oxygen and carbon isotopes in modern fresh water ostracod valves assessing vital offsets and autecological effects of interest for palaeoclimate studies abstract the isotopic composition of modern benthic ostracod and mollusc carbonate the oxygen isotope composition of lake water 18ow the carbon isotope composition of dissolved inorganic carbon 13cdic and water temperatures were monitored during a year at different water depths in two lakes ammersee and starnberger see southern germany the aim was to test whether the valves are built in isotopic equilibrium and how seasonal water temperatures are recorded in the shells we find systematic offsets between 18o of valve carbonate compared to 18o expected for a theoretical calcite formed in isotopic equilibrium offsets are higher than 2 for different species of the candona group 1 5 for cytherissa lacustris and around 0 8 for limnocythere inopinata and darwinula stevensoni they seem to be constant for all instars of a species and temperature independent mean water temperatures of the calcification period are readily reflected in the valve 18o if corrected for the offsets 13c of valve carbonate is mainly controlled by 13c of the dissolved carbonate in ambient lake water but seems to be biased by micro habitat effects and vital offsets the study provides information on the seasonality of valve formation thus potentially allowing the quantification of temporal and spatial water temperature gradients from specific 18o records

10be derived sub milankovitch chronology of late pleistocene alluvial terraces along the piedmont of sw tian shan abstract using topographic maps and terrestrial cosmogenic nuclide tcn 10be exposure dating methods we reconstructed a chronology with robust age constraints based on four alluvial terrace abandonment features in two study sites along the sw piedmont of kepingtage mountain in sw tian shan agreement between alluvial terrace abandonment ages and guliya ice core 18o lr04 stack of benthic 18o epica dome c ch4 and solar insolation records suggests that alluvial terraces with 10be age sequences at 63 7 5 9 ka 40 9 3 84 ka 36 2 3 4 ka and 22 1 5 1 4 7 ka correspond to three wetter climate intervals possibly triggered by intensified south asian summer monsoons since the late pleistocene given that the active thrust kepingtage fault experienced sustained uplift during this period we suggest that the abandonment of alluvial terraces that formed since 22 1 5 1 4 7 ka may be related to sudden tectonic uplift the occurrence of these four younger well preserved alluvial terraces may also be related to the fact that the transient climatic incision has been no higher than the temporary tectonic uplift since 22 1 5 1 4 7 ka

timing of the matuyama brunhes geomagnetic reversal decoupled thermal maximum and sea level highstand during marine isotope stage 19 recent high resolution magnetic and microfossil data from a long core penetrating the osaka group japan are astronomically tuned and reassessed to reveal detailed stratigraphic features across the matuyama brunhes mb polarity transition during marine isotope stage mis 19 the sediments have a uniform and high average accumulation rate of 63 cm ky astronomical tuning based on six calibration points including a clear mis 19 2 sea level lowstand dates the main mb boundary mbb to 777 6 ka the sea level peak of the mis 19 3 highstand to 780 7 ka and the climatic thermal maximum tm to 776 4 ka the mb transition began with a short lived normal polarity episode that occurred before the highstand at mis 19 3 and terminated with multiple rapid reversals that occurred between highstand mis 19 3 and lowstand 19 2 the tm just postdates the termination of the mb transition and occurs about 4000 years after the sea level peak the delayed tm is also observed at gesher benot ya aqov israel and on the mediterranean coast and possibly at lake baikal in high resolution records from chinese loess paleosols and deep sea sediments the rapid reversal zone of the mbb has a very similar climatostratigraphic character these magneto climatostratigraphic features in mis 19 are useful for correlating between terrestrial and marine sediments the delay in warming relative to the sea level highstand seems to have been due to a cloud albedo effect induced by an increase in galactic cosmic ray flux during an extremely low magnetic field intensity interval

eight glacial cycles from an antarctic ice core the antarctic vostok ice core provided compelling evidence of the nature of climate and of climate feedbacks over the past 420 000 years marine records suggest that the amplitude of climate variability was smaller before that time but such records are often poorly resolved moreover it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records here we report the recovery of a deep ice core from dome c antarctica that provides a climate record for the past 740 000 years for the four most recent glacial cycles the data agree well with the record from vostok the earlier period between 740 000 and 430 000 years ago was characterized by less pronounced warmth in interglacial periods in antarctica but a higher proportion of each cycle was spent in the warm mode the transition from glacial to interglacial conditions about 430 000 years ago termination v resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases but there are significant differences in the patterns of change the interglacial stage following termination v was exceptionally long 28 000 years compared to for example the 12 000 years recorded so far in the present interglacial period given the similarities between this earlier warm period and today our results may imply that without human intervention a climate similar to the present one would extend well into the future

