the formation and evolution of the barrier islands of inhaca and bazaruto mozambique abstract the barrier islands of inhaca and bazaruto are related to the extensive coastal dune system of the mozambican coastal plain south east africa optically stimulated luminescence osl dating of key stratigraphic units indicates that accretion of sediment within these systems is episodic both islands appear to have been initiated as spits extending from structural offsets in the coastline superposition of significant quantities of sediment upon these spits during subsequent sea level highstands formed the core of the islands which were anchored and protected by beachrock and aeolianite formation at least two distinct dune building phases occurred during marine oxygen isotope stage mis 5 tentatively attributed to marine transgressions during sub stages 5e and 5c although some localized reactivation of dune surfaces occurred prior to the holocene large quantities of sediment were not deposited on either island during the low sea levels associated with mis 2 significant dune building and sediment reworking occurred immediately prior to and during the holocene though it is not clear whether these processes were continuous or episodic significant erosion of the eastern shoreline of bazaruto suggests that it is far less stable than inhaca and may suffer further large scale erosion a model is presented for the formation of barrier islands along the mozambican coastal plain

persistent millennial scale climatic variability over the past 25 000 years in southern africa abstract data from stalagmites in the makapansgat valley south africa document regional climatic change in southern africa in the late pleistocene and holocene a new tims u series dated stalagmite indicates speleothem growth from 24 4 to 12 7 ka and from 10 2 to 0 ka interrupted by a 2 5 ka hiatus high resolution oxygen and carbon stable isotope data suggest that postglacial warming was first initiated 17 ka was interrupted by cooling probably associated with the antarctic cold reversal and was followed by strong warming after 13 5 ka the early holocene experienced warm evaporative conditions with fewer c4 grasses cooling is evident from 6 to 2 5 ka followed by warming between 1 5 and 2 5 ka and briefly at ad 1200 maximum holocene cooling occurred at ad 1700 the new stalagmite largely confirms results from shorter holocene stalagmites reported earlier the strongest variability superimposed on more general trends has a quasi periodicity between 2 5 and 4 0 ka also present are weaker 1 0 ka and 100 year oscillations the latter probably solar induced given similarities to the antarctic records the proximate driving force producing millennial and centennial scale changes in the makapansgat record is postulated to be atmospheric circulation changes associated with change in the southern hemisphere circumpolar westerly wind vortex

holocene aeolian activity in the southwestern kalahari desert southern africa significance and relationships to late pleistocene dune building events little is known about the timing of dune building episodes in the southwestern kalahari desert previously arid phases when dune activity occurred have been inferred from gaps in chronologies derived from information that attests to former humid periods to redress this optically stimulated luminescence osl dating was applied to sediment samples taken from a range of aeolian landforms in the sw kalahari four periods of dune building are identified in the late pleistocene and holocene holocene aeolian activity at 6 ka and 1 2 ka led to the construction of localised dune forms in contrast to late pleistocene times when the extensive field of linear dunes that dominates the region was emplaced late holocene aridity was however sufficient to allow rapid emplacement of the lunette dune at witpan the record of aeolian activity is evaluated in the context of humid chronologies and an ocean atmosphere model of holocene climate change with good agreement obtained it is concluded that the application of

late quaternary paleotemperatures derived from a speleothem from cango caves cape province south africa abstract an oxygen isotope temperature record over a large part of the past 30 000 yr has been obtained for the southern cape province of south africa by combining data on the isotopic composition of a stalagmite from a deep cave with that of a confined groundwater aquifer in the same region results show that temperatures during the last glacial maximum were on average about 6 c lower than those today with peaks up to 7 c lower a detailed analysis of the past 5000 yr suggests multiple fluctuations with generally lower temperatures 1 2 c around 4500 and 3000 yr b p the carbon isotopic composition of the stalagmite indicates significant vegetation changes between the late pleistocene and today and also during the second half of the holocene

depositional and sea level history from mis 6 termination ii to mis 3 on the southern continental shelf of south africa abstract pleistocene shoreline deposits comprised of calcified shallow marine palaeobeach and aeolian palaeodune facies found along mid latitude coastlines can be useful indicators of past sea levels here we describe a succession of such deposits that are presently exposed both above subaerial and below submerged mean sea level along the southern cape coast of south africa 18 km east of the town of mossel bay the submerged units provide a window on late pleistocene coastal processes as palaeoshoreline deposits in this study extend to water depths of up to 55 m on the mid shelf five sedimentary facies were identified in the strata and were compared to modern depositional environments of the local littoral zone which include aeolian dune upper shoreface foreshore intertidal swash and back barrier settings twenty two geological units were observed and mapped some of these units were directly dated with optically stimulated luminescence osl dating osl ages were obtained for ten samples from the subaerial and twelve samples from the submerged deposits those geological units not directly dated were interpreted based on sedimentology and field stratigraphic relationships to dated units the stratigraphy and chronology of the succession indicates a record of initial deposition during termination ii t ii meltwater events preceding and leading to marine isotope stage mis 5e indicators for multiple sea level fluctuations between mis 5d and mis 4 and sediment deposition at the end of mis 4 and start of mis 3 are also found both regressive and transgressive depositional cycles are well preserved in the succession we propose that palaeodune and palaeobeach deposits along the south coast of south africa have no clear preference for deposition during sea level transgressions or regressions sediment deposition more closely mirrors the rate of sea level change with deposition and preservation either during times of rapid sea level movement or oscillation around still stand events periods of relatively slow average rise or fall of sea level are represented by erosional planation surfaces in this record

the stratigraphic evolution of a large back barrier lagoon system with a non migrating barrier abstract lake st lucia the largest estuarine system in africa is enclosed by a 120 m high compound quaternary barrier dune system in northern kwazulu natal south africa it comprises several discrete sedimentary basins within a single shallow back barrier water body this paper reports the first very high resolution seismic study of the system seven seismic units a g are identified and interpreted based on their geometry acoustic properties and a sediment coring programme the units are bounded by regionally developed sequence boundaries and lower order unconformity surfaces corresponding to bay and tidal ravinement and hiatus surfaces the lowermost subaerial unconformity formed during regression related to late pliocene hinterland uplift initial infilling of this surface in the proximal areas reflects estuarine sedimentation in a mixed wave and tide dominated system during the subsequent lowstand and early transgressive systems tracts overlain by prograding highstand deltaic deposits that developed as sea levels began to stabilise distally this cycle of sedimentation is initially reflected by the infilling of a similar estuarine system that gradually transitioned to a back barrier lagoon superimposed stillstands drove imbalances in the rate of sediment supply and accommodation space and this coupled with the development of an early barrier complex caused lagoon aggradation and shallowing a second similar trend is repeated for the recent postglacial sea level cycle there appears to be no preservation of the intervening pleistocene cycles of erosion and deposition the system is capped by estuarine lacustrine deposits the onset of lower energy estuarine lake conditions began 6235 cal bp in north lake and started earlier in the proximal false bay owing to sheltering by the antecedent barrier of a rocky peninsula this study reveals a markedly different evolutionary history in adjacent basins of the same back barrier system during two full sea level cycles these are attributed to a long established non migrating barrier and to the influence of antecedent conditions on the system response to transgression unlike the us atlantic margin where migrating barriers truncate the infilling sequences the main stratigraphic unconformities within each fill sequence correspond to tidal and bay ravinement surfaces

n alkan 2 one biomarkers as a proxy for palaeoclimate reconstruction in the mfabeni fen south africa abstract the sub tropical mfabeni fen is the only continuous coastal peat deposit that documents glacial and interglacial palaeoenvironmental conditions since the late pleistocene ca 47 cal kyr bp in southern africa published bulk geochemical biomarker and leaf wax 13c data along with palynology and stratigraphic studies of the mfabeni peat sequence render it an ideal record for testing new palaeoreconstruction proxies in this study we aimed to establish the proxy potential of n alkan 2 one n ket compounds by tracing their source origin and post depositional diagenetic change and if they preserve or not a robust palaeoenvironment signal that complements our understanding of palaeoclimatic variations in the mfabeni archive the most likely source for n kets is via microbial decarboxylation of n 1 alkanoic acids n fas and to a lesser degree oxidation of same chain length n alkanes n alks the n ket average chain length aclket and n c23 and c25ket precursor ratios displayed a statistical significant negative relationship with the n alk aquatic plant proxy paq suggesting the source of n kets to be submerged aquatic plants during waterlogged conditions that suppressed microbial activity during the ensuing anoxic conditions both the mid chain and long chain n ket precursor ratios displayed predominant water level fluctuation controls with temperature as a secondary regulator by comparing the n ket data with published environmental and climate reconstructions from the same core and with geomorphology and palynological studies of the mfabeni basin we conclude that the n kets show promise as a palaeoclimate proxy and can be used in conjunction with other biomarker proxies to reconstruct ancient hydrological changes in sub tropical peatlands

