In this view of The Nautilus look at the top of the left side rock on the opening view. You can see a vestige of the curl of rock that was the namesake of the Nautilus. The curling, overhanging lip has broken off thus shortening the curl. Now, look at the floor of the wash and you can see the fresh colored broken rocks that fell from above. The Nautilus formation was created by water erosion as it flooded and cut through the desert sandstone. As the water cut down it eroded farther and farther under one side of the channel and undercut the upper layer of the small slot. That left a thin, overhanging curved piece of sandstone suspended over the stream bed which, as mentioned, has partially fallen.