Mapping, KwaZulu-Natal

Geomorphological and lithostratigraphic mapping of dune systems on the Maputaland coastal plain of northeastern KwaZulu-Natal Province, South Africa has defined the relative-age relationships between the complex pattern of Quaternary parabolic and hummocky dunes, sand megaridges and the composite coastal barrier dune cordon. Here infra-red-stimulated luminescence (IRSL) ages are presented in the context of regional stratigraphic relationships and serve to bracket the period of accumulation of the main dune systems. The luminescence ages challenge the widely held belief that the north–south aligned dune pattern reflects a coastward-younging sequence. The framework of ages highlights the spatial variations in dune mobilization and long accretion history on some dune forms. Weathered dune and interdune wetland sediments spanning from prior to marine isotope stages (MIS) 11 and up to MIS 7 underlie the coastal plain. At least two generations of decalcified aeolianite of MIS 5 and 4 form the core of the complex coastal barrier dune. On the coastal plain, frequent sand mobilization events during MIS 3–2 resulted in the development of discrete complexes of highly extended, northward directed parabolic dune systems and reworking of the crest of the central sand megaridge. The luminescence-dated dune mobilization history brackets the period of formation of interdune and lacustrine peat and diatomite deposits. During the Holocene marine transgression at least four laterally extensive, complex transverse ridges of coalesced ascending parabolic dunes accreted against the aeolianite core of the coastal barrier. Polyphase dune formation and remobilization is discussed in the context of the regional groundwater and vegetation responses to global climatic changes, wind regimes and glacio-eustatic sea-level fluctuations.

This paper summarizes the results of a recent survey of the South African "Wild Coast" in Pondoland, Eastern Cape Province. The purpose of the survey was to locate and to describe coastal caves and rock shelters that may contain Early and Middle Stone Age archaeological deposits for future study. The study is part of a much larger research design to understand three basic and interlinked paleoanthropological questions: When did coastal intertidal foraging develop? How did it develop? What role did coastal intertidal foods have on the evolution and survival of early modern humans?

Hillslopes in central and western parts of KwaZulu-Natal, South Africa are often mantled by colluvial sediments of the Masotcheni Formation. These sediments have accreted in response to several cycles of deposition, pedogenesis and incomplete erosion. Climatic controls on these cycles are incompletely known. Results from fieldwork, micromorphology, stable carbon isotope analysis and Optically Stimulated Luminescence dating of Masotcheni Formation sediments from Okhombe valley in the Drakensberg foothills are combined. Deposition in the area had at least 11 phases, starting before 42 ka and ending before 0.17 ka. The first six deposits (from before 42 ka to after 29 ka) resulted from the interplay between slope processes and fluvial redistribution under cold conditions. Solifluction was the most important slope process. No deposits have been found from the Last Glacial Maximum, arguably because this period was too dry. The last five deposits (from about 11 ka to before 0.17 ka) resulted from fluvial redistribution of upslope material and older deposits under increasing precipitation. Current extreme gully erosion in the Masotcheni Formation indicates a lack of available upslope material, leaving downslope deposits as the only sediment source for fluvial redistribution. This model for landscape response to climate change may be able to explain how climate controlled landscape processes in other Masotcheni Formation sites in KwaZulu-Natal. In the research area and elsewhere, this proposition may be tested with numerical landscape evolution models.

