styles of failure in late holocene highstand prodelta wedges on the adriatic shelf on the continental shelves of the northern mediterranean basin the late holocene highstand systems tract hst prograded un der the influence of major rivers after the attainment of the present sea level highstand about 5 5 cal kyr bp on the adriatic shelf the thickness distribution of the late holocene hst reflects the location of major deltas on the western side of the basin and the geostrophic cir culation which prevents a more uniform sediment dispersal toward the center of the basin very high sediment accumulation rates 1 to 10 cm year resulted in the construction of a hst depocenter up to 35 m thick this shore parallel depocenter is affected by failure of limited displacement over as much as 40 of its extent gas impregnation is common in the topset region and occurs at very shallow levels a few meters below the sea floor five areas are characterized by a variety of sea floor and subsurface crenulations although locally some of these crenulations have an intriguingly regular geometry sediment failure is the most plausible mechanism for their formation sediment failure better explains the large variety of geometries that characterizes the coastal mud prism of the late holocene hst furthermore we observe that these crenulations occur only where the downlap surface at the base of the hst is disrupted and affected by geometries that are con sistent with fluid escape processes this relationship suggests that the basal surface acts as a weak layer for sediment failure failure occurred in variable water depths from the northern slope of the modern po prodelta 10 20 m water depth to the narrow shelf offshore bari 40 110 m water depth in all these areas the proximal part of the hst prodelta wedge is intensely gas charged the thickness and age of the sediment sections affected by failure are slightly differ ent from place to place but appear everywhere younger than 5 5 cal kyr bp where failure affects the entire hst the detachment occurs on the downlap surface at its base failure geometries characterize the head region whereas compressional features such as pressure ridges and mud diapirs dominate in the toe region ranging in depth between 70 and 110 m where failure is limited to the upper few meters of the hst there is a clear lithologic change decrease in carbonate fraction and grain size across the basal surface this lithological change reflects a switch in sediment supply from local apennine rivers below to po derived mud this change occurred at the onset of the little ice age documenting the indirect control of short term climate change and hu man impact on sediment architecture the deformations affecting the late holocene hst in the various areas show differences in internal geometry but appear everywhere to be characterized by limited downward displacement and can be attri buted to shear dominated retrogressive failure it is suggested that some degree of consolidation occurred immediately after mobilization possibly induced by the escape of fluids nowhere has failure evolved into disintegration and flow likely because the type of cyclic loading that triggered it was not prolonged over a long enough interval short lived radionuclides in the uppermost stratigraphic layers which postdate the failure in the area offshore ortona allowed us to quantify systematic changes in sediment accumulation rates as a func tion of the underlying deformed sea floor in areas of wavy sea floor troughs show sediment accumulation rates of greater than 16 mm yr a figure that is fourfold the rate measured on the flanks of the troughs

balanced section in thrust belts part 1 construction balanced geological cross sections are an important aid to understanding thrust belt structures and to estimating their hydrocarbon bearing potential two approaches to section balancing have been taken in the past construction of retrodeformable sections from raw data and modification of previous interpretations after an evaluation procedure these approaches may be unified by use of a langrangian grid projection of datum locations dips and stratigraphic thicknesses onto the section plane is performed directly by calculation or graphically using plunge lines spline interpolation and parallel fold modeling are the simplest ways of filling gaps in the sectional data but isogon interpolation yields rheologically more realistic results faults are interpolated using cutoff geometries as constraints fault tips are located from distance displacement plots whereas the depth to detachment is obtained by a modified chamberlin construction interpolations made on the section are directed back to the geologic map via plunge lines although these techniques of section construction do not guarantee a balance especially when complexities such as growth structures diapirs or strike slip faults are present they eliminate many potential errors

the silence of the layers archaeological site visibility in the pleistocene holocene transition at the ebro basin abstract the ebro basin constitutes one of the most representative territories in sw europe for the study of prehistoric societies during the pleistocene holocene transition the correlation of palaeoenvironmental and geomorphological proxies obtained from sedimentary records with chronologically well constrained reference archaeological sites has allowed defining this time frame precisely such that three main pilot areas haven been broadly depicted the alavese region the pre pyrenees and the bajo aragon overall the human imprint in the ebro basin was rare during the upper palaeolithic but more visible from the upper magdalenian 14500 13500 cal bp to neolithic times up to 5500 cal bp local environmental resources were continuously managed by the prehistoric communities in the different areas of study in fact the ebro basin acted during those millennia as a whole developing the same cultural trends industrial techniques and settlement patterns in parallel throughout the territory however some gaps exist in the 14c frequency curve scdpd curve this is partially related to prehistoric sites in particular lithologies and geological structures that could have partly been lost by erosional processes especially during the early holocene in addition this gap also parallels the reconstructed climate trend for the pre pyrenean and the bajo aragon areas which are defined by high frequencies of xerophilous flora until ca 9500 cal bp suggesting that continental climate features could have hampered the presence of well established human communities in inland regions the interdisciplinary research archaeology geomorphology and palaeoclimatology discussed in this paper offers clues to understand the existence of fills and gaps in the archaeological record of the ebro basin and can be applied in other territories with similar geographic and climate patterns

changes in mobility patterns as a factor for site density variation in the recent epigravettian of northern italy and southeastern france abstract this paper critically considers the use of radiocarbon dates as a demographic proxy for past population our goal is not to reject or valid this approach we even did not focus on the various bias of this approach or on the several correction methods used to reduce them we rather argue that when trying to interpret 14c dates in a demographic perspective it is essential to analyze socio economic parameters studying the case of the lateglacial upper palaeolithic of southeastern france and northern italy we demonstrate that the use of techno economic approaches allows discussing this way to interpret the radiocarbon data from this analysis we argue that a change in the density of dates cannot be simply interpreted in term of demography we demonstrate that these variations can be the result of changes in the way people organize themselves in a territory in other word we argue that mobility patterns are somehow responsible for the density of dates and sites

crustal shortening in the palmyride fold belt syria and implications for movement along the dead sea fault system an edited version of this paper was published in tectonics by the american geophysical union agu copyright 1990 agu see also http www agu org journals tc http atlas geo cornell edu syria chaimov tectonics 1990 html

