More than fifty transgressive-regressive depositional sequences are present in Carboniferous and Permian shallow marine successions on stable cratonic shelves worldwide. These were synchronous depositional events resulting from eustatic sea-level changes that generally ranged from 100 to 200 m. Each transgressive-regressive sequence is correlatable using current fossil knowledge. They average about 2 m.y. and range from 1.2 to 4 m.y. in length.
The presence within these strata of numerous, synchronous unconformities of considerable duration and worldwide extent suggests that the fossil record is very incomplete and that we are studying a punctuated fossil record and not a punctuated evolution based on a highly irregular mutation rate. These late Paleozoic transgressive-regressive depositional sequences facilitate correlations because depositional histories of a rock succession can support interpretations of faunal assemblages and faunal similarities in evaluating age relationships.