temporal variation of seismic b values beneath northeastern japan island arc 1 analysis of a high quality seismic catalog reveals that the average of seismic b values in the crust beneath most part of northeastern japan island arc decreased from 0 86 between 1984 and 1990 to 0 73 between 1991 and 1995 the two areas with the largest decrease are found to be in the same areas where the coupling between the north american and the pacific plates is the highest as suggested by a recent geodetic study in the same time period the annual seismic moment release increased by 10 times in addition there seems to be a corresponding increase in volcanic activities in the same area one of the most likely interpretations for the observations is an increase in the subduction rate starting from 1991 the timing of this possible increase in subduction rate is consistent with an apparent increase in global seismic activity

modeling pleistocene local climatic parameters using macrophysical climate modeling and the paleoecology of pleistocene megafauna application of macrophysical climate modeling to sites containing specimens with reliable radiocarbon dates of the extinct giant beaver castoroides ohioensis allows an examination and comparison of their climatic parameters and the establishment of a rudimentary climatic envelope for this extinct species two climatic parameters were examined for this study temperature and precipitation an analysis of eight sites with the giant beaver indicates that the species was cold tolerant and lived under colder january and july temperatures than exist at these sites today at five of the eight sites the model suggests there was a shift in seasonal precipitation from the greatest amount of precipitation taking place during the late summer fall in the pleistocene to spring early summer today

dancing to the rhythms of the pleistocene early middle paleolithic population dynamics in nw iberia duero basin and cantabrian region the northwest of iberia has yielded one of the most complete european middle paleolithic records despite this wealth of information very little is known about population dynamics during this period for that reason the main concern of this paper is to provide socio environmental models that may help explain early middle paleolithic emp population dynamics in nw iberia assessing to what extent they were shaped by climate forces the archaeological record is analyzed on the basis of the heuristics of ecological models already employed in the european pleistocene record but never at a regional scale in order to detect long term changes in the composition of emp populations and the environmental biological and sociocultural process influencing those changes according to the models proposed we have detected a long term population dynamic between mis 11 and mis 6 characterized by low environmental stress high biological productivity interaction among populations and sociocultural complexity eventually this population dynamic was broken due to an extreme climate phase in late mis 6 that had a profound impact on populations and sociocultural structures as a result the upper pleistocene population of nw iberia was concentrated in the cantabrian region this area became an isolated neanderthal glacial refugium that hosted a population with different origins and fragile long term demographic stability

spatial and temporal variations of fennoscandian seismicity summary we present an evaluation of the seismicity in fennoscandia b values have been assessed for the region between 54 72 n and 4 32 e and for the time period 1967 83 a presented contour map with different b values indicates the relative seismicity between different regions during the time period considered strain release rate has also been mapped and recalculated to give the possible maximummagnitude earthquake at a given point for time intervals of 17 and 90yr the observed time variation of b in epicentral regions of some of the major earthquakes that occurred in fennoscandia reveals that b has the tendency to increase several years prior to the occurrence of the event and decreases again about two years before the event takes place this has been the case for at least two of the major fennoscandian events i e for the solberg 1983 earthquake in sweden and the southwestern norway event in 1989 on the other hand similar changes in the behaviour of b have not been observed for the skovde 1986 earthquake in southern sweden space time variations of b were studied for the region with the highest observed b value i e for the region between 64 68 n and 17 32 e not associated with any particular event as well as in the vicinity of the epicentre of the solberg earthquake we will be discussing temporal and spatial variations of b in relation to the state of stress in the region and we believe that a better understanding of the behaviour of b may well help our efforts towards medium term earthquake

seismicity associated with the christmas 1965 event at kilauea volcano a seismo volcanic event of unusual intensity and location occurred during a 6 day period beginning on christmas eve 1965 at kilauea volcano this event centered on the koae fault zone was marked by thousands of small earthquakes extensive ground cracking harmonic tremor and a minor eruption on the east rift the koae fracture zone lies between the east rift zone and the southwest rift zone of kilauea thus separating the south flank from the summit caldera historical records reveal a seismic gap between the rift zones the christmas 1965 activity filled this gap except near its eastern and western boundaries abutting the east and south west rift zones this event is different from other seismic gap filling events in that 1 it was marked by an earthquake swarm rather than a main shock aftershock sequence 2 it was partly volcanic in nature and 3 it did not occur on a plate boundary this paper discusses this event with emphasis on its seismic character and its significance in terms of kilauea tectonics and volcanism

a chronicle of crisis the late mousterian in north iberia cueva del esquilleu cantabria spain abstract during the last decades the cantabrian region has become one of the zones of greater interest in the study of the final mousterian on the european scale the particular ecological and physiographic conditions of this region provide an especially attractive picture for analyzing the advanced moments of this period almost all the mousterian levels of cantabrian sites are dated to the later part of wurm ii as occurs in some other european regions close to 35 ka bp the esquilleu sequence expresses a process of change in archaeological record and probably in the subsistence strategies this late occupation extends through the h4 cold event and the interglacial to wurm iii between level vif 34 3 ka bp approx ams and level iv 22 8 ka bp approx ams all the archaeological evidence non selective and directly adjacent to the river catchment limited technical investment with fast discoid production mainly points but objectively indeterminate from a morphological point of view lithic and even microlithic production and their interpretation in a spatial contextual perspective high fragmentation of the chaine operatoire between the river and the cave would indicate changes in the site function within an articulated network archaeologically the change in the significance of el esquilleu intervals is evident the raw material catchment analysis indicates a much more fuzzy relationship of the site in relation to the environment esquilleu would have ceased functioning as a place of integration of elements of the territory there is no evidence of transport or territorial relationship defined between sites another point for reflection is that in the esquilleu sequence different production methods and the archaeological evidence interpretation can be grouped easily into discrete sets the lower interval is technically variable probably representing the time with more functional complexity in the cave subsequently the quina levallois discoid and final intervals occur archaeological evidence of these higher levels including the technical domains changes gradually with clearly recognizable features along the sequence these common elements sometimes very slightly detected selected lithologies very small size discoid productions pointed morphologies from diametric fractures would refer to a cultural continuity in the communities that inhabited the esquilleu region for millennia

