Accueil > Documentations scientifiques > Revues récentes > Madagascar : revue de géographie > Archives > Volume 7, juillet-décembre 1965 > Problèmes géomorphologiques de l’extrême Nord de Madagascar

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  Problèmes géomorphologiques de l’extrême Nord de Madagascar
  Madagascar : revue de géographie, Volume 7, juillet-décembre 1965 pp:1 - 61

  Auteur(s) :Battistini R.

  Auteur correspondant :

  Mots-clés : GEOGRAPHIE PHYSIQUE/GEOLOGIE/GEOMORPHOLOGIE/ MADAGASCAR/ANTSIRANANA
  
  

  Résumé de l’article

  [FR]

  [MG]

  [EN] The northern extremity of Madagascar is one of the regions which displays the greatest morphological variety in the island. There is a complete sedimentary series (as from Permo- Trias) in contact with old undermass of tsaratanana in the Southern part and sloping down towards Northeast : in the Sedimentary, erosion has created interesting relief features such as impressive cuestas and deep karsts in the Ankarana and Montagne des Français areas (Jurassic and Eocene). Montagne d’Ambre, ahuge volcanic edifice has risen up above these sedimentary foundations covering them up partially.The volcano, 1445 metres high and 80 kilometres wide in diameter, is one of the most remarkable complex of this kind in Madagascar. As a consequence of volcanic activity during the late quaternary, a set of minor strombolian volcanoes has appeared on the slopes of the main edifice. The forms of these minor volcanoes show an excellent stage of preservation. The study of Quaternary of the Northern extremity of Madagascar is very rewarding. In several places there are fossil coral reefs uplifted at different altitudes. On the Eastern part of the region exposed to the trade wind, these fossil reefs are associated to a series of dunes, sometimes rubefied or even made of sandstone. The stages which Battistini has defined in the south end of Madagascar are also found here : Tatsimian, a positive movement of sea-level yielding deposits covered themselves by the rubefied \’High Dune\’ the Karimbolian, another positive movement associated to a \’Lower Dune\’ before Flandrian. At last, it must also be pointed out that the Northern extremity of the island has undergone tectonic movements during recent times. In this respect, it is worthwile to indicate that these movements are likely to be fated relatively owing to the distortions of the ancient shorelines. These distorsions have been caused by enormous lava accumulation of Montagne d’Ambre. In the center of the accumulation subsidence has occurred but around Cap d’Ambre and along the Northeast coast up lift is visible and can be estimated with enough precision