The shaly-sandy Bou M’Haoud Formation is the youngest Ordovician Formation of the Ougarta Range (Algerian Sahara) below the disconformity associated with the fini-Ordovician glacial episode. The original definition of the formation was ambiguous and was then corrected. Part of the beds wrongly attributed to the glacial episode has been returned to the Bou M’Haoud Formation, but most of the formation is still poorly known. The results of research lasting more than forty years but often interrupted by a number of reasons are summarized herein. New sections have enabled us to bring lighting an unsuspected development of facies in the Ougarta Mountains extending from the northwest to the southeast. The highest beds which age according to the fauna should be Middle Katian (middle Caradocian), suggest a possible para-unconformity extending as far as the Southern Tassili. The sequential analysis of the beds at this level has also been questioned. Some outstanding aspects of the disconformity associated to the fini-Ordovician glacial episode have been highlighted. The position of the Bou M’Haoud Formation in the regional context is briefly discussed and some possible practical applications are indicated.

Mots clés : Algerian Sahara – Ougarta mountain Range – Bou M’Haoud Formation – Finished – Ordovician glacial episode – Sandbian – Katian.