shell mounds as environmental proxies on the southern coast of brazil despite the multiple constraints of using shell mounds for building relative sea level rsl curves one of the premises behind this use is still valid in modern archaeological research this refers to the sites being continuously built near bodies of water rich in fish species and mollusk beds studies that combine the evolution of settlement patterns with the geological evolution of coastal areas in brazil reach analogous results the distribution of shell mounds in time and space follows the landscape transformations induced by rsl variations through the holocene although shell mounds are not precise indicators of rsl they provide evidences of the paleo geographical changes during the holocene of which rsl is one of the many control variables by collecting and transporting mollusks to the shell mounds humans inevitably carry sediments from the substrate where mollusks live for example the beaches and lagoons near the sites in this work the geoarchaeological study of three shell mounds located in the southern coast of santa catarina state combined with mollusk taxa identification show the direct association of shell mound content with the changing landscape the predominance of ostrea sp versus anomalocardia brasiliana the presence of colluvial versus lagoonal sediments and the occurrence of echinoid spines versus muddy aggregates with diatoms gastropods and glauconitic clay characterize the distinction between sites built before and after the maximum holocene transgression respectively this attests the potential of geoarchaeological analyses in shell mounds as a complementary proxy for paleo environmental reconstructions

lake banyoles northeastern spain a last glacial to holocene multi proxy study with regard to environmental variability and human occupation analyses of a 67 m long sediment core from lake banyoles northeastern spain have revealed evidence for the palaeoclimate history of the northern iberian peninsula investigations have included hi

palaeoecological significance of late pleistocene pine macrofossils in the lower guadalquivir basin donana natural park southwestern spain article i nfo this paper reports on analysis of plant macrofossils in aeolian deposits exposed in el asperillo cliff in the province of huelva a significant find of a large number of macrofossils of pinus pinus pinaster ait and pinus nigra arnold makes a major contribution to our understanding of the role of pine in the upper pleistocene landscapes of iberia p pinaster ait and p nigra arnold are meso microthermic species and inhabited valleys excavated in aeolian sediments mainly deposited during ois 4 and ois 3 based on osl and radiocarbon ages their presence in these valleys during the last part of ois4 and ois 3 reflects a significant fall in temperature during certain periods of these isotopic stages and helps us better understand the response of coastal dynamics to climate change published by elsevier b v

the mesolithic neolithic transition in southern iberia new data and a review of historiographic information from neolithic sites of the malaga and algarve coasts southern iberian peninsula and from the maghreb north africa reveal the existence of a neolithic settlement at least from 7 5 cal ka bp the agricultural and pastoralist food producing economy of that population rapidly replaced the coastal economies of the mesolithic populations the timing of this population and economic turnover coincided with major changes in the continental and marine ecosystems including upwelling intensity sea level changes and increased aridity in the sahara and along the iberian coast these changes likely impacted the subsistence strategies of the mesolithic populations along the iberian seascapes and resulted in abandonments manifested as sedimentary hiatuses in some areas during the mesolithic neolithic transition the rapid expansion and area of dispersal of the early neolithic traits suggest the use of marine technology different evidences for a maghrebian origin for the first colonists have been summarized the recognition of an early north african neolithic influence in southern iberia and the maghreb is vital for understanding the appearance and development of the neolithic in western europe our review suggests links between climate change resource allocation and population turnover

geomorphic and sedimentary plio pleistocene evolution of the nerja area northern alboran basin spain abstract the nerja area s spain on the northern edge of the alboran basin underwent palaeogeographic sedimentary and geomorphic changes during the pliocene and pleistocene that were controlled by tectonics and by eustatic climatic variations the existence of nw se fault lines and the particular lithology of the area played a fundamental role in differentiating two sectors of divergent geomorphic evolution the ne sector which forms part of the sierra almijara and the sw sector in the area of nerja the ne sector contains outcrops of alpujarride marbles and is characterised as a continental domain that has been permanently emerged and subjected to uplifting at intervals under which the relief becomes progressively steeper today the sw sector is constituted of alpujarride schists and plio quaternary sediments this sector was partially affected by the marine transgression of the early pliocene during which time alluvial fans developed distally these are connected to littoral and shallow marine environments during the early zanclian a tectonic event separated the pliocene sediments into two lithostratigraphic units that rest unconformably but without any significant sedimentary interruption as a consequence of this event some fluvial courses changed direction towards the end of the early zanclian falling sea levels led to the emergence of the nerja region during the late pliocene marine sediments were restricted to the innermost areas of the alboran sea but continental deposits did not develop probably due to the warm humid climate that did not favour clastic sediment supply another tectonic event in the pliocene tilted the sediments of the zanclean ii unit in the western sector during the cold period in the final pliocene and in the basal pleistocene a pediment developed over the pliocene units and the alpujarride basement three phases of sedimentation of alluvial fans took place during the pleistocene becoming progressively more limited towards the sw the deposition phases are separated by stages of erosion and trenching of the fluvial network mainly occurring during periods of low sea levels another tectonic pulse has been identified in the mid pleistocene between the first and the second generation of fans which caused further changes in the direction of some fluvial courses

shallow hypersaline lakes as paleoclimate archives a case study from the laguna salada malaga province southern spain abstract although numerous studies concerning the holocene climate of the southern iberian peninsula were accomplished within the last few decades the climate history of this region is still poorly understood various studies deal with a combination of proxies which are neither easy to compare nor is their connection easy to explain e g due to spatial patterns and time transgression within this study the suitability of the lacustrine sediments from the laguna salada andalucia region southern spain as a paleoclimate archive is investigated the lake sediments were evaluated using a multi proxy approach including sedimentological mineralogical geochemical and biological analyses the sediments reflect the evolution of the lake from pre medieval times onwards and characeae as well as ostracod analyses give an indication of paleosalinity moreover does the geochemical composition provide profound information concerning changes of elemental and mineralogical composition nevertheless a robust high resolution chronology could not be achieved owed to the scarcity of material available for radiocarbon dating and contamination problems furthermore poor preservation of pollen restricted the reconstruction of vegetation history which could have complemented important information concerning climatic changes and human activity

