Creationists have addressed uniformitarianism, evolution, and deep time as foundation blocks of the geological timescale, but have failed to assess its cornerstone. That key principle is the assumption that elements of the rock record represent global correlative synchronous time periods. It is an assumption that dates to the earliest days of modern stratigraphy, but one of questionable value in diluvial geology. Our increasing knowledge of the rock record; of its local variations in tectonic, hydraulic, sedimentary, and diagenetic environments makes it unlikely that globally correlative synchronous time periods can be readily and practically identified in the rocks.