the geomorphologic evolution of the wilderness dune cordons south africa abstract the wilderness dune cordons consist of steep sided ridges up to 207 m high separated by coastal lakes they probably formed during the sea level highstands of the pleistocene interglacials three major dune cordons are developed there is an additional huge coalesced mass of older fossil dunes landward of these cordons forming hills up to 340 m high in places lying on the coastal platform 150 260 m generally locally 210 260 m the dunesand reaches thicknesses in excess of 300 m the cordons form by accretion of transgressive dunefields and large compound imbricate parabolic dunes an individual cordon can result from numerous phases of dune formation during periods of sea level highstand the dunes of the present interglacial are mostly accreting on top of the seaward cordon which was initiated during the last interglacial during the complex sea level history there have been numerous phases of dune building followed by coastal erosion that formed seacliffs in the dune cordons in some areas almost all the cordon was subsequently eroded away these fossil seacliffs form large steep seaward facing slopes parallel to the present coastline and form a major element in the morphology of the cordons trailing arms of parabolic dunes form another major topographic element oriented at 15 30 to the shoreline river erosion has altered the cordon morphology in places the geomorphology of the cordons is thus a function primarily of dune cordon construction accentuated by coastal erosion in the form of cliff cutting secondarily of dune morphology and thirdly of fluvial erosion the evolution of the cordons can be dated tentatively using palaeontologic stratigraphic and sediment dynamic data the seaward cordon formed during the eem and holocene a fairly reliable dating the middle cordon probably formed between 200 500 ka and the landward cordon probably formed between 600 900 ka the coalesced dune deposits lie inland of the cordons and are thus older this would place the minimum age of the younger coalesced dune deposits in the middle pleistocene about 1000 ka early miocene fossil plant remains in the knysna lignites which underlie the older coalesced dunes indicate their maximum possible age westerly winds dominated in the area for the past few million years

shoreline deposits and diagenesis resulting from two late pleistocene highstands near 5 and 6 metres durban south africa in exposures of pleistocene rocks on the east coast of south africa eight sedimentary facies were distinguished on the basis of petrology grain size internal structures and field relationships these are interpreted as deposits of surf zone breaker zone swash zone backbeach boulder beach and dune environments three phases of deposition and diagenesis are recognized as a result of the stabilising effect of pre existing coastal facies the deposits from successive sea level stands are stacked vertically in a narrow coast normal strip early cementation prevented erosion of the deposits during subsequent transgressions deposition of subsequent facies took place on an existing coastal dune facies 1 a terrace was cut into this dune at a sea level 4 5 to 5 m above present at this sea level clastic shoreline sediments were deposited which make up the main sedimentary sequence exposed facies 2 7 the steep swash zone coarse grain size and comparison with modern conditions in the study area indicate clastic deposition on a high energy wave dominated microtidal coastline vertical stacking of progressively shallower water facies indicates progradation associated with slightly regressive conditions prior to stranding of the succession above sea level during a subsequent transgression to 5 5 or 6 m above present sea level a second terrace was cut across the existing facies which by then were partly lithified a boulder beach facies 8 deposited on this terrace is indicative of high wave energy and a rocky coastline formed by existing cemented coastal facies comparison with dated deposits from other parts of the south african coast suggest a late pleistocene age for facies 2 8 deposition was terminated by subsequent regression and continuing low sea levels during the remainder of the pleistocene cementation of the facies took place almost entirely by carbonate precipitation the presence of isopachous fibrous cements suggests early cementation of facies 1 2 3 and 4 under marine conditions initially as aragonite which has since inverted to calcite facies 5 6 and 7 are cemented only by equant calcite spar evidence of cementation in the meteoric phreatic and vadose zones lowering of the water table during regression caused the remaining pore space in facies 1 2 3 and 4 to be filled with equant calcite spar decementation in a 130 cm wide zone is attributed to water table shifts associated with the later transgression which deposited facies 8 the vertical stacking of the two depositional sequences may be attributed to rapid cementation of facies 2 3 4 5 6 and 7 under humid subtropical conditions this lithified sequence then acted as a focus for deposition of coarse grained shoreline facies facies 8 during the subsequent transgression

late quaternary coastal evolution and aeolian sedimentation in the tectonically active southern atacama desert chile abstract analyses of aeolianites and associated dune surficial carbonate and marine terrace sediments from north central chile 27 54 s yield a record of environmental change for the coastal southern atacama desert spanning at least the last glacial interglacial cycle optically stimulated luminescence dating indicates phases of aeolian dune construction at around 130 111 98 77 69 and 41 28 ka thin section and stable carbon and oxygen isotope analyses suggest a predominantly marine sediment source for the three oldest dune phases aeolianites appear to have accumulated mainly from tectonically uplifted interglacial marine sediments that were deflated during windier and or stormier intervals bedding orientations indicate that sand transporting winds varied in direction from s ese during mis 5e and wnw ese during mis 5c 5a winds from the southeast quadrant are unusual today in this region of the atacama suggesting either major shifts in atmospheric circulation or topographic airflow modification thin section evidence indicates that the aeolianites were cemented by two phases of vadose carbonate tentatively linked to wetter periods around 70 and 45 ka tectonic uplift in the area has proceeded at an average rate of 305 542 mm kyr 1 the study illustrates the complexity of understanding onshore offshore sediment fluxes in the context of late quaternary sea level fluctuations for an area undergoing rapid tectonic uplift

aeolianite calcrete microbialite and karst in southwestern australia as indicators of middle to late quaternary palaeoclimates abstract the mid late pleistocene and holocene aeolianites of the tamala limestone on the northern swan coastal plain in southwestern western australia consist of six members that show cyclic deposition of coastal aeolianite overlain by calcrete microbialite karstified surface and palaeosol field work combined with mineralogical chemical stable isotope analysis and uranium thorium u th and optically stimulated luminescence osl dating provides an insight into the repetitive glacial and interglacial climatic periods over the past 500 kyr deposition of the carbonate aeolianites occurred during interglacial episodes marine isotope stage mis 1 5 7 9 11 and possibly 13 due to migration of coastal dunes under the influence of strong southerly to southwesterly winds rainfall was insufficient to support vegetation cover on the dunes and so was probably limited or seasonal the transition from interglacial to glacial climates was characterised by higher effective rainfall accompanied by aeolianite dissolution and karstification during the colder climates and less effective rainfall of the glacial periods there was no carbonate sand deposition instead laminated microbialite and or laminar calcrete formed followed by palaeosol formation the oxygen isotope composition of the microbialites indicates average temperatures during glacial periods 4 c 8 c lower than today and 13 c values demonstrate a higher proportion of c4 plants and therefore a drier or more seasonal climate data from individual members of the tamala limestone show that the wettest interglacial period was mis 5 when extensive karstification and pinnacle development occurred and rainfall was probably higher than at any other time in the past 500 kyr of the glacial periods mis 10 was relatively wet or less seasonal whereas mis 8 and the last glacial maximum lgm were relatively dry and windy the low rainfall during the peak of the glacial periods was probably intensified by colder water offshore due to weakening of the leeuwin current and its replacement by the cold north flowing west australian current

chronology of upper quaternary offshore successions from the southeastern mediterranean sea israel pleistocene and holocene transgressions advancing over the shelf that was exposed during glacial maxima drowned any continental and shallow marine sediments deposited during low sea level stands to complement records from sequences exposed on land core material from the shallow continental shelf is needed to reconstruct climatic and sea level fluctuations two cores drilled offshore ashqelon off the southern mediterranean coast of israel in a water depth of 10 and 25 m were analyzed sedimentary facies and faunal analyses indicate that most of the sediments were deposited in nearshore environments with only short intervals of continental episodes luminescence dating of alkali feldspar and quartz as well as 14 c ages of mollusks date the cores to marine oxygen isotopic stages 6 1 between b140 and 5 ka comparison between the dating methods shows that most alkali feldspar ages agree with independent sea level and sedimentological constraints while quartz ages are overestimated r 2003 elsevier science ltd all rights reserved

last interglacial climates the last interglacial commonly understood as an interval with climate as warm or warmer than today is represented by marine isotope stage mis 5e which is a proxy record of low global ice volume and high sea level it is arbitrarily dated to begin at approximately 130 000 yr b p and end at 116 000 yr b p with the onset of the early glacial unit mis 5d the age of the stage is determined by correlation to uranium thorium dates of raised coral reefs the most detailed proxy record of interglacial climate is found in the vostok ice core where the temperature reached current levels 132 000 yr ago and continued rising for another two millennia approximately 127 000 yr ago the eemian mixed forests were established in europe they developed through a characteristic succession of tree species probably surviving well into the early glacial stage in southern parts of europe after ca 115 000 yr ago open vegetation replaced forests in northwestern europe and the proportion of conifers increased significantly farther south air temperature at vostok dropped sharply pulses of cold water affected the northern north atlantic already in late mis 5e but the central north atlantic remained warm throughout most of mis 5d model results show that the sea surface in the eastern tropical pacific warmed when the ice grew and sea level dropped the essentially interglacial conditions in southwestern europe remained unaffected by ice buildup until late mis 5d when the forests disappeared abruptly and cold water invaded the central north atlantic ca 107 000 yr ago