numerical modelling of drainage basin evolution and three dimensional alluvial fan stratigraphy abstract a forward numerical model is presented to study the effects of bedrock erodability thrust displacement rate pulsating tectonic activity and sea level fluctuations on drainage basin morphology and stratigraphy of large alluvial fan systems a low value of the bedrock erodability coefficient k b 0 5 10 4 year 2 3 vs thrust rate 2 0 m ky is associated with a time lag between cessation of tectonic activity and maximum sedimentation rates observed on the alluvial fans applying higher k b values ranging between 1 0 and 8 0 10 4 year 2 3 results in higher sediment yields due to more rapid headward catchment erosion and elaborate sideways branching of drainage networks pulsating tectonic activity is reflected in a stratigraphic alternation of prograding and retrograding alluvial fan gravels during tectonic activity fan gravel fronts and coastlines retreat because catchment yields are insufficient to fill the accommodation space created by the flexural response due to thrust loading phases of tectonic quiescence and cessation of flexural subsidence are indicated by progradation of the gravel front depending on the position in the basin the lag time for arrival of the gravel associated with tectonic cessation is several tens to hundred thousands of years a combination of pulsed tectonic activity with sinuous sea level fluctuation leads to a more complex stratigraphic pattern in that case stratigraphic response to tectonic pulses is masked by a similar but higher order frequency stacking pattern especially in the more distal parts

alluvial fan morphology distribution and formation on titan abstract titan is a hydrologically active world with dozens of alluvial fans that are evidence of sediment transport from high to low elevations however the distribution and requirements for the formation of fans on titan are not well understood we performed the first global survey of alluvial fans on titan using cassini synthetic aperture radar sar data which cover 61 of titan s surface we identified 82 fans with areas ranging from 28 km2 to 27 000 km2 a significant fraction 60 of the fans are restricted to latitudes of 50 80 suggesting that fluvial sediment transport may have been concentrated in the near polar terrains in the geologically recent past the density of fans is also found to be correlated with the latitudes predicted to have the highest precipitation rates by titan global circulation models in equatorial regions observable fans are not generally found in proximity to dune fields such observations suggest that sediment transport in these areas is dominated by aeolian transport mechanisms though with some degree of recent equatorial fluvial activity the fan area drainage area relationship on titan is more similar to that on earth than on mars suggesting that the fans on titan are smaller than what may be expected and that the transport of bedload sediment is limited we hypothesize that this has led to the development of a coarse gravel lag deposit over much of titan s surface such a model explains both the morphology of the fans and their latitudinal concentration yielding insight into the sediment transport regimes that operate across titan today

the rate of pleistocene subsidence and sedimentation in the hula basin as compared with those of other time spans in other israeli tectonic regions absolute dating of quaternary sediments in the hula basin northern israel by means of radiocarbon and 230th 234u gives the rate of subsidence of the basin the rate of sedimentation which can be obtained by adding the calculated compaction is quite a bit higher from the hula basin and other parts of the country it is evident that different rates of subsidence and vertical displacements are obtained for different time spans rates become higher as the time span becomes shorter and the age younger rates calculated for time spans since the neogene since the quaternary and for the last decades are on the order of magnitude of 10 1 mm y 100 mm y and 101 mm y respectively

influence of lithologic erodibility on alluvial fan area western white mountains california and nevada differences in lithologic erodibility and sediment storage within a drainage basin affect the relationship between alluvial fan area and drainage basin area along the western white mountains large fans are produced by basins underlain by resistant rocks which have steep and narrow trunk stream canyons with little sediment in storage small fans are produced by basins composed of erodible lithologic units which have wider valley floors lower valley side slopes and considerably more sediment stored along trunk stream canyons than is the case in basins underlain by resistant rocks

