thermoluminescence dating of a stillbay howiesons poort sequence at diepkloof rock shelter western cape south africa new excavations have been undertaken at diepkloof rock shelter drs south africa since 1999 it is one of the very few sites where howiesons poort and stillbay assemblages can be collected from the same archaeological sequence these middle stone age techno complexes are particularly interesting for their af nities with the much younger later stone age facies and their association with evidence for symbolic behaviour establishing their chronology is therefore particularly important for the understanding of the apparition and the evolution of the so called modern behaviours data already available suggest ages ranging from 55 to 80 ka for the howiesons poort and from 70 to 80 ka for the stillbay techno complexes in several south african sites the thermoluminescence dating undertaken at drs on 22 stone samples originating from the entire stratigraphic record indicates intervals starting 10 50 ka earlier for these techno complexes in this site possible caveats in the dating process are examined but to the best of our current knowledge must be rejected

structures caused by repeated freezing and thawing in various loamy sediments a comparison of active fossil and experimental data in this paper the authors present the results of both macroscopic and microscopic investigations on structure development created by repeated ice lensing in various loamy experiments experimental data are compared with observations performed on active forms in high arctic and alpine mountain environments those observations are also compared with phenomena observed in fossil periglacial formations of western europe platy and short prismatic structure formation is bonded to the hydraulic and thermal conditions during ice segregation when a long series of alternating freezing and thawing affects platy structures the fabric evolves also being influenced by slope and drainage conditions cryoturbations frostcreep and gelifluction can appear they are characterized by specific microfabrics which are better developed with an increasing number of cycles this is clear in experiments where hydraulic and thermal parameters are better controlled vesicles are also a prominent characteristic of the surface horizon in experiments and arctic soils the genesis of vesicles is discussed on the basis of new observations and is related to the mechanical collapse of frost created aggregates under the mechanical work of soil air escape during soil saturation by water at thaw

high thermal maturity in the lower saxony basin intrusion or deep burial abstract the lower saxony basin lsb is situated at the southern rim of the northern permian basin the most important hydrocarbon bearing province in europe in its southern part areas of high thermal maturation up to 6 rr occur which were previously explained as being caused by magmatic intrusions of turonian to santonian age that affected carboniferous to lower cretaceous rocks in this area 2d numerical basin modelling was carried out in order to reconstruct the temperature histories along two parallel n s trending seismic sections along these sections new data about maturity distribution and temperature history were obtained by vitrinite reflectance measurements and apatite fission track analysis for the areas with highest maturity values low coalification gradients were established which agree well with earlier published data on wells further towards the west this new information does not support previous hypotheses on high heat flows from magmatic intrusions even if lateral heat transport is taken into account instead comparisons with a recently published map of the subsurface structure of the lsb indicate that maturity distribution may be closely related to major tectonic structures deep burial of individual structures of the lsb which are bordered by deep e w to ese wnw trending faults is further suggested by a rapidly increasing thicknesses of preserved cretaceous strata towards the south and b structural restoration of one of the seismic sections to achieve a fit between measured and calculated palaeo temperature and vitrinite reflectance data deep burial of carboniferous source rocks during cretaceous time has to be assumed due to an inversion phase in the early and middle upper cretaceous major amounts of sediment were removed and further uplift occurred in tertiary times in contrast the northern part of the lsb experienced maximum burial and temperatures during tertiary times

reappraisal of the upper weichselian periglacial environment from danish frost wedge casts abstract in ditches dug for the oil and gas pipe line systems in jutland in 1983 many frost wedge casts were recorded sand wedge casts composite wedge casts and ice wedge casts were all common these phenomena indicate the former existence of continuous permafrost probably during the period of advance and presence of the weichselian ice cap the changes of environment which took place during the colder parts of the weichselian may have promoted relatively unstable soil surface and vegetation conditions when compared to present arctic areas where frost wedges form today it is suggested that even though primary sand infilling in wedges was common in denmark the climate need not have been very arid for their formation and further the environmental conditions in europe during the last ice age can not be readily compared with present arctic regions where frost wedges grow today

