Just before P.O. 9 the rocks change their features completely: the change goes from grey carbonatic rocks (Panormide Tectonic Unit) to pelitic shales with intercalated quartzarenitic layers (Numidian Flysch Unit). The rocks are not in stratigraphic sequence (in a normal temporal succession the young rocks overlie the old ones) but are disturbed by tectonics (the rocks above are older than those below).