the karst site of las palomas guadalteba county malaga spain a preliminary study of its middle late pleistocene archaeopaleontological record abstract cleaning works in the cave of las palomas in teba malaga spain developed by the guadalteba consortium have provided a number of lithic tools and knapping products that may be ascribed to the mode iii technotypological tradition as well as remains of a number of large mammal species typical of middle late pleistocene times topographic measurements help to place this ancient cave within a karst landform this discovery opens up new perspectives in the research on the neanderthal groups that inhabited the valleys of guadalteba and turon rivers in the middle basin of the guadalhorce river and thus in the southern region of the iberian peninsula

trench parallel flow beneath the nazca plate from seismic anisotropy shear wave splitting of s and sks phases reveals the anisotropy and strain field of the mantle beneath the subducting nazca plate cocos plate and the caribbean region these observations can be used to test models of mantle flow two dimensional entrained mantle flow beneath the subducting nazca slab is not consistent with the data rather there is evidence for horizontal trench parallel flow in the mantle beneath the nazca plate along much of the andean subduction zone trench parallel flow is attributale utable to retrograde motion of the slab the decoupling of the slab and underlying mantle and a partial barrier to flow at depth resulting in lateral mantle flow beneath the slab such flow facilitates the transfer of material from the shrinking mantle reservoir beneath the pacific basin to the growing mantle reservoir beneath the atlantic basin trenchparallel flow may explain the eastward motions of the caribbean and scotia sea plates the anomalously shallow bathymetry of the eastern nazca plate the long wavelength geoid high over western south america and it may contribute to the high elevation and intense deformation of the central andes

palaeoenvironmental and cultural dynamics of the coast of malaga andalusia spain during the upper pleistocene and early holocene abstract the impact of late upper pleistocene climate change in the western mediterranean region has been mainly documented through marine records archaeological and geomorphological continental records now available for the coast of malaga complement these records for the second part of the last major glacial episode and the early stages of the holocene this paper provides an overview of the archaeological chronological and palaeoenvironmental data from the end of the middle palaeolithic period to the epipalaeolithic sequences from the two major sites nerja and bajondillo indicate a mosaic type response of ecosystems to the rapidly shifting conditions of the last glacial episode terrestrial mammals for example show no major variations from present day communities plant remains in contrast demonstrates the existence of localised refuge areas for species that would not otherwise have survived in the more widely prevailing climatic conditions of the time whereas remains of fish and secondarily birds demonstrate the existence of communities without any present day analogues combining mediterranean and boreal i e northern atlantic taxa from an archaeological standpoint the major cultural shift is the onset of marine fishing beginning in the solutrean this coincided with the end of the last glacial maximum lgm episode the faunal record also testifies to the rising importance of marine resources more generally although the data have not been used systematically to test the validity of the broad spectrum revolution bsr hypothesis the hints for it in the area seem compelling from the start of the solutrean onwards

marine mollusc exploitation in mediterranean prehistory an overview abstract marine molluscs have been recovered from sites around the mediterranean sea dating as far back as the lower palaeolithic when hominins might have started consuming them ca 300 ka during the middle palaeolithic and the early upper palaeolithic humans homo neanderthalensis and homo sapiens ate molluscs at many sites across the mediterranean at least as early as the last interglacial although the scale of this exploitation is still unclear due to biases produced in the coastal archaeological record by late glacial and post glacial sea level rise the exploitation of marine molluscs apparently increased in the late glacial and early holocene when humans collected them in relatively large quantities and from all available ecosystems the consumption of shellfish and of other small animals aquatic and continental probably contributed to the success of the flexible and opportunistic subsistence strategies adopted by mediterranean hunter gatherers for much of prehistory this is particularly evident in later foraging economic systems i e late upper palaeolithic and mesolithic in which coastal resources probably acted as buffers against the negative outcomes of environmental and anthropogenic impacts on available resources

effects of tidal amplitude on intertidal resource availability and dispersal pressure in prehistoric human coastal populations the mediterranean atlantic transition abstract in this paper i argue that there is a growing body of evidence supporting an increasingly central position of coastal environments in human evolution and dispersals rather than as merely peripheral habitats eustatic fluctuations during glacial cycles have meant that most prehistoric coastlines are now underwater and lack of evidence to date of a close relationship between people and the coast can be most plausibly ascribed to the limited studies so far on submerged sites coastal environments provide high diversity in food resources consisting of multiple ecotones in close proximity which reduces the need to forage widely one of the richest and most easily exploited coastal resources by human populations living on the coast are molluscs from marine rocky intertidal communities which recent evidence has highlighted as important as far back as the middle palaeolithic however the density of these resources is limited by a number of factors and this varies geographically one of the main large scale factors limiting rocky intertidal mollusc densities is tidal amplitude beyond which smaller scale local factors such as exposure to wave action and shore aspect further affect species distributions the area around the strait of gibraltar is used as a case study of an area which is affected by large variations in tidal amplitudes thus allowing for quantitative comparisons between taxonomically and climatically similar regions shorelines along the mediterranean coast with reduced tidal amplitudes exhibit compressed zonations and harbour fewer macro mollusc individuals with the reverse being the case along the atlantic coast which has significantly larger tides data from middle and upper palaeolithic sites along the strait are used to establish harvested species and present day data are used to model the potential distributions and associated variables such as calorific returns of key food species an optimal foraging model is used to explore the effects of differential levels of resource availability along these coastlines results suggest that the nature and variability of the coastline has a direct influence on the tempo and mode of subsistence strategy followed and whether certain strategies can be adopted at all the possible implications of these biogeographical distributions for foraging economics dispersals and social structures in homo are discussed