the reconstruction of quaternary freshwater lakes from the chemical and isotopic composition of gastropod shells the dead sea rift israel abstract sr ca ba ca and 87sr 86sr ratios in fossil freshwater aragonitic gastropods melanopsis praemorsum and melanoides tuberculata have been used to reconstruct the water sources of quaternary lakes in the jordan river rift valley the reconstruction is based on the assumption that the same waurces which supply freshwater into the rift valley in the present i e carbonate water basaltic water and rift brines were active throughout the quaternary the distribution coefficients for sr and ba were obtained from live gastropods which were collected from modern water bodies in the region by using these distribution coefficients the composition of the ancient waters could be derived from the fossil shells chemistry altogether four ancient sites were sampled of which mishmar ha yarden and gesher benot ya akov formations are located in the upper jordan valley and erq el ahmar and ubeidiya formations are in its central part low salinity carbonate waters 300 mg l comprised the main h2o source into the hula basin in the upper jordan valley these solutions display a 87sr 86sr ratio of 0 7082 0 0002 which is significantly higher than the corresponding modern ratio 0 7070 suggesting that the ancient drainage system was initially fed by upper eocene carbonate aquifers and shifted later to a jurassic carbonate system the erq el ahmar lake in the central jordan valley was supplied by approximately equal proportions of carbonate and basaltic waters resulting in a water body of low salinity 300 mg l the water source of lake ubeidiya also in the central jordan valley was predominantly basaltic yet its chemistry bears a strong rift brine signature resulting in a salinity of about 1000 1300 mg l the values obtained are in good accord with the biological evaluation of the fossil biota

modeling alluvial landform change in the absence of external environmental forcing alluvial fan evolution and morphology are often considered to respond primarily to external forcing e g tectonics climate and base level change here we present a numerical model of alluvial fan evolution that shows that dramatic and persistent fan entrenchment may occur in the absence of such forcing this process is driven by positive autogenic feedbacks between flow width sediment transport and rate of fan aggradation entrenchment is initiated where sediment accommodation space limits continued fan growth our results highlight a need to rethink both the representation of fluvial width adjustment in landscape evolution models and the established framework for the interpretation of fluvial landforms as archives of environmental change

corrigendum to an integrated model for dune morphology and sand fluxes on mars earth planet sci lett 457 2017 204 212

climate as main factor controlling the sequence development of two pleistocene alluvial fans in the vienna basin eastern austria a numerical modelling approach abstract tectonics climate base level and source lithology are the main controlling factors on alluvial fan development and evolution in this study a numerical model approach was used to investigate climate induced aggradation and degradation cycles the influence of tectonic subsidence and the impact of an axial main river on austria s largest pleistocene alluvial fan setting the mitterndorf basin eastern austria a simulation time frame of 25 ka was applied climatic variations were mainly modelled through variations in sediment supply whereas the impact of subsidence was modelled through variations in slip rates along faults incision and aggradation tendencies of the axial main river were modelled by rising or lowering of the water level the sequence development and geometry of mitterndorf basin s alluvial fans are mainly controlled by pleistocene climate oscillations cold periods generally led to a decrease in vegetation cover and to an increase of periglacial weathering processes which is associated with abundant sediment release and aggradation on fan surface in contrast decreasing sediment supply and increasing precipitation during warmer periods led to fan degradation our models indicate that the alluvial fan development is primarily affected by the distinct sediment supply pulses during phases of short climatic perturbations subsidence becomes the determining factor again when models approach a steady state behaviour similarly the impact of the axial main river becomes more important during simulated warm periods when sediment release to the drainage basin is low the overall basin slope additionally controls the evolution of fan and drainage variations in sediment supply and subsidence do also significantly control the long term evolution of the drainage network during simulated warm periods and thus control the sequence preservation potential of fans and therefore its long term sequence evolution

early and middle pleistocene faunal and hominins dispersals through southwestern asia abstract this review summarizes the paleoecology of the early and middle pleistocene of southwestern asia based on both flora and fauna retrieved from a series of windows provided by the excavated sites the incomplete chrono stratigraphy of this vast region does not allow to accept the direct chronological correlation between the available sites and events of faunal and hominin dispersals from africa it also demonstrates that hominins survived in a mixed landscape of open parkland with forested surrounding hills in addition the prevailing environmental conditions are not sufficient to explain successful adaptations to new ecological niches away from the african savanna of the bearers of core and flake and the acheulian industries the differences in knapping and secondary shaping of stone artifacts probably reflect the learned traditions of different groups of hominins the current distribution of lithic industries across eurasia is undoubtedly incomplete due to lack of cultural continuities as well as paucity of field research in several sub regions this observation supports the contention that what we view as a constant stream of migrants was actually interrupted many times the continuous occupation of southwestern asia by the makers of the acheulian is in contrast with neighboring regions such as the iranian plateau and eastern europe a more complex model is required to explain the recorded eurasian archaeological cultural mosaic

