The northern KwaZulu-Natal coast is backed by a continuous aeolian dune cordon that rises in places, to a height of more than 100 metres and a width of 2 kilometres. This MSc thesis documents the geomorphology of the area, as well as the mineralogical, geochemical and textural variation of nine boreholes within a small part of the coastal dune cordon between Lake Nhlabane and Cape St.-Lucia. The results provide useful constraints on the identification of individual beach and aeolian dune systems, their age relationships and spatial distribution. Aeolian dunes within the coastal dune cordon were studied using aerial photographs and grouped into five dune classes that reflect their relative age. These comprise 1) a system of highly weathered dunes inland of the present coastal dune cordon, that are thought to represent older dune cordons; 2) a system of weathered and reworked dunes located on the most inland portion of the coastal dune cordon; 3) a less altered, large field of linear parallel dunes located in the northern part of the study area; 4) a system of large scale parabolic dunes; and 5) a system of coastal, relatively unweathered small parabolic dunes. Mineralogy, geochemistry, texture and SEM analysis of borehole samples revealed a complex internal structure within the present coastal dune cordon. In the most inland part of the dune cordon, a basal light grey unit (Unit K) presents similar characteristics to the Kosi Bay Formation. This is overlain by Unit A, comprising beach and dune systems, characterised by a very high heavy mineral content. Unit A also forms the basal unit of the central and coastal portions of the dune cordon. Unit B contains a mixture of reworked sediments from Unit A and younger sediments. Aeolian Units D and E form the upper part of the dune cordon. Units D and E were derived from beach - foredune systems and contain a high carbonate bioclast content. All units are interpreted to be derived from immature sediment from the Tugela River and mature sediment from the continental shelf. In the southern part of the study area, an additional unit (Unit C) with unique characteristics has been interpreted as an aeolian deposit reworked from local fluvial sediments. The units identified from their sedimentological characteristics can be directly correlated to the regional dune classes identified from the geomorphology. Luminescence dating of two calcareous dunes was undertaken, revealing that only the sediment of the small coastal parabolic dunes (Dune Class 5, Unit E2) is of Holocene age. The deposition of the large field of linear dunes (Dune Class 3, Unit D2) took place between 15 000 and 11 000 BP, during the marine transgression following the last glaciation. Luminescence dating also indicated that both dunes were subject to at least one major reworking event. A study on the weathering characteristics of the dunes can be used to attribute a relative age to the nine sedimentological units. With the help of sea level curves and the two luminescence dates, the nine units were attributed an approximate absolute age and regrouped into four sediment packages thought to broadly represent four interglacial periods. The three younger packages are attributed to the penultimate interglacial (lower part of Unit A), last interglacial (upper part of Unit A, Units B and C) and "Holocene" interglacial (Units D and E). Hence the northern KwaZulu-Natal coastal dune cordon under study represents a complex stacking of three generations of coastal dune cordons, and appears to be constituted of sediments with age ranging from at least two hundred thousand years ago to present. The oldest sediment package (Unit K), interpreted as the Kosi Bay Formation, and the older dune cordons (Dune Class I) must be older than 200 000 years, which is older than considered by previous studies. The "Holocene" dune cordon (Units D and E) is interpreted as the Sibayi Formation. / Thesis (M.Sc.)-University of Natal, Durban, 1999.