numerical forward modelling of fluxoturbidite flume experiments using sedsim abstract delta front fluxoturbidity deposits in rift basin margins as well as sand avalanches are influenced by topography water level fluctuation and wave action instability of prior sediments deposited on the delta front is a prerequisite for the generation of fluxoturbidity in this study sedsim a three dimensional numerical stratigraphic forward model is used to replicate and extend a set of physical flume tank experiments investigating the formation of fluxoturbidites from different initial conditions this study has investigated the influence of topographic slope relative water level change and wave action on the formation of fluxoturbidites and hopefully improves our understanding and insight into the dynamic processes of fluxoturbidity resulting from different initiation mechanisms the study also illustrates the value of numerical modelling in complementing and extending physical flume tank studies we show that at least at the scale of a flume tank there exists an optimum window of topographic slopes within which fluxoturbidites arise due to slumping this window ranging from 9 to 18 may be useful in distinguishing the effects of topographic slope from other fluxoturbidite causal mechanisms the amplitude and frequency of water level oscillation appears to be a significant control on fluxoturbidite thickness while wave attributes especially wave angles appear to affect fluxoturbidite locality relative to the sediment source

radiocarbon dates as data quantitative strategies for estimating colonization front speeds and event densities abstract archaeological analysis of large scale prehistoric population history requires us to estimate rates of spatial spread during dispersals and rates and magnitudes of temporal contraction during crashes using oxcal s mcmc sampling routine i introduce and demonstrate a simple and easily implemented method of estimating front speeds that takes due account of the uncertainty in the archaeological data in both dates and distances and argue that this method is more appropriate than those most often used in front speed estimation at present i also propose a simple and easily implemented method of estimating event densities as a demographic proxy as an alternative to summed calibrated probability distributions i argue that this alternative is a significantly better technique and show that its use also enables us to identify individual archaeological dates that are exerting particularly strong influence on the results so that we can efficiently allocate our attention when assessing the possible effects of exogenous sampling uncertainty to illustrate these methods i re analyse two published datasets relating to the early paleoindian colonization of north america my results with the new technique indicate that even with a very noisy dataset there was clear evidence in the framework of the intcal04 calibration curve for a drastic reduction in archaeological event densities following the younger dryas onset followed by a prolonged period of reduced human activity and a possible renewed phase of rapid growth after the younger dryas termination and onset of the holocene however the revised estimate of the younger dryas marine reservoir offset in the intcal09 calibration curve for 12 550 12 900 cal bp changes the picture significantly by flattening the peak in clovis age events and pushing it forward in time into the early younger dryas itself

orbital ice sheet and possible solar forcing of holocene lake level fluctuations in west central europe a reply to magny in his comment on bleicher 2013 magny presents a revised version of his score method and reaffirms that it can prove a possible influence of solar activity on central european lake levels he also stresses the diagnostic value of archaeological lake site settlements this paper points at methodological problems that are not yet resolved in the revised version since there is great consensus that not only is the the sun a primary forcing factor in the climate s system but also that its effect cannot be expected to be linear for all of the holocene the use of the score record is questioned the proposed relation between archaeological lake site settlements and solar activity is shown to be doubtful

benthic fluxes and porewater concentration profiles of dissolved organic carbon in sediments from the north carolina continental slope abstract numerous studies of marine environments show that dissolved organic carbon doc concentrations in sediments are typically tenfold higher than in the overlying water large concentration gradients near the sediment water interface suggest that there may be a significant flux of organic carbon from sediments to the water column furthermore accumulation of doc in the porewater may influence the burial and preservation of organic matter by promoting geopolymerization and or adsorption reactions we measured doc concentration profiles for porewater collected by centrifugation and sipping and benthic fluxes with in situ and shipboard chambers at two sites on the north carolina continental slope to better understand the controls on porewater doc concentrations and quantify sediment water exchange rates we also measured a suite of sediment properties e g sediment accumulation and bioturbation rates organic carbon content and mineral surface area that allow us to examine the relationship between porewater doc concentrations and organic carbon preservation sediment depth distributions of doc from a downslope transect 300 1000 m water depth follow a trend consistent with other porewater constituents co2 and so42 and a tracer of modern fine grained sediment fallout pu suggesting that doc levels are regulated by organic matter remineralization however remineralization rates appear to be relatively uniform across the sediment transect a simple diagenetic model illustrates that variations in doc profiles at this site may be due to differences in the depth of the active remineralization zone which in turn is largely controlled by the intensity of bioturbation comparison of porewater doc concentrations organic carbon burial efficiency and organic matter sorption suggest that doc levels are not a major factor in promoting organic matter preservation or loading on grain surfaces the doc benthic fluxes are difficult to detect but suggest that only 2 of the dissolved organic carbon escapes remineralization in the sediments by transport across the sediment water interface

sedimentary processes on the atlantic continental slope of the united states abstract until recently the sedimentary processes on the united states atlantic continental slope were inferred mainly from descriptive studies based on the bathymetry and on widely spaced grab samples bottom photographs and seismic reflection profiles over the past 6 years however much additional information has been collected on the bottom morphology characteristics of shallow subbottom strata velocity of bottom currents and transport of suspended and bottom sediments a review of these new data provides a much clearer understanding of the kinds and relative importance of gravitational and hydrodynamic processes that affect the surface sediments on the rugged slope between georges bank and cape lookout n c these processes include 1 small scale mass wasting within submarine canyons and peripheral gullies 2 density flows within some submarine valleys 3 sand spillover near the shelf break 4 sediment creep on the upper slope and 5 hemipelagic sedimentation on the middle and lower slope the area between georges bank and hudson canyon is further distinguished by the relative abundance of large scale slump scars and deposits on the open slope the presence of ice rafted debris and the transport of sand within the heads of some submarine canyons between cape lookout and southern florida the slope divides into two physiographic units and the topography is smooth and featureless on the florida hatteras slope offshelf sand spillover and sediment winnowing related to gulf stream flow and possibly to storm driven currents are the major processes whereas hemipelagic sedimentation is dominant over the offshore slope along the seaward edge of the blake plateau north of the blake spur slumping generally is absent south of cape lookout although one large slump scarp related to uplift over salt diapirs has been identified east of cape romain future studies concerning sedimentary processes on the atlantic slope need to resolve 1 the ages and mechanisms of mass wasting 2 the accumulation rates and thicknesses of hemipelagic sediments and 3 the causes and variability of offshelf sand spillover sediment winnowing and canyon transport

