At the beginning of this century, A. Wegener clearly and successfully formulated the theory of contii~ental drift and many geologists transformed this useful theory into a dogma which was sometimes defended more fervently than scicntifically. As a result, this raft so magtmificently launched, did not take long to sink. Today this method of geological thought, albcit seen from a different perspective, is more fiimly rooted than ever and appears to be particularly fertile. It now only remains to rigorously tcst its validity through regional studies which could, of themselves, benefit from its logic. On a planet where all (known, present-day) occans arc of relatively recent origin, it is only right that we search for those of the past and compare their history with the history of those now evolving. To play this game there are a certain number of elementary rules to be respected. In the geological history of a region, all information at our disposal must bc assembled, critically examined, and placcd within the framework of thc theory, situatiing and establishing in the accessible regions, the major and distinctive traits which speak in favor of the basic hypothesis. The validity and advantage of this approach should shed a new and generally simplified light upon the region studied but should not swecp away certain acquired, basic facts. Schenk ( 1 971) begins with the idea that the north Atlantic Ocean has opened and closed several times since the Precambrian. These successive openings lcd to a modification of the continental outlines, Africa being progressively robbed of fractions of her continental crust which clung to that of North America. To prove his theory, Schenk compares tlnc geological history of the southeastern Atlantic Canadian provinces with those of southern Morocco. It is imimediately evident that the Canadian regions considered are of much greater extent than those of Morocco because the entire Saharan hinterland has been ignored. The analysis is made by examining profiles which are meant to cross-cut the pdeogeographic provinces by placing them more or less perpendicularly to the former oceanic coastlines. As 6. Choubert has shown for Morocco, the idea of an cast-west paleogeographic evolutiora could be succcssf~mlly applied during the InfraCambrian, perhaps also at the beginning of the Cambrian, however, no known facts confirm this same line of evolution for the remainder of the primary times or for the Precambrian. On the basis of principle, an attempt to trace profilcs of the Anti-Atlas toward the ocean passing by way of the High-Atlas, runs into very serious difficulties because thc gcoHogical knowledge o f ehcse provinces is by n o means comparable. It can be qualified as good to cxcelIent in the Anti-Atlas thanks to the syntheses of Choubert and to the work of Destonnbcs (1970) and Hollard (4970); it is still in the exploration stage irn the High-Atlas (Schaer 1966); it is conjecturabIe in thc ocean. Seen from this perspective, i t is sonnewhat unreasonable to have the Migk-Atlas play the role of hinge which would thus permit the