Review of research in internal-wave and internal-tide deposits of China:Discussion

This discussion of a review article by Gao et al.(2013),published in the Journal of Palaeogeography(2(1):56-65),is aimed at illustrating that interpretations of ten ancient examples in China and one in the central Appalachians(USA) as deep-water deposits of internal waves and internal tides are unsustainable.This critical assessment is based on an in-depth evaluation of oceanographic and sedimentologic data on internal waves and internal tides derived from 332 print and online published works during 1838-January 2013,which include empirical data on the physical characteristics of modern internal waves and internal tides from 51 regions of the world’s oceans(Shanmugam,2013a).In addition,core and outcrop descriptions of deep-water strata from 35 case studies worldwide carried out by the author during 1974-2011,and a selected number of case studies published by other researchers are evaluated for identifying the sedimentological challenges associated with distinguishing types of bottom-current reworked sands in the ancient sedimentary record.The emerging conclusion is that any interpretation of ancient strata as deposits of internal waves and internal tides is premature.