late quaternary hillslope evolution recorded in eastern south african colluvial badlands abstract infrared stimulated luminescence irsl ages have been obtained from a sequence of sandy colluvial deposits in northern kwazulu natal comparison of the irsl ages on sand sized potassium rich feldspars with radiocarbon dates on a horizon organic matter from buried palaeosols within the colluvial succession shows good agreement between the dating techniques when compared with palaeoenvironmental records the data suggest that the colluvium accumulated during arid stages of the late quaternary whilst pedogenesis repeatedly occurred at intervals of hillslope stability which may reflect periods of greater humidity temperature does not seem to have been a forcing factor in the landscape development extensive colluviation took place during the arid last glacial maximum but the occurrence of several palaeosols indicates that it was a time of fluctuating climatic conditions

boulder emplacement on a tectonically stable wave dominated coastline mission rocks northern kwazulu natal south africa abstract the presence of large boulders along rocky coastlines is a useful indicator as to the occurrence and nature of past storms and or tsunami field observations from mission rocks northern kwazulu natal south africa allowed for the assessment of historical high magnitude wave events in the area a total of 143 anomalously large boulders were assessed in terms of their dimensions morphologies and distribution along a regionally developed 3 m raised shore platform based on long intermediate and short axes relationships we calculate boulder masses of up to 9 03 t that were found to have been transported horizontally shoreward for up to 65 m based on geomorphological evidence we infer that the majority of boulders encountered were from a joint bound pre transport setting additionally overturning of the boulders was apparent we assess the boulder field numerically via the numerical model of pignatelli et al 2009 which we deemed most applicable for slab like boulders such as those encountered here results yielded a maximum breaking storm wave height of 11 36 m or a maximum tsunami height of 2 84 m an analysis of swell data revealed that the modelled storm wave heights fell within the range defined by the storm wave records for the area within the past 32 years boulder alignments were likewise compatible with the wave regime of the northern kwazulu natal coastline additional review of offshore seismic records and landslide hazards on the tectonically stable passive margin show that the tsunami hazard for landslides within the area is negligible the findings suggest a storm provenance as the causal mechanism for boulder emplacement at mission rocks

rapid climate shifts in the southern african interior throughout the mid to late holocene a detailed climate proxy record based on 18o 13o and grey index of a well dated stalagmite from cold air cave in the makapansgat valley of north eastern south africa suggests that regional precipitation temperatures and vegetation oscillated markedly and rapidly over the last 6500 years on centennial and multi decadal scales the mid holocene prior to 5200 years ago was humid and warm a fundamental transition occurred 3200 years ago leading to drier and cooler conditions that culminated at 1750 ad comparisons with ice core records suggest synchronous changes implicating rapid global teleconnections

stratigraphic architecture and hierarchy of fluvial overbank splay deposits splay deposits represent an important sand prone component of the otherwise fine grained stratigraphic record of fluvial overbank systems this work presents a hierarchical approach to the classification and palaeoenvironmental interpretation of ancient preserved splay deposits supported by the analysis of the stratigraphic architecture of 11 exhumed examples from the jurassic morrison formation and the cretaceous mesaverde group western usa and analysis of the morphology of splays from nine modern fluvial systems a hierarchical arrangement of splay deposits is proposed categorized into lithofacies beds elements and complexes recognition criteria for each tier of the hierarchy include identification of bounding surfaces thinning and fining trends of splay elements and complexes and palaeocurrent variability progradational and compensational stacking trends control the stratal architecture of splay deposits and these are influenced by the following factors 1 the rate of local accommodation generation which influences the erosive power of floodwaters and whether splay elements are laterally offset owing to compensational stacking 2 the nature of the topographic confinement of the floodplain 3 the preservation potential linked to migration direction of channel splay bodies can contribute volume to fluvial reservoirs and may form significant connectors that link otherwise isolated primary channel bodies thereby enhancing reservoir connectivity supplementary material thickness and facies types with global positioning system gps coordinates length and width v thickness and modern data and coordinates are available at https doi org 10 6084 m9 figshare c 4461026

9000 years of sea level change along the southern african coastline abstract beachrocks are good indicators of sea level stillstands on microtidal coastlines and data for this sea level curve is mainly based on dating a series of holocene beachrocks and planation episodes on the southeast african coastline sea level reached its present level along the southern african coastline at ca 6500 bp sea level then rose depositing a series of beachrocks at an elevation of 2 75 m this mid holocene sea level highstand persisted for a period of 2500 years with a 3 5 m stillstand dated at 4480 bp being the highest sea level reached during the holocene in post holocene sea level optimum times a regression occurred lowering sea level to its present level at 3880 bp and down to 2 m at approximately 3000 bp subsequently sea level rose to 1 5 m at 1610 bp and attained its present level at about 900 bp the mid holocene sea level highstand appears to have resulted from a combination of isostatic emergence and the steric expansion of seawater relating to warmer ocean temperatures associated with the holocene hypsithermal event on the eastern agulhas bank

late quaternary sea level change in south africa abstract a late quaternary sea level curve for south africa is presented on the basis of new and published data from a range of sea level indicators and a variety of locations available evidence suggests that sea level in south africa broadly follows that described from the caribbean but that deviations occur during sea level highstands during the last interglaciation oxygen isotope stage 5 and the late holocene coastal emergence produced higher sea levels in south africa than those identified in the caribbean during the same time intervals this is tentatively ascribed to predicted lithospheric deformation in continental margin settings

marine geology of the sodwana bay shelf southeast africa abstract the geostrophic current controlled northern zululand shelf displays a unique assemblage of interesting physical sedimentological and biological phenomena the shelf in this area is extremely narrow 3 km and is characterised by submarine canyons coral reefs and steep gradients on the continental slope three submarine canyons occur in the study area and are classified as mature or youthful phase canyons depending on the degree to which they breach the shelf these canyons originated as mass wasting features which were exploited by palaeo drainage during sea level regressions shelf lithology is dominated by a series of coast parallel patch coral reefs which have colonised beachrock and aeolianite sequences that extend semi continuously from 5 to 95 m and delineate late pleistocene palaeocoastline events the unconsolidated sediment on the shelf is either shelf sand mainly terrigenous quartz grains or bioclastic sediment large scale subaqueous dunes commonly form in the unconsolidated sediment on the outer shelf due to the agulhas current flow these dunes occur as two distinct fields at depths of 35 to 70 m the major sediment transport direction is towards the south but occasional bedload parting zones exist where the bedform migration direction changes from south to north

eustatic and climatic controls on the development of the wahiba sand sea sultanate of oman aeolian sand sea accumulations can serve as valuable archives of climate change in continental environments the wahiba sand sea is situated at the northern margin of the area presently affected by indian summer monsoon circulation and it records environmental changes associated with this major climatic boundary over the last 160 000 years the internal stratigraphy and evolution of the sand sea is investigated using a combination of outcrop borehole seismic and luminescence data proximity to the indian ocean means that the sand sea succession shows the influence of sea level changes on the sedimentary architecture and composition of the dune deposits during the last two glacial periods low global sea level was associated with a high input of bioclastic grains reflecting the significance of subaerially exposed shelf areas as one of the main sources of aeolian sediment the onset of aeolian sediment transport and deposition was related to the breakdown of stabilizing vegetation during arid periods that equate with sea level lowstands the preservation of aeolian sediments by the formation of supersurfaces and associated palaeosoils took place during times of increased wetness and elevated groundwater tables this interplay of constructive and destructive periods greatly influenced the sedimentary architecture oscillations of wet and dry periods between 160 000 and 130 000 years and 120 000 105 000 years ago are attributed to the evolution of a wet aeolian system younger periods of aeolian deposition around and after the last glacial maximum were characterized by dry aeolian conditions no soil horizons developed during these times

ubiquity of anomalous fading in k feldspars and the measurement and correction for it in optical dating anomalous fading rates were measured in k feldspars separated from 49 sediment samples mainly from north america the intensity of the optically stimulated luminescence was found to decrease linea

