The Triassic terrestrial deposits at the northern edge of the High Atlas near Marrakech are mainly represented by thick sequences of massively layered, red sandstone. These are topped by a formation of silt and pink-brown clay containing large deposits of evaporites consisting mainly of rock salt and gypsum. The silt and clay formations form domed structures characterised by intruded gypsum and irregular (disharmonic) folds capped by fine sandstone beds, as well as by small, isolated anticlines only a few metres in scale. The direction of folding shows no relationship to that of the major tectonic folding that gave rise to the Atlas Mountains. In contrast, the folding is closely linked to the deposition of rock salt and gypsum in the High Atlas near Marrakech during the Late Triassic. The same phenomenon is observed in the passive margins of the Atlantic of western Morocco.
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