on the probability of the time of occurrence of the largest aftershock and of the largest foreshock in a seismic sequence abstract an attempt is made at a probabilistic prediction of the time of occurrence of the largest aftershock and of the largest foreshock of a seismic sequence for this purpose we used worldwide data which cover the period 1904 1983 it is shown that the probabilities n t of occurrence of the largest aftershock and of the largest foreshock are given by the formulae n t 0 647 0 299 logt and n t 0 544 0 170 logt respectively where t is the time interval between the main shock and its largest aftershock and between the main shock and its largest foreshock

glacial and interglacial refugia within a long term rainforest refugium the wet tropics bioregion of ne queensland australia an artificial neural network is used to classify environments including climate terrain and soil variables according to their suitability for fifteen structural environmental forest classes in the wet tropics bioregion of north east queensland we map the environments characteristic of these forest classes in four climate regimes the present and three past climate scenarios quantify the changes in area of these environments in response to past regional changes in climate and identify areas that would have been environmentally suitable for rainforests at last glacial maximum glacial refugia we also identify areas that would have been suitable for upland and highland rainforest classes during the warmest parts of the interglacial interglacial refugia and map locations that consistently remain favourable to specific forest classes despite large changes in climate in the climate of the last glacial maximum lgm rainforest environments are predicted in three relatively distinct refugia in the northern central and southern wet tropics only three percent of the total area contains lowland mesophyll vine forest and the majority of the area of the rainforest refugia supports upland rainforest classes in the cool wet climate of the pleistocene holocene transition pht rainforest environments expand to form a more or less continuous block from the northern limits of the region to the walter hill range except for discontinuous patches extending through the seaview and paluma ranges in the south during the holocene climatic optimum hco rainforest environments become more fragmented especially in the south lowland rainforest environments are very extensive in this climate while upland rainforest classes are restricted to what we term interglacial refugia estimated distributions and stable locations consistently predicted in all four climate scenarios for the various rainforest environment classes are our main novel contribution each forest environment responds individualistically to climate change our results confirm the highly dynamic nature of the wet tropics landscape and present a much more detailed picture of landscape change since the late pleistocene than previously has been available this mapping exercise should be useful in the future for analyses of present day biogeographic patterns we argue that empirical modelling approaches have an important role in palaeoecology and global change research that is complementary to the developing mechanistic methods crown copyright 2007 published by elsevier b v all rights reserved

rapid changes of glacial climate simulated in a coupled climate model abrupt changes in climate termed dansgaard oeschger and heinrich events have punctuated the last glacial period approximately 100 10 kyr ago but not the holocene the past 10 kyr here we use an intermediate complexity climate model to investigate the stability of glacial climate and we find that only one mode of atlantic ocean circulation is stable a cold mode with deep water formation in the atlantic ocean south of iceland however a warm circulation mode similar to the present day atlantic ocean is only marginally unstable and temporary transitions to this warm mode can easily be triggered this leads to abrupt warm events in the model which share many characteristics of the observed dansgaard oeschger events for a large freshwater input such as a large release of icebergs the model s deep water formation is temporarily switched off causing no strong cooling in greenland but warming in antarctica as is observed for heinrich events our stability analysis provides an explanation why glacial climate is much more variable than holocene climate

the middle paleolithic site of cuesta de la bajada teruel spain a perspective on the acheulean and middle paleolithic technocomplexes in europe here we present a pluridisciplinary study of cuesta de la bajada site teruel spain our findings show that the site contains an early middle paleolithic assemblage similar to other european early middle paleolithic industries allowing us to evaluate the coexistence of this industrial tradition with the acheulean technocomplex in southwest europe the process of lithic production at cuesta de la bajada represents a technology focused on debitage the application of technical concepts such as ramified production sequences and the recycling of flakes via the resharpening of tools and exhausted cores this site was formed around a pond not far from a river and contains remains of large macrofauna other than equids and cervids taphonomic analysis highlights the abundance of cut marks on bones and supports the hypothesis of selective hunting by hominids the numerical ages derived from the combination of esr osl and aar dating methods indicate that the archaeological site was very likely formed around the mis 8 mis 9 the appearance of middle paleolithic industries in europe could represents the autochthonous development of a technocomplex distinctly different from the acheulean characterised by chaines operatoires of debitage and a progressive increase of levallois technology and retouched tools these results suggest that there is a clear coexistence of assemblages with acheulean and middle paleolithic industries during the last third of the middle pleistocene at least in the iberian peninsula

using species distribution models in paleobiogeography a matter of data predictors and concepts article i nfo the increasing interest in the effects of climate changes on species distributions has been followed by the development of species distribution models sdms although these techniques are starting to be used to study the location and dynamics of past species distributions a sound theoretical framework for their use in paleoecology is still lacking in this paper we are reviewing the main challenges for constructing paleo species distribution models to describe and project the past distribution of species namely data limitations selection of predictors and choice of a biologically relevant modeling procedure we also review and discuss the current state of the art in paleo sdms providing a series of recommendations for their use and proposing future research lines to improve the use of these techniques in paleobiogeography