ice lens formation at a silt sand interface a major experiment simulating ground freezing around a buried chilled pipeline in a controlled environment facility provided an opportunity to examine the form and orientation of ice lenses associated with a vertical interface between silt and sand the heave of the silt decreased towards the interface and ice lenses in the silt were found to dip at an increasing angle in the same direction consideration of the thermal regime suggests that the direction of heat flow influences the orientation of the lenses the interface was irregular and ice lenses at the lower part of the interface were closely aligned to it indicating that changes in soil texture also influence ice lens orientation deformation of ice lenses appears to have occurred in the silt near to the interface the arrangement of the lenses can be explained by the different thermal properties and thermodynamic behaviour of the two materials and by the mechanical anchorage of the sand in which there is no ice lens formation cycles of freezing

the direction of ice wedge cracking in permafrost downward or upward field studies have been carried out along the western arctic coast of canada in an attempt to determine whether all ice wedge cracks originate at the ground surface and therefore propagate downward or whether some cracks originate near the top of permafrost and then propagate both upward and downward the field studies have been concentrated upon 1 low and high centred tundra polygons a few thousand years old and 2 ice wedges growing for the first time on the bottom of a lake experimentally drained in 1978 the field instrumentation has included electronic crack direction indicators electronic elapsed timers and continuous temperature measurements the field studies reveal that many of the ice wedge cracks originated near the top of permafrost and then propagated upward to the ground surface as well as downward into ice wedge ice for the 1974 1982 period the field observations showed that about 57 of the ice wedges cracked from the ground surface downward and 43 cracked both upward and downw

occupational intensity and environmental changes during the howiesons poort at klipdrift shelter southern cape south africa abstract the howiesons poort characterised by sophisticated lithic technologies and evidence of innovative behaviours was a significant cultural phase in southern africa during marine isotope stage 4 it also coincided with substantial palaeoenvironmental and possible demographic changes in the southern cape of south africa especially with regard to the shifting palaeo coastline off the agulhas bank the newly excavated klipdrift shelter in the southern cape presents a rare opportunity to compare faunal lithic and palaeoenvironmental evidence from a single howiesons poort site along the present day southern coast of south africa here we use faunal data from klipdrift shelter to explore the relationship between occupational intensity subsistence behaviour and environment in the southern cape during the howiesons poort period our results suggest a shift from a mixed terrain browse dominated environment during the earlier howiesons poort to open grasslands in the mid later howiesons poort this environmental shift corresponds to potential changes in occupational intensity or frequency throughout the sequence with evidence of increased occupations associated with grassier environments aspects of the cultural sequence for example raw material procurement strategies may be associated with shifting environmental conditions the faunal evidence suggests links between occupation environment and prey selection at klipdrift this raises interesting questions about the interplay between population density and the environment of the southern cape and its influence on subsistence behaviour during marine isotope stage 4

nature and significance of the howiesons poort to post howiesons poort transition at klein kliphuis rockshelter south africa abstract this paper considers the transition from howiesons poort to post howiesons poort technologies at the rock shelter site of klein kliphuis south africa the transition at this site is shown to be gradual with incremental changes in material selection and in the size and shapes of flakes and cores implements which appear to blend characteristics of those distinctive of the earlier and later industries appear briefly at the mid point of the transition the results suggest that there is unlikely to have been an occupational hiatus between the howiesons poort and post howiesons poort explanations for the howiesons poort phrased in terms of population expansion and contraction are also difficult to support technological changes at this time may relate to environmental variation though the limited nature of terrestrial archives documenting changes in resource productivity necessitate that any such suggestion be made with caution

