John Howell, Christian Haug Eide, Adrian Hartley

A core component of the sequence stratigraphic model is the implicit assumption of a semi-sinusoidal relative sea-level curve, and the occurrence of “sequence boundaries” formed during intervals of sea-level fall, recognized primarily by the presence of incised valleys. Late Cretaceous paralic deposits in the Book Cliffs, Utah, have been one of the main testing and teaching grounds for high-resolution sequence stratigraphy. The commonly accepted sequence stratigraphic model for the Santonian-Campanian section recognises up to ten sequence boundaries. Analysis of each proposed sequence boundary indicates no conclusive stratigraphic evidence for any relative sea-level falls during this period of deposition in the Book Cliffs area. These observations indicate that a key aspect of the sequence stratigraphic model is not applicable in outcrops which are widely considered to be one of the type areas for sequence stratigraphic teaching and research. This has important implications for sequence stratigraphic applications during greenhouse times.