preferred directions of flow on alluvial fans in this paper modifications of the method used to delineate flood plains on active alluvial fans for the national flood insurance program are suggested given new data regarding the deviations of channels from the medial radial line at the apex of the fan in the original methodology it was assumed that every point on an alluvial fan contour had an equal probability of being impacted during a flood event that is a uniform probability distribution was assumed data now available suggest that a normal distribution better describes the probability of points on an alluvial fan contour being hit during a flood event results from an example of the application of the modified methodology are compared with the results obtained using the original methodology

fluvial fan deltas linking channel processes with large scale morphodynamics 1 alluvial fan deltas are built by aggrading and avulsing river channels a numerical model of flow and sediment transport in channels is combined with a condition for channel avulsion to describe evolution of the fan surface the model combines elements of two recent approaches 1 diffusional models of depositional basin filling which describe the evolution of overall morphology and 2 cellular models of channel evolution which provide simplified descriptions of channel dynamics here the cellular formulation is used simply as a template for discretizing a standard set of equations describing flow and sediment transport within channels the basic formulation is thus grid invariant and the results are in actual rather than arbitrary time and length scales the model captures the interaction between microscale channel morphodynamics including converging and diverging flow and avulsion and morphodynamics at the macroscale fan it provides a starting point for the study of a wide range of topics including the three dimensional stratigraphy of fan delta deposits and the response of fan deltas to engineering activities

holocene climate change evidence from high resolution loess paleosol records and the linkage to fire climate change human activities in the horqin dunefield in northern china abstract the combination of high resolution sedimentary paleoclimate proxies of total organic carbon and magnetic susceptibility of a loess paleosol section with black carbon bc records provides us with information about climate change and the linkage of fire climate change vegetation human activities in the horqin dunefield over the past 11 600 cal yr bp we found that during 11 600 8000 cal yr bp the early holocene the area was dominated by a dry climate the vegetation coverage was low which limited the extent of fire the holocene optimum can be placed between 8000 and 3200 cal yr bp and during this period anthropogenic fire was a key component of total fire occurrence as the intensity of human activity increased the development of agricultural activities and the growing population during this period increased the use of fire for cooking food and burning for cultivation and land fertilization purposes during 2800 2600 cal yr bp a warm moister climate prevailed and was associated with a high degree of pedogenesis and vegetation cover density evident at 2700 cal yr bp fires may have contributed to human survival by enabling the cooking of food in the warm and wet climate in the period since 2000 cal yr bp fires linked to agriculture may have led to increased biomass burning associated with agricultural activity

stratigraphy and isotope records of middle and late pleistocene mollusks from a continuous corehole in the hula basin northern jordan valley israel morphological changes in melanopsis shells and the sudden disappearance of viviparus were observed in a continuous core representing about 700 000 yr taken from the l 12 corehole in the hula basin northern jordan valley israel two major events in 18o values are recorded the first at about 435 000 yr b p is accompanied by a shift in 13c values and indicates a shallowing phase with slightly higher evaporation this event is concurrent with the abundant occurrence of a monotypic distorted melanopsis suggesting an ecophenotypic event during deposition of the lake s pleistocene lower lacustrine beds the second major isotopic event is evidenced in the lower part of the section as a gradual depletion in 18o toward the bottom of the corehole minor shifts of 1 20 in the oxygen isotope content along the core may represent changes in the 18o values of the water from glacial to interglacial periods representing the major climatic cycles of the pleistocene five of these cycles were observed along the core

modelling alluvial fan morphology a mathematical model which estimates the scale independent sediment surface profile of alluvial fans has been developed this model utilizes a diffusive sediment transport model and an unsteady radial flow conservation relationship these equations are approximately solved assuming a quasi steady state closure with appropriate modelling assumptions for two end member fan types 1 fans where most of the fan surface is depositionally active denoted here as homogeneous and 2 fans characterized by channelling and sediment sorting processes the fundamental result for these two fan types is a dimensionless sediment profile relationship which approximates most fan surfaces the model suggests that the overall dimensionless morphology of alluvial fans is governed more by fundamental diffusion principles in sediment deposition than by individual environmental or basin characteristics additionally this work potentially can be extended to model temporal variation in fan development preliminary comparison with alluvial fan profiles is reasonable indicating that this model provides useful qualitative and quantitative information relating to alluvial fan process and morphology copyright 1999 john wiley sons ltd