ocean surface water response to short term climate changes revealed by coccolithophores from the gulf of cadiz ne atlantic and alboran sea w mediterranean the response of coccolithophore assemblages to short term millennial and centennial climatic changes over the last 50 kyr is studied in core m39029 7 from the gulf of cadiz atlantic ocean and core md95 2043 from the alboran sea western mediterranean sea the nannoplankton data are compared with oxygen isotopes u37k sst and other biogeochemical and sedimentological proxies to obtain a new perspective of the paleoceanography and paleoecology of the area during these short term climatic changes coccolithophores indicate that heinrich events he were characterised by the presence of cold low salinity and turbid water masses on both sides of the strait of gibraltar high abundances of the lower photic zone lpz species florisphaera profunda in the gulf of cadiz synchronous with he are interpreted as being an evidence of upper water column stratification on the atlantic side these episodes coincided with input of terrigenous material especially during h2 surface waters during dansgaard oeschger do stadials were also cold and turbid while most of do interstadials were characterised by warm water flora the increase in small placoliths small gephyrocapsa and emiliania huxleyi 4 m which is considered here as a cold water indicator the sharp decrease in large specimens of e huxleyi related to the warming trend in the last deglaciation can be used as a biostratigraphic reference level that marks at least approximately the deglaciation and the beginning of the holocene peaks of f profunda are observed during termination 1 t1 in the alboran sea they are isochronous with the organic rich layer 1 recognised in the western mediterranean in this interval the water column of the region was stratified as a consequence of the global increase in the sea level following the deglaciation quantitative analyses of the coccolithophore assemblage allow us to interpret that coccolithophore production has been higher in the alboran sea than in the gulf of cadiz during the holocene

high rates of arc consumption by subduction processes some consequences new estimates of long term consumption of japanese and peruvian continental fore arc margins together with recent drilling data ocean drilling program on some other erosional island arcs such as izu bonin mariana or tonga allow the calculation of a mean rate of 7 3 km m y landward migration of the arc trench system on both east and west sides of the pacific basin during cenozoic time such relative arcward retreat counterbalances seaward migration of the slab hinge line to accommodate opening of the atlantic ocean retreat can thus be interpreted as a delay in seaward or retrograde migration due to upper mantle resistance to contraction of the pacific basin mass transfers in subduction zones must be reconsidered in the light of these new estimates especially the balance between net growth and loss of continental crust in recent geologic time a 50 m y period is long enough to erode the initial width of the volcanic arc and fore arc massif of any subduction zone assuming a mean trench volcanic arc landward migration of 5 km m y and a mean trench volcanic arc distance of 250 km this circumstance thus raises the question of whether the izu bonin mariana and tonga arcs are older than their reported eocene age

weichselian palynological records from southern europe correlation and chronology abstract the high resolution independently dated palynostratigraphic record from lago grande di monticchio spanning the last 101 530 calendar years provides a basis for re evaluating the correlations between palaeoenvironmental events in europe during the last glacial as well as a means to determine their chronology the interstadial events recorded from various localities throughout europe are combined into a single scheme of correlations and a chronological framework is suggested this provides a basis for assessing the evolution of the vegetation and environmental patterns across europe during the last glacial revealing a general tendency for the latitudinal climatic gradient to have been steeper than it has been during the holocene the vegetation has also generally been subject to greater moisture deficiency either because of prevailing climatic conditions or as a reflection of the lower atmospheric concentration of co 2 the scheme of correlations is shown to be capable of being extended beyond europe not only to marine and ice core records from the north atlantic region but also to a palynological record from north west north america

marine mollusc exploitation as evidenced by the gorham s cave gibraltar excavations 1998 2005 the middle upper palaeolithic transition abstract there is increasing evidence that humans have exploited intertidal and shallow water species for much longer than has been previously considered and certainly not restricted to anatomically modern humans amh one of the principal reasons for the lack of evidence up till recently has been a lack of consideration for the temporal and spatial backdrop to such activities throughout human evolution in particular related to changes in sea level during the pleistocene bailey et al 2008 this study reports on the marine molluscs excavated from gorham s cave between 1998 and 2005 focussing in particular between levels iii and iv corresponding to the upper amh and middle palaeolithic neanderthals respectively given that gorham s cave was never more than approximately 2 km away from the coastline it still preserves evidence of exploitation of marine molluscs for food by neanderthals and in this article the data obtained are compared across the middle upper palaeolithic transition the results obtained suggest a high degree of consistency in the mode of marine mollusc exploitation between levels and comparisons with extant communities supports the contention that marine molluscs were exploited in direct proportion to their relative abundance and accessibility patterns in shell size distributions for some of the main species exploited are discussed as are possible anthropic valve selection and the marine climatic signals that can be extracted from such data the main difference that emerges between upper and middle palaeolithic levels was a lack of evidence of collection for decoration in middle palaeolithic levels but even here the relatively small size of the level iv sample precluded totally excluding this possibility based only on absence of evidence