palaeodistribution modelling of european vegetation types at the last glacial maximum using modern analogues from siberia prospects and limitations we modelled the european distribution of vegetation types at the last glacial maximum lgm using present day data from siberia a region hypothesized to be a modern analogue of european glacial climate distribution models were calibrated with current climate using 6274 vegetation plot records surveyed in siberia out of 22 initially used vegetation types good or moderately good models in terms of statistical validation and expert based evaluation were computed for 18 types which were then projected to european climate at the lgm the resulting distributions were generally consistent with reconstructions based on pollen records and dynamic vegetation models spatial predictions were most reliable for steppe forest steppe taiga tundra fens and bogs in eastern and central europe which had lgm climate more similar to present day siberia the models for western and southern europe regions with a lower degree of climatic analogy were only reliable for mires and steppe vegetation respectively modelling lgm vegetation types for the wetter and warmer regions of europe would therefore require gathering calibration data from outside siberia our approach adds value to the reconstruction of vegetation at the lgm which is limited by scarcity of pollen and macrofossil data suggesting where specific habitats could have occurred despite the uncertainties of climatic extrapolations and the difficulty of validating the projections for vegetation types the integration of palaeodistribution modelling with other approaches has a great potential for improving our understanding of biodiversity patterns during the lgm

species richness in the phanerozoic compensating for sampling bias sampling biases are the greatest impediment to resolving the history of species richness of fossilizable marine invertebrates in the phanerozoic actual patterns of species richness have remained uncertain because no method is available to compensate for variations in sampling intensity data are not obtainable which would permit application of techniques that allow direct compensation for sampling intensity such as rarefaction but actual patterns can be estimated with a sampling model designed to account for sampling bias one can estimate the total species richness of a geologic period if one knows the relative sampling intensity devoted to that period the original species abundance distribution of all species that existed during the interval and the number of species that existed during the cenozoic the model presented here is based on the assumption that the species abundance distributions of fossilizable marine invertebrates were lognormal and that sampling was proportional to sediment area volume or paleontologist interest units the model produces consistent results with different estimates of total cenozoic species richness and sampling intensity and strongly suggests low diversity during the paleozoic and mesozoic followed by a dramatic early cenozoic increase in standing species richness these results are consistent with valentine9s 1970 empirical model of species richness

compressive failure of mudstone samples containing quartz veins using rapid ae monitoring the role of asperities this paper presents the results of an ongoing experimental investigation of compressive failure of homogeneous and heterogeneous rocks we used a rapid data acquisition system to monitor the spatio temporal distribution of acoustic emission ae during fault nucleation under conditions of either constant rate loading or static loading in order to examine the effect of asperities on faulting we conducted a series of experiments on mudstone with quartz veins the bedding planes of the mudstone were oriented at an angle of 30 with the maximum compressive stress and were expected as the fracture plane the quartz veins are much stronger than the bedding plane of mudstone and thus the samples model faults having strong asperities experimental results show that 1 ae activity initiated close to the peak stress and almost all ae hypocenters appeared at the intersections of the veins and the fault planes suggesting that the vein asperities control faulting 2 the b value changed with time and shows multiple large and short term fluctuations 3 the change of the b value correlated closely with the spatio temporal hierarchy of the fracture process and 4 fault segments along the bedding plane show behavior of slip having large compressive deformation before the peak stress while the vein asperities show large precursor dilatancy prior to dynamic rupture these experimental results are helpful for the understanding of seismic precursor phenomena associated with strain localization dilatancy change in level of ground water as well as the b value

taphonomic bias in fish diversity from cenozoic floodplain environments abstract the fossil record of cenozoic floodplain fishes increases from few species in the paleocene and eocene to about 5 15 species per locality in the pliocene and pleistocene modern floodplain habitats usually have more than 5 10 times this many species the trend could be interpreted as an evolutionary increase except that there seem to be no ecological or evolutionary reasons to expect ancient floodplains to have fewer species than modern floodplains the alternate hypothesis is that ecological and fluvial processes destroy most fish bones before they are finally buried although floodplain depositional environments trap many fishes these are subjected to extensive predation and scavenging thereby reducing the opportunities for bones of small fishes which make up most of the diversity to be preserved in the fossil record abrasion in bedload probably destroys most small bones that are reworked surface collecting methods exaggerate the bias further because fish bones from fluvial rocks are fragmentary difficult to discover and difficult to identify screen washing for fossils from fine grained sedimentary lenses should increase the known diversity from floodplain deposits

