Fig. 3 in Concentrations of juvenile and small adult cephalopods in the Hirnantian cherts (Late Ordovician) of Porkuni, Estonia

Fig. 3. Detail of the Siuge Member of Porkuni, Estonia. Line drawing outlines the bedding surfaces in the bioclastic limestone. Shaded areas emphasize the fossiliferous chert nodule beds. The chert nodules occur occasionally at the bottom of small scaled channels and other topographic depressions.