aeolianite and barrier dune construction spanning the last two glacial interglacial cycles from the southern cape coast south africa the southern cape region of south africa has extensive coastal aeolianites and barrier dunes whilst previously reported limited knowledge of their age has precluded an understanding of their relationship with the climatic and sea level fluctuations that have taken place during the late quaternary sedimentological and geomorphological studies combined with an optical dating programme reveal aeolianite development and barrier dune construction spanning at least the last two glacial interglacial cycles aeolianite deposition has occurred on the southern cape coast at ca 67 80 88 90 104 128 160 189 and 200 ka before the present using this and other published data coupled with a better understanding of late quaternary sea level fluctuations and palaeocoastline configurations it is concluded that these depositional phases appear to be controlled by interglacial and subsequent interstadial sea level high stands these marine transgressions and regressions allowed onshore carbonate rich sediment movement and subsequent aeolian reworking to occur at similar points in the landscape on a number of occasions the lack of carbonates in more recent dunes oxygen isotope stages 1 2 and 4 5 is attributed not to leaching but to changes to carbonate production in the sediment source area caused by increased terrigenous material and or changes in the balance between the warm agulhas and nutrient rich benguela ocean currents

climatic and sea level controls on late quaternary eolian activity on the agulhas plain south africa abstract located at the interface between the temperate westerly and sub tropical climate systems south africa s winter rainfall zone wrz is a key location in understanding late quaternary atmospheric circulation dynamics inactive eolian deposits in the wrz comprising pan fringing lunette and coastal dunes were investigated to establish their depositional ages and utility as paleoenvironmental indicators the resulting optical luminescence chronology reveals episodic lunette accretion at 60 000 45 000 yr 12 000 13 000 yr 2800 2600 yr 1200 yr and episodes of lunette and coastal dune accretion on the agulhas plain are temporally distinct reflecting differing fundamental controls on their activity comparisons to previously published data also reveal that the lunettes differ in age from more ancient coastal eolianites lunette deposition is asynchronous between locations reflecting the topographic and hydrological setting of the individual pans in near coastal settings with limited surface recharge lunette accretion appears to be at least partially controlled by sea level induced changes in groundwater levels those pans with more significant surface recharge particularly from fluvial systems may produce less ambiguous paleoenvironmental records with pan status more strongly reflecting regional hydrological conditions lunette orientation is indicative of strong westerly winds during both the pleistocene and holocene lunette accretion would have been promoted by reduced on shore moisture transport during the summer months enhancing rainfall seasonality such conditions would have been promoted by increased continentality as the agulhas bank was exposed during low sea level stands

evolution of late holocene coastal dunes in the cauvery delta region of tamil nadu india widespread occurrences of coastal dunes are observed in the cauvery delta region of tamil nadu in vedaranniyam in the south east coast of india these dunes were studied to establish the chronology of their formation and to understand their evolution using optically stimulated luminescence osl dating in combination with sedimentological studies quartz grain surface morphology using scanning electron microscope grain size and heavy mineral analysis the study shows that on the south east coast of india widespread periodic dune formation reactivation has taken place during the late holocene to very recent times due to a variety of reasons such as climatic variation and land use changes the sand mobility index shows that the dunes in the area have been largely active during the past century in the southern part in nagapattinam region and many of the crests were active in the northern cauvery delta in cuddalore region the angularity and fresh appearance of sand in the inland dunes suggest a short distance of sand transport and a source proximal sand deposition was proposed for the dune formation the study demonstrates the sensitivity of sand dunes on the south east coast of india to varying climatic conditions and changes in regional land use

paleoenvironmental implications of fixed dune systems in southern africa extensive systems of fixed linear dunes occur in the kalahari region of southern africa from 28 s to 16 30 s they provide evidence for large scale expansion of arid climates in the subcontinent during the quaternary on the basis of differing dune morphologies and alignments three periods of upper pleistocene aridity are recognised patterns of dune alignments reflect paleosand flow regimes and permit deduction of past winds and circulation patterns leading to the conclusion that arid episodes were associated with and probably caused by greater strength and persistence of the south african anticyclone a tentative chronology of the arid periods tends to support the hypothesis that subtropical aridity was contemporaneous with glacial conditions in high latitudes

late quaternary environmental change in central southern africa new data synthesis issues and prospects much of the interior of central southern africa is a sand sea within which aeolian and lacustrine landforms and sediments of local and regional extent are preserved closed cave sites are restricted to very few locations while fluvial systems traverse the margins of the interior until the early 1990s chronologies of late quaternary environmental and climatic changes developed for this region were based on only a limited number of proxy data sets derived largely from lacustrine deposits and precipitates in particular directly determined ages from aeolian deposits the most extensive suite of features in the region were absent the application of luminescence dating techniques to dune sediments and the development of further detailed chronologies from cave precipitates is now providing a more comprehensive record for the last 50 ka with some chronologies extending back a further 100 ka we present and review these data assess their contribution to enhanced understanding of late quaternary environmental changes in the region and for the first time assess them against corrected radiocarbon ages from lacustrine sites it is concluded that there is now an enhanced understanding of the spatial and temporal complexity of climate changes affecting the region in the last glacial cycle including a complex record of punctuated aridity but that many issues including data set integration and forcing mechanism controls are imperfectly understood

first evidence for onshore marine isotope stage 3 aeolianite formation on the southern cape coastline of south africa abstract the southern cape coast of south africa boasts an impressive suite of plio pleistocene aeolian dune deposits aeolianite previous research has shown that in this region onshore dune accumulation was generally focused around interglacial sea level highstands with the locus of coastal dune accumulation shifting onto the adjacent continental shelf during glacial sea level lowstands here using new luminescence dating results we present the first evidence for preserved onshore glacial age dunes specifically on the robberg peninsula a rocky headland 28 km east of knysna two phases of aeolianite formation are identified corresponding to early 45 60 ka and late 35 30 ka marine isotope stage mis 3 subsequently during the holocene all substantive dune accumulation occurred between 10 2 and 7 0 ka forming cliff fronting dunes and filling the limited accommodation space on the headland including an archaeological rock shelter combining these ages with bathymetric data we infer that this distinct onshore glacial age aeolianite record reflects 1 restricted accommodation space during sea level highstands 2 a regional narrowing of the continental shelf and 3 liberation of sediments lying on a prominent 45 to 60 m offshore terrace which would have been exposed during mis 3 this demonstrates that despite broad regional scale trends in the timing of coastal aeolian activity driven by commonalities in relative sea level trends and climate distinct local variations in late quaternary coastal evolution can be identified this is ascribed to local controls on preservation accommodation space and sediment supply shoreline position and antecedent offshore sediment supplies such findings may have wider implications for interpretations of site context resource availability at several notable coastal archaeological sites and more broadly suggest that local offshore or onshore geologic contexts can at times assume greater influence on a preserved coastal aeolianite record than the regional scale trends in sea level and climate

biomarker records of palaeoenvironmental variations in subtropical southern africa since the late pleistocene evidences from a coastal peatland abstract southern africa s unique global position has given rise to a dynamic climate influenced by large sea surface temperature gradients and seasonal fluctuations in the inter tropical convergence zone due to the semi arid climate of the region terrestrial palaeorecords are rare and our understanding of the long term sensitivity of southern african terrestrial ecosystems to climatic drivers is ambiguous a 810 cm continuous peat core was extracted from the mfabeni peatland with a 14 c basal age of c 47 thousand years calibrated before present kcal yr bp positioning it as one of the oldest known sub tropical coastal peatlands in southern africa this peat core provides an opportunity to investigate palaeoenvironmental changes in subtropical southern africa since the late pleistocene biomarker n alkane n alkanoic acid and n alkanol analysis in conjunction with previously published bulk geochemical data was employed to reconstruct organic matter om sources rates of om remineralisation and peatland hydrology our results showed that the principal om source into the peatland was emergent and terrestrial plants with exception of shallow lake conditions when submerged macrophytes dominated c 44 5 42 6 29 7 26 1 23 1 16 7 7 1 and 2 2 kcal yr bp n alkane proxies suggest that local plant assemblages were predominantly influenced by peatland hydrology by incorporating temperature sensitive n alkanoic acid and n alkanol proxies it was possible to disentangle the local temperature and precipitation changes we report large variations in precipitation intensities but subdued temperature fluctuations during the late pleistocene the holocene period was characterised by overall elevated temperatures and precipitation compared to the preceding glacial period interspersed with a millennial scale cooling event a close link between the mfabeni archive and adjacent indian ocean marine core records was observed suggesting the regional ocean surface temperatures to be the dominant climate driver in this region since the late pleistocene

