Contenu du sommaire

Abstract. The Messinian endoreic recession in the Mediterranean has its origin in eustatic displacement. The base level collapsed down to the floor of the abyssal plains. The drying up episode which produced the evaporites revealed the presence of a deep pre-existent basin. A study of the continental margins and of those deep long incisions in the european and african cratons made by the Rhone and the Nile (thist, along a distance of a few hundred kilometers and to a depth over a few hundred meters) between the Tortonian and the Tabianian confirms the theory of a « desiccated deep-basin model ». During the whole of the subsequent period, the sea obviously wormed its way up these valleys (Pliocene rias). This would tend to show that an interpretation of this phenomena in terms of mobilism is not worthy of note. When it comes to orogenesis fini-Miocene and the contemporaneous hollowing out of valleys, the relation between cause and effect is generally accepted. It can be ruled out in this case because the second processus precedes the first. The erosion which started up again in the entire Mediterranean area is a direct consequence of the massive regression of the waters in the Messinian age. In view of this change of optic, we must revise some theories : it makes the formation of a Pontian erosion surface, in the context of overdeepening, inconceivable ; it implies that, outside the orogenic sectors, the organisms which we observe to be unadapted to those structures and untill now seemed antecedent, are in fact superposed ; it also implies the fact the overthrusts, which have affected the continental margins, have progressed on a gullied topography and that these had already undergone a determinating morphotectonic evolution. We can visualise, in this new perspective, a definite tectonophysic relationship between rhodanian tangential accidents of the « domaine Provençal » (and the Subalpine Provençal) and the concurrent emersion of the Tethysian oceanic basin. poraneous hollowing out of valleys, the relation between cause and effect is generally accepted. It can be ruled out in this case because the second processus precedes the first. The erosion which started up again in the entire Mediterranean area is a direct consequence of the massive regression of the waters in the Messinian age. In view of this change of optic, we must revise some theories : it makes the formation of a Pontian erosion surface, in the context of overdeepening, inconceivable ; it implies that, outside the orogenic sectors, the organisms which we observe to be unadapted to those structures and untill now seemed antecedent, are in fact superposed ; it also implies the fact the overthrusts, which have affected the continental margins, have progressed on a gullied topography and that these had already undergone a determinating morphotectonic evolution. We can visualise, in this new perspective, a definite tectonophysic relationship between rhodanian tangential accidents of the « domaine Provençal » (and the Subalpine Provençal) and the concurrent emersion of the Tethysian oceanic basin.

Abstract. - Iran is an interesting place for the study of closed arid basins. They are spreading everywhere inside Iran, except in the Northwestern part of the country. Their number and varieties are related to the geological structure. A typology is proposed. The aggradation basins are either rather small basins located in central Iran or ancient or present day fluvio-lacustrine basins, nearby humid mountains. The Djaz Mourian basin is specially described. II is quite different from the neighbouring Lut basin where planation surfaces, pediments and « kalut » can be noticed, and from the Great Kewir where large « regredation » plains are eroded in folded evaporites. Neotectonic movements, more humid paleoclimates and present day geomorphological processes are working together to differenciate those basins.

Abstract. - Ottoman features in the geographical physionomy of Cyrenaica. Between the reoccupation of Tripoli (1835) and the Italian conquest (1911), the Ottoman government undertook a policy of creation of military posts and administrative divisions in Cyrenaica. After a first stage consisting in the building of forts (Al-Marj, Al-Qayqab) in 1851-1852 along the main inner road from Benghazi to Derna, a coherent network of administrative centers (muduriyet) had been established up to the beginning of the XX th century. The geographical and political conditions which determined their sites are examined, their relationships with the preexisting nucleus of the tribes are discussed, particularly the situation of the Ottoman posts as to the Sanusi lodges (zawiya). Around Benghazi, in a region where the net of muduriyets reached its maximum density and where the Turkish authority was unchallenged, Ottoman settlements are strictly intermingled between the lodges, and always separated from them. In other cases, on the high plateau (Cyrene, Bishâra), the muduriyets were established close to the zawiyas. A typical case is Al-Haniyya, whose lodge was an active political center. The Ottoman post was built on a small hill just opposite to the lodge, in the obvious purpose of controling it. However, other settlements were still established merely for strategical reasons (Bumba). The sole attempt to a settlement colonization was the establishment of the Cretan muhajirs at Marsa Susâ (1897). The structure of the primitive nucleus, and the subsequent evolution, characterized specially by a penetration in small groups on the plateau long before the Italian conquest, are studied. In conclusion, the author attempts to appraise the scanty legacy of the Ottoman period in the present geographical physionomy of Cyrenaica. The geographical and political conditions which determined their sites are examined, their relationships with the preexisting nucleus of the tribes are discussed, particularly the situation of the Ottoman posts as to the Sanusi lodges (zawiya). Around Benghazi, in a region where the net of muduriyets reached its maximum density and where the Turkish authority was unchallenged, Ottoman settlements are strictly intermingled between the lodges, and always separated from them. In other cases, on the high plateau (Cyrene, Bishâra), the muduriyets were established close to the zawiyas. A typical case is Al-Haniyya, whose lodge was an active political center. The Ottoman post was built on a small hill just opposite to the lodge, in the obvious purpose of controling it. However, other settlements were still established merely for strategical reasons (Bumba). The sole attempt to a settlement colonization was the establishment of the Cretan muhajirs at Marsa Susâ (1897). The structure of the primitive nucleus, and the subsequent evolution, characterized specially by a penetration in small groups on the plateau long before the Italian conquest, are studied. In conclusion, the author attempts to appraise the scanty legacy of the Ottoman period in the present geographical physionomy of Cyrenaica.