synchroneity between marine and terrestrial responses to millennial scale climatic variability during the last glacial period in the mediterranean region land sea climatic proxies have been obtained from the last glacial section of images core md95 2043 western mediterranean sea vegetation and alkenone derived sst curves indicate rapid 150 years and synchronous terrestrial and marine climatic changes paralleling the dansgaard oeschger d o climatic variability over greenland this frequency of climate change can be related to shifts between the two modes of operation of the north atlantic oscillation nao transfer functions applied to the pollen data indicate that there was an amplification of the climatic signal during heinrich events hes in comparison with other d o stadials the development and persistence of both scandinavian and atlantic mobile polar highs over southwestern europe may explain the extreme cooling 10 c and dryness 400 mm during heinrich events 5 and 4 in the mediterranean region comparison of the results of core md95 2043 with similar climatic data from images core md95 2042 located off portugal indicates that thermal and precipitation gradients occurred between the mediterranean and the atlantic sides of iberia within hes hes 4 and 5 are associated with more humid conditions in the atlantic by 200 mm than in the mediterranean site as is the case at the present time this comparison also illustrates the different behaviour of these areas during the d o stadials in contrast with the mediterranean site the atlantic site shows similar precipitation and temperature drops for all the d o stadials including those related to the hes here we propose the operation of different mobile polar highs mph as the driving mechanism for this difference in behaviour between the atlantic and mediterranean sides of iberia hes are related to a stronger influence of the scandinavian mph forcing a severe aridification and cooling of the full iberian peninsula the atlantic mph may have been dominant during the other stadials which would preferentially affect southwestern iberia

neandertal extinction and the millennial scale climatic variability of ois 3 population models seeking climate as a triggering factor for the extinction of neandertals and the colonisation of europe by anatomically modern humans are contradictory due to uncertainties in the dating methods in the cultural attribution of archaeological layers and to the lack of terrestrial continuous and well dated palaeoclimatic sequences this is particularly the case for the iberian peninsula where neandertal populations seem to have survived later than in other regions of europe a review of the available palaeoclimatic evidence for ois3 of iberia reveals that this mainly consists of low resolution fragmentary ill dated and often ill interpreted records correlation between palaeoenvironmental sequences from two images pollen rich deep sea cores and archaeological data from western europe the electronic archive of the radiocarbon dates is available at qsr website http www elsevier nl locate quascirev indicates that aurignacian moderns colonised france and the north of iberia at the onset of the h4 event during this cold episode a probable contraction of neandertal populations is recorded in southern iberia where no aurignacian settlements are detected such a decline in population density is correlated with the particular desert steppe like environments made up of artemisia chenopodiaceae and ephedra characterising the h4 of this area while reducing the size of neandertal populations this inhospitable environment may have favoured their persistence in this region mainly exploiting herds of herbivores adapted to graminees rich grasslands the aurignacian moderns were probably not interested in colonising these arid mediterranean biotopes and did that only after the h4 event

thermal modeling of the geometry of subduction with implications for the tectonics of the overriding plate the path which subducting lithosphere follows can be broken into three zones zone i a subhorizontal region of nearly constant dip near the trench zone ii a region of rapidly increasing dip and zone iii a region generally deeper than 125 km again of nearly constant dip we have modeled the thermal evolution of slabs as they pass through these three zones using the method of lines a numerical technique well suited to the solution of time dependent partial differential equations by use of appropriate initial conditions and time dependent boundary conditions we can simulate subduction with variations in age of subducting lithosphere slab velocities and paths followed by the slab thermal modeling results indicate that the geometry of the slab in region ii can be empirically related directly to the thermal structure of the slab in that region and thus indirectly to age and velocity it follows that low angle subduction can extend several hundred kilometers inland only in cases of high convergent velocities 15 cm yr 1 and old 120 m y lithosphere we further suggest that rapid variations in the convergence velocities can provide an enabling mechanism for back arc spreading while slow changes in convergence velocities and or age variations in the subducting lithosphere lead to migration of volcanic arcs

the development of slabs in the upper mantle insights from numerical and laboratory experiments we have performed numerical and laboratory experiments to model subduction of oceanic lithosphere in the upper mantle from its beginnings as a gravitational instability to the fully developed slab a two dimensional finite element code is applied to model newtonian creep in the numerical experiments scaled analog media are used in the laboratory a sand mixture models the brittle crust silicone putty simulates creep in the lower crust and mantle lithosphere and glucose syrup is the asthenosphere analog both model approaches show similar results and reproduce first order observations of the subduction process in nature based on density and viscosity heterogeneities in a stokes flow model subduction nucleates slowly and a pronounced slab forms only when the viscosity contrast between oceanic plate and mantle is below a threshold we find that the subduction velocity and angle are time dependent and increase roughly exponentially over tens of millions of years before the slab reaches the 670 km discontinuity the style of subduction is controlled by the prescribed velocity of convergence the density contrast between the plates and the viscosity contrast between the oceanic plate and the mantle these factors can be combined in the buoyancy number f which expresses the ratio between driving slab pull and resisting viscous dissipation in the oceanic plate variations in f control the stress in the plates the speed and the dip of subduction and the rate of trench retreat reproducing the contrasting styles of subduction observed in nature the subduction rate is strongly influenced by the work of bending the lithosphere as it subducts

