An atypical (without intertidal and supratidal environment) carbonate platform settles down along the margin. Shallow water oolithes and oncoids are deposited in a narrow zone between a basin with Cancellophycus to the north and a marine/swampy plain with abundants mollusc fauna. However the Mytilus formation, rich in bathonian and callovian foraminifera (Septfontaine, 1984 etc.), develop thick limestone beds tenth of meter above, wrongly attributed to the upper Jurassic. See discussion in Septfontaine (1984).