Field study of purported hardgrounds of the Cincinnatian
Journal of Creation
A number of samples conventionally believed to be indicators of hardgrounds are located in the Cincinnatian (Upper Ordovician) carbonates of the east-central USA. These consist of borings (especially Trypanites) in both fossil and limestone surfaces, as well as some encrusting bryozoans. The ostensible evidence for protracted sedimentation (hardgrounds) must be juxtaposed against a much more commonly occurring set of evidences pointing to rapid sedimentation. The latter include storm deposits, cross-bedded carbonates, large ripple marks and a large suite of orthocone nautiloids that are crowded into a single bed.
Woodmorappe, John and Whitmore, John, "Field study of purported hardgrounds of the Cincinnatian" (2004). Science and Mathematics Faculty Publications. 207.