intra slope canyon morphology and its modification by rockfall processes u s atlantic continental margin abstract side scan sonar data have been acquired at three different range settings and scales for a section of the continental slope the data allow new perspectives on canyon morphology at varying complementary resolutions both regional context and site specific details are provided intra slope canyons on the lower slope are associated with outcrops of middle eocene carbonate rocks canyon geometries are heavily influenced by structural patterns of intersecting joints drop core analyses of surface sediments suggest that intra slope canyon formation is not a geologically recent event but occurred before 50 000 yrs b p within the canyons rocky debris results from episodic rockfall activity from the steep canyon walls dating of canyon floor sediments with inclusions of rockfall debris at one location suggests the last discrete period of rockfall there began about 10 000 yrs b p and ended about 6000 yrs ago the rockfall activity may have coincided with a period of increased submarine dissolution along the margin that accompanied the upslope migration of the western boundary undercurrent elements of the lower slope terrain may reflect surface solutional degradation of the joint patterns associated with the eocene outcrops over longer time periods

a continental narrative human settlement patterns and australian climate change over the last 35 000 years drawing on the recent synthesis of australian palaeoclimate by the oz intimate group reeves et al 2013a we consider the effects of climate systems on past human settlement patterns and inferred demography we use 5044 radiocarbon dates from 1750 archaeological sites to develop regional time series curves for different regions defined in the oz intimate compilation as the temperate tropics interior and southern ocean sectors to explore human climate relationships in australia over the last 35 000 years correlations undertaken with improved palaeoclimatic data and archaeological records indicate that the regional time series curves are robust and can be used as a proxy for human behaviour however interrogation of the datasets is essential with artificial peaks and taphonomic over correction being critical considerations the time series curves are interpreted as reflecting population growth stasis and even decline in phase with terminal pleistocene early holocene climatic fluctuations this coupling however decreases during the last 5000 years most likely due to increased population levels greater territoriality technological solutions to stress and social and ideational innovation curves from all sectors show exponential population growth over the last 5000 years we identify future research priorities highlighting the paucity of archaeological records across several parts of australia 1 dated site 4 000 km2 especially around the fringes of the arid zone and the need for improved taphonomic correction techniques finally we discuss how these time series curves represent a first order framework not dissimilar to global climate models which researchers can continue to test and refine with local regional and continental records

regional response to drought during the formation and decline of preclassic maya societies abstract the earliest complex societies and a distinctive set of pan regional social political and economic institutions appeared in the southern maya lowlands during the preclassic period ca 1200 1100 cal bce cal 300 ce the timing of these cultural changes was variably influenced by local developments interaction with other regions of mesoamerica and climate change we present a high resolution radiocarbon chronology for the growth of the early polity of cahal pech belize one of the first permanent settlements in the southern maya lowlands we compare our results to a database containing over 1190 radiocarbon dates from cultural contexts reported from five major regions of the southern lowlands to interpret the expansion and decline of emerging complex social groups during the preclassic comparisons to paleoclimate proxy datasets suggest that fluctuating climate regimes may have promoted alternating integration and fragmentation of early hierarchically organized societies stable climatic conditions during the middle preclassic 1000 900 300 cal bce fostered the centralization of populations and the formation of large regional polities across the southern lowlands an extended drought at the end of the late preclassic cal 150 300 ce likely contributed to the decline of some major polities in the central peten but smaller sites located in productive environments were more resilient and persisted in to the classic period this research provides a framework for understanding the complex social and environmental factors that influenced localized adaptations to climate change and the episodic growth and decline of early complex societies in prehistory

strike slip duplexes abstract strike slip fault systems often contain zones of steep imbricate faults geometrically similar to imbricate fans and duplexes in dip slip thrust and normal fault systems they are evident in map view rather than in vertical sections examples of duplexes are cited from both active and ancient systems and from theoretical and physical models duplexes may form at bends on strike slip faults by a process kinematically analogous to the sequential imbrication of ramps on dip slip faults however some may form and many may initiate as non sequential riedel fractures at fault offsets or on straight fault segments this process is more marked than in dip slip systems where primary anisotropy such as bedding exerts more control on fault geometry strike slip duplexes may be shunted along the fault system parallel to the regional slip vector however duplexes or individual horses will usually also move up or down perpendicular to the slip vector because of the unconstrained upper surface to the fault system these factors mean that no section through a strike slip system should be expected to area balance the faults of strike slip duplexes and imbricate fans may root in kinematically necessary low dip faults or may converge downwards and appear in vertical sections as flower structures

late quaternary sedimentation in the western north atlantic stratigraphy and paleoceanography abstract a detailed analysis of stratigraphic indices was undertaken to study paleoclimatic change in the western north atlantic three stratigraphic indicators carbonate content globorotalia menardii and uvigerina peregrina were tested in ten radiocarbon dated cores from the north american continental margin of these carbonate content appears to be most accurate carbonate content exhibits two major increases from late glacial time to the present estimated ages of the average of the mid point of these increase are 13 200 b p and 8600 b p an absolute chronology was established down fifteen cores using these stratigraphic indicators and the radiocarbon dates sea surface temperature sst estimates derived from planktonic foraminifera were mapped at 2000 yr intervals from 2000 b p to 14 000 b p sst warms rapidly from 12 000 to 8000 b p reaches a maximum between 8000 and 6000 b p and gradually cools after 6000 b p bottom waters were monitored with uvigerina peregrina and dissolution indices the disappearance of uvigerina suggests that the water type it lives in low o 2 started to thin from both the top and bottom by 13 000 b p and by 7300 b p had disappeared fragmentation of planktonic foraminifera was used as an index of dissolution in most cores dissolution was intense during late glacial time lessened during early postglacial time and resumed in the late postglacial

challenges in sample processing within radiocarbon dating and their impact in 14c dates as data studies abstract for decades researchers have employed sets of radiocarbon dates to reconstruct trends in ancient human populations the overarching assumption in this analysis is that the frequency of dates is proportional to the magnitude of past human activity thus the distribution of summed or otherwise summarized dates is used to extrapolate population density and mobility patterns there are however a number of underlying assumptions associated with this analysis that workers address to varying degrees and which if false and not critically accounted for will introduce bias misrepresent the magnitude of activity and ultimately prove misleading in archaeological interpretations in this regard research has so far mainly focused on correcting for the effects of time dependent degradation of archaeological sites and constituent materials calibration irregularities and the efficacy of the statistical methods used assumptions directly related to sample processing in radiocarbon dating however are less discussed in 14c dates as data analyses it is for example assumed that all carbonaceous materials will yield sufficient endogenous carbon for radiocarbon measurement yet sample failure in radiocarbon dating is common and contingent on largely deterministic factors such as post depositional environment sets of radiocarbon dates analyzed therefore represent successful measurements independent of reliability in this work we discuss the biases introduced by challenges in radiocarbon processing and their impact on 14c dates as data studies