investigating the use of alluvial fan volume to represent fan size in morphometric studies studies of the morphometric properties of alluvial fans have predominantly used a two dimensional planimetric area to represent fan size even though fans are three dimensional sediment deposits but the validity of this substitution has been questioned volumes of fans in nonsubsiding settings were estimated with the objective of investigating the relationship between fan volume and fan area a simple geometric approach was developed so that volumes of noncoalescent fans could be estimated with measurements from topographic maps data were collected from two study areas with humid temperate climates the bow valley in alberta canada and the absaroka range in wyoming usa because these landscapes were glaciated the fans are of paraglacial origin and are not related to contemporaneous tectonic subsidence using functional relation analysis results indicate that the proportional power law relationship between fan volume and fan area is not significantly different from 1 1 in both study areas morphometric relationships between fans and drainage basins are also examined with fan volume and cumulative sediment yield employed as variables

gis analysis of depositional slope change at alluvial fan toes in japan and the american southwest abstract slope change at alluvial fan toes provides a clue to understanding differences between alluvial fans and other depositional landforms this paper analyses topographic data for 430 alluvial fans and their adjacent lowlands in japan and the american southwest asw typical humid and arid regions with abundant alluvial fans arcs showing fan toes were identified and representative areas above and below each arc were then delineated based on a gis buffer analysis the mean slope of the area above sa and below the fan toe sb and the ratio of sa to sb rs were computed overall fan slope so total fan length l and angle of the fan apex af were also measured relationships among these morphometric parameters reflect differences in climate and sedimentary processes fans in the asw tend to have straight profiles with similar values for sa and so indicating that fan gradients from deposition resulted from low frequency high magnitude storms have been preserved well under an arid climate higher rs values result from good preservation of both steep fan surfaces and gentle adjacent lowlands which is also ascribable to infrequent sediment redistribution in japan sa tends to be smaller than so and rs is often close to unity reflecting frequent sediment redistribution on fans and across fan toes under a humid climate rs in both the regions tends to converge into unity with increasing l longer alluvial fans are more strongly dominated by fluvial processes than by mass flows especially at their toes longer fans also tend to have small af leading to fluvial processes similar to those on floodplains sediment re mobilisation at the toes of such fans is more frequent resulting in smaller differences between sa and sb

evidence for climatic changes around the matuyama brunhes boundary mbb inferred from a multi proxy palaeoenvironmental study of the gby 2 core jordan river valley israel the acheulian site of gesher benot ya aqov gby in the upper jordan valley revealed important data on environment and material culture as well as evidence for hominin behavioural and cognitive patterns documented at the margins of the hula palaeo lake a 50 m long core gby 2 drilled at the archaeological site has provided a long pleistocene geological environmental and climatological record which expands the existing knowledge of hominin habitat relationships bracketed by two basalt flows dated by 40ar 39ar and based on the identification of the matuyama brunhes boundary mbb and correlation with the gby excavation site the sedimentary sequence provides the climatic history around the mbb multi proxy data including pollen and non pollen palynomorphs macro botanical remains molluscs and ostracods provide evidence for lake and lake margin environments during marine isotope stages mis 20 and 19 semi moist conditions were followed by a pronounced dry phase during mis 20 and warm and moist conditions with quercus pistacia woodlands prevailed during mis 19 in contrast to the reconstructed climate change from relatively dry to moister conditions the depositional environment developed from an open water lake during mis 20 to a lake margin environment in mis 19 generally shallower conditions at the core site in mis 19 resulted from the progradation of the lake shore due to the filling of the basin micro charcoal analysis suggests a likelihood of human induced fire in some parts of the core which can be correlated with artefact containing layers of the gby excavation site the hula palaeo lake region provided an ideal niche for hominins and other vertebrates during global glacial interglacial climate fluctuations at the end of the early pleistocene

patterns in mobility and modification of middle and high latitude southern hemisphere dunes on mars nasa mars data analysis program mdap nnx14ao96g mdap grant nnx12aj38g nnx16aj43g 123117

