Septarien; gegevens uit de literatuur

The occurrence of septaria is not restricted to a special geological period but is determined by sedimentary circumstances. They are known to be present in the neighbourhood of a stratigraphical hiatus. Septarian horizons can be treated as stratigraphical units. The nodular habit is thought to be a result of load cast effects combined with differences in diffusion velocity in horizontal and vertical direction. The cracks are formed when dessication takes place in a nodule with an already consolidated outer wall. Nodules, cracks and crack-fillings will have formed short after sedimentation.