The late Quaternary stratigraphy of coastal dunes and associated deposits in southern Africa

Abstract

Coastal sand dune sediments with associated intraformational aeolianite, palaeosols and beachrock are found throughout much of the southern African coast, and have important roles as both Quaternary environmental archives and in recording the interplay of sediment supply, coastal processes and sea-level change. This paper examines the stratigraphy and palaeoenvironmental significance of coastal sand dunes and associated sediments, using examples mainly from South Africa but also with reference to the sandy coasts of Namibia and southern Mozambique. Based on morphological, sedimentary and dating evidence reported in the diverse literature, the stratigraphic relationship of coastal sand dune sediments to Marine Isotope Stages (MIS) is summarized, and a chronostratigraphic diagram for the period MIS 6 to 1 along the South African coast is used to identify spatially coherent sedimentary units that correspond to different regional climatic and sea-level phases. This framework provides a stratigraphic context to better examine the relationship between coastal sand dunes and external forcing during the late Quaternary in southern Africa, and to guide future field studies.