antiquity of the continental slope along the middle atlantic margin of the united states a detailed high resolution geophysical study of part of the continental slope along the mid atlantic margin of the united states indicates that it is an ancient relict landscape largely unmodified by modern slope processes the slope morphology is heavily influenced by bedrock outcrops including joints and bedding planes rather than by any single degradational process a pelagic drape averaging 3 to 5 meters in thickness blankets the slope carbon 14 dates from eight drop cores show that the drape was deposited in late pleistocene and holocene times the holocene part of the drape comprising the uppermost 1 meter was deposited at a continuous rate of 10 centimeters per 1000 years most features on the slope predate the drape cover

organic carbon deposition on the north carolina continental slope off cape hatteras usa abstract the continental slope off cape hatteras nc is a region of high sediment accumulation and organic matter deposition sediment accumulation rates range from 3 to 151 cm kyr 1 organic carbon deposition rates are 5 13 moles c m 2 yr 1 the highest reported for the slope off the eastern us burial efficiencies are 3 40 the organic matter deposited is marine in origin and a mix of old and young particles high organic carbon deposition rates support remineralization throughout the upper 2 3 m of sediment deep bioirrigation to depths of 60 100 cm within the seabed affects the biogeochemistry of the sediments by extending the zone of sulfate reduction and by steepening dic porewater gradients through the non local exchange of porewater stable and radiocarbon isotope mixing curves for porewater dissolved inorganic carbon dic indicate that the dominant source of dic accumulating in the upper 2 3 m of the seabed is of nearly uniform 13c 21 10 and 14c 546

characterisation of the recent big 95 debris flow deposit on the ebro margin western mediterranean sea after a variety of seismic reflection data swath bathymetry and backscatter data side scan sonographs high resolution hr and very high resolution vhr reflection seismic profiles and sediment cores reveal the complexity of the seafloor and subseafloor features resulting from a large debris flow event that affected the ebro continental slope and base of slope at the beginning of the holocene the big 95 debris flow as it has been named disturbed more than 2200 km2 including a 26 km3 deposit of remobilised sediment covering 2000 km2 swath bathymetry and backscatter imagery allow to distinguish four main areas within the debris flow the source area the proximal depositional area the intermediate blocky depositional area and the distal depositional area in the source area a sinuous headwall scar 20 km long and up to 200 m high and several other secondary scars have been identified sediment released from the source area flowed southeastwards to the proximal depositional area which is the main depocentre of the big 95 debris flow deposit with accumulations over 90 m thick large slabs of sediment detached from this area and from the headwall scar and moved southeastwards embedded in a more mobile matrix thus forming the intermediate blocky depositional area only the looser matrix reached the distal depositional area finally freezing in and partially burying the valencia channel a mid ocean type channel digitisation of vhr seismic reflection profiles where the debris flow deposit is shown as a body of mainly transparent seismic facies has allowed the construction of isobath and isopach maps showing the thickness distribution of the deposit and its interplay with preexisting canyons and channels dating of two sediment cores gives a minimum age of 11 000 calendar years bp for the big 95 debris flow a set of triggering mechanisms including seismicity and oversteepening of the slope due to the existence of a volcanic structure underneath the main headwall is invoked

seismic reflection structure of intracratonic palmyride fold thrust belt and surrounding arabian platform syria copyright 1990 aapg reprinted by permission of the aapg whose permission is required for further use see also http aapgbull geoscienceworld org http atlas geo cornell edu syria mcbride aapg 1990 html

hydrodynamic modeling of tsunamis from the currituck landslide article i nfo article history accepted 24 september 2008 tsunami generation fromthe currituck landslide offshore northcarolina and propagation of waves towardthe u s coastline are modeled based on recent geotechnical analysis of slide movement a long and intermediate wave modeling package coulwave based on the non linear boussinesq equations are used to simulate the tsunami this model includes procedures to incorporate bottom friction wave breaking and overland flow during runup potential tsunamis generated from the currituck landslide are analyzed using four approaches 1 tsunami wave history is calculated from several different scenarios indicated by geotechnical stability and mobility analyses 2 a sensitivity analysis is conducted to determine the effects of both landslide failure duration during generation and bottom friction along the continental shelf during propagation 3 wave history is calculated over a regional area to determine the propagation of energy oblique to the slide axis and 4 a high resolution 1d model isdeveloped to accuratelymodel wavebreakingand the combined influence of nonlinearity and dispersion during nearshore propagation and runup the primary source parameter that affects tsunami severity for this case study is landslide volume with failure duration having a secondary influence bottom friction during propagation across the continental shelf has a strong influence on the attenuation of the tsunami during propagation the high resolution 1d model also indicates that the tsunami undergoes nonlinear fission prior to wave breaking generating independent short period waves wave breaking occurs approximately 40 50 km offshore where a tsunami bore is formed that persists during runup these analyses illustrate the complex nature of landslide tsunamis necessitating the use of detailed landslide stability mobility models and higher order hydrodynamic models to determine their hazard published by elsevier b v

bouguer gravity trends and crustal structure of the palmyride mountain belt and surrounding northern arabian platform in syria copyright 1990 geological society of america see also http dx doi org 10 1130 2f0091 7613 281990 29018 3c1235 3abgtacs 3e2 3 co 3b2 http atlas geo cornell edu syria best 1990 html

statistics sunspots and settlement influences on sum of probability curves abstract large data sets of radiocarbon dates are becoming a more common feature of archaeological research the sheer numbers of radiocarbon dates produced however raise issues of representation and interpretation this paper presents a methodology which both reduces the visible impact of dating fluctuations but also takes into consideration the influence of the underlying radiocarbon calibration curve by doing so it may be possible to distinguish between periods of human activity in early medieval ireland and the statistical tails produced by radiocarbon calibration