multiple episodes of aridity in southern africa since the last interglacial period there is generally a dearth of evidence of the nature of quaternary climate change within desert systems which has limited previous interpretations of past environmental change at low latitudes the last glacial maximum has previously been identified as the peak of late quaternary aridity when desert systems expanded to five times their present extent1 2 3 and low latitude aridity has been described for previous glaciations4 but little evidence has been derived directly for large desert basins particularly southern africa here we report new chronological optical dating evidence of arid episodes recorded in aeolian sediments from the mega kalahari sand sea episodic aeolian activity is recorded at the northeastern desert margin whereas more sustained activity is evident from the southwestern desert core several significant arid events are apparent since the last interglacial period with dune building arid phases at 95 115 41 46 20 26 and 9 16 kyr before present existing atmospheric general circulation model simulations and independent palaeoclimate data indicate that the changes in aridity are related to changes in the northeast southwest summer rainfall gradient which are in turn related to sea surface temperatures in the southeastern atlantic ocean

relationships among soil carbon distributions and biophysical factors at nested spatial scales in rain forests of northeastern costa rica forested soils in the tropics contain a large carbon pool that may respond to global environmental changes such as climate warming and land use change a better understanding of the distribution of tropical soil carbon c pools is necessary in order to manage soil c as well as to predict its potential responses to global change the goals of this study were to quantify the relationships among soil c and environmental variables for 35 forest plots in a 140 000 ha landscape in northeastern costa rica and to identify variables that can predict soil c storage at unsampled sites the biophysical variables included indices of net primary productivity forest floor mass root biomass and an index of productivity derived from satellite imagery soil particle size distribution and mineralogy elevation and slope soil carbon storage in these volcanic soils was relatively high ranging from 51 1 to 138 6 mg c ha 1 in the top 30 cm of mineral soil the relationships among forest soil c and biotic and abiotic variables were different for low elevation 120 m and high elevation 120 800 m sites and elevation explained much of the variability in soil c concentrations soil particle size distribution and mineralogical variables are correlated in this landscape and co vary in predictable ways along the elevation gradient thus elevation represents a weathering gradient with younger allophanic soils at higher elevations and older soils with gibbsite goethite and kaolinite as dominant clay minerals in the lowlands we propose two mechanisms of c stabilization soil c concentrations and contents are positively correlated to the amount of noncrystalline clays e g allophane imogolite and ferrihydrite in the high elevation soils and positively correlated to aluminum in organo metal complexes in the low elevation sites the strong correlations among soil c concentrations contents and elevation mediated through effects on soil mineralogy indicate that it is possible to predict soil c in this landscape using variables that are easily mapped in a geographic information system

luminescence dating of the niederweningen mammoth site switzerland abstract luminescence dating is used to further constrain the so far controversial age of the mammoth site at niederweningen switzerland gamma spectrometric analyses reveal the presence of radioactive disequilibria in the uranium decay chain in most of the samples but these cause only minor uncertainties in the age estimates the major uncertainty is actually related to the problem of estimating the average water content for the whole burial time nevertheless even considering these problems involved with dose rate determination the dating results clearly indicate that the peat is significantly younger than early wurmian in contrast to some previous assumptions together with the results of radiocarbon dating and pollen analyses the luminescence ages point to a correlation of the mammoth peat with interstadial conditions during the early part of the middle wurmian at around 45 ka ago

luminescence dating of sediments using single aliquots new procedures abstract the application of luminescence dating to quaternary sediments has been hampered by the labour intensive procedures involved determination of equivalent doses using single aliquots measured using an automated luminescence reader offers a significant reduction in labour equivalent dose determinations using two single aliquot additive dose methods are compared with equivalent doses measured using standard multiple aliquot methods for a suite of 12 dune sand samples from southwest north island new zealand the single aliquot correction method based upon adjusting the magnitude of the measured luminescence signal is found to give underestimates for those samples whose equivalent dose is greater than 80 gy and whose luminescence response to dose is non linear a second correction method based upon adjusting the value of the total added dose that the sample has received is described this second method gives equivalent dose results similar to those measured using standard multiple aliquot methods over the range from 0 1 to 400 gy

investigations into the potential effects of pedoturbation on luminescence dating much effort has been focussed on understanding the luminescence properties of natural minerals to achieve a reliable accurate and precise dating technique however some field related aspects such as the influence or effect of post depositional disturbance on luminescence dates are as yet underexplored in the case of pedoturbation depending on its intensity the rate of sedimentation and unit thicknesses potentially the whole sedimentary record at a site can be affected this may lead to distorted osl chronologies and erroneous sediment burial ages pedoturbation can result in sediment mixing and or exhumation that affect luminescence both at the bulk and single grain level effects of these two principle processes on luminescence ages are examined using standard multigrain and single grain protocols high resolution sampling of surface gopher mounds was used to determine the efficiency of bio exhumation in resetting luminescence signal results show this is an inefficient mechanism for onsite sediment bleaching the effects on luminescence signal of bio mixing were explored by comparing a sample collected from within a krotovina infilled burrow to an adjacent undisturbed sample results show the difficulties in identifying pedoturbated samples at the single aliquot level and the possible inaccuracies in using the lowest palaeodose values to calculate osl ages where pedoturbation of samples is suspected use of probability plots of palaeodoses data is recommended from these plots it is proposed that only data falling within a normal distribution centred on the peak probability be used to calculated osl ages and to mitigate problems arising from pedoturbation

geological inheritance and its role in the geomorphological and sedimentological evolution of bedrock hosted incised valleys lake st lucia south africa abstract the morphology of lake st lucia africa s largest estuary has been strongly influenced by antecedent topography throughout its quaternary evolution the 5 20 km southern basin is bounded to landward by a 50 m high early mid pleistocene dune ridge and to seaward by a 100 m high late pleistocene holocene dune barrier nine seismic units a i are identified in the enclosed basin along with two regionally developed sequence boundaries sb1 and sb2 and two tidal ravinement surfaces trs1 and trs2 the lowermost sequence boundary sb1 is related to regional late pliocene hinterland uplift sb2 is related to the last glacial maximum lgm when sea levels fell 130 m below present lowstand fluvial sediments occupy the base of both sb1 and sb2 incisions thick central basin deposits dominate the valley fills more so in the pliocene age valleys the occurrence and thickness of which is attributed to sheltering by a seaward barrier dune system as well as to the low gradient settings prograding tidal bedforms occupy the minor incisions formed within the tidal ravinement surfaces marking the onset of lagoonal conditions in the area the system is capped by lagoonal deposits deposited above tidal flats a series of prograding spits mark the early stages of lagoonal segmentation in the holocene the preservation of only one incision and fill sequence prior to the development of an lgm aged valley succession is attributed to geological inheritance whereby older valleys were repeatedly re incised by younger valleys throughout the pleistocene causing partial preservation of pleistocene fills up to the most recent cycle the older fill remnant relates to a larger magnitude base level fall prior to the quaternary which survived erosion during subsequent sea level falls adjacent topography in the form of rocky cliffs and the seaward fronting barrier limit the accommodation space in which infilling material can be hosted outside the major valley network the competent basement rock into which these valleys have incised protected lowstand fluvial sediments from subsequent tidal ravinement

late holocene dune accretion and episodes of persistent drought in the great plains of northeastern colorado abstract the great plains of the mid west usa contain dunefields which display stratigraphic evidence of episodic sand drift throughout the holocene and in some cases the late pleistocene widespread aeolian activity has been linked to persistent megadroughts caused by a weakening of the tropical moisture laden circulation from the gulf of mexico and equatorial pacific infrared stimulated luminescence irsl dating has been applied to two exposures in the fort morgan dunefield of northeastern colorado where radiocarbon dated buried soils provide ages for land surface stability irsl ages show that sand drift occurred episodically during the late holocene at 4 85 2 37 1 06 0 80 0 6 0 53 and 0 37 ka

late pleistocene wetting and drying in the nw kalahari an integrated study from the tsodilo hills botswana abstract the sediments and landforms at the tsodilo hills in the northwestern kalahari desert provide an opportunity to directly investigate the late quaternary wetting and drying of the region from evidence at a single site lacustrine carbonates including incorporated molluscs and diatoms a lake shoreline feature and stabalised linear dunes were investigated for their constituent palaeoenvironmental signals chronometric control is provided by calibrated 14 c ams and osl dating the evidence suggests that linear dune construction has not occurred since the last glacial maximum with particular development from 36 to 28 ka lake stands indicating wetter regional conditions than present occurred at 40 32 ka with more seasonal conditions from 36 ka and at 27 12 ka with a possible drying out at 22 19 ka data are consistent with other independent studies from the region and with recent evidence obtained from atlantic cores off the coast of namibia it is concluded that careful consideration of multi proxy data from a single location can assist in resolving discrepancies that arise from independent studies of lake cave and dune records in the kalahari