paleoenvironmental and human behavioral implications of the boegoeberg 1 late pleistocene hyena den northern cape province south africa boegoeberg 1 bog1 is located on the atlantic coast of south africa 850 km north of cape town the site is a shallow rock shelter in the side of a sand choked gully that was emptied by diamond miners abundant coprolites chewed bones and partially digested bones implicate hyenas as the bone accumulators the location of the site quantity of bones and composition of the fauna imply it was a brown hyena nursery den the abundance of cape fur seal bones shows that the hyenas had ready access to the coast radiocarbon dates place the site before 37 000 14c yr ago while the large average size of the black backed jackals and the presence of extralimital ungulates imply cool moist conditions probably during the early part of the last glaciation isotope stage 4 or stage 3 before 37 000 14c yr ago or perhaps during one of the cooler phases isotope substages 5d or 5b within the last interglaciation comparisons of the bog1 seal bones to those from regional middle stone age msa and later stone age lsa archeological sites suggest 1 that hyena and human seal accumulations can be distinguished by a tendency for vertebrae to be much more common in a hyena accumulation and 2 that hyena and lsa accumulations can be distinguished by a tendency for hyena accumulated seals to represent a much wider range of individual seal ages differences in the way hyenas and people dismember transport and consume seal carcasses probably explain the contrast in skeletal part representation while differences in season of occupation explain the contrast in seal age representation like modern brown hyenas the bog1 hyenas probably occupied the coast year round while the lsa people focused their coastal visits on the august october interval when nine to eleven month old seals were abundant the msa sample from klasies river mouth cave 1 resembles bog1 in seal age composition suggesting that unlike lsa people msa people obtained seals more or less throughout the year

orbital forcing of climate over south africa a 200 000 year rainfall record from the pretoria saltpan late pleistocene variations in rainfall in subtropical southern african are estimated from sediments preserved in the pretoria saltpan a 200000 year old closed basin crater lake on the interior plateau of south africa we show that south african summer rainfall covaried with changes in southern hemisphere summer insolation resulting from orbital precession as predicted by orbital precession geometry berger 1978 this south african record is out of phase with north african palaeomonsoon indices street and grove 1979 rossignol strick 1983 mcintyre et al 1989 the amplitude of the rainfall response to insolation forcing agrees with climate model estimates prell and kutzbach 1987 these results document the importance of direct orbital insolation forcing on both subtropical north and south african climate as well as the predicted antiphase sensitivity to precessional insolation forcing

late quaternary dynamics of southern africa s winter rainfall zone abstract variations in the nature and extent of southern africa s winter rainfall zone wrz have the potential to provide important information concerning the nature of long term climate change at both regional and hemispheric scales positioned at the interface between tropical and temperate systems southern africa s climate is influenced by shifts in the intertropical convergence zone the westerlies and the development and position of continental and oceanic anticyclones over the last glacial interglacial cycle substantial changes in the amount and seasonality of precipitation across the subcontinent have been linked to the relative dominance of these systems central to this discussion has been the extent to which the region s glacial climates would have been affected by expansions of antarctic sea ice equatorward migrations of the westerlies more frequent intense winter storms and an expanded wrz this paper reviews the developing body of evidence pertaining to shifts in the wrz and the evolution of ideas that have been presented to explain the patterns observed dividing the region into three separate axes along the western and southern margins of the continent and across the interior into the karoo and the kalahari a range of evidence from both terrestrial sites and marine cores is considered and potential expansions of the wrz expansions are explored despite the limitations of many of the region s proxy records a coherent pattern has begun to develop of a significantly expanded wrz during phases of the last glacial period with the best documented being between 32 17 ka while more detailed inferences will require the recovery and analysis of longer and better dated records this synthesis provides a new baseline for further research in this key region

a method for estimating edge length from flake dimensions use and implications for technological change in the southern african msa abstract this paper presents a method for estimating edge length from flake dimensions comparison of estimated values with data from measured flake edges demonstrates the robusticity of the method building on the work of braun braun d r 2005 examining flake production strategies examples from the middle paleolithic of southwest asia lithic technology 30 107 125 braun d r harris j w k 2003 technological developments in the oldowan of koobi fora innovative techniques of artifact analysis and new interpretations of oldowan behavior in mora r de la torre i eds oldowan rather more than smashing stones treballs d arqueologia 9 pp 132 144 this estimate is used to generate an edge length to mass value for complete flakes taken to be a proxy for flaking efficiency it is shown that this value is useful in tracking the onset variability and decline of a well known technological phase the howiesons poort of south africa the results suggest that the howiesons poort was a time in which flaking efficiency was emphasised furthermore comparison of upper limits of edge to mass values for different raw materials may provide an insight into changes in raw material selection

