint and glass. In the course of a few years loess covers everything. Something from 30,000 years ago would be buried, but some sites can be found simply by looking at the terrain and thinking --this would be a good site for a hunting camp or hunting lookout post. Then dig. Who knows, you might find a tooth and then you can get your doctorate.
I think it was a cave. I'll alert you when I come across it (the article) again.