interglacial glacial climatic signatures preserved in a regressive coastal barrier southeastern australia abstract regressive barriers persisting in the landscape over interglacial glacial cycles are important repositories of paleoclimatic signatures such as past sea level and regional aridity the gippsland region of victoria contains a multi barrier system formed during past interglacial glacial cycles and the late holocene an extensive series of parallel foredune ridges forming the elongate inner barrier was sampled for luminescence dating with ages indicating deposition ca 125 000 108 000 years ago coinciding with the later phase of the last interglacial lig marine isotope stage mis 5e and the transition to mis 5d ground penetrating radar gpr imaged beach face reflectors within the lig barrier indicate that sea level was within 2 to 3 m of present level during mis 5e in this far field location significant reworking of the barrier system through blowout and parabolic dune activity occurred between 23 000 18 000 years ago corresponding to the last glacial maximum lgm with an estimated 160 000 000 m3 of coastal sediments eroded and redistributed the morphological changes to this coastal barrier over the most recent interglacial glacial cycle mis 5e to present also imply significant landscape instability during the lgm in southeastern australia and are further evidence for extension of the geographical range and intensity of aridity at this time

late quaternary paleoenvironments in the southwestern kalahari abstract landforms of the southwestern kalahari in southern africa include linear dune systems pans and associated lunette dunes and the valleys of ephemeral rivers present day climates in the region are transitional from arid to semi arid making the area sensitive to climatic change the linear dunes are part of an extensive system of fixed dunes developed in the surface kalahari sands the dunes were in existence prior to 32 000 yr b p but have been reactivated on a number of occasions since then in conditions of increased wind velocities more nw winds and reduced rainfall especially in northern and eastern parts of the region periods of dune activity probably occurred at 19 000 17 000 10 000 6000 and 4000 3000 yr b p the development of pans in the region has been strongly influenced by changes in groundwater conditions deflation from pans and formation of lunettes occurred in periods when groundwater levels were higher and fluctuated seasonally more than they do today such periods probably occurred 25 000 20 000 yr b p around 10 000 yr b p and just prior to 1000 yr b p still higher groundwater discharges promoted by increased regional rainfall resulted in the formation of spring tufas and seasonal or permanent lakes in the pans which were also fed by surface runoff during the intervals between 33 000 28 000 23 000 21 000 17 000 15 000 and 12 000 11 000 yr b p the headwaters of the major ephemeral streams lie outside the region but within the same climatic zone increased flow in the molopo river occurred prior to 19 000 and between 15 000 and 13 000 yr b p

relationship between antarctic sea ice and southwest african climate during the late quaternary here we compare late quaternary southwest african climate records from the west coast of southern africa published winter rainfall and trade wind intensity records from a core off the coast of namibia to records of antarctic sea ice extent this comparison reveals coherent changes between antarctic sea ice extent and the southwest african winter rain region since 45 k y b p with enhanced winter rainfall and trade wind vigor during periods of increased sea ice presence we propose an oceanic and atmospheric coupling between antarctic sea ice and the winter rainfall zone of southwest africa that may lead to increased desertification in the region if global warming persists

last glacial pollen record from lanzhou northwestern china and possible forcing mechanisms for the mis 3 climate change in middle to east asia abstract the vegetation on the northeastern margin of the tibetan plateau is highly sensitive to climatic changes and thus represents a potentially interesting environmental archive pollen samples from the fanjiaping loess section in lanzhou on the western chinese loess plateau clp were analyzed in conjunction with osl dating the results indicate that pollen zone b 60 6 46 0 ka correlative to the early mis 3 had the greatest abundances of cupressaceae tsuga gramineae and cyperaceae of the entire section suggesting a warm phase during the last glacial period these pollen taxa decreased significantly in abundance in the zones c 46 0 39 0 ka and d 39 0 27 0 ka reflecting a substantial climate cooling from the middle mis 3 to mis 2 these results correlate with climate records from the south china sea the clp baikal lake north america north atlantic ocean and other regions and probably correspond with the decline of northern high latitude insolation and the increase of global ice volume from 50 to 20 ka in particular arboreal pollen fern spore and algae abundances declined sharply since 40 ka while shrub and herb pollen reached the highest abundances conifer pollen picea and abies abundance also rose markedly and increased up the section this implies significant climate deterioration and likely corresponded with substantial growth of the polar ice sheets since 40 ka the decreasing temperature caused by an insolation decline during the last glacial period probably reinforced the cooling effect in a snow ice albedo feedback which would result in less climate sensitivity to radiative forcing meanwhile vegetation decline in the northern hemisphere during the last glacial period and tundra development at high latitudes possibly caused additional cooling enhancing the growth of polar ice sheets since 40 ka the development of polar ice sheets increased the polar to equator temperature and pressure gradients strengthening the westerlies and supplying plenty of moisture to northwest china during 40 30 ka lake sediments developed widely on the tibetan plateau during 40 30 ka probably related to an increase in the seasonality of middle to low latitude insolation which caused an enhancement of glacier melting on the plateau

seasonal control on coastal dune morphostratigraphy under a monsoon climate mui ne dunefield se vietnam abstract having developed in the later quaternary period the mui ne dunefield representing the upper most portion of a major coastal barrier complex in se vietnam formed by wind regimes associated with the asian monsoon climate the barrier complex is 100 km long and higher than 150 m in elevation but despite its large dimensions research on its geomorphological and geological characterization is limited several active dune fields extend 2 10 km landwards from the coast while the rest of the barrier surface is stabilized we applied ground penetrating radar gpr and quartz optically stimulated luminescence osl dating to the transverse dunes of the mui ne dunefield to characterize the morphostratigraphy and recent aeolian sedimentation history currently the dunes have a relief of typically 5 10 m and a wavelength of 50 100 m they are driven by the northeasterly winter monsoon winds and reversed with minor relief in response to the southwesterly summer monsoon gpr profiles and osl ages define three morphostratigraphic units the modern holocene and pleistocene dune units the gpr data of the modern dune unit is dominated by a series of steep reflections that dip exclusively towards the west reflecting the winter monsoon and is punctuated by reactivation surfaces evidence for the wind reversal is not preserved in the sediment successions but is represented by reactivation surfaces thus a subunit bounded by the reactivation surfaces defines annual deposition the preservation potential of a subunit varies with the migration rate of the transverse dune and in the fastest migrating dunes approximately one subunit was preserved every year 1 1 0 6 subunit yr the modern dunes are generally younger than 100 years and have migrated wsw at net rates of 0 6 2 5 m yr the holocene dune unit is as thick as the modern unit although it spans a period ten times longer reflecting the lower preservation potential of the transverse dunes as sedimentary records due to erosion associated with their migration the rate of dune migration suggests that an aeolian contribution of coastal sands has occurred following the sea level highstand of the middle holocene accounting for the extent of the active dunefields this mode of the barrier accumulation is considered as an analogue for earlier highstand events however the dunefields only cover a fraction of the entire barrier it is thus inferred that barrier formation occurred over a long period probably encompassing several glacial interglacial cycles sand accumulation during the lowstand either by transport of sand from the subaerially exposed shelf and or reworking of sand emplaced during the prior highstand may contribute significantly to the barrier development

quaternary sea level history and the origin of the northernmost coastal aeolianites in the americas channel islands national park california usa abstract along most of the pacific coast of north america sand dunes are dominantly silicate rich on the california channel islands however dunes are carbonate rich due to high productivity offshore and a lack of dilution by silicate minerals older sands on the channel islands contain enough carbonate to be cemented into aeolianite several generations of carbonate aeolianites are present on the california channel islands and represent the northernmost quaternary coastal aeolianites on the pacific coast of north america the oldest aeolianites on the islands may date to the early pleistocene and thus far have only been found on santa cruz island aeolianites with well developed soils are found on both san miguel island and santa rosa island and likely date to the middle pleistocene the youngest and best dated aeolianites are located on san miguel island and santa rosa island these sediments were deposited during the late pleistocene following the emergence of marine terraces that date to the last interglacial complex 120 000 yr to 80 000 yr based on radiocarbon and luminescence dating the ages of these units correspond in time with marine isotope stages mis 4 3 and 2 sea level was significantly lower than present during all three time periods reconstruction of insular paleogeography indicates that large areas to the north and northwest of the islands would have been exposed at these times providing a ready source of carbonate rich skeletal sands these findings differ from a previously held concept that carbonate aeolianites are dominantly an interglacial phenomenon forming during high stands of sea in contrast our results are consistent with the findings of other investigators of the past decade who have reported evidence of glacial age and interstadial age aeolianites on coastlines of australia and south africa they are also consistent with observations made by darwin regarding the origin of aeolianites on the island of st helena in the south atlantic ocean more than a century and a half ago