an ocean bottom seismometer study of shallow seismicity near the mid america trench offshore guatemala five ocean bottom seismometers recorded seismicity near the mid america trench offshore guatemala for 27 days in 1979 the array was emplaced in the lower slope region just above the topographic trench in the area investigated during deep sea drilling project legs 67 and 84 approximately 170 events were recorded by three or more seismometers and almost half were located with statistical hypocentral errors of less than 10 km most epicenters were located immediately landward of the trench axis and many were further confined to a zone northwest of the array in terms of depth most events were located within the subducting cocos plate rather than in the overlying plate or at the plate plate boundary their apparent concentration in the lower crust and upper mantle may suggest that the upper crust does not have the strength to support earthquake generating stresses the data permit construction of a magnitude duration scale calibrated with mb magnitudes for events located by the world wide standard seismograph network wwssn and recorded by our array and by the network recording foreshocks and aftershocks of the 1979 petatlan earthquake most magnitudes ranged between 3 0 and 4 0 mb and the threshold magnitude of locatable events was about 2 8 mb two distinct composite focal mechanisms were determined one appears to indicate high angle reverse faulting in the subducting plate in a plane parallel to trench axis strike the other constructed for some earthquakes in the zone northwest of the array seems to show normal faulting along possible fault planes oriented quasi perpendicular to the trench axis the normal faulting is consistent with the segmentation of the cocos plate that has been proposed from land evidence such segmentation might be evidenced offshore by normal faulting along planes subperpendicular to trench strike alternatively the seismicity zone and associated normal faulting mechanism may be the subsurface expression of the tectonics responsible for the san jose canyon a prominent submarine canyon located farther upslope finally projection of our seismicity sample and of well located wwssn events from 1954 to 1980 onto a plane perpendicular to the trench axis shows a distinct gap between the shallow seismicity located by our array and the deeper wadati benioff zone seismicity located by the wwssn we tentatively ascribe this gap to inadequate sampling but we suggest that it requires further investigation

microseismic properties of a homogeneous sandstone during fault nucleation and frictional sliding summary the formation and evolution of faulting in three initially intact oil saturated specimens of clashach sandstone is examined under conditions of constant strain rate loading at three different confining pressures simulating the effect of tectonic loading at different depths in the earth s upper crust after a fault is formed the specimens are slid for a time and then the initial confining pressure is increased to simulate the long term recovery of strength expected in the earth the differential stress u and natural acoustic emissions ae are measured during the three separate phases of fault nucleation sliding and strengthening at the end of each individual phase the fluid permeability is measured by a pulse decay technique at constant stress the ae are interpreted using a mean field theory for damage evolution which calculates a mean crack length c from the seismic event rate n and the b value and a mean energy release rate g from u and c c and g both increase non linearly in the nucleation stage and are associated with large fluctuations in the scaling exponent b in contrast the b value remains almost constant at a value near unity in the sliding phase even when the fault is mechanically strengthened small fluctuations in g observed during sliding may be associated with the breaking of individual asperities the relative stability of b combined with a relatively constant sliding stress implies that frictional sliding has all the hallmarks of a self organized critical soc phenomenon in contrast the fresh fracture of intact rock shows a continuum of states with power law scaling at a variety of b values where b is negatively correlated to g during the fault nucleation stage the implied subcritical crack growth index n obtained from the ae data shows a distinct break of slope during the failure of the intact specimens from n 2 consistent with a theoretical transition from stable damage to dynamic instability a possible mechanism is the transition from local mechanisms dominated by dilatant hardening negative feedback to microcrack coalescence positive feedback interpreted in this way the results imply that the organized coalescence of microcracks to form a fault occurs before the ultimate strength peak stress is reached this emphasizes the fact that local mechanisms of softening or hardening do not always scale simply to the macroscopic rheology in a heterogeneous medium the fluid permeability reduces steadily throughout all phases of deformation testament to the self sealing nature of deformation in porous sedimentary rocks

classification of earthquake precursors from a fracture mechanics model abstract a new classification of earthquake precursors is proposed based on a fracture mechanics approach which includes the effects of stress and the acceleration of a fracture through an asperity two phases of earthquake warning associated with intermediate term and short term anomalies can be related in a simple manner to two peaks in the stress intensity the first broad peak is further split into two halves associated with precursory strain release strain hardening followed by precursory stress drop strain softening and the second peak responds to the transition from quasi static fracture and slip to dynamic rupture the model predicts a seismic b value anomaly which is in good agreement with laboratory experiment and some aspects of empirical observation of earthquakes in particular evidence is presented of the distinctive short term b value anomaly predicted by the second stress intensity peak and a critical foreshock related b value of 0 5 other earthquake precursors can also be classified into this unifying model and it is suggested that those anomalies which respond to the cumulative production of microcracks e g coda q 1 could produce a more distinctive two stage anomaly after differentiation with respect to time such a two stage anomaly especially if it were observed in several independent earthquake precursors could be a very useful method of deciding when a low level earthquake warning should be changed to a higher level warning

spatial distribution of the difference between the magnitudes of the main shock and the largest aftershock in the circum pacific belt the distribution of the magnitude difference d 1 between the main shock and the largest aftershock for large circum pacific earthquakes is observed to be peaked at 1 2 magnitude units in accord with bath s law but also at 1 8 magnitude units the peak at 1 8 has been not noted before and is shown here with the t test to be statistically valid the observed spatial distribution of the sequences is the basis to suggest that along circum pacific convergent plate boundaries values of d 1 tend to be larger for earthquake sequences within back arc areas as compared to sequences closer to the plate interface although admittedly a good number of exceptions to this generalization are also observed to exist

surface ocean temperatures in the north east atlantic during the last 500 000 years evidence from foraminiferal census data changes in north atlantic sea surface temperature sst are regarded as a key element of the climate during the quaternary however there are relatively few long term records providing quantitative sst estimates from this region using planktic foraminiferal derived ssts together with changes on species level and iceberg rafted debris the last 500 ka were studied pronounced sst changes as determined from the last glacial interglacial cycle characterize most colder periods peak interglacial temperatures were found for marine isotope stages mis 1 5e and 11 the latter two being the warmest the warm substages within mis 7 and 9 are marked by enhanced dissimilarity coefficients indicating that ssts obtained for these times appear to be overestimated this is corroborated by differences within the species assemblage which show enhanced cold water components it is therefore concluded that detailed analysis down to species level is a crucial prerequisite to better reconstructions of sst