the structure and morphotectonics of the gesher benot ya aqov area northern dead sea rift israel abstract geological geomorphological and morphotectonic studies at the gesher benot ya aqov acheulean site northern jordan valley provide 1 a unique opportunity to establish the ecological background of hominid behavior during the early stages of widespread human occupation 2 crucial data for understanding the paleo environment and the various processes that affected the area near the gesher benot ya aqov site and 3 a basis for further comprehensive research in the region quaternary tectonic activity near the acheulean archeological site has produced a complex local setting that controls the surrounding landscape tectonic activity formed the benot ya aqov embayment which attracted hominids and a variety of other fauna sediments of the benot ya akov formation deposited in the embayment facilitated excellent preservation of the remnants of acheulean hominid activities and of abundant floral and faunal remains the formation was subsequently affected by faulting and folding local uplift ended the deposition of lacustrine sediments in the embayment of hula valley basin and caused erosion and vertical incision of the jordan river that resulted in the capture of the rosh pinna river and the exposure of the benot ya akov formation these deposits are found in different structural positions along the north south oriented morphotectonic embayment the outcrops contain numerous archeological sites giving the study area an unusually high potential for future hominid discoveries

air humidity and lake δ18o during the latest paleocene earliest eocene in france from recent and fossil fresh water and marine gastropod δ18o δ13c and 87sr 86sr detailed isotopic 18 o 13 c 87 sr 86 sr analyses have been performed on aragonitic fresh water brackish water and marine gastropod shells of latest paleocene earliest eocene age from northwestern europe fresh water shells e g viviparus lymnaea from sparnacian deposits in the paris basin show relatively high 18 o values in the range 4 to 0 1 large intrashell 18 o variability typically 3 is consistent with significant seasonal variation in precipitation and or temperature we also present intrashell isotopic profiles for 22 recent fresh water shells mainly viviparidae representing the major middle to low latitude climate zones e g sweden france portugal lake chad ceylon gambia congo lake victoria new guinea distinct isotopic patterns reflecting humidity and temperature characterize each of the climate zones comparing the results for recent and fossil shells suggests that the climate in northern france during sparnacian time was warm subtropical with a pronounced seasonal drought the 18 o composition of sparnacian lake water has been estimated from the fossil fresh water shell 18 o and by using seasonal temperatures derived from 18 o profiles of fully marine shells the best estimate of the 18 o composition of sparnacian lake water compared with eocene mean ocean water is 1 this is consistent with paleorain 18 o values of 3 to 5 similar to present mean rain 18 o standard mean ocean water values close to 4 in portugal at 40 n the paleolatitude of the paris basin during earliest eocene time the evaporated nature of sparnacian lake water contradicts hypotheses of globally equable humid conditions in the warm early eocene and instead suggests that dry subtropical highs occurred over the eastern parts of the oceans similar to today the results of this study demonstrate the potential of fossil fresh water carbonates to reconstruct the development of subtropical highs and hadley cell circulation in the past

alluvial fans formed by channelized fluvial and sheet flow i theory alluvial fans and fan deltas are of three basic types those built up primarily by the action of constantly avulsing river and stream channels those constructed by sheet flows and those resulting from the successive deposition of debris flows the present analysis is directed toward the first two types a mechanistic formulation of flow and sediment transport through river channels is combined with a simple quantification of the overall effect of frequent avulsion to derive relations describing the temporal and spatial evolution of mean i e averaged over many avulsions bed slope and elevation in an axially symmetric fan an example of a fan formed predominantly by the deposition of sand is compared to a similar one formed predominantly by the deposition of gravel in each example the case of channelized flow is compared to the case of sheet flow the model is applied to the tailings basin of a mine in the companion paper

the shells of etheria elliptica as recorders of seasonality at lake victoria abstract reconstruction of past environments is an essential part of evaluating the ecology of organisms including early man and assessing the pressures for evolutionary change in this study we have demonstrated that etheria elliptica the freshwater oyster of equatorial africa accretes layers of shell having a lunar month periodicity separation and oxygen isotopic analyses of the individual monthly layers affords a qualitative picture of seasonal change fourteen monthly samples of e elliptica collected near kisumu on the winam gulf of lake victoria gave oxygen isotope ratios in the penultimate layer of their shells in excellent agreement with the individual layers of a shell whose growth covered the same period the variation in isotope ratios correlates clearly with the rainfall pattern of that region of east africa