Abstractr The Maputaland area ofno(heaslern South Africa is characterized by extensn,e dunefields which devcloped during polyphase reworking of regional aeolian cover sand from the Mid Pleistocene io the Holocene-Extended parabolic dunes. nany preserved only as wind-rifi trailing limbs. as well as areas of sinuous crested dunes. humnocky dune systems and the high. composite. accretionary coastal bader dune cordon are the dominant dune lbrms. There are lew natural sections exposing lhe ntuligraphic succession and unequivocal relali!e age relationships between dune sys(ems are uncommon. A grcund penetrating radar (CPR) survey of dunes and representa(ive aeolian sand straligraphic units was uodertaken in order to investigate the rnternal structure of the difleren( dune forms and identify stratigraphic relationships between buried sedimentary units. The GPR proliles revealed (hal the trailing limbs of almost rll thc parabolic dunes that were surveyed comprise stacked sand unirs. separated by low angle reflcctions rntcr preted as boundirg surfaces. which accumulaled through polyphasc v€rtical accretion. Most exlended parabolic dunes are aligned north \outh and the upper parts of the dunes are characlerized by inclined rellections in CPR profile interpreted as large-scale sets of cross-stratihcatron with apparent dips toward the west. A humnocky dune revealed cross-stratilied aeolian sand superimposed on a truncated dune folm and probably formed rhrough deflation ol pre existing dunes. Using 100 MHz ,rnd 100 MHz antennae. it is clear thar GPR is capable ol imaging lery line sedimentary structures and buried erosional surlaces in lhe homogeneous ueolian sand oi Maputaland. At some of the sites investigated. the buried sand unils identilied werc sumpled by hmd-augering for infrared-stimrlated luninescence daling. The age detenninations on lhese samples suggest that vertical accretion of up to 7 m of sand occuned intennitlently over variable rime scales up to 25 000 years on soDe parabolic dune limbs during lhe Lale Pleislocene. In some complex dunelields. adjacent dunes were mobilized al dillerenl times, suggesling thal remobilizalion was loc,rlircd. Thc inplications of the conplex internal structrre and vertical accrction of extended parabolic dunes are discussed in the context of changes iD velerlriun co\cr and watcr (able due to seasooal and short-term cyclical climate variations as well as longtcnn climrte change pattems during the last glacial cycle and the Holocene.

Dunes have accreted on the southeast African coastal plain in coast-parallel patterns of degraded whaleback ridges, sand megaridges and extended parabolic dunes since the Pliocene. In the Maputaland dune field, relative dating is complicated by soil degradation, erosion and vegetation cover. This project assessed alternative relative and numeric dating techniques that can be used to differentiate dune systems and eolian sand bodies. Soil profile characteristics were used to calculate soil development indices (SDI) for soil horizons sampled from hand augered holes and rare exposures. Infrared stimulated luminescence (IRSL) dating of representative dunes and sand units helped define the pedogenesis achieved since deposition.

Geomorphological and lithostratigraphic mapping of dune systems on the Maputaland coastal plain of northeastern KwaZulu-Natal Province, South Africa has defined the relative-age relationships between the complex pattern of Quaternary parabolic and hummocky dunes, sand megaridges and the composite coastal barrier dune cordon. Here infra-red-stimulated luminescence (IRSL) ages are presented in the context of regional stratigraphic relationships and serve to bracket the period of accumulation of the main dune systems. The luminescence ages challenge the widely held belief that the north-south aligned dune pattern reflects a coastward-younging sequence. The framework of ages highlights the spatial variations in dune mobilization and long accretion history on some dune forms. Weathered dune and interdune wetland sediments spanning from prior to marine isotope stages (MIS) 11 and up to MIS 7 underlie the coastal plain. At least two generations of decalcified aeolianite of MIS 5 and 4 form the core of the complex coastal barrier dune. On the coastal plain, frequent sand mobilization events during MIS 3-2 resulted in the development of discrete complexes of highly extended, northward directed parabolic dune systems and reworking of the crest of the central sand megaridge. The luminescence-dated dune mobilization history brackets the period of formation of interdune and lacustrine peat and diatomite deposits. During the Holocene marine transgression at least four laterally extensive, complex transverse ridges of coalesced ascending parabolic dunes accreted against the aeolianite core of the coastal barrier. Polyphase dune formation and remobilization is discussed in the context of the regional groundwater and vegetation responses to global climatic changes, wind regimes and glacio-eustatic sea-level fluctuations. r

St Lucia's complex biodiversity is driven by varia-tions of salinity over time and space, which control the occurrence and growth of plants and animals at any particular time and locality (Starfield et al. 1989; Taylor 1993). For management it is necessary to know how the biota survive ...