soil chronosequence development in dunes on the southeast african coastal plain maputaland south africa abstract 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 the quartzose dune sands have weathered to form very deep soil profiles enhanced sdi values for horizons or sampled intervals down the profile reflect ph decrease advanced rubification or distinct mottling clay increase and harder consistency with depth the youngest holocene profiles exhibit decreasing horizon index values with depth below the a horizon whereas late pleistocene profiles display sdi values increasing with depth within the upper 3 m of the profile within some mid to late pleistocene eolian sands greater profile horizonation and catena complexity manifests as complex soil profiles or distinctly mottled clay enriched horizons at depths of 2 5 m below the surface the sdi profiles from specific dune systems or stratigraphic units cluster well and effectively characterize soil development in dune sand units of different ages depositional age plotted against sampled horizon index values makes it possible to determine generalized rates of soil profile development and to compare pedogenic processes on the high rainfall coastal barrier dunes to those found in the drier interior sampled horizon index values distinguish buried soil profiles and highlight possible localized surficial reworking

the late cenozoic evolution of coastal water bodies in northern kwazulu natal south africa abstract three large coastal water bodies st lucia sibaya and kosi of markedly different contemporary morphology occur on the eastern margin of the northern kwazulu natal coastal plain south africa this paper examines their late cenozoic evolution and investigates the controls on their evolution that have produced the observed differences in morphology all three systems origins were due to mio pliocene low sea level still stands allowing rivers to scour channels into cretaceous and palaeocene sedimentary sequences during the last interglacial oxygen isotope stage 5e sea level was approximately 5 m above present level and the morphology of the three systems was similar an offshore barrier archipelago partially isolated a back barrier environment that comprised intertidal sand flats localised reefs and tidal channels the area around bazaruto island mozambique provides a modern analogy river rejuvenation and associated incision up to and during the last glacial maximum 16 000 18 000 bp caused a minimum of 40 m scour which is still reflected in the bathymetry of lake sibaya and kosi accumulation of barrier sands partly against pre existing interglacial barrier remnants during the holocene marine transgression 16 000 4500 bp ramsay p j 1995 9000 years of sea level change along the south african coastline quaternary int 27 1 5 was responsible for lagoon isolation although the extent and nature of separation from the sea varies markedly between the systems the northern part of lake st lucia was closed from the sea during the late holocene probably during a sea level fall from a holocene high stand of ca 3 m at 3000 bp the kosi system had a late pleistocene to early holocene outlet situated at bhanga nek lake nhlange but this inlet mouth closed approximately at 3000 bp the present mouth was established by 1600 bp lagoonal conditions within lake sibaya terminated ca 5000 bp when coastal barrier dune formation caused complete impoundment and enabled the lake water level to rise to 20 m above mean sea level lake st lucia s large catchment has meant that fluvial sediment input has kept pace with the holocene transgression whereas the localised drainage associated with sibaya and kosi has resulted in a negligible fluvial sediment input allowing for deep lacustrine conditions to develop lagoonal segmentation is present to some extent in each system as a result of mobile coastal sediments and their reworking by short period wind waves the differential stages of lagoonal segmentation in the three systems can be explained by a the presence of cohesive sediment and bedrock around st lucia which reduce shoreline mobility and b the great water depths in sibaya compared to kosi which require longer periods of infilling before segmentation is complete

synchrony of southern hemisphere late pleistocene arid episodes a review of luminescence chronologies from arid aeolian landscapes south of the equator abstract luminescence dating chronologies that have been reported in various studies of late pleistocene arid land aeolian sequences from australia southern africa and south america are reviewed with the objective of determining whether any pan hemispheric synchroneity existed in the timing of landscape responses to late quaternary climate changes south of the equator the results broadly show that contemporaneous regional arid land aeolian activity occurred in australia and southern africa during the periods ca 65 41 and 36 9 ka the relatively limited luminescence data from the south american subcontinent also point to recurrent arid land aeolian deposition between 63 and 8 ka with increasing frequency in the period ca 32 8 ka records from all three continents suggest a period of reduced aeolian activity between 41 and 36 ka overall the data are indicative of extensive landscape instability of the low to mid latitudes in the southern hemisphere during the last glacial period particularly at the last glacial maximum which accords with mainstream opinions aeolian activity during the holocene has generally been localised the rigour with which comparisons can be made between the different studies however is constrained by variations in practices between laboratories and changes that have occurred to luminescence dating procedures over the years

punctuated aridity in southern africa during the last glacial cycle the chronology of linear dune construction in the northeastern kalahari abstract the mega kalahari of central southern africa is one of the most extensive quaternary desert basins on a regional scale present day aeolian activity is restricted to episodic dune crest reactivation in the most arid southwestern desert core there is however abundant evidence of former periods of both more arid and more humid conditions many of which have little or no chronological control we have employed optical dating of quartz sand grains to develop a chronology of arid intervals as recorded by phases of linear dune construction in the northeastern sector of the mega kalahari we identify repeated phases of aeolian deposition during the last interglacial glacial cycle at ca 95 115 41 46 20 26 and post 20 ka which are separated by depositional hiatuses that we infer to correspond to more humid periods these aeolian depositional events correlate with and are inferred to relate to millennial scale cold sea surface temperature events in the southeast atlantic which have been linked to sub milankovitch climate changes recognised in northern hemisphere oceanic and cryospheric environmental archives covering the same time period while the present landscape is the product of either post 20 ka hwange national park dune field or 20 30 ka victoria falls dune field aeolian activity and subsequent erosion and reworking much of the vertical expression of the larger dune forms corresponds to the earlier periods of activity the linear ridges of the area are rich archives of late quaternary terrestrial climate change

transferring radiometric dating of the last interglacial sea level high stand to marine and ice core records in order to derive a radiometric age marker for the end of the penultimate glacial interglacial transition we compiled published u series isotope measurements on corals from the period extending from stage 6 to the middle of the last interglacial and computed the corresponding open system ages using thompson et al model thompson w g spiegelman m w goldstein s l speed r c an open system model for u series age determinations of fossil corals earth planet sci lett 210 2003 365 381 we obtain a global mean age of 126 calendar kyr bp ka 1 7kyr 2 for the beginning of the last interglacial sea level high stand after showing that the phase relationships observed between changes in sea level north atlantic benthic and planktonic foraminifera oxygen isotopic records and atmospheric methane over the last deglaciation were likely also valid over the penultimate deglaciation we derive an age of 131 2ka 2kyr 2 for the abrupt increase in atmospheric ch4 and north atlantic surface temperature marking the end of the penultimate glacial interglacial transition this age is consistent with u th dates of the penultimate glacial interglacial transition recorded in speleothems from sites where speleothems isotopic records are synchronous with north atlantic temperature records over the last deglaciation finally we show that the phase obtained between the climatic response and northern hemisphere summer insolation is not constant from termination ii to termination i implying that northern hemisphere summer insolation alone cannot explain the timing of terminations

the luminescence chronology of dune development on the maputaland coastal plain southeast africa abstract 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

aeolian beach ridges and their significance for climate and sea level concept and insight from the levant coast east mediterranean abstract relict beach ridges of aeolian origin and associated soils are often used for inferring relative sea level and climate with contrasting results most studies link the aeolian coastal deposits to regressive phases some to high sea level stands and a few to intermediate relative sea level positions we interpret the apparent contradictions as indicating the lack of an over arching concept and the inconsistent usage of sea level related terms in this paper we present an integrated morpho sedimentological concept for a microtidal mid latitudinal coast and review existing data from the levant east mediterranean coast to evaluate the concept and to eliminate nomenclatural confusion a coastal depositional environment in a semi arid environment consists of shallow marine aeolian and alluvial facies which together form an aeolian beach ridge complex as a package of strata which respond simultaneously to sea level change a transgressive complex forms through reworking or overstepping of the coastal foredune and a regressive complex forms by downstepping under transgression the aeolian beach ridge represents the highstand deposit and its adjacent shallow marine sediment is the transgressive deposit under regression the complex represents the falling stage and the associated downdip surface marks the lowstand on the levant coast we find chronologically well constrained offlapping aeolian beach ridges as parts of six downstepping beach ridge complexes formed between 200 ka and 10 ka the complexes represent the falling stage systems tract fsst of a short lived 5th order depositional sequence when the shoreline shifted from a position close to the modern coastline to the shelf or below the shelf edge three of these fssts and their up dip and down dip super bounding surface together form the 4th order 100 ka sequence of the last interglacial glacial cycle the absence of transgressive highstand and lowstand systems tract is explained by the poor preservation potential due to the small sediment budget of the complex the falling stage complex has a high preservation potential because sediment source area increases while the sand drift potential remains above the local threshold on the levant coast sand delivery to the backshore continued during relative sea level falls for distances of up to 10 km between dune and coastline which is unprecedented in most modern analogues the significance of the dune soil succession for climate is limited because the dunes are governed by relative sea level change the vegetation response to changes in precipitation is non linear and the dune dynamics are characterised by low resilience and hysteresis

