No abstract

The material studied in this work comes from excavations of five hydraulic soundings in the localities of Fresco and Grand-Lahou located in the Southwest in the "onshore" part of the Ivorian sedimentary basin. These surveys are part of the national program for drinking water supply from aquifers. The lithological and sedimentological analyzes of the cuttings of these holes are carried out in order to identify the different lithological units crossed, to understand the sedimentary processes that have prevailed during the deposition of these sediments and to better characterize the

Plusieurs pays africains ont adhéré au Réseau Africain de Géoparc (AGN) et ont entrepris de nombreuses études sur le géopatrimoine suite aux investigations menées par cette organisation pour promouvoir les richesses naturelles des pays africains. Les falaises de Fresco, premiers sites identifiés en Côte d’Ivoire, sont connues pour leurs richesses géologiques et écologiques. Ainsi, une étude bibliographique approfondie et complétée par l’analyse des données géologiques sur l’ensemble de ces affleurements ont permis de faire l’inventaire des éléments de valeur des falaises et de les évaluer sur le plan scientifique. L’évaluation de ces géosites (ensemble des cinq falaises) a livré une valeur moyenne de 0,7/1 et a ainsi confirmé leur importance en tant que géosites potentiels. L’environnement naturel aux alentours des falaises renferme une riche biodiversité de végétation littorale abritant de nombreuses espèces animales dont certaines sont en voie de disparition. Cette étude aura permis d’évaluer les falaises comme élément important de la géodiversité pouvant favoriser la promotion du géotourisme et contribuer au développement socio-économique de la région de Fresco. Several African countries have joined the African Geopark Network (AGN) and have undertaken numerous studies on geoheritage following the investigations carried out by this organization to promote the natural resources of African countries. The Fresco escarpments, the first site identified in Côte d’Ivoire, are known for their geologic and biologic wealth. Thus, an in-depth bibliographical study completed by the analysis of geological data made it possible to make an inventory of the elements of geodiversity of the five escarpments and to evaluate their scientific value. The evaluation of these geosites (all five cliffs) yielded an average of 0.7/1; and confirmed their importance as potential geosites. The natural environment around the cliffs contains a rich biodiversity of coastal vegetation, home to many animal species that some of them are endangered. This study will have made it possible to assess the cliffs as an important element of geodiversity that can allow the promotion of geotourism and contribute to the socio-economic development of the Fresco region.

Cliffs of Fresco located southwestern part of ivorian coastal basin are subjet of this study. Lithostratigraphy of upper Cretaceous and Tertiary series were reviewed from the five (5) surveyed, described and daded. This aimed to define the dynamics of an environment (at a time), based on identification and interpretation of sedimentary figures and ichnofossils. A proposed synthesis description allowed to deduce paleoenvironmental interest of analyzed deposits. 44 samples taken from the five (5) cliffs sections upported this study. The lithology indicates a dominant clay and sand sedimentation with intercalations of sandstone and glaucanious and phosphated limestone. Sedimentary structures described are of various types. These figures appear as forms built by a fluid flow action, produced by asymmetrical wrinkles and dunes. They result from mass transport (slumping, casting) and turbidity flow; The stratifications are various shapes : intertwined, fishbone and tabular, dish structures, flasers and lenticulars beddings. Deformation imprints produced after deposition and before consolidation have been identified by load figures, sedimentary structures are good stratigraphic criteria and good indicators of the direction of flow. These ichnofossils are post-depositional event and occur in a variety of environments, from continental to marine. They are generally associated with coastal margins and shallow marine environments.