After posting that photo, I just noticed for the first time that the cliff to the right of the middle section of the falls is (I think) a fossil dune bed. There are layers in the rock, just like ordinary sedimentary rock. But the layers are not parallel -- they curve and intersect. Similar dune beds are visible in and around Zion.
I was told by a ranger in Zion that the dunes got buried by more and more sand -- eventually the pressure of the sand cemented the buried dunes into those interlocking formations.
Also, one more important point. I am obligated to state that in this shot, DW is wearing baggy hiking pants that were flapping in the strong breeze flowing down the cliff face. Very unflattering and misleading picture. That is not her real "profile," so to speak.