the seismic b value and its correlation with bouguer gravity anomaly over the shillong plateau area tectonic implications abstract clues to the understanding of intra and inter plate variations in strength or stress state of the crust can be achieved through different lines of evidence and their mutual relationships among these parameters bouguer gravity anomalies and seismic b values have been widely accepted over several decades for evaluating the crustal character and stress regime the present study attempts a multivariate analysis for the shillong plateau using the bouguer gravity anomaly and the earthquake database and establishes a causal relationship between these parameters four seismic zones zones i iv with widely varying b values are delineated and an excellent correlation between the seismic b value and the bouguer gravity anomaly has been established for the plateau low b values characterize the southwestern part zone iv and a zone zone iii of intermediate b values separates the eastern and western parts of the plateau zones i and ii which have high b values positive bouguer anomaly values as high as 40 mgal a steep gradient in the bouguer anomaly map and low b values in the southwestern part of the plateau are interpreted as indicating a thinner crustal root uplifted moho and higher concentration of stress in comparison the negative bouguer anomaly values flat regional gradient in the bouguer anomaly map and intermediate to high b values in the northern part of the plateau are consistent with a comparatively thicker crustal root and lower concentration of stress with intermittent dissipation of energy through earthquake shocks further depth wise variation in the b value for different seismic zones delineated under this study allowed an appreciation of intra plateau variation in crustal thickness from 30 km in its southern part to 38 km in the northern part the high b values associated with the depth coinciding with lower crust indicate that the shillong plateau is supported by a strong lithosphere

co occurrence of mylodontid sloths and insights on their potential distributions during the late pleistocene abstract species distribution models sdms for the last interglacial lig the global last glacial maximum lgm and the holocene climatic optimum hco were generated for three extinct south american pleistocene mylodontid giant sloths glossotherium robustum lestodon armatus and mylodon darwinii they are recorded co occurring in some localities including arroyo del vizcaino site adv in uruguay co occurrence records were studied based on the overlap of their generated areas of potential distributions and compared with the available biome reconstructions of south america during the lgm to analyze their distribution patterns ecological requirements and possible interactions between them our results suggest that these sloths could have co existed mainly in the chaco parana basin and the plains in the rio de la plata area areas of high suitability were observed for submerged parts of the continental shelf that were exposed during the lgm showing an overall increase in potential habitat compared to the lig and hco this suggests that there was a drastic reduction in total available areas of preferred habitat at the end of the pleistocene the co occurrence of these sloths at the adv site suggests the presence of vegetation indicative of mainly open cold to temperate habitats but with mixed patches typical of humid climates

small mammal taphonomy and the middle pleistocene environments of dolina northern spain abstract the study of past ecosystems can be complex due to taphonomic processes these processes may alter the spatial and temporal location of fossils during site formation the dolina site burgos spain provides an example of the contribution of taphonomy to the interpretation of the past environments this site belongs to the atapuerca ibeas cave complex with extensive evidence of human activity throughout the pleistocene the small mammal assemblages from dolina show evidence that predation has biased species composition to some degree especially in two levels td4 and td11 predator activity appears to have interfered with palaeoecological interpretations and exaggerated inferred climatic changes during the middle pleistocene once possible bias due to taphonomic agents is recognized a more realistic and precise interpretation of the palaeoecology of this area is possible as well as a history of the cave infilling as a background to human use of the cave

estimating the rock volume bias in paleobiodiversity studies to interpret changes in biodiversity through geological time it is necessary first to correct for biases in sampling effort related to variations in the exposure of rocks and recovery of fossils with age data from new zealand indicate that outcrop area is likely to be a reliable proxy of rock volume in both stable cratonic regions where the paleobiodiversity record is strongly correlated with relative sea level and on tectonically active margins in contrast another potential proxy the number of rock formations is a poor predictor of outcrop area or sampling effort in the new zealand case

constraint envelope analyses of macroecological patterns reveal climatic effects on pleistocene mammal extinctions abstract quantitative analysis of macroecological patterns for late pleistocene assemblages can be useful for disentangling the causes of late quaternary extinctions lqe however previous analyses have usually assumed linear relationships between macroecological traits such as body size and range size range shift that may have led to erroneous interpretations here we analyzed mammalian datasets to show how macroecological patterns support climate change as an important driver of the lqe which is contrary to previous analyses that did not account for more complex relationships among traits we employed quantile regression methods that allow a detailed and fine tuned quantitative analysis of complex macroecological patterns revealed as polygonal relationships i e constraint envelopes we showed that these triangular shaped envelopes that describe the macroecological relationship between body size and geographical range shift reflect nonrandom extinction processes under which the large bodied species are more prone to extinction during events of severe habitat loss such as glacial interglacial transitions hence we provide both a theoretical background and methodological framework to better understand how climate change induces body size biased species sorting and shapes complex macroecological patterns

