Contenu du sommaire

Abstract. — Where it quits the Jura, the meandering Rhône draws, in its alluvial plain, a fantastic network of ramifications enclosing a large number of islands. In these islands and ancient Rhône'beds, natural vegetation is very diversified and well represented. Numerous mosquito larvals biotopes are found there, and their localisation ami mapping were essential to mosquito control operations. The knowledge of morphogenetic processes combined with the analysis of the different plant communities permitted the understanding of mosquito larval bio- topes genesis, their evolution in time and space, as well as their functioning in the periods of flooding.

Abstract. — The Dhar Ou Senn presents as a sandstone bridge following to the east the Tagant Plateau (South-eastern Mauritania). It looks as a bridge between the Majabat al Kondra and Aouker sand seas. It is made of two landscapes. The northern slope, with sandstones on the foreground, keeps some patches of an ancient ferrugineous Cuirasse. The southern one, a true (Cretaceous ?) cuesta is evoluting with alternate erosive systems. Moisty systems give diatomile-lakes against the lower slopes of the cuestas and arid systems - like the today one, along the slopes glacis with block cover. Torrential forms are of the same kind than these of non tropical mountains.

Summary. — Geographers mainly interested in mountain communities will find an ideal laboratory in that crossroads of Central Morocco, the High Atlas south of Midelt. A rich variety of living conditions may be observed there between 1 600 and 2 Î00 m, including pure tent and camel nomads, ksar-dwelling transhumants and essentially agricultural sedentary villagers. The author analyses five little communities, each of which presents characteristics of its own, and attempts to explain how, in each case, man has had to come to terms environment.

Summary. — Near Tehran, the central Alborz mountains are mainly inhabited by Caspian- type populations whose income was formerly provided by tree culture and cattle breeding. This traditional system is still at work in isolated spots which are now surounded by an urban economic system which implies migrations, the leaving of cattle breeding, and the extension of urban land tenures. These changes are especially quick and effective because of the economic growth of Iran, of the impact of several legal dispositions (land reform, nationalization of ranges), and of cultural schemes superimposed on the touristic environment of Tehran.

Abstract. — In Mauritius, economical and demographical problems are bound since the very start of the 19 th century : in order to develop the sugar economy, promoted by the British, They must call for the indián labour as a substitute of the slaves fred by the english law. Contrarily to the other tropical islands that, facing same problems, try to diversify their agricultural outputs, Mauritius remains devoted to sugar monoculture. It was clever enough to use other opportunities : thanks to its numerous and skilful labour, it could have established an important sector of light industries devoted to export, and its natural features have gone into service of touristic development through the establishment of modern understructures. The results are the effects of a dynamical policy and constant efforts but problems of empoyment and commercial balance are not resolved for that.