sliding and regional slope stability in active margins north aegean trough mediterranean continuous seismic air gun sub bottom profiling in the north aegean has revealed a large submarine slide the failure zone extends from a depth of about 300 m down to 850 m and covers an area of 85 km2 the mean thickness of the slide reaches about 55 m and an estimated total volume of 3 8 km3 of late pleistocene sediments has slid a distance of 6 7 km chronostratigraphic analysis of the acoustic reflectors imply that the major and secondary glide planes are the transitional zones between a lower sequence of strongly stratified reflectors stiff relatively coarser sediment layers and the overlying acoustically transparent and or poorly stratified sequence weaker muddy layers with higher water content and lower shear strength these weak transparent layers have been deposited during interglacial high sea level stands isotopic stages 7 5 3 the major glide plane is assumed to have been developed within a muddy layer that was deposited about 170 245 ka bp stratigraphic sedimentological data and ams dates indicate an early holocene age of the major failure event not earlier than about 5 5 ka bp and not later than 7 8 ka bp the regional seismic hazard and slope stability analysis shows that the north aegean marginal upper middle slopes are highly unstable the calculated values of horizontal ground acceleration able to initiate failures kc range from 80 to 300 gal downslope this is lower than what is expected within 50 yr especially in the upper middle slopes

correcting temporal frequency distributions for taphonomic bias in this paper we expand upon a prior study surovell t a brantingham p j 2007 a note on the use of temporal frequency distributions in studies of prehistoric demography journal of archaeological science 34 1868 1877 that explored the problem of taphonomic bias taphonomic bias refers to the tendency for younger things to be over represented relative to older things in the archaeological record due to the operation of destructive processes like erosion and weathering using a database of radiocarbon dated volcanic deposits from bryson r u bryson r a ruter a 2006 a calibrated radiocarbon database of late quaternary volcanic eruptions earth discussions 1 123 124 we develop an empirical model of taphonomic bias in contrast to our prior study in which we modeled taphonomic bias as an exponential function wherein the likelihood of site loss remains constant through time we argue that the probability of site destruction actually decreases with site age we further demonstrate how this model can be used to correct temporal frequency distributions and extract demographic histories we illustrate this approach using databases of radiocarbon dates from rockshelter and open air sites in the bighorn basin wyoming usa and mammoths and humans in siberia russia

mind the gaps testing for hiatuses in regional radiocarbon date sequences long gaps in regional radiocarbon sequences are often considered evidence for occupation hiatuses but they might also be a product of stochastic processes of occupation and limited numbers of dates here we show that if radiocarbon dates over a span of time are distributed as a poisson random variable such that any point in that span has an equal probability of being dated the gaps between dates will approximate a negative exponential distribution with many short gaps and a few long ones long gaps between dates are to be expected under these conditions even in the absence of true occupation hiatuses this exponential distribution of gap lengths is robust even when the uniform probability assumption is relaxed though true hiatuses have a distinctive if subtle signature we use this model to assess the regional radiocarbon sequence from qinghai lake basin western china which shows two long possible occupation hiatuses during the period 12 500e4200

wildfire and abrupt ecosystem disruption on california s northern channel islands at the allerod younger dryas boundary 13 0 12 9 ka abstract sedimentary records from california s northern channel islands and the adjacent santa barbara basin sbb indicate intense regional biomass burning wildfire at the allerod younger dryas boundary 13 0 12 9 ka all age ranges in this paper are expressed in thousands of calendar years before present ka radiocarbon ages will be identified and clearly marked 14c years multiproxy records in sbb ocean drilling project odp site 893 indicate that these wildfires coincided with the onset of regional cooling and an abrupt vegetational shift from closed montane forest to more open habitats abrupt ecosystem disruption is evident on the northern channel islands at the allerod younger dryas boundary with the onset of biomass burning and resulting mass sediment wasting of the landscape these wildfires coincide with the extinction of mammuthus exilis pygmy mammoth the earliest evidence for human presence on these islands at 13 1 12 9 ka 11 000 10 900 14c years is followed by an apparent 600 800 year gap in the archaeological record which is followed by indications of a larger scale colonization after 12 2 ka although a number of processes could have contributed to a post 18 ka decline in m exilis populations e g reduction of habitat due to sea level rise and human exploitation of limited insular populations we argue that the ultimate demise of m exilis was more likely a result of continental scale ecosystem disruption that registered across north america at the onset of the younger dryas cooling episode contemporaneous with the extinction of other megafaunal taxa evidence for ecosystem disruption at 13 12 9 ka on these offshore islands is consistent with the younger dryas boundary cosmic impact hypothesis firestone r b west a kennett j p becker l bunch t e revay z s schultz p h belgya t kennett d j erlandson j m dickenson o j goodyear a a harris r s howard g a kloosterman j b lechler p mayewski p a montgomery j poreda r darrah t que hee s s smith a r stich a topping w wittke j h wolbach w s 2007 evidence for an extraterrestrial impact 12 900 years ago that contributed to the megafaunal extinctions and younger dryas cooling proceedings of the national academy of sciences 104 16016 16021

human environment interactions in australian drylands exploratory time series analysis of archaeological records exploratory time series analysis of radiocarbon data from archaeological contexts is used to reconstruct the population history of arid australia allowing this to be read in concert with records of climatic variability over the last 20 000 years probability distribution plots of 971 radiocarbon ages from 286 sites in five dryland regions the arid west coast pilbara and murchison nullarbor arid interior and the southeastern arid zone provide a proxy record of prehistoric population fluctuations in these areas there is regional variation but the radiocarbon density plots suggest a step wise pattern of population growth and expansion with significant thresholds at 19 8 and 1 5 cal kyr bp within this the plots suggest a saw tooth pattern of rapid population growth and decline on a 1 3 kyr frequency with a marked collapse of dryland hunter gatherer populations around 3 2 5 cal kyr bp affecting most regions comparison with climate data shows broad correlations with past temperature and rainfall

