Trace fossils at a regional discontinuity surface: the Austin/Taylor (Upper Cretaceous) contact in central Texas

The Austin/Taylor contact in the Waxahachie area of central Texas preserves a complex record of reworking and phosphatisation during early Campanian (Upper Cretaceous) time. Three main phases in the evolution of the surface, the soft ground, firm ground and remanié phases, are recognised on the basis of faunal and sedimentological criteria. The first is represented by the Austin Chalk, the second by a suite of well-preserved trace fossils referred to Rhizocorallium jenense Zenker, Spongeliomorpha sp., Strophichnus xystus new ichnogenus and ichnospecies, and Remulichnus bicarinatus new ichnogenus and ichnospecies, and the third by a phosphatised fauna which records the former presence of a glauconitic unit now destroyed by post-Austin erosion and reworking