Résumé
The Constantine geological map of 1/10,000 scale, concerns the Directory Urban Plan of this city, equivalent to 100 km (super 2) . It shows a various lithostratigraphic series, including cretaceous limestone and marls bed rock, neritic limestone unit and Mio-Pliocene to quaternary clays and conglomerates. Beside alpine deformations of eocene to low miocene age, which affected the bed rock, the quaternary and neogene tectonic are characterised by kilometric folds of N10 to N30 degrees East directions, vertical faults of N10, N130 and N150 degrees East directions with very important vertical displacement. The actual morphology is conformed in its large features, to this recent tectonic. The Rhumel river crosses, by very deep cliffs (150 m), the Cenomanian-Turonian, thick and hard limestone formation, through these main neogene faults. The Neogene clays and the conglomerates formations, covering a large surface of the Constantine urban plan, are failed with a very sensitive water presence, and then, are subject to landsliding.