The Silurian rocks in the Mendips are relatively poor in fossils, their remains mainly occurring in the mudstone-rich lithologies at the base and in a bed of water-lain tuff (consolidated volcanic ash) present in the overlying volcanic succession. The fauna of the shales is dominated by brachiopods, including Isorthis clivosa, Salopina conservatrix, Protochonetes sp. and Eocoelia angelini, the record of the last named species allowing the base of the succession to be assigned to the lower Wenlock part of the Silurian. The fauna from the tuff includes bivalves and the brachiopods Lingula and Salopina conservatrix. Overall the brachiopod fauna suggests that a shallowing of the marine environment occurred near the base of the Silurian succession in the Mendips, perhaps related to local uplift associated with impending Silurian volcanism.