Synsedimentary deformation structures are observed on the armorican border of the Angle-Paris Basin in the late Oxfordian ''Calcaire greseux de Hennequeville'' Formation. These detrital sediments are well exposed on the Normandy coast between Trouville and Honfleur, outcropping both in the cliffs and on the beach. They comprise silty limestone with abundant sponge spicules (Rhaxella) deposited in a restricted subtidal depression mostly above the storm-wave base, and located in the northern flanks on the Sables de Glos delta. The formation is subdivided into three members. Deformational structures observed at a centimetre to metre scale and associated with massive early diagenetic cherts, are developed only in the middle member which is 1.5 m thick. This depositional environment was the shallowest of the whole formation. The soft-deformation structures are various, comprising: (1) low-amplitude structures observed at the lower and upper surfaces of the limestone beds; (2) features with a ''wash-basin form''; (3) boudinage structures; and (4) large-scale ''ball and pillow'' structures or ''blagues a tabac'' (''tobacco-pouches'' showing vertical dimension of over 1 m and observed only in a few sections of the cliffs). All deformational structures are overlain by undisturbed silty limestones and silty clays, suggesting a synsedimentary deformation. The soft deformations are interpreted to have been induced by the liquefaction of unconsolidated spiculitic silty muds during earthquakes. Liquefaction may have been induced by a number of processes which affect grain-supported sediments. A seismic origin is supported not only from particular palaeogeographic context (by reference to the whole NW of Europe in the late Oxfordian), but also by the great lateral extent of the deformational structures which occurs along more than 4 km of coastal outcrops. There is only one deformed unit. The morphology and size of the seismites are directly controlled by the stratonomy and thicknesses of the limestone. Most of the structures have a dominant vertical trend, with an upward or a downward polarity. Earthquakes are always difficult to recognize in the sedimentary record. They were recorded in the case of the ''Calcaire greseux de Hennequeville'' because of a set of exceptional conditions which led to their preservation. These were: seismic activity associated with recurrent faulting; alternating beds of porous, wet and well sorted fine sands with muds favourable to thixotropic processes, and deposition in a relatively protected depositional environment.