describing a drowned pleistocene ecosystem last glacial maximum vegetation reconstruction of the palaeo agulhas plain abstract pleistocene ecosystems provided the stage for modern human emergence terrestrial vegetation communities structure resources for human foragers providing plant food wood for fuel and tools and fibre as well as habitat for animal prey the pleistocene distribution of vegetation communities is seldom considered as a key constraint on hunter gatherers foraging across the landscape we used modern vegetation patterns along the cape south coast to develop a rule based model of the expected vegetation for a given soil type precipitation regime and fire regime we then applied this ruleset to present day environmental conditions to test and validate the model we also scaled the climate vegetation ruleset to account for likely effects of low atmospheric co2 and lower temperature in the last glacial maximum lgm on plant water use efficiency the model was then used to postdict vegetation patterns for the lgm using palaeo landscape reconstruction of geological substrata and soils and palaeoclimate simulations this palaeoscape comprised the extensive palaeo agulhas plain pap which was exposed at lower sea levels during glacial periods our model predicts that the pap was dominated by limestone fynbos in its southern part and by shale grassland with cappings of dune fynbos thicket mosaic in the north shale and sandstone fynbos were restricted to the western zone which experienced a stronger winter rainfall regime during the lgm than at present the entire pap was dissected by broad and shallow floodplains supporting a mosaic of woodland and grassland on fertile alluvial soils this savanna like vegetation as well as shale grassland are poorly represented in the modern landscape and would have been capable of supporting the diverse megafauna typical of glacial periods these pleistocene periods would have presented a very different resource landscape for early modern human hunter gatherers than the interglacial landscape such as is found in the cape coastal lowlands today

discontinuity in the record for hominin occupation in south western europe implications for occupation of the middle latitudes of europe abstract recent discoveries of evidence for hominin activity in britain before mis 13 challenge previous understanding of the nature of the earliest colonization of nw europe insights into the nature of colonization in this region may be obtained by examining the much richer fossil and archaeological record from iberia it has generally been assumed that southern europe was permanently occupied after the first appearance of hominins in the region and that it provided a reliable source for populations re colonizing areas further north however continuity of occupation in these southern areas is still to be demonstrated this paper provides an outline of the palaeoenvironmental archaeological and fossil evidence from iberia during the early pleistocene and early middle pleistocene this evidence is used to argue that hominin occupation in this region and time period was discontinuous this may help to address a number of questions about the earliest occupation history of nw europe who were the colonists and where did they come from were they strongly limited by climatic conditions were source populations always available in nearby areas and did this influence the permanency of occupation in this region

high resolution climate simulations of oxygen isotope stage 3 in europe abstract oxygen isotope stage 3 ois 3 climate and its variations are the focus of the stage 3 project the objective of the ois 3 modeling effort is twofold 1 to explore the importance of different boundary conditions on the climate of europe and 2 to develop climate simulations that best reproduce the wealth of ois 3 observations given the complexity of the topography and coastlines the modeling effort is based on a nested general circulation model gcm and mesoscale model regcm2 with climate simulations for europe on a 60 km grid spacing the key conclusions are as follows 1 the mesoscale model driven by gcm output does a reasonable job of reproducing the modern european climate 2 ois 3 variations in orbit co2 and ice sheet size are of little significance in explaining the observed climate variability 3 the model results focus attention on north atlantic sea surface temperatures sst as a major factor in explaining ois 3 climates 4 experiments for different sst values capture a number of systematic changes in sea level pressure and precipitation 5 climate models simulate substantial european cooling and significant changes in precipitation but they do not explain large differences between ois 3 warm and cold episodes

an assessment of the contribution of fossil cave deposits to the quaternary paleontological record mammal bearing cave deposits are an important part of the quaternary fossil record but the exact nature of the contribution that caves make to the fossil record is a research area that is largely unexplored to explore this issue late pleistocene species representation in cave versuses non cave deposits was examined additionally this study examined how fossiliferous cave deposits influence perceptions of past biogeographic distributions and evaluated factors that impact the distribution of cave deposits across the united states cave deposits account for a high proportion of the individual species records known from the late pleistocene and caves provide the only late pleistocene records of 14 individual taxa calculated ratios of individual taxonomic records from caves relative to the total number of individual taxonomic records resulted in a value of 0 62 the impact of cave data on understanding of late pleistocene biogeographic distribution patterns vary among individual species of sciurid rodents geographic analyses comparing the distribution of cave and non cave sites in texas suggest a strong relationship between site distribution and specific geologic and hydrologic features ultimately understanding potential biases recorded in distinct depositional settings provides improved frameworks for interpreting the adequacy of the fossil record

understanding the ancient habitats of the last interglacial late mis 5 neanderthals of central iberia paleoenvironmental and taphonomic evidence from the cueva del camino spain site the cueva del camino site pinilla del valle madrid represents the most complete mis 5 record from the iberian peninsula away from the mediterranean margin including a large accumulation of fossilized remains of small and large vertebrates and two human teeth the presence of carnivores mainly hyenas and humans suggests that the site should be interpreted as a spotted hyena den a human occupation or both during an earlier phase of excavation undertaken during the 1980s an anthropic origin was suggested for the accumulation at the site however research was resumed in 2002 leading to an increase in the number of vertebrate remains recovered as well as the recognition of new vertebrate species these have now been incorporated into the site s list of fauna in addition new palaeobotanical geochronological and stratigraphic data have been recorded and analysed and the human teeth identified as being of neanderthal origin floristic data pollen and charcoal remains obtained for the north sector of this site indicate an open landscape with pinus sylvestris nigra as the main arboreal taxon the available evidence suggests this accumulation to be the result of spotted hyena activity during a warm phase of marine isotope stage 5 mis 5 in an environment in which fallow deer was the most abundant herbivore

