Salient geological results from the Biocal cruise are based on 3.5 khz echosondeur profiles. Slopes morphology is controlled by tectonics and erosion/sedimentation balance. From Thio to Lifou, an uniform basin bottom is depressed southwestward by tectonic subsidence and uneven northeastward by a tectonic ridge (the Levi Ridge). Sedimentation is fed by 5 main sources: Great-Land of New-Caledonia, yielding an important terrigenous flux, reefal barriers surrounding it and raised reefs of Loyalty islands, benthic communities dwelling on slopes and in the basins, plankton and volcanoes of New-Hebridean arc. The development of Quaternary reefal barriers around islands of the new-caledonian archipelago has reduced severely the input from emerged lands and platforms to the basins where the rates of sedimentation are weak.