Friday Field Foto #77: Liesegang banding in cross-bedded sandstone
The photo below shows the chemical/diagenetic banding knowns as Liesegang bands.
The rocks above are (if I remember correctly) within Jurassic eolian units, which are great rocks for seeing some of the most beautiful expressions of the Liesegang phenomenon. In some cases, the banding will follow primary stratification, in other cases, it will cross-cut it.
See Hindered Settling’s post about Liesegang features.