Holocene shoreline sequences and associated shelf stratigraphy are described from a high gradient, high wave energy shelf offshore the central KwaZulu-Natal and northern KwaZulu-Natal coastlines. These are examined using high resolution single-channel seismic and multibeam bathymetric means in order to describe the shallow stratigraphy and seafloor geomorphology of each area. The development and preservation of two distinct planform shorelines at -100 m (northern KwaZulu-Natal) and -60 m (northern KwaZulu-Natal and central KwaZulu-Natal) is described. The shallow seismic stratigraphy of northern KwaZulu-Natal comprises three seismic units (Units 1-3) corresponding to calcarenite barriers (Unit 1), back barrier lagoonal sediments (Unit 2) and the contemporary highstand sediment wedge (Unit 3). At intervening depths between each shoreline the shelf is characterised by erosional surfaces that reflect ravinement processes during periods of slowly rising sea level. Where shorelines are not preserved, areas of scarping in the ravinement surface at depths coincident to adjoining shorelines are apparent. These areas represent rocky headlands that separated the sandy coastal compartments where the shorelines formed and are a function of the high gradient. In central KwaZulu-Natal where the shelf is notably wider and gentler, shoreline building was more intense. Five major seismic units are identified (Units 1-5) with several subsidiary facies. The formation of the -60 m barrier complex (Unit 2) in central KwaZulu-Natal was accompanied by the simultaneous formation of a back-barrier system comprising lake-lagoon depressions (Unit 3) and parabolic dune fields aligned to the local aeolian transport direction, formed on a widened coastal plain. On the seaward margins of the barrier, gully and shore platform features developed coevally with the barrier system. Several relict weathering features (Unit 4) are associated with the barrier and reflect similar processes observed in contemporary aeolianite/beachrock outcrops on the adjacent coastline. The two submerged shoreline sequences observed are attributed to century to millennial scale periods of stasis during which shoreline equilibrium forms developed and early diagenesis of beachrock and aeolianite occurred. These extensive phases of shoreline development are thought to have occurred during periods of stillstand or slowstand associated with the Bølling-Allerod Interstadial (~14.5 ka BP) and the Younger Dryas Cold Period (~12.7-11.6 Ka BP). Shoreline preservation in such an environment is considered unlikely as a result of intense ravinement during shoreline translation, coupled with the high energy setting of the KwaZulu-Natal shelf. Preservation of both the 100 m and 60 m shorelines occurred via overstepping where preservation was promoted by particularly rapid bouts of relative sea-level rise associated with meltwater pulses 1A and 1B (MWP-1A and -1B). This was aided by early cementation of the shoreline forms during stillstand. Differences in shelf setting have led to variations in the style of barrier preservation and associated transgressive stratigraphies between the central KwaZulu-Natal and northern KwaZulu-Natal shelves. The main differences include a much thicker post-transgressive sediment drape, higher degrees of transgressive ravinement and an overall simplified transgressive system’s tract (TST) architecture on the steeper and narrower continental shelf of northern KwaZulu-Natal. In comparison, the central KwaZulu-Natal shelf’s 60 m shoreline complex reflects more complicated equilibrium shoreline facets, large compound dune fields formed in the hinterland of the shoreline complex, higher degrees of preservation and a more complicated transgressive stratigraphy. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2013.

The morphology of Lake Sibaya is a product of an ancient fluvial system that drained a coastal landscape dominated by aeolian processes. The sedimentary processes within the lake are driven by wind generated currents. The dominant sedimentary process is one of lake segmentation, whereby prograding bedforms isolate the lake into smaller water bodies. The prograding bedforms include cuspate forelands and sand spits. The size and mobility of these bedforms is a function of sediment availability and current regime. The bathymetry of Lake Sibaya is discussed, with emphasis on geomorphic features derived from the ancient aeolian landscape as well as features related to modern sedimentary processes. The presence of underwater knickpoints and terraces indicate that lake level fluctuations have been common in Lake Sibaya. It is during lake highstands that large volumes of sand are eroded from aeolian dunes which surround the lake and made available for shoreline progradation. Ancient dune topography is preserved to depths of 20 m below water-level within the lake. Surface sediment distribution maps were compiled from 515 grab samples and thirteen core samples. Fine grained, well sorted, coarse skewed quartz sand comprises the majority of the surface area of the lake floor. Gyttja is the other dominant sediment type and accumulates in palaeovalleys and depressions on the lake floor. Sediment distribution in Lake Sibaya is discussed in terms of modern lacustrine processes as well as inherited sedimentary characteristics. The stratigraphy of the sediments underlying Lake Sibaya was investigated using a Uni-Boom seismic profiling system. Seismic profiles were compiled by identifying acoustically reflective surfaces that show regional development. Thirteen seismic overlays were prepared, and are illustrated as west - east and north - south seismic profiles. Five sequences ranging in age from late Cretaceous to Holocene were identified from the seismic profiles, and are described in terms of sequence stratigraphic principles. The seismic sequences were interpreted within a lithostratigraphic framework and are presented as a series of idealised geological sections. Thirteen sediment cores were collected from the Lake Sibaya area in order to ascertain the accuracy of the stratigraphic interpretation of the seismic records, to investigate reflective horizons identified from seismic records and to collect dateable material. Interpretation of the sediment cores reveals that a proto Lake Sibaya existed on drowned dune topography, during the period ± 43500 BP to ± 25500 BP prior to the Last Glacial Maximum. During the early to mid Holocene the Lake Sibaya site was occupied by a saline lagoon which underwent isolation from the sea ± 5030 BP. Since the mid-Holocene the lake has evolved to totally freshwater conditions and has undergone little sedimentation. The geological evolution of the Lake Sibaya area is discussed in terms of the geometry of the identified seismic sequences, the sedimentary characteristics of these sequences and the radiocarbon dates provided from the sediment cores. Palaeo-environmental conditions during the accumulation of the sedimentary sequences is discussed where fossil remains permit. / Thesis (M.Sc.)-University of Natal, Durban, 1998.