Here there are no significant harder layers of any substantial thickness to shape the steady erosion caused by the occasional rush of water through this landscape.
(no significant harder layers of any substantial thickness; to shape; the steady erosion caused by the occasional rush of water through this landscape) (the steady erosion; caused; by the occasional rush of water through this landscape)
no significant harder layers of any substantial thickness the steady erosion
to shape caused
the steady erosion caused by the occasional rush of water through this landscape
by the occasional rush of water through this landscape