a new greenland ice core chronology for the last glacial termination 1 we present a new common stratigraphic timescale for the north greenland ice core project ngrip and grip ice cores the timescale covers the period 7 9 14 8 kyr before present and includes the bolling allerod younger dryas and early holocene periods we use a combination of new and previously published data the most prominent being new high resolution continuous flow analysis cfa impurity records from the ngrip ice core several investigators have identified and counted annual layers using a multiparameter approach and the maximum counting error is estimated to be up to 2 in the holocene part and about 3 for the older parts these counting error estimates reflect the number of annual layers that were hard to interpret but not a possible bias in the set of rules used for annual layer identification as the grip and ngrip ice cores are not optimal for annual layer counting in the middle and late holocene the timescale is tied to a prominent volcanic event inside the 8 2 kyr cold event recently dated in the dye 3 ice core to 8236 years before a d 2000 b2k with a maximum counting error of 47 years the new timescale dates the younger dryas preboreal transition to 11 703 b2k which is 100 150 years older than according to the present grip and ngrip timescales the age of the transition matches the gisp2 timescale within a few years but viewed over the entire 7 9 14 8 kyr section there are significant differences between the new timescale and the gisp2 timescale the transition from the glacial into the bolling interstadial is dated to 14 692 b2k the presented timescale is a part of a new greenland ice core chronology common to the dye 3 grip and ngrip ice cores named the greenland ice core chronology 2005 gicc05 the annual layer thicknesses are observed to be log normally distributed with good approximation and compared to the early holocene the mean accumulation rates in the younger dryas and bolling periods are found to be 47 2 and 88 2 respectively

a review of the tectonics of the northern middle east region the structure of the northern part of the arabian platform is reviewed in the light of hitherto unpublished exploration data and the presently accepted kinematic model of plate motion in the region the palmyra and sinjar zones share a common history of development involving two stages of rifting one in the triassic jurassic and the other during late cretaceous to early tertiary times deformation of the palmyra zone during the mio pliocene is attributed to north south compression on the eastern block of the dead sea transcurrent system which occurred after continental collision in the north in southeast turkey the asymmetry of the palmyra zone is believed to result from northward underthrusting along the southern boundary facilitated by the presence of shallow triassic evaporites an important nw se cross plate shear zone has been identified which can be traced for 600 km and which controls the course of the river euphrates over long distances in syria and iraq transcurrent motion along this zone resulted in the formation of narrow grabens during the late cretaceous which were compressed during the mio pliocene to a large extent present day structures in the region result from compressional reactivation of old lineaments within the arabian plate by the transcurrent motion of the dead sea fault zone and subsequent continental collision

high resolution greenland ice core data show abrupt climate change happens in few years the last two abrupt warmings at the onset of our present warm interglacial period interrupted by the younger dryas cooling event were investigated at high temporal resolution from the north greenland ice core project ice core the deuterium excess a proxy of greenland precipitation moisture source switched mode within 1 to 3 years over these transitions and initiated a more gradual change over 50 years of the greenland air temperature as recorded by stable water isotopes the onsets of both abrupt greenland warmings were slightly preceded by decreasing greenland dust deposition reflecting the wetting of asian deserts a northern shift of the intertropical convergence zone could be the trigger of these abrupt shifts of northern hemisphere atmospheric circulation resulting in changes of 2 to 4 kelvin in greenland moisture source temperature from one year to the next

temporal frequency distributions of alluvium in the american southwest taphonomic paleohydraulic and demographic implications abstract the use of radiocarbon frequency distributions to reconstruct prehistoric human and animal populations must account for taphonomic loss and other factors that affect the archaeological and paleontological records surovell et al jas 36 1715 1724 have recently proposed a correction for taphonomic bias that is based on the radiocarbon frequency of a global sample of volcanic deposits analysis of 717 radiocarbon dates sampled from the alluvium of the san pedro and santa cruz rivers and their tributaries in southeastern arizona shows that discovery and scientific biases also play an important role in the creation of radiocarbon frequency distributions and that the rate of taphonomic bias in prehistory is not predicted by the radiocarbon frequency of volcanic deposits the latter principle is further argued using a sample of 123 pliocene to clovis age proboscideans from the san pedro valley we propose an alternative model that is based on the nature of the stratigraphic record with discovery bias scientific bias taphonomic loss and the shape of the calibration curve all operating to influence the temporal frequency distribution of radiocarbon dated prehistoric phenomena

regional variation in the terminal pleistocene and early holocene radiocarbon record of eastern north america in this paper we use radiocarbon dates to evaluate the signature of the younger dryas chronozone ydc in eastern north america using an approach that examines radiocarbon dates by region we argue that the northeastern united states shows a better overall representation of radiocarbon dates when compared to the mid atlantic and southeast these data result in a peak in summed probability distributions during the ydc which is often interpreted as evidence of population growth further examination of these distributions however illustrates that differential standard deviations varying sample size and the effect of taphonomic and research biases likely overwhelm any demographic signatures in our study sample consequently the frequency of radiocarbon dates by itself is insufficient for understanding the relationship between climate culture and demography in eastern north america

constraints on arabian plate motion and extensional history of the red sea analysis of the geologic and geophysical data from the western and northern margin of the arabian plate combined with data from the red sea gulf of aden leads to an interpretation of arabian plate motion that supports an episodic extensional history in the red sea and gulf of aden phase 1 extension began in medial to late eocene and was caused by the nw propagation of the reoriented central indian ridge spreading center it stretched and thinned continental crust along numerous wrench and normal faults that reactivated preexisting structures first phase extension stopped when the arabian plate terminally sutured to eurasia in the medial miocene and halted northward movement of arabia relative to africa the combined african arabian plates moved north more slowly constricting and thickening continental crust in the bitlis zagros sutures while the red sea remained technically quiescent and accumulated salt by the early pliocene continued northward movement was accommodated by lateral extrusion of large continental wedges north of the bitlis zagros sutures this allowed arabia to move northward faster than africa and reopen the red sea where phase 2 extension was expressed by seafloor spreading extension within the red sea gulf of aden rift system has been controlled by the interactions and effects of two factors 1 convergent processes between the north margin of the arabian plate and the eurasian plate to the north and 2 northwest propagation of extension associated with the medial eocene reorganization of the central indian spreading center

the currituck slide mid atlantic continental slope revisited high resolution survey data including deep tow side scan sonar and sub bottom profiles have been acquired over part of a slide complex first described by bunn and mcgregor 1980 on the continental slope northeast of cape hatteras the data permit further consideration of slide geometry sediments ages and origins the slide complex is the result of two slides one within another an upslope headwall encloses a stripped smooth area and a second headwall sidewall system bounds a trough filled with chaotic and poorly stratified slide debris the slides have basal shear surfaces inclined at 4 and 2 close to the regional dips of the underlying strata 3 the total volume of sediment in the slides is at least 128 km3 and the entire slide complex is mantled by surface sediment 4 9 m thick published deposition rates indicate that the slides are late pleistocene in age and are perhaps associated with rapid deposition around the ancestral james and roanoke river delta located on the outer shelf and upper slope during a period of lowered sealevel

