At present, little work has been done on the Cyclostratigraphy of the Abidjan margin, so the base level, which is a dynamic surface controlled by factors such as (tectonics, eustatism and climate), represents a very complex environment, which makes it difficult to characterize its rise or fall. This study aims to determine the major lithological ensembles with the evolutionary trends of the logs. The studies carried out concern the analysis of two boreholes located on the Abidjan margin, In this paper, the INPEFA technology of Gamma-Ray logs was used to study the cycle of deposition systems. The negative trend in the INPEFA curve indicates the half-cycle of sea-level decline, the positive trend suggests the rise in sea level of another half-cycle. This allowed us to determine respectively a negative trend, dominated by a positive trend and symmetric cycles (negative trend-positive trend).

The aim of this study, which focuses on beach sediment extraction, is to highlight the impact of these practices on the accelerated erosion of the San Pedro coastline. These practices, linked to the needs of the local population for construction materials, often have catastrophic repercussions. To carry out the work, data on marine sand production was collected, and systematic observation and interview surveys were carried out at the three marine sand quarries in the village of Digboué and at the mouth of San Pedro. This research revealed that both clandestine and official extractions were taking place on a daily basis in these areas. The annual volume of sediment extracted amounts to more than 15,000 m3, not counting clandestine extractions carried out by local villagers, for which the data remain undefined. These activities have disastrous consequences, such as the gradual depletion of sand stocks and a consequent shortage of sediment, which disrupts the equilibrium of the coastal system, causing the coast to retreat and endangering the environment being exploited. Accelerated flooding poses a real threat to the local population. Marine sand extraction causes a great deal of damage and contributes effectively to coastal erosion. It is essential to take defensive measures against this activity.