stresses and plate boundary forces associated with subduction plate margins primary tectonic stress in the lithosphere is predominantly caused by lateral density variations within the earth and associated topographical loading when such a stress system caused by major sublithospheric density anomalies is intersected by a weak zone which cuts across the lithosphere plate boundary forces develop and modify the plate interior stresses in this paper unite element analysis is used to model the stresses and plate boundary forces associated with subduction plate boundaries with dipping and vertical slabs extending to about 270 and 400 km depths having the subduction fault both locked and unlocked in such regions several types of horizontal deviatoric stress may occur including 1 local compression in the trench arc region caused by the dense sinking slab and the associated surface downflexure 2 plate interior tension which occurs when this compression is intersected by a weak subduction fault 3 local tension associated with thickening of the crust at the arc and elsewhere 4 local tension in the back arc region produced by the underlying low density upper mantle and 5 downbending stresses in the subducting slab thermal stresses and transmitted ridge push which are not included in the modelling here a gradient from compression in the forearc to tension in the back arc can be modelled in terms of these stresses when the fault is partially locked it is however the intersection of the local compression 1 by an unlocked or partially locked subduction fault that modifies the plate interior stresses and gives rise to the slab pull and trench suction plate boundary forces the state of stress in the interior of the overriding plate is also crucially influenced by back arc spreading where this occurs plate boundary forces have been evaluated for each of the models it is shown that slab pull and trench suction may be of comparable magnitude

late quaternary paleoenvironmental record from a sedimentary fill in cucu cave almeria se spain abstract cucu cave is a small cavity 1600 m above sea level on the southern slope of sierra de maria almeria province se spain where current mean annual precipitation is

late pleistocene raised beaches of coastal estremadura central portugal abstract we present new stratigraphic sedimentological and chronological data for a suite of tectonically raised beaches dating to marine isotope stages 5 4 and 3 along the estremadura coast of west central portugal the beach deposits are found in association with ancient tidal channels and coastal dunes pollen bearing mud and peat and middle paleolithic archaeological sites that confirm occupation of the coastal zone by neanderthal populations the significance of these deposits is discussed in terms of the archaeological record the tectonic and geomorphic evolution of the coast and correlation with reconstructions of global climate and eustatic sea level change direct correlation between the estremadura beach sections is complicated by the tectonic complexity of the area and the age of the beach deposits which are near or beyond the limit of radiocarbon dating evidence from multiple sites dated by ams radiocarbon and optical luminescence methods suggests broad synchroneity in relative sea level changes along this coast during marine isotope stage 3 two beach complexes with luminescence and radiocarbon age control date to about 35 ka and 42 ka recording a rise in relative sea level around the time of heinrich event 4 at 39 ka depending on assumptions about eustatic sea level at the time they were deposited we estimate that these beaches have been uplifted at rates of 0 4 4 3 mm yr 1 by the combined effects of tectonic halokinetic and isostatic processes uplift rates of 1 2 mm yr 1 are likely if the beaches represent sea level stands at roughly 40 m below modern as suggested by recent eustatic sea level reconstructions evidence from coastal bluffs and the interior of the study area indicates extensive colluvial fluvial and aeolian sedimentation beginning around 31 ka and continuing into the holocene these geomorphic adjustments are related to concomitant changes in climate and sea level providing context that improves our understanding of late pleistocene landscape change and human occupation on the western iberian margin

unravelling the holocene environmental history of south western iberia through a palynological study of lake medina sediments lake medina is a small shallow and endorheic salt lake sensitive to climate variation in south western spain close to cadiz in western andalusia it is located in an evaporitic and karstic enviro

the landes de gascogne southwest france periglacial desert and cultural frontier during the palaeolithic abstract during the last glacial period a large part of the aquitaine basin southwest france was a periglacial desert comprising coversands with low relief dune fields surrounded by loess accumulations osl and radiocarbon dates show that the phase of maximum sand deposition coincides with marine isotope stage mis 2 peats and gleyic palaeosoils intercalated within the sands at some sites indicate that vegetation cover was able to develop locally during short events possibly d o interstadials due to raised groundwater levels in interdunal depressions few palaeolithic sites have been discovered in the coversand area in contrast to the peripheral loess region systematic survey along a future highway corridor demonstrates that this paucity of sites is not the result of insufficient survey nor deep site burial but rather reflects an archaeological reality this strongly suggests that the sand area was not attractive for hunter gatherer populations due to its reduced levels of water resources and available vegetation and animal biomass the distribution of cultural markers such as art items and projectile points also shows that the coversand area probably acted as a barrier separating two different cultural sub areas one in the pyrenees and cantabria the other in the perigord as a consequence the commonly accepted view that southwest france as a whole served as a refugia during the cold and arid phases of the pleistocene should be replaced by a more complex one that reflects the fact that a large part of the territory was almost unoccupied and that human populations were concentrated along alluvial valleys

deformation of a weak subducted slab and variation of seismicity with depth oceanic lithosphere is assumed to possess platelike properties whether it is lying at the earth s surface or descending deep into the mantle yet the geometries of subducting slabs indicate significant deformation as they descend through the mantle1 4 suggesting that lithospheric plates might be so weakened during subduction as to act not as a rigid solid but as a viscous fluid numerical and laboratory experiments have shown that fluid slabs can indeed take on realistic profiles5 7 however it has not been clear whether a fluid or weak model of slab dynamics can account for deep earthquakes which are usually ascribed to the deformation of a rigid or strong slab here we show using numerical simulations of slab evolution that a weak slab model is in fact consistent with seismic observations assuming that earthquakes occur at a rate proportional to deformation rate we reproduce the observed variation with depth of seismicity rate and focal mechanisms and the cessation of seismicity at 670 km depth provided that sinking material encounters resistance at depth here modelled as a viscosity jump at 670 km the pattern of seismicity can be explained by any mechanism for deep earthquakes in which the rate of seismicity is proportional to strain rate in the slab