comment on near surface location geometry and velocities of the santa monica fault zone los angeles california by r d catchings g gandhok m r goldman d okaya m j rymer and g w bawden catchings et al 2008 hereafter referred to as catchings et al effectively duplicated our acquisition of a high resolution seismic reflection profile across a fault scarp near the tip of the santa monica fault one of the major faults in the northern los angeles basin the profiles crossed a distinct topographic scarp which is one of a series of scarps that indicate the fault extends about 11 km across the northern los angeles basin before continuing undersea to the west dolan et al 2000 based primarily on the seismic reflection and refraction data catchings et al argued that there are two active fault strands in the near surface 100 m depth in contrast to the single fault that we interpreted from a combination of seismic reflection geomorphologic and trench data at the same site dolan and pratt 1997 pratt et al 1998 dolan et al 2000 acceptance of the interpretation of catchings et al would significantly change seismic hazard assessments in the west los angeles santa monica area in two ways first the addition of a second shallow active fault strand about 200 m south of the known fault scarp and a zone of rotated strata between the two strands as proposed by catchings et al would widen by 200 m the zone of active faulting and surface deformation inferred in our earlier studies although catchings et al figs 5 and 9 show fault b to reach the surface about 140 m south of the scarp and their fig 10 shows it to be about 100 m south of the scarp if this same geometry were assumed along the portion of the topographic scarps for which it has not been documented the additional zone of inferred active faulting would encompass a substantial area in this densely urbanized corridor second catchings et al argue for a 20 dip for the shallowest 700 m length of

pleistocene amphibians and squamates from the upper jordan rift valley gesher benot ya aqov and nahal mahanayeem outlet mis 20 18 and mis 4 3

winter and summer temperatures of the early middle eocene of france from turritella δ18o profiles the mean annual range of temperature is from a climatological point of view at least as important as the mean annual temperature in order to examine intra annual temperature variations in the warm early cenozoic we have analyzed stable oxygen and carbon isotopes along the transect of growth on excellently preserved specimens of the gastropod turritella imbricataria and the bivalve venericardia imbricata from sedimentary rocks of early middle eocene age ca 46 ma in the paris basin turritella shell growth is fast throughout the year and the isotopic records give the first detailed information about early middle eocene seasonal variations the oxygen isotope profiles indicate winter temperatures of about 14 c and summer temperatures of up to 28 c i e a seasonality indistinguishable from the present situation but an annual temperature some 10 c higher our results contradict the opinion that the climate during this period was more equable than that of today

climate variability in the upper jordan valley around 0 78 ma inferences from time series stable isotopes of viviparidae supported by mollusc and plant palaeoecology abstract the early middle pleistocene lacustrine sediments at gesher benot ya aqov gby in the upper jordan valley span ca 100 ka across the matuyama brunhes boundary mbb at 780 ka and oxygen isotope stages oiss 20 to 18 provide a continuous record of their sedimentary history and prevailing climate the lacustrine environment is investigated using ecological and stable isotope characteristics of gastropods belonging to the family viviparidae supplemented by other molluscan and floral indicators the sedimentary framework of the 34 m thick sequence is bounded by channel conglomerates at its base and top and consists of six sedimentary cycles each one starts with shore sediments coquina and sand and ends with deeper water sediments black mud or gray mud time series of 18o and 13c values were determined in individual shells belonging to two sympatric genera of viviparid gastropods viviparus apameae galileae and bellamya sp found in the sedimentary cycles 2 through 5 the total overall range of 18o in the time series of all the shells is from 10 5 to 5 2 vpdb and the 13c from 9 2 to 4 8 vpdb the 13c values of shells recovered from black mud are lower than those from the other sediment types suggesting a higher proportion of carbon of organic origin the 18o values show only a weak relation with sediment type the time series of the individual shells indicate a relative constancy in the water 18o and temperature whilst the variation in 13c could be related to the annual productivity cycle growth and decay of aquatic plants of the lake the 13c patterns in the time series and winter rings indicate that the rate of growth of the individual snails was ca 15 30 mm year the isotopic characteristics of the viviparid shells from these beds indicate diverse sedimentary environments and suggest that above the mbb cycles 2 5 the gby lake received constant and isotopically consistent water inflow our integrated data isotopic and ecological of molluscs and ecological of plants indicates that the geophysical magnetic phenomenon of mbb coincides with an environmental change from a relatively cold dry climate towards a warmer temperate subtropical climate in this region this change coincides with the occurrence of hominin artifacts which were found mainly in layers of the sedimentary cycles 3 5