a techno functional perspective on quartz micro notches in sibudu s howiesons poort indicates the use of barbs in hunting technology abstract in this paper we present the results of a use wear study of quartz micro notches identified during a technological analysis of lithics from the howiesons poort layers of sibudu cave building on the technological analysis and preliminary functional screening of the archaeological material a series of experiments was designed to evaluate different hypotheses for notch formation blank production intentional notching hafting projectile use and trampling the experimental reference collection was compared with archaeological micro notches and a large sample of other archaeological quartz pieces including bladelets bipolar blanks flakes and retouched pieces this allowed us to evaluate the causes of micro notch formation in the studied assemblage results indicate two novelties in the howiesons poort hunting technology at sibudu the use of quartz barbs and non retouched quartz blanks it seems that in addition to backed pieces segments obliquely backed points etc unretouched pieces were mounted as elements in hunting weapons during the howiesons poort techno tradition seven probable and 29 tentative barbs were identified we thus present one of the strongest and oldest bodies of evidence for the use of barbs as projectile elements

the howiesons poort and msa iii at klasies river main site cave 1a we present the results of a technological analysis of the howiesons poort and msa iii lithic artifacts from cave 1a at klasies river we studied most of the debitage and retouched pieces from deacon s excavations about 3000 pieces and all the cores and retouched pieces from three layers of singer and wymer excavations 640 pieces our analysis shows 1 that hp blade production was based on the use of marginal percussion by soft stone hammer as at rose cottage 2 that impact scars at klasies rose cottage and sibudu indicate that the backed pieces were hafted in two differentways and 3 that the hp backed pieces were an innovativeway of hafting spear tips but are not clear evidence of the invention of bows and arrows we document the gradual evolution of debitage techniques within the hp sequence with progressive abandonment of the hp technological style very similar trends occur in the upper part of the hp sequence at rose cottage the similarity in temporal trends between sites separated by more than 600 km has significant implications for the disappearance of the hp industry we suggest that the disappearance of the hp was not due to a phenomenon of population contraction and isolation that caused the collapse of social networks the internal evolution and parallel process of change documented at klasies and rose cottage speak against a collapse of social systems and are associated with evidence of environmental and subsistence changes at the transition mis 4 3

the significance of cryoturbation phenomena in environmental reconstruction cryoturbation results mainly from differential heave related to 1 drainage and thermal conditions and 2 frost susceptibility loadcasting and cryostatic pressures are restricted to wet soils such as pure silt or silty sand the translocation of fine particles resulting from repeated freezing and thawing can promote frost susceptibility in a previously non susceptible material as well as a loss in stability of the surface horizons liquefaction small and metric scale cryoturbations can be explained by this process large scale deformations and injections may be related to abnormal liquefaction not necessarily associated with frost regular patterns are associated with fissure nets upturned injections in a downslope direction attest to cryoturbation and frost creep a lowering of the water table promotes the formation of drop like cryoturbations most of which can be related to seasonal frost in imperfectly to poorly drained soils they are not indicative of permafrost except in well drained situations or in the case of flat bottomed involutions

dynamics of periglacial sorted circles in western spitsbergen a working hypothesis for the development and maintenance of sorted circles which are finegrained soil domains delineated by borders of coarser material involves clast motion relative to soil and intermittent circulatory motion of soil in the active layer the hypothesis is compatible with the observed size regularity sorting microtopography surface soil motion vegetation cover and subsurface organic carbon content of soil patterns studied in spitsbergen theoretical considerations of buoyancy driven convection suggest that intermittent convection of thawed soils is plausible and that the requisite bulk density decrease with depth arises naturally from moisture gradients that develop during the thaw consolidation of ice rich soils these considerations also help in understanding the dependence of sorted circles on soil characteristics and on moisture moreover they point to the possible use of sorted patterns as paleoclimatic indicators based on the expected relation between pattern size and active layer depth