multivariate analysis of remains of molluscan foods consumed by latest pleistocene and holocene humans in nerja cave malaga spain abstract nerja cave is a karstic cavity used by humans from late paleolithic to post chalcolithic times remains of molluscan foods in the uppermost pleistocene and holocene sediments were studied with cluster analysis and principal components analysis in bothqandrmodes the results from cluster analysis distinguished interval groups mainly in accordance with chronology and distinguished assemblages of species mainly according to habitat significant changes in the shellfish diet through time were revealed in the late magdalenian most molluscs consumed consisted of pulmonate gastropods and species from sandy sea bottoms the epipaleolithic diet was more varied and included species from rocky shorelines from the neolithic onward most molluscs consumed were from rocky shorelines from the principal components analysis inqmode the first factor reflected mainly changes in the predominant capture environment probably because of major paleogeographic changes the second factor may reflect selective capture along rocky coastlines during certain times the third factor correlated well with the sea surface temperature curve in the western mediterranean alboran sea during the late quaternary

palaeoceanography of the last deglaciation in the alboran sea western mediterranean stable isotopes and planktonic foraminiferal records abstract oxygen isotope changes of the foraminiferal species globigerina bulloides and uvigerina peregrina eleven radiocarbon dates on the sediment fraction above 50 m and 13 biostratigraphical events allow us to correlate and to date the sediment record of the last climatic cycle in four cores from the alboran sea nine ecozones are recognized which differ from those previously established for atlantic sediments cored immediately west of gibraltar these ecozones can be grouped into two broad phases from the last glacial maximum up to near 9 500 yr b p cold north atlantic microfaunas are the major component of the assemblages during this interval dominant species replace each other according to the varying temperature and density stratification of the water masses from 9 500 yr b p up to the present time subtropical forms from the central atlantic dominate the northern atlantic forms an abrupt increase in the percentages of g inflata occurred near 7 000 b p this event was diachronous within the mediterranean during the last glacial g inflata was endemic inside the mediterranean and its abrupt increase near the end of the deglaciation did not result from replenishment from the atlantic between 4 000 and 5 000 yr b p percentages of g bulloides also increased abruptly warming conditions associated with the onset of a seasonal thermal stratification and a contrasting winter vertical convection are strongly suggested

differential diagenesis of rhythmic limestone alternations supported by palynological evidence alternating cemented and uncemented fine grained layers from pliocene periplatform carbonates of the great bahama bank have fundamentally different diagenetic features the cemented layers consist predominantly of microspar interpreted as an early marine shallow burial cement the intercalated uncemented softer layers are devoid of microspar cement and exhibit signs of mechanical compac tion precursor sediments of both cemented and uncemented layers apparently consisted largely of aragonite needles the needles in the compacted layers show signs of dissolution suggesting that the calcium carbonate required for cementation of the uncompacted layers was provided by aragonite dissolution within the compacted layers the lack of compaction in the cemented layers shows that cementation and hence aragonite dissolution in the adjacent compacted layers took place in the shallow burial realm the dissolved carbonate was trans ported by diffusion to adjacent layers and reprecipitated as calcite cement thereby preventing significant compaction of these layers these processes are not yet complete in the material examined and some aragonite remains in the compacted layers the sedimentary composition of the two rock types compacted and uncompacted is similar indicating a similar precursor sediment for both between 1 5 and 7 times the concentration of palynomorphs oc curs in the compacted layers apparently the result of passive diage netic enrichment although the trigger for diagenetic differentiation has not been determined the pure limestone succession studied here appears to serve as a clay free analog to limestone marl alternations

evidence for enhanced mediterranean thermohaline circulation during rapid climatic coolings molecular biomarkers c37 alkenones n nonacosane and n hexacosanol and toc are used together with benthic 18o and 13c data to document the hydrographic response of the western mediterranean sea to rapid climatic variability these proxies are recorded in core md 95 2043 alboran sea affording the study of the dansgaard oeschger d o and heinrich he variability during the last glacial period the results suggest that rapid changes in the western mediterranean thermohaline circulation occurred in parallel to sea surface temperature oscillations enhanced deep water ventilation occurred during cold intervals he and d o stadials probably driven by a strengthening of north westerly wind over the north western mediterranean sea in contrast decreased intensity of the thermohaline circulation is detected during warm intervals d o interstadials which led to low oxygenated deep water masses and better preservation of the organic matter in the sediment

variability of the western mediterranean sea surface temperature during the last 25 000 years and its connection with the northern hemisphere climatic changes sea surface temperature sst profiles over the last 25 kyr derived from alkenone measurements are studied in four cores from a w e latitudinal transect encompassing the gulf of cadiz atlantic ocean the alboran sea and the southern tyrrhenian sea western mediterranean the results document the sensitivity of the mediterranean region to the short climatic changes of the north atlantic ocean particularly those involving the latitudinal position of the polar front the amplitude of the sst oscillations increases toward the tyrrhenian sea indicating an amplification effect of the atlantic signal by the climatic regime of the mediterranean region all studied cores show a shorter cooling phase 700 years for the younger dryas yd than that observed in the north atlantic region 1200 years this time diachroneity is related to an intra yd climatic change documented in the european continent minor oscillations in the southward displacement of the north atlantic polar front may also have driven this early warming in the studied area during the holocene a regional diachroneity propagating west to east is observed for the sst maxima 11 5 10 2 kyr b p in the gulf of cadiz 10 9 kyr b p in the alboran sea and 8 9 8 4 kyr b p in the thyrrenian sea a general cooling trend from these sst maxima to present day is observed during this stage which is marked by short cooling oscillations with a periodicity of 730 40 years and its harmonics

