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. This discussion of a review article by Gao et al. (2013), published in the Journal of Palaeogeography (2 (1): 56-65), is aimed at indicating 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 includes 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-cu rrent 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.