south african palaeoenvironments during marine oxygen isotope stage 4 a context for the howiesons poort and still bay industries abstract spanning the period from 74 58 ka and being broadly coeval with marine oxygen isotope stage 4 mis 4 the still bay and howiesons poort industries represent important phases in the development of the material culture of early modern humans how and why these industries occurred when they did however remain matters for speculation a key element of this debate has been the question of what role environmental change during the early stages of the last glacial period may have had on influencing human activity unfortunately well dated palaeoenvironmental evidence from this period is limited and the debate has out of necessity been driven by the application of conceptual models of environmental change many of which associate colder and warmer global climates with increased aridity and humidity respectively in this paper the regional marine and terrestrial evidence is synthesised to create an evidence based palaeoenvironmental context based on the information available to date it appears that rather than being characterised by dry conditions mis 4 was a period of relatively cool moist climates the ubiquity of which transcends the modern regional climate boundaries it is suggested that orbital parameters at this time created greater interaction between tropical and temperate circulation systems bringing more moisture to the subcontinent these findings highlight the distinct nature of southern african climate systems and caution against the application extra regional conceptual models or inferring linear relationships with polar records

putslaagte 1 pl1 the doring river and the later middle stone age in southern africa s winter rainfall zone abstract existing data suggest weak human occupation of southern africa s winter rainfall zone wrz during later marine isotope stage mis 3 the causes of which are unknown here we report briefly on the results of recent surveys of alluvial terrace sites of the doring river in the wrz which document occupation over a broad expanse of the later middle stone age msa and pleistocene later stone age we then report on test excavations at one terrace site denoted putslaagte site 1 pl1 describe in detail the assemblage of flaked stone artefacts produced from that excavation and present two osl ages obtained from 0 8 m to 1 5 m below surface the results suggest that a artefact accumulations at pl1 are dense b the technological systems documented are characteristically msa but differ in form from the range of systems known from other excavated sites in the region and c that the assemblages accumulated in mis 3 taken together with the survey data the results introduce new variation into the later msa in southern africa and imply reorganisation of land use in the wrz in late mis 3 rather than abandonment we suggest that a research emphasis on rock shelter deposits may have produced misleading depictions of regional occupation

pleistocene sea level fluctuations and human evolution on the southern coastal plain of south africa abstract humans evolved in africa but where and how remain unclear here it is proposed that the southern coastal plain scp of south africa may have served as a geographical point of origin through periodic expansion and contraction isolation in response to glacial interglacial changes in sea level and climate during pleistocene interglacial highstands when sea level was above 75 m human populations were isolated for periods of 360 3400 25 yr generations on the scp by the rugged mountains of the cape fold belt climate and vegetation barriers the scp expands five fold as sea level falls from 75 to 120 m during glacial maxima to form a continuous unobstructed coastal plain accessible to the interior an expanded and wet glacial scp may have served as a refuge to humans and large migratory herds and resulted in the mixing of previously isolated groups the expansive glacial scp habitat abruptly contracts by as much as one third in 300 yr during the rapid rise in sea level associated with glacial terminations rapid flooding may have increased population density and competition on the scp to select for humans who expanded their diet to include marine resources or hunted large animals successful adaptations developed on an isolated scp are predicted to widely disperse during glacial terminations when the scp rapidly contracts or during the initial opening of the scp in the transition to glacial maxima the hypothesis that periodic expansion and contraction of the scp as well as the coastal plain of north africa contributed to the stepwise origin of our species over the last 800 thousand years kyr is evaluated by comparing the archeological dna and sea level records these records generally support the hypothesis but more complete and well dated records are required to resolve the extent to which sea level fluctuations influenced the complex history of human evolution