sedimentary facies and geomorphic evolution of a blocked valley lake lake futululu northern kwazulu natal south africa blocked valley lakes are formed when tributaries are impounded by the relatively rapid aggradation of a large river and its floodplain these features are common in the landscape and have been identified in the floodplains of the solimoes amazon brazil and fly strickland rivers papua new guinea for example but their inaccessibility has resulted in studies being limited to remotely sensed image analysis this paper documents the sedimentology and geomorphic evolution of a blocked valley lake lake futululu on the mfolozi river floodplain margin in south africa while also offering a context for the formation of lakes and wetlands at tributary junctions the study combines aerial photography elevation data from orthophotographs and field survey and longitudinal sedimentology determined from a series of cores which were sub sampled for organic content and particle size analysis radiocarbon dating was used to gauge the rate and timing of peat accumulation results indicate that following the last glacial maximum rising sea levels caused aggradation of the mfolozi river floodplain by 3980 years bp aggradation on the floodplain had impounded the futululu drainage line creating conditions suitable for peat formation which has since occurred at a constant average rate of 0 13 cm year 1 continued aggradation on the mfolozi river floodplain has raised the base level of the futululu drainage line resulting in a series of back stepping sedimentary facies with fluvially derived sand and silt episodically prograding over lacustrine peat deposits blocked valley lakes form where the trunk river has a much larger sediment load and catchment than the tributary stream similarly when the relative difference in sediment loads is less palustrine wetlands rather than lakes may be the result in contrast where tributaries drain a steep well connected catchment they may impound much larger trunk rivers creating lakes or wetlands upstream

holocene geoarchaeology of the sixteen mile beach barrier dunes in the western cape south africa holocene evolution and human occupation of the sixteen mile beach barrier dunes on the southwest coast of south africa between yzerfontein and saldanha bay are inferred from the radiocarbon ages of calcareous dune sand limpet shell patella spp manuports and gull dropped white mussel shells donax serra a series of coast parallel dunes have prograded seaward in response to an overall marine regression since the mid holocene with dated shell from relict foredunes indicating periods of shoreline progradation that correspond to drops in sea level at around 5900 4500 and 2400 calibrated years before the present cal yr b p however the active foredune extensively covered by a layer of gull dropped shell has migrated 500 m inland by the recycling of eroded dune sand in response to an approximate 1 m sea level rise over the last 700 yr manuported limpet shells from relict blowouts on landward vegetated dunes indicate human occupation of coastal dune sites at 6200 and 6000 cal yr b p and help to fill the mid holocene gap in the regional archaeological record coastal midden shells associated with small hearth sites exposed in blowouts on the active foredune are contemporaneous 1600 500 cal yr b p with large midden sites on the western margin of langebaan lagoon and suggest an increase in marine resource utilisation associated with the arrival of pastoralism in the western cape

dating the lower paleolithic open air site of holon israel by luminescence and esr techniques abstract the open air acheulian site in holon israel was dated by the luminescence methods and by electron spin resonance esr situated in the coastal plain quaternary kurkar group the holon site was first excavated in the late 1960s when typical lower paleolithic lithics and middle pleistocene fauna were found in order to date the site new test pits were dug adjacent to the earlier excavations and the archaeological bed was exposed in a section comprising a series of paleosols and aeolianites alkali feldspars separated from the sediments were dated using the infrared stimulated luminescence and thermoluminescence signals and quartz was dated using the optically stimulated luminescence signal the age of the archaeological bed is constrained by two samples to 198 000 22 000 201 000 17 000 yr the age of the base of the section is 240 000 29 000 yr and the age of the top is 81 000 8000 yr two teeth from the archaeological bed recovered from the original excavation collection yielded an average esr age of 204 000 16 000 yr calculated using the linear uptake model which is in a very good agreement with the luminescence ages these dates place holon within the range of other late acheulian and acheulo yabrudian sites in this region such as tabun e younger chronology yabrud i archaeological level 18 and berekhat ram

rapid sea level fall and deep ocean temperature change since the last interglacial period we have dated huon peninsula papua new guinea and barbados corals that formed at times since the last interglacial period applying both 230 th and 231 pa dating techniques as a test of age accuracy we show that marine isotope stage mis 5e ended prior to 113 1 8 0 7 kyr when sea level was 319 m during mis 5b sea level was 357 m at 92 6 8 0 5 kyr having dropped about 40 m in approximately 10 kyr during the mis 5c 5b transition sea level then rose more than 40 m during the mis 5b 5a transition also in about 10 kyr mis 5a lasted until at least 76 2 8 0 4 kyr at a level of 324 m at that time combined with earlier data that places mis 4 sea level at 381 m at 70 8 kyr our late mis 5a data indicate that sea level fell almost 60 m in less than 6 kyr 10 6 m kyr during the mis 5 4 transition the magnitude of the drop is half that of the glacial interglacial amplitude and approximatelyequivalent to the volume of the present dayantarctic ice sheet during this interval the minimum average rate of net continental ice accumulation was 18 cm yr likely facilitated by efficient moisture transport from lower latitudes at three specific times 60 6 8 0 3 50 8 8 0 3 and 36 8 0 2 kyr during mis 3 sea level was between 385 and 374 m sea level then dropped to 3107 m at 23 7 8 0 1 kyr early in mis 2 before dropping further to last glacial maximum lgm values and then rising to present values during the last deglaciation times of rapid sea level drop correspond to times of high winter insolation at low northern latitudes and high winter latitudinal gradients in northern hemisphere insolation supporting the idea that these factors mayhave resulted in high water vapor pressure in moisture sources and efficient moisture transport to high latitude glaciers therebycontributing to glacial buildup we combined our sea level results with deep sea n 18 o records as a means of estimating the temperature and ice volume components in the marine n 18 o record this analysis confirms large deep ocean temperature shifts following mis 5e and during termination i deep ocean temperatures changed bymuch smaller amounts between mis 5c and 2 maximum temperature shift in the deep pacific is about 2 whereas the shift at a site in the atlantic is 4 under glacial conditions temperatures at both sites are near the freezing point the shift in the atlantic is likelycaused bya combination of changing proportions of northern and southern source waters as well as changing temperature at the sites where these deep waters form

late holocene sea level changes and paleoclimate recorded in lake lungue southern mozambique abstract we report on late holocene paleoenvironmental and sea level changes in southern mozambique based on analysis of diatom stratigraphy mineral magnetic susceptibility saturation isothermal remnant magnetization sirm and organic carbon content in a sediment core from lake lungue located ca 30 km north of xai xai city in the limpopo river floodplain eleven radiocarbon dates performed on terrestrial shells allowed establishment of an age depth model high content of brackish marine taxa especially diploneis suborbicularis and navicula yarrensis suggests that the lake lungue basin was part of the indian ocean coastal zone between ca 740 and 910 ce suggesting higher relative sea level during this phase a similar diatom distribution in older parts of the sequence of unknown age indicates that the site was connected to the indian ocean also at some stage prior to 740 ce between ca 910 and 1130 ce the basin was under a combined effect of sporadic marine water influx and limpopo river actions a freshwater lake was established sometime between 1130 and 1360 ce when the basin became less affected by marine influences due to lower sea levels instead the lake system was more influenced by limpopo river meandering dynamics and flooding events and eventually isolated into a more or less independent lake ecosystem where diatom diversity most likely responded to lake levels fluctuations driven by shifts in relative humidity and rainfall amounts within the floodplain and also from upstream sources during this phase high abundance of freshwater planktonic species i e aulacoseira granulata and a ambigua indicates high lake levels and wetter conditions dated to ca 1360 1560 ce from 1560 ce until present the lake has been subject to drier conditions and higher evaporation as indicated by lower lake levels reported by a decline in freshwater planktonic taxa and increase in brackish taxa e g amphora robusta

late holocene dune activity linked to hydrological drought nebraska sand hills usa dunee elds of the great plains contain stratigraphic records of episodic holocene aeolian activity potentially providing a valuable record of climatic change it has been dife cult to establish unambiguous links between activity at specie c sites and regional palaeoclimate however here we demonstrate that widespread late holocene aeolian activity in the nebraska sand hills the largest dunee eld on the great plains of north america occurred during a period of hydrological drought aeolian sand sheets are interbedded with peat that accumulated in interdunes throughout much of the holocene the youngest of these sand sheets was deposited between 950 and 650 cal bp about the same time as the most recent major episode of aeolian activity at upland sites up to 120 km apart sand sheets could only have advanced across the interdunes if the local groundwater e ow systems that maintain interdune wetlands were temporarily reduced or eliminated by a reduction in recharge both reduced recharge and upland aeolian activity are best explained by regional megadrought