high precision ams 14c chronology for gatecliff shelter nevada abstract gatecliff shelter provides a deeply stratified record of human environment interaction in the desert west spanning most of the middle and late holocene the well preserved 10 m deep deposits serve as an important reference sequence for technological and subsistence change in the great basin archaeological work started at gatecliff in 1970 and a geochronological framework was established based on 47 uncalibrated radiocarbon 14 c dates obtained from several conventional radiometric laboratories between 1972 and 1982 these radiocarbon dates are not well accommodated within a bayesian chronological model for these important deposits due to multiple temporal reversals and large analytical errors this model was discarded in favor of one based on a combination of high precision ams 14 c dates of short lived carbonized plant remains supplemented with existing 14 c dates culled from the original set using a bayesian chronological model summed probabilities of the modeled posterior distributions of these 14 c dates n 24 show episodic use of the shelter as a logistic hunting camp between 6050 and 3315 cal bp a significant hiatus in occupation between 3315 and 2145 cal bp and more persistent use by family bands after this time in the future this high precision chronology will provide the foundation for reinterpreting broader patterns of technological and subsistence change in the intermountain west and evaluating these changes relative to high resolution climate records

slump structures in the late tertiary of the porcupine basin offshore ireland abstract a large late tertiary slump complex from the porcupine basin offshore western ireland is described it occurs in deep water probably mud prone sediments on the south west margin of a thermal subsidence basin overlying a pre cretaceous synrift succession the slump consists of head body and toe regions each with diagnostic internal characteristics the head region contains extensional features whereas the toe region suffered compression the main body acted as a relatively rigid unit in the southern zone of the slump complex while in the north it suffered gravity driven internal duplex thrusting a series of elongate channels infilled with material eroded from the crestal parts of the toe and body regions comprise a prominant chute zone local reworking of the basinward edge of the toe region also occurred a period of local turbidite deposition towards the centre of the basin appears to be coeval with the slumping the slump movement was probably influenced by a complex combination of fault induced earthquake movement facies and slope variations and by the local presence of an overpressured mud horizon which acted as a decollement surface

pleistocene suvero slide paola basin southern italy abstract the suvero slide covers an area of about 225 km 2 in the paola slope basin on the eastern tyrrhenian margin the shape and lateral extent of the deposit reflect topographic confinement of the slide between the continental slope and a morphologic barrier formed by a margin parallel slope ridge no headwall or slide plane comparable in scale with the slide deposit were found suggesting that quasi in situ deformation of semi consolidated sediments took place when the failed materials reached the floor of the slope basin the failure occurred downslope from a basement high originating from local uplift continued uplift after the suvero slide occurred is documented by the presence of steep upper slope gradients within the study area and by the presence of small scale creep and failure events that postdate the suvero slide

radiocarbon calibration curves summed probability distributions and early paleoindian population trends in north america archaeologists increasingly examine summed probability distributions of radiocarbon dates to search for temporal trends in ancient human populations including early north american population trends across the onset of the younger dryas climatic period 10 900 bc we use both intcal04 and intcal09 to simulate and calibrate sequences of radiocarbon dates that represent evenly spaced calendar ages from 12 000 to 9000 bc and use intcal09 to simulate two different demographic processes across this interval the shapes of the calibrated summed probability distribution from our first set of simulations mirror many trends that have been interpreted in demographic terms and this shape shows clear links to the shape of the radiocarbon calibration curve this is true for both intcal04 and intcal09 although these different curves produce different probability distributions the shapes of the calibrated summed probability distribution from our second set of simulations differ somewhat but show virtually identical trends at points where the actual frequencies of calendar dates are very different we conclude that changing frequencies of radiocarbon dates over time probably do contain demographic information but that extracting this information is more difficult than archaeologists have acknowledged

mechanisms of collapse of the cretaceous helvetiafjellet formation at kvalvagen eastern spitsbergen coastal cliffs at kvalvagen eastern spitsbergen expose palaeolandslide blocks and related slope failure features that record local collapse of an otherwise undisturbed succession of paralic sediments the collapse occurred along a shallow sloping shelf at the edge of an epicontinental sea in the early cretaceous the event was coincident with a rise in relative sea level along a coast that had just previously experienced a major paralic regression across a muddy marine environment the low relief environment in which the slope failure structures formed as well as the timing of the collapse raise questions regarding the cause of the topographic instability and the possible influence of sea level changes or tectonic activity these outcrops have been previously interpreted as the collapse of a deltaic system triggered by local seismic activity or collapse of a shelf break in the headwall regions of submarine canyons this paper presents new structural and stratigraphic data that refine and adjust the previous interpretations through the evaluation of a variety of possible mechanisms for collapse based on the new data our data suggest that active delta deposition was not occurring at kvalvagen at the time of collapse and that the collapse was likely due to allogenic forcing despite the possible influence of pore fluids and rheological controls on the collapse we find that the geometry and kinematics of landslide slip planes synsedimentary folds and other slope failure related features require over steepened topography and that these are most consistent with westward directed collapse off of a north striking escarpment with elevated topography on the east side fault exposures a large contrast in palaeo elevation and liquifaction features support previous interpretations of a tectonic cause for the collapse and suggest that this topographic feature may have been a fault or fold scarp this study demonstrates the importance of combining stratigraphic and sedimentological data with structural data and kinematic analysis in the interpretation of sedimentary processes

calibration of radiocarbon ages and the interpretation of paleoenvironmental records abstract calibration of the radiocarbon timescale of paleoecological records is essential if they are to be explained correctly in terms of their governing ecological or climatological controls the differences between calendar ages and radiocarbon ages that arise from variations in 14c production through time can distort the chronologies of individual records and the interpretations based on them misleading impressions of synchrony or diachrony of events among multiple records can result and estimates of the apparent duration of episodes and rates of sedimentation and local population changes can be biased displays of the temporal patterns of migration or extinction may also be affected spurious correlations may arise between records with radiocarbon controlled chronologies and time series of potential controls that are expressed on a calendar time scale support for particular explanations of features in a paleoecological record may vary depending on whether radiocarbon ages are calibrated or not this situation is illustrated using the eastern beringian populus subzone as an example when the radiocarbon ages that control the timing of the populus subzone are calibrated the contemporaneous decrease in ice volume and increase in summer insolation are implicated as the ultimate controls of the occurrence of the subzone

