Field images of the Ludwigskanal section and ammonites. A. Western section of the canal cutting, showing basal parts of the exposure, from the “Delta-Fossil Bed” to the basis of the Posidonienschiefer Formation. B. Eastern section of the canal cutting, showing the Amaltheenton, Posidonienschiefer, Jurensismergel, and basal parts of the Opalinuston Formation. C. Harpoceras falciferum (Sowerby), “Falciferum Shale”, bed 10, field image (specimen not recovered). D. Polished section of rock sample, from “Fucoid Bed” (bed 17), basal marl of Jurensismergel (bed 18) and “Belemnite Battlefield” (bed 19) to the “Main Phosphorite Bed” (bed 20).