Résumé
The western part of the Moroccan Meseta contains thick Middle Cambrian terrigenous deposits, in places 7000 m thick. Field data and geophysical investigations indicate subsident grabens controlled by major N30°E and N60°E fault zones on the northwestern part of the African shield. These grabens correspond to the late evolution of an intracontinental rift that originated during Late Precambrian and Early Cambrian time and can be considered evidence of the opening of the Iapetus paleo-ocean in Morocco.