breaking the waves human use of marine bivalves in a microtidal range coast during the upper pleistocene and the early holocene vestibulo chamber nerja cave malaga southern spain abstract this paper presents the results obtained from the study of the bivalves recovered during the archaeological excavations in the vestibulo chamber of nerja cave malaga southern spain carried out by professor francisco jorda cerda between 1983 and 1987 these excavations recovered the archaeological record of the sequence from the gravettian to the neolithic the mollusc remains from the vestibulo chamber of nerja cave record constitute an extraordinary collection composed of more than 136000 specimens which correspond to more than 78 kg in this work only marine bivalves were studied the bivalve remains are more than 124000 specimens corresponding to more than 65 kg from 31 taxa more than 115000 of these specimens 59 kg are derived from the shell midden dated to gs 1 the archaeological record of nerja cave is distinguished by the abundant presence of human provided marine and continental molluscs with a high presence of bivalves marine bivalves increased clearly from the lgm to the mid holocene and the human inhabitants of the cave accumulated an important shell midden in the contact between mis 2 and mis 1

site formation and chronology of the new paleolithic site sima de las palomas de teba southern spain abstract the newly identified paleolithic site sima de las palomas de teba hosts an almost seven m thick sediment profile investigated here to elucidate the rock shelter s chronostratigraphy and formation processes at its base the sediment sequence contains rich archeological deposits recording intensive occupation by neanderthals luminescence provides a terminus ante quem of 39 4 2 6 ka or 44 9 4 1 ka osl and 51 4 8 4 ka tl this occupation ended with a rockfall event followed by accumulation of archeologically sterile sediments these were covered by sediments containing few middle paleolithic artifacts which either indicate ephemeral occupation by neanderthals or reworking as suggested by micromorphological features above this unit scattered lithic artifacts of undiagnostic character may represent undefined paleolithic occupations sediment burial ages between about 23 0 1 5 ka osl and 40 5 3 4 ka pirir provide an upper paleolithic chronology for sediments deposited above the rockfall finally a dung bearing holocene layer in the uppermost part of the sequence contains a fragment of a human mandible dated to 4032 39 14 c yr bp overall the sequence represents an important new site for studying the end of neanderthal occupation in southern spain

archaeology of the continental shelf marine resources submerged landscapes and underwater archaeology we provide a critical review of the evidence for the long term use of marine resources and coastal environments in human evolution and later development we emphasise the importance of the coastal archaeological record in understanding patterns of human settlement and dispersal and draw attention to the large potential biases introduced by the destructive or obscuring effects of pleistocene sea level change we note that lowered sea levels have been the norm for most of the pleistocene and that periods of high sea level have been too short lived to provide other than a fragmentary coastal record and one that is beset with ambiguities and uncertainties we examine the geological processes of coastal uplift and underwater preservation that may help to mitigate these biases coastlines elevated by isostatic and tectonic processes or with very steep offshore drop offs at plate boundaries are important in providing a potential window into coastal landscapes and archaeology formed during periods of lowered sea level however we conclude that the opportunities afforded by these geological factors are too limited to obviate the need for underwater exploration we review the evidence now available from submerged landscapes across the africa eurasia interface from the atlantic coastlines of northwest europe to the southern red sea we show that geomorphological conditions for the preservation of archaeological and palaeoenvironmental data are commonly present that much material has already been discovered and that new techniques technologies and projects are providing the momentum for a rapidly expanding field of investigation the results do not simply add to what we already know from sites on land but are likely to produce qualitatively different evidence for coastal adaptations and landscapes that have no analogue on present day coastlines we note the strong probability that many coastal landscapes exposed at lowered sea level provided relatively fertile and productive refugia for plants land mammals and humans at a time when increased aridity would have reduced or deterred hinterland occupation we conclude that underwater investigation is essential if hypotheses of early human adaptation and dispersal are to be fully tested

at the land s end marine resources and the importance of fluctuations in the coastline in the prehistoric hunter gatherer economy of portugal abstract this paper focuses on the importance of aquatic resources in economy and subsistence strategies during the middle and upper palaeolithic of portugal modern theoretical biases in archaeology have led to a marginalization of marine resources and a dismissal of their use by palaeolithic hunter gatherers geological and archaeological data show that changes in the position of the coastline had a direct impact on the visibility of marine resources in the archaeological record marine regressions and transgressions have significantly altered the record of pleistocene coastal settlement using recent studies on changes in upwelling intensity during the last glacial we offer a new perspective on palaeolithic hunter gatherer economy that emphasizes the importance of the coast as a focus of subsistence and settlement

late quaternary climatic changes on the southwestern balearic slope western mediterranean isotopic faunal and mineralogical relationships abstract we report the results of a research on the carbonate mineralogy planktonic foraminifera distribution and oxygen and carbon isotope composition of g bulloides in hemipelagic carbonate oozes of the southwestern balearic slope western mediterranean to contribute to the understanding of climatic and ecological variations during the last quaternary interglacial glacial cycle and their influences on the carbonate sedimentary processes of the western mediterranean oxygen isotope stages 1 2 and 3 have been identified and correlated to those established in tyrrhenian cores the carbon isotope records display several anomalies which are explained by productivity variations and diagenetic processes pelagic carbbonates low mg calcite and aragonite and detrital minerals quartz high mg calcite and dolomite display variations that are climate related pelagic carbonates increase during warm intervals while intense low mg calcite dissolution and greater quantities of detrital minerals are found in colder intervals our results suggest that the carbonate distribution of the western mediterranean correlates to the reported from the atlantic ocean nevertheless the molar mgco3 content in low mg calcite disagree to the established temperature relationship in other oceans