technological successions in the middle stone age sequence of diepkloof rock shelter western cape south africa the southern african msa comprises a series of phases of unique technological innovations that fuel current models on the evolutionary processes of anatomically modern humans however the nature and variability of these technological phases remain poorly documented this study reports on the previously unpublished sequence of diepkloof rock shelter south africa and investigates the main technological changes therein particularly emphasizing the emergence succession and disappearance of the still bay sb and the howiesons poort hp we argue for technological change that occurred at different rates and under the influence of variable driving factors our model implies that the sb and the hp are not related to the influx of new populations but have regionally specific origins unlike the other techno complexes the hp at diepkloof is subdivided into different phases early intermediate and late but only the upper phases resemble the so called classic hp finally the technological sequence of diepkloof questions the homogeneous picture which has been so far assumed for the southern african msa and places emphasis on the importance of exploring long regional sequences

a high resolution and continuous isotopic speleothem record of paleoclimate and paleoenvironment from 90 to 53 ka from pinnacle point on the south coast of south africa abstract coastal south africa draws interdisciplinary interests due to the co occurrence of a rich record for early human behavioral modernity hyper diverse vegetation with very high endemism the cape floral region and globally influential oceanic and climate systems high resolution and continuous climate and environmental records are needed to provide the context for the evolution of behavioral modernity and this diverse flora here we present the first such record for climate and environmental change from 90 000 to 53 000 years ago from the southern cape coast this important time span covers a burst of expression of several indicators of human behavioral modernity as well as several key cycles in global climate change our research location is ideally placed near the location of several critical archaeological sites near the boundary of the winter and summer rainfall regimes and close to isotopically distinct floral zones we used isotopic analysis of precisely dated speleothems to document shifting vegetation and rainfall and show that the presence of winter rain and c3 grasses waxes and wanes in response to southern hemisphere shifts in ssts and global temperature when proxies of global temperatures indicate warmer conditions 18 o and 13 c indicate more winter rain and more c3 grasses respectively and vice versa this record displays abrupt and short term changes previously undocumented it is often argued that the cape floral region partially owes its high diversity to relative climatic stability our record shows isotopic variability that at least matches that displayed in the levantine mediterranean system so climatic stability may not have characterized the south coast one short lived phase of human technological innovation the still bay associated with early evidence for behavioral modernity occurs synchronous with an abrupt environmental perturbation early modern humans in this region confronted a variable climate and adapted quickly in a manner similar to behaviorally modern humans

a 300 kyr record of aridity and wind strength in southwestern africa inferences from grain size distributions of sediments on walvis ridge se atlantic abstract the terrigenous fraction of sediments recovered from walvis ridge se atlantic ocean reveals a history of southwestern african climate of the last 300 kyr end member modelling of a data set of grain size distributions n 428 results in three end members the two coarsest end members are interpreted as eolian dust the third end member as hemipelagic mud the ratio of the two eolian end members reflects the eolian grain size and is attributed to the intensity of the se trade winds trade winds were intensified during glacials compared to interglacials changes in the ratio of the two eolian end members over the hemipelagic one are interpreted as variations in southwestern african aridity late quaternary southwestern african climate was relatively arid during the interglacial stages and relatively humid during the glacial stages owing to meridional shifts in the atmospheric circulation system during glacials the polar front shifted equatorward resulting in a northward displacement of the zone of westerlies causing increased rainfall in southwestern africa the equatorward shift of the polar front is coupled with an increase of the meridional pressure gradient leading to enhanced atmospheric circulation and increased trade wind intensity

downward water movement into frozen ground western arctic coast canada field studies carried out mainly since 1975 in permafrost areas of alaska canada china and the soviet union have been combined with the results of laboratory investigations to show that in summer water can move from the thawing active layer into the subjacent frozen active layer and under certain conditions even into the top of permafrost direct field evidence discussed includes data from drilling and neutron probe logging which show a summer increase in the ice content of already frozen ground summer heave of heavemeters with heave occurring in the frozen active layer and increase in the ice content of the subjacent frozen ground in both permafrost and non permafrost areas caused by snowmelt infiltration indirect field and laboratory evidence is also added to support the direct lines of evidence the conditions that favor the downward migration of water from thawed to frozen ground are examined in terms of thermally induced hydraulic gradients hydraulic conductivity content of unfrozen pore