Studies of acoustic data (3.5 kHz seismic and EM12 swath bathymetry data) and deepsea cores (Kullenberg) give new insight on the Celtic and Armorican margin sedimentation during the last 30 000 years BP. Our results show that the whole Celtic and Armorican turbidite systems corresponds to a mud/sand-rich multisource ramp. Indeed, the Celtic and Armorican deep-sea environments are fed by 8 main channels on the lower slope forming several small sized turbidite systems and contrast with the point-source submarine fan fed by a single feeder channel. Sedimentary facies and sequences analysis document the evolution of the sedimentation in relation to environmental conditions on the Celtic continental shelf during the Marine Isotopic Stage 1 and 2. During the last sea-level lowstand (Marine Isotopic Stage 2), overbank deposits give evidence of the occurrence of relatively low-density turbidity currents that would have originated at the front of the English Channel Delta on the Celtic continental shelf. During the last sea-level highstand (Holocene), despite the disappearance of rivers and deltaic edifices on the shelf, recent sandy layers indicate episodic high-density turbidity currents. These sandy holocene supplies seem derived from reworked outer shelf sand in relation to the high-energy (storms and spring tidal currents) conditions on the outer shelf and to the net sand transport from the near shore to the margin slope that prevail during high sealevel periods.
