Dérive des continents : paléoclimats et distribution des couvertures pédologiques tropicales (Continental drift : paleoclimates and distribution of the pedological tropical covers)

Abstract. - The pedological tropical covers, commonly called laterites, can be considered as living witnesses of climatic zonality, the evolution of which is controled by the slow migration of the continents with respect to equator and tropics. However, the heritage of the ancient paleoclimatic successions are everywhere present in soils, so that laterites are excellent archives of the global climatic oscillations and of the shift of regional climates towards humidity or aridity, warming or cooling, determined by the continental drift.Résumé. - Les couvertures pédologiques tropicales, rangées sous la dénomination de latérites sont des témoins vivants de zonalité climatique, dont l'évolution accompagne la lente migration des continents par rapport à l'équateur et aux tropiques. Cependant les héritages des successions paléoclimatiques anciennes sont partout présents dans les sols, de sorte que les latérites sont aussi d'excellentes archives de l'oscillation du climat global ainsi que, sous l'effet de la dérive des continents, du glissement des climats régionaux, tantôt vers l'humide ou l'aride, tantôt vers le chaud ou le frais.Tardy Yves, Roquin Claude. Dérive des continents : paléoclimats et distribution des couvertures pédologiques tropicales (Continental drift : paleoclimates and distribution of the pedological tropical covers). In: Bulletin de l'Association de géographes français, 77e année, 2000-4 ( décembre). Géographie des lacs (Henri Rougier) / Thèmes de géographie tropicale (Jean Demangeot) sous la direction de Henri Rougier et Jean Demangeot. pp. 373-383

Premiers résultats de cartographie des couvertures latéritiques par images Spot, région de Kangaba (Sud-Mali)

Cartographie des unités du paysage latéritique dans la région de Kangaba (Sud-Mali) à partir des données multispectrales recueillies par le satellite Spot. Correlation entre les formations superficielles et le couvert végétal ainsi que les unités de paysage et la distribution des constituants minéralogiques et chimiques du sol

Wind-driven waterbodies: a new category of lake within an alternative sedimentologically-based lake classification

Lakes are common natural systems for which sedimentation is considered to be relatively simple, generally dominated by fluvial processes along the margin and prevailing low-energy settling in the central, deeper parts. However, for many lakes, higher-energy wind-driven processes dominate. As such, a new category of lakes is proposed, herein referred to as wind-driven waterbodies (WWB). WWB display a sedimentation largely dominated by wave related processes and wind-induced lake-scale water circulation evidenced by the construction of beach ridges, spits or cuspate spits along their shorelines, and by sediment drifts, sedimentary shelf progradation and erosional surfaces in their deeper, offshore domains. WWB are observed worldwide, they share a common physiography that favours wind-forced hydrodynamics and related sedimentation patterns. This physiography is expressed by the IWWB index, a ratio of the maximum representative fetch relative to mean basin depth. It is proposed that an index value greater than three favours the evolution of a lake as a WWB. The WWB concept represents a new end-member in an alternative, sedimentologically-based lake classification that is proposed in this paper