radiocarbon dating and stable isotopes analyses of caiman latirostris daudin 1801 crocodylia alligatoridae from the late pleistocene of northeastern brazil with comments on spatial distribution of the species abstract caiman latirostris is a crocodilian reptile widely distributed in south america the fossil records for this species are limited in the continent and radiocarbon dating plus isotope analysis has not been performed to the existing records which prevent accurate paleoecological reconstructions thus the present study aimed to record the occurrence of a fossil of c latirostris in sergipe state northeastern brazil providing the first data of radiocarbon dating and stable isotopes 13 c and 18 o for this species as well as maps of the potential distribution for the present time and for the last glacial maximum 21 ka our results indicate that the analyzed specimen occurred in sergipe brazil between 11 068 11 211 cal bp 9680 30 bp and fed on mixed feeder animals 13 c 3 00 possibly insects shrimp snail fish and birds it appears that its body temperature was 26 c similar to the extant crocodilian species crocodylus niloticus indicating that the species lived in the nearby rivers or in tanks ancient lagoons a map displays the current distribution while the map for 21 ka indicates a restricted distribution for this species in south america perhaps caused by the dry and cold climate in the last glacial maximum which affected the distribution of water sources for this organism

relative stress variations as determined by b values from earthquakes in circum pacific subduction zones abstract assuming a relation of b to stress state the possibility of globe wide stress variation and transmission was investigated the noaa earthquake data file served to determine the temporal change in b of log n a bm from 1963 to 1975 periods of six to eight years are observed in the b values stress pattern for most circum pacific areas south america tonga kermadec new hebrides kamchatka and eastern aleutians in the kurils fore and aftershock sequences of large earthquakes seem to mask any characteristic global pattern that might exist these sequences exhibit low b values high stress through the time of foreshocks and early stages of aftershocks followed by rapid increase in b values decrease in stress use of a worldwide earthquake data file clearly yields less resolution of the temporal b variation than the use of local network studies published by other authors incidental to the study 1124 earthquakes of the noaa data file yield the ms mb relations ms 1 16mb 0 835 for 4 5 mb 6 and log10ms 0 1432mb 0 0629 formb 6 with correlative coefficients of 0 994 and 0 992 respectively

analyzing niche stability and biogeography of late ordovician brachiopod species using ecological niche modeling abstract gauging the potential impacts of environmental change on the geographic distributions of species is a central area of modern biogeographic analysis often involving complex models of species environment interactions the geographic distribution of fossil species can also provide a framework to test the impact of environmental change on biogeography and ecological niches of species yet few paleontological analyses have attacked this question in deep time herein we present a quantitative biogeographic analysis to examine the stability of ecological niches and geographic ranges of rhynchonelliform brachiopods during an interval of sea level change preserved in upper ordovician strata of the cincinnati arch the intensive sampling excellent preservation and numerous prior paleoecological and sedimentological analyses within the tri state region of kentucky indiana and ohio provide a robust framework for detailed paleobiogeographic study quantitative biogeographic modeling methods incorporating gis geographic information systems are utilized in order to spatially analyze the geographic ranges of brachiopod species of the corryville and mt auburn formations of the c3 uppermost maysvillian depositional sequence this study employs the ecological niche modeling program garp genetic algorithm using rule set prediction to predict the geographic distribution of eight brachiopod species during three time slices within the c3 sequence this method estimates a species geographic range by modeling the ecological niche of the species based on a set of known species occurrence data coupled with environmental data inferred from sedimentologic proxies once environmental tolerances for a species are modeled the species is predicted to occur wherever its preferred set of environmental conditions occurs within the study region distributional patterns were reconstructed for three time slices during the c3 sequence recovered range predictions were quantitatively analyzed for evidence of temporal range changes results indicate that average species range within the study area decreased and species tracked their preferred niche with high fidelity during the transition from the early to middle portions of the c3 depositional sequence an interval of rapid relative sea level change however during the transition from the middle to late portions of the sequence gradual shallowing within the basin and development of discontinuous habitat patches correlates with niche evolution of five of the eight species modeled the average area a species occupied within the basin increased during this interval but there is a mixed response including both increases and decreases in range size within the study group in general the species that exhibit niche evolution increased their geographic range size while those that continue to track their niche with high fidelity experience a decrease in geographic range size during the latter half of the c3 sequence previously continuous habitats become fragmented thereby isolating individual populations and providing a mechanism for niche evolution the rate of sea level change and the corresponding fragmentation of previously continuous habitats into isolated patches appear to be the primary controls on both mean geographic range size and relative degree of niche evolution

seismicity focal mechanisms and tectonics in the last four years there has been a tremendous increase in the detail of tectonic processes reported in the typical seismotectonic study new data from many local and regional networks of seismographs established during the previous four year period plus the now routine application of improved hypocentral location procedures long period body wave modelling and moment tensor inversion using digitally recorded data have increased resolution of both the hypocentral location and the nature of the faulting process consequently research emphasis has been on local tectonics or those aspects of regional and global tectonics requiring high resolution i briefly describe below some of the highlights of these studies

