Abstract Dune systems along the South African coast are sensitive barometers of fluctuations in palaeoenvironments, as archived in their orientation, geometry, internal architecture, composition, granulometry, diagenesis, palaeontology and archaeological content. Presently, the pronounced climatic/oceanographic gradients around the southern African coastline, including the west coast Mediterranean climate type, with cold upwelling to progressively warmer in terms of climate and sea temperatures eastwards, are mirrored by variations in these parameters. Here, we review and contribute new information concerning their fluctuations from the Miocene to the present to track changes in the bio-, hydro- and geospheres through time. West coast dunes take the form of dune plumes, which have an orientation since the Miocene that mirrors the southerlies of the South Atlantic Anticyclone (SAA), muted during the warm Pliocene, as reflected by intense bioturbation. Shoreline-parallel, vertically aggraded dune cordons dominate along the southern and eastern coasts, formed by (winter) polar westerlies since the Miocene. The contrasting dunefield morphologies relate to seasonality of wind strength and precipitation. Subtropical east coast dunes are profoundly weathered – on the shelf, glacial-period dunes indicate different atmospheric circulations. The long-term stability of the warm Agulhas Current contrasts with variability in the Benguela. The aeolianites host a rich human and faunal archive, including human ichnofossils. Supplementary material: Tables S1 and S2, which provide details of the data and data sources for Figure 9 in the text, are available at http://www.geolsoc.org.uk/SUP18711 .

Abstract The Maputaland area of northeastern South Africa is characterized by extensive dunefields which developed during polyphase reworking of regional aeolian cover sand from the Mid-Pleistocene to the Holocene. Extended parabolic dunes, many preserved only as wind-rift trailing limbs, as well as areas of sinuous crested dunes, hummocky dune systems and the high, composite, accretionary coastal barrier dune cordon are the dominant dune forms. There are few natural sections exposing the stratigraphic succession and unequivocal relative age relationships between dune systems are uncommon. A ground penetrating radar (GPR) survey of dunes and representative aeolian sand stratigraphic units was undertaken in order to investigate the internal structure of the different dune forms and identify stratigraphic relationships between buried sedimentary units. The GPR profiles revealed that the trailing limbs of almost all the parabolic dunes that were surveyed comprise stacked sand units, separated by low-angle reflections interpreted as bounding surfaces, which accumulated through polyphase vertical accretion. Most extended parabolic dunes are aligned north-south and the upper parts of the dunes are characterized by inclined reflections in GPR profile interpreted as large-scale sets of cross-stratification with apparent dips toward the west. A hummocky dune revealed cross-stratified aeolian sand superimposed on a truncated dune form and probably formed through deflation of pre-existing dunes. Using 100 MHz and 200 MHz antennae, it is clear that GPR is capable of imaging very fine sedimentary structures and buried erosional surfaces in the homogeneous aeolian sand of Maputaland. At some of the sites investigated, the buried sand units identified were sampled by hand-augering for infrared-stimulated luminescence dating. The age determinations on these samples suggest that vertical accretion of up to 7 m of sand occurred intermittently over variable time scales up to 25 000 years on some parabolic dune limbs during the Late Pleistocene. In some complex dunefields, adjacent dunes were mobilized at different times, suggesting that remobilization was localized. The implications of the complex internal structure and vertical accretion of extended parabolic dunes are discussed in the context of changes in vegetation cover and water table due to seasonal and short-term cyclical climate variations as well as long-term climate change patterns during the last glacial cycle and the Holocene.