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

a model for raw material management as a response to local and global environmental constraints abstract identifying the causes of visible changes in the archaeological record is one of the major goals of archaeological and anthropological research environmental shifts have been often suggested as one of the primary drivers of anthropological changes due to their impact on biotic resources considerably less attention has been given to changes in the availability of lithic raw materials if raw materials for tool production were available in constant predictable amounts then stability or slow shifts of technological strategies would be expected in the archaeological record however this is not the case in the iberian paleolithic even considering that some of the observed changes may be driven by culture setting or function in this paper we investigate the possibility of changes in raw material availability through the action of geodynamic processes which could have exerted selective pressures on the technological strategies employed by human populations this approach highlights the possible impact of environmental factors on human populations not just through food and habitat but also through geology the maritime climates of southwestern iberia are good candidates for such a connection because the region faced dramatic fluctuations between cold dry and warm wet periods during the late pleistocene with well documented impacts on biotic and geomorphic systems a link between environmental conditions and human tool making strategies is suggested by the correlation between cold climate during the last glacial maximum and an abrupt shift in lithic assemblages toward reliable technological strategies using the climatic conditions that define this reliable phase of upper paleolithic technology between 17 and 23 ka bp two climate driven scenarios are suggested for technological strategies in the iberian paleolithic a cold dry phase with restricted availability of raw materials favoring a technological shift towards reliability and a warm wet phase with greater raw material availability and a more flexible maintenance based lithic technology applying this reasoning to paleoenvironmental proxy records for southwestern iberia it is likely that numerous episodes of climate induced raw material stress occurred towards the end of the middle paleolithic and around the time of the middle upper paleolithic transition at present insufficient data exist to properly test this hypothesis but ongoing investigations at sites throughout portugal hold promise toward achieving this goal

a chrono cultural reassessment of the levels vi xiv from el cuco rock shelter a new sequence for the late middle paleolithic in the cantabrian region northern iberia abstract a large number of sites dated to the late middle paleolithic and the early upper paleolithic have been recorded in the cantabrian region northern iberia making this area a key location to investigate the lifeways of the last neanderthals and the first anatomically modern humans the stratigraphic sequence from el cuco rock shelter was originally attributed to the early upper paleolithic based on radiocarbon dates measured on bone apatite however new radiocarbon dates on shell carbonates from the lower levels produced inconsistent dates with those previously published in order to clarify this anomaly a reassessment of the chronology of levels vi to xiv was undertaken the review was based on new radiocarbon dates performed on bones and shells and a re evaluation of the lithic assemblages bone samples did not produce radiocarbon dates due to a lack of collagen preservation but radiocarbon dating of shell carbonates provided dates ranging from 42 3 to 46 4 ka bp these dates are significantly older than that previously obtained for level xiii using biogenic apatite from bones 30 ka uncal bp suggesting that the bone apatite used for radiocarbon dating was rejuvenated due to contamination with secondary carbonate lithic assemblages defined in the first place as evolved aurignacian have now been confidently attributed to the mousterian techno complex these results suggest a middle paleolithic chronology for this part of the sequence the new chronology proposed for el cuco rock shelter has significant implications for the interpretation of neanderthal subsistence strategies and settlement patterns especially for coastal settlement and use of marine resources not only in northern iberia but also in atlantic europe

holocene climatic and environmental evolution on the southwestern iberian peninsula a high resolution multi proxy study from lake medina cadiz sw spain abstract the climatic and environmental history of the sw iberian peninsula is explored to fill in the gap of continental palaeoclimate data by a high resolution study of lake medina sediments from core co1313 a multi proxy approach comprising sedimentary facies analysis elemental geochemistry mineralogy palynology and micropaleontology was employed to reconstruct the complex limnological response to climate change and catchment dynamics since the early holocene the further definition of abrupt climate change events was supported by a robust age model and rapid sediment accumulation rate at the study site proxies indicate arid and warm climate conditions during the early holocene from around 9 5 to 7 8 cal ka bp with a desiccation event at 8 8 cal ka bp as well as tentative evidence for the regional expression of a cold and abrupt arid climate event centering on ca 8 2 cal ka bp the holocene climate optimum from around 7 8 to 5 5 cal ka bp is characterized by a humid climate and maximum lake level anoxic bottom water conditions are indicated by the preservation of sediment laminae and the occurrences of sulfur mottles which were observed for the first time within holocene sediments of saline lakes mid to late holocene times are governed by the 4 2 cal ka bp dry event as well as progressive aridification accompanied by the development of typical mediterranean low land vegetation during recent times further progressive loss in precipitation as well as fluctuating but overall increasing anthropogenic influence on lake medina sediments is observed

paleolithic vs epipaleolithic fisheries in northern iberia abstract a comparison of paleolithic and epipaleolithic fisheries in nw iberia shows an overall high trophic level of catch freshwater fisheries and thus their impacts are ca 8000 yr older than marine fisheries and have suffered virtually no changes in the region except for the increase in numbers being focused on two families salmonidae and anguillidae to a very minor extent marine fisheries in the paleolithic likely had a low impact but rapidly increased in importance raising the average trophic level of the catch the number of affected taxa and the proportion of marine to freshwater fisheries with time

the style of the tyrrhenian subduction momentum and energy equations are solved simultaneously for an incompressible viscous fluid in order to model the changes in the shape of a subducted slab when active convergence between the subducting and overriding plates comes to the end and slab pull becomes the dominant tectonic mechanism this model can be applied to the tyrrhenian domain where it has been suggested that active convergence terminated about 7 9 myr ago during the active phase the angle of immersion of the slab at intermediate depths between 100 and 270 km is small about 45 50 and large about 80 90 at depths greater than 300 km the phase of passive gravitational sinking is characterized by a substantial modification in the shape of the slab with a large angle of immersion of 70 now at intermediate depths decreasing to 50 in proximity of the tip of the slab when the shape of the modelled slab is compared with the seismogenic portion of the subducted ionian lithosphere in the tyrrhenian our results are consistent with subduction driven by slab pull and with cessation of active convergence between 7 9 myr before present