climate and humans set the place and time of proboscidean extinction in late quaternary of south america abstract the late quaternary extinctions have been widely debated for a long time but the varying magnitude of human vs climate change impacts across time and space is still an unresolved question here we assess the geographic range shifts in response to climate change based on ecological niche models enms and modeled the timing for extinction under human hunting scenario and both variables were used to explain the extinction dynamics of proboscideans during a full interglacial glacial cycle from 126 ka to 6 ka in south america we found a large contraction in the geographic range size of two proboscidean species studied cuvieronius hyodon and notiomastodon platensis across time the largest contractions of their geographical ranges occurred in the northern part of south america where we previously reported no evidence of coexistence among earliest humans and non sloth megafauna including proboscideans our results herein support a strong effect of climatic changes on geographical range dynamics of proboscideans throughout late quaternary although this does not fully support climate change as the single cause of their extinctions we show that both proboscideans were narrowly distributed on scattered patches of suitable habitats i e refugia around 11 ka period in which the earliest humans potentially arrived in south america increasing the population density thereafter under this overall unsuitable climatic condition at 11 ka both proboscideans would be extinct after around 550 years of human hunting but if climatic conditions were suitable like in last glacial maximum lgm the time for extinction would be at least 3 times longer under the same human hunting pressures thus our findings support the broken zig zag model and show that south american proboscideans might have been completely extinct due to human impacts during periods of climate crisis we conclude in agreement with an increasing body of evidence in the recent literature that the late quaternary megafaunal extinction event was the result of additive effects from different stressors and that the relative magnitude of these impacts vary across space and time indeed climate changes set the place where the proboscideans were extinct in south america whereas the humans set the time of these extinctions

one million years of cultural evolution in a stable environment at atapuerca burgos spain abstract the present paper analyses the evidence provided by three sites sima del elefante gran dolina and galeria located in the trinchera del ferrocarril of the sierra de atapuerca these three sites are cave infillings that contain sediments deposited from approximately 1 2 ma to 200 kyr pollen herpetofauna and small and large mammal remains are used as proxies to obtain a general picture of the environmental changes that occurred at the sierra de atapuerca throughout the one million year period represented at these sites similarly cultural changes are tracked analyzing the evidence of human behavior obtained from the study of several bone and lithic assemblages from these three sites at least three periods with different cultural features involving technology subsistence and behavior are determined from the available evidence the first two periods correspond to the mode 1 technology and homo antecessor the first is dated around 1 2 to 1 0 ma and reflects opportunistic behavior both in technology and subsistence the second period is around 800 kyr bp mode 1 technology is still maintained but subsistence strategies include systematic hunting and the use of base camps the third period is dated between 500 ka and 200 ka and corresponds to the mode 2 technology and the acquisition of directional hunting and other organizational strategies by homo heidelbergensis a transition from mode 2 to mode 3 seems to appear at the end of this time range and may reflect the early phases of a fourth cultural change with regard to the environment our main conclusion is that there was an absence of extremely harsh conditions at atapuerca throughout this time period the presence of mediterranean taxa was constant and the dominant landscape was a savannah like open environment probably with small forest patches an alternation of mediterranean and mesic species as the dominant component of the tree storey was induced by the climatic cycles and steppes spread across the landscape during the drier periods in any case it is not possible to establish clear cut off points separating entirely different environmental episodes our results show no evidence of any relationship between environmental change and cultural change at the sierra de atapuerca

temporal variations in seismicity during quasi static and dynamic rock failure abstract a comprehensive model is presented which can explain temporal fluctuations in seismic b values in the period leading to mechanical failure in terms of the underlying physical processes of time varying applied stress and stress corrosion enhanced crack growth under conditions of constant strain rate the form of the b value anomaly in the period leading to failure depends on the form of the stress time relationship for the case where dynamic failure occurs at peak stress after a period of strain hardening the model predicts a single cusp like b value anomaly reaching a critically low value of 0 5 at failure for the physically most realistic case where dynamic failure is preceded by a period of precursory strain energy release during strain softening the model predicts two minima in the b value separated by a temporary maximum or inflection point these fluctuations in the b value are consistent with reported intermediate term and short term earthquake precursors separated by a period of seismic quiescence for the case of quasi static cataclastic flow the b value mirrors the stress and never falls to the critical value because there is no critical rupture new results from a series of controlled laboratory experiments are presented in which microseismic event rates and b value were monitored contemporaneously with stress time data for all variants of the stress time relationship recent field observations of temporal changes in seismicity rates and b value preceding major earthquakes are also reported both data sets exhibit b value anomalies which are consistent with the model predictions

evaluating the effect of plowing on the archaeological record the early middle palaeolithic in the river duero basin plateaus north central spain an abundant open air early middle palaeolithic record has been preserved in the duero basin plateaus castilla y leon region north central spain a long term landscape archaeology project has been underway in this area and since 1996 a number of studies have been carried out in order to evaluate the role played by post depositional factors in the refuse patterns observed the main post depositional disturbance forces are cultural ones and relate to the development of intensive mechanized agriculture the landscape project on the duero basin plateaus constitutes the first case in the iberian peninsula in which the effects of plowing have been monitored from a wide variety of approaches in a single area and on a long term basis at the same time this region offers a unique opportunity to evaluate the effect of plowing in palaeolithic spatial patterns this paper summarizes the main research lines on plowzone archaeology carried out between 1996 and 2007 within the landscape archaeology project undertaken in the palaeolithic sites of the duero plateaus and stresses the main assets of the archaeological record affected primarily by plowing

the extent and chronology of cenozoic global glaciation abstract the quaternary is synonymous with extensive glaciation of earth s mid and high latitudes although there were local precursors significant glaciation began in the latest eocene ca 35 ma in eastern antarctica it was followed by glaciation in mountain areas through the miocene in alaska greenland iceland and patagonia later in the pliocene e g in the bolivian andes and possibly in tasmania and in the earliest pleistocene e g in the alps new zealand iceland and greenland today evidence from both the land and the ocean floors demonstrates that the major continental glaciations outside the polar regions rather than occurring throughout the 2 6 ma of the quaternary were markedly restricted to the last 1 ma 800 ka or less marine isotope stage mis 22 ca 870 880 ka included the first of the major worldwide events with substantial ice volumes that typify the later pleistocene glaciations i e mis 16 12 10 6 4 2