neoglacial ice expansion and late holocene cold based ice cap dynamics on cumberland peninsula baffin island arctic canada abstract radiocarbon dating of fossil flora and fauna collected along receding cold based ice caps and cold based sections of polythermal glaciers on cumberland peninsula reveal insights into neoglacial ice expansion and late holocene ice dynamics the taphonomic advantages of subfossilized moss were exploited to precisely document regional expansions of ice caps through the late holocene when compared with climate proxies and records of volcanic eruptions the moss radiocarbon age distributions indicate i onset of neoglaciation shortly after 5 ka concomitant with increased sea ice cover ii intensification of ice expansion between 1 9 and 1 1 ka followed by halt of ice growth or ice recession during the medieval warm period and iii renewed ice expansion after 0 8 ka in response to cooling related to a combination of large volcanic eruptions and low solar activity overall the observations support a model of near instantaneous glacial response to regional climate controls and that these responses were synchronous throughout eastern canadian arctic and possibly eastern greenland

biostratigraphic evidence supports paleoindian population disruption at 12 9 ka buchanan et al 1 interpret an 40 reduction in the cumulative probabilities of radiocarbon dates at the beginning of the younger dryas 12 9 ka as noisy data inconsistent with human population decreases predicted by the extraterrestrial impact hypothesis 2 this reduction is in fact consistent with other biostratigraphic evidence suggesting an abrupt environmental perturbation at the

spatiotemporal dynamics of the clovis folsom transition despite the importance of the clovisefolsom transition for understanding the history of western north america its spatiotemporal dynamics remains unclear here we report a three part study in which we investigated the transition using radiocarbon dates from clovis and folsom sites in the first part of the study we used dates from folsom site phases to determine when and where folsom originated in the second part of the study we employed clovis and folsom dates in analyses designed to determine whether folsom spread via demic diffusion or cultural diffusion in the third part of the study we investigated the velocity of the clovisefolsom transition the analyses suggest that folsom first appeared around 12 800 calbp in the northern high plains and spread north and south from there they also suggest that the spread of folsom was at least in part the result of population expansion in addition the analyses indicate that the spread of folsom was relatively fast for a prehistoric diffusion but well below the maximum velocity that has been estimated for such events these findings in turn have implications for the hypotheses that have been put forward to explain the clovisefolsom transition they refute the idea that the clovisefolsom transition resulted from an extraterrestrial impact over northern north america at 12 900 100 calbp but are consistent with the alternative proposal that the transition was a response to climate driven environmental change

a braided strike slip model for the northern continuation of the dead sea fault and its implications for levantine tectonics abstract the assumption that the 100 110 km sinistral displacement on the dead sea fault is transmitted northwards along a single structure the yammouneh fault which runs ne sw across lebanon is here reviewed a number of valid objections to this concept exist a more attractive model supported by the limited data available from the area is that the motion is transmitted along a number of faults on this basis the temporary rightward flexure of the levant fracture through lebanon has given rise to a braided strike slip fault complex the yammouneh serrhaya fault system this model overcomes the objections against the older concept and allows the explanation of the mt lebanon bekaa valley anti lebanon complex in terms of transpressive and transtensive blocks a tentative outline of the cenozoic structural evolution of the area in terms of two or more phases of motion along the levant fracture is presented

summed radiocarbon probability density functions cannot prove solar forcing of central european lake level changes it has been argued that central european lake levels were driven by solar activity this interpretation rests on the comparison of a score record of radiocarbon dates with the 14c residual curve this score record is a variant of a cumulative probability density function cpf in this paper it is argued that this method is not valid because the shape of the cpf is determined by the calibration curve this hypothesis is tested by a set of null models an alternative interpretation is given according to which only few episodes of holocene lake level changes were climatically driven while most of the time non climatic factors were dominating on a more general level some methodological issues of cpfs are discussed and exemplified by the comparison of dendrochronological results from archaeological settlements and a cpf created using radiocarbon dates from the same settlements

sand dune materials and polar layered deposits on mars abstract the relationship of dark sand dunes to the polar layered deposits of mars is investigated by mapping the colors and morphologic settings of the dunes in and near the polar deposits in the north polar region the dunes have restricted sources in the layered deposits that are associated with are arcuate scarps 10 50 km in length and

timing of occupation and regional settlement patterns revealed by time series analyses of an archaeological radiocarbon database for the south central andes 16 25 s abstract developing spatially resolved high resolution datasets of robust long term changes in human demography constitutes a major challenge for archaeology one approach is to use the distribution of summed radiocarbon age probabilities to infer long term population dynamics i e palaeodemography however these can often be biased by preservation potential site taphonomy or researcher priorities among other aspects all of which require large datasets to resolve adequately for this report we have created such a dataset for the south central andes 16 25 s here termed the south central andes radiocarbon scar database scar spans the last 15 000 years and incorporates 1700 14c dates from 519 archeological sites reported across an extreme bioclimatic gradient that includes the hyperarid coastal atacama desert and adjacent cold high elevation altiplano among the possible methodological biases we first evaluated those related to calibration procedures otherwise changes in summed probability curves show no other relevant biases except for possible research interest priorities that could be responsible for the gaps in the record from the bolivian altiplano our temporally continuous time series indicates that prehispanic populations exhibited significant demographic changes during the last 13 100 cal bp except for coastal populations most regions show strongly coordinated demographic fluctuations that follow the same major patterns thus we identified two broad scale population events across the south central andes atacama inland bolivian altiplano from 13 100 4000 cal bp and then from 4000 cal bp to the present in contrast the atacama coastal records suggest a different and more variable occupation pattern over the last 13 460 cal bp which could be driven by the interaction with oceanographic processes i e upwelling a widespread major decline at 700 cal bp clearly predates the spanish colonization and occurs in all of our regions this widespread decline does not appear to be due to methodological biases and suggests that a population crash occurred before european occupation overall the scar database constitutes a valuable proxy for establishing the long term dynamics of prehistoric societies that inhabited the western andean slope time series analyses that use scar will shed new light on the demographic and cultural dynamics at different spatial scales and help clarify the processes involved in the migrational trajectories and cultural evolution of the peoples that inhabited the south central andes over the last 15 000 years