For the geologists among us... (pic heavy)

[Tohatchi NM]

Last thing I saw that looked like the green jungle-y picture was a line of sand dunes (ok, formerly sand dunes) that had been bent by tectonic activity. You could tell that the dunes were bent after lithification, rather than laid down in an arc, by the way the bedding was oriented.

It's probably not that, but the arc could reflect fault activity.