simulation of modern and middle cretaceous marine δ18o with an ocean atmosphere general circulation model 1 we have developed a coupled ocean atmosphere general circulation model the genesis mom model with the ability to transport and fractionate water isotopes in the ocean and atmosphere the model is used to predict modern and cretaceous precipitation and seawater 18o the model reproduces the large scale modern day isotopic distribution in the zonal mean the difference between simulated and observed seawater 18o is within 0 2 in the low and middle latitudes and within 1 at high latitudes in comparison to modern simulated cretaceous surface seawater 18o is systematically depleted by 0 3 at low and middle latitudes these differences are attributed to equilibrium fractionation during surface evaporation at low latitudes and an increased partitioning of 18o from the surface into the deep ocean due to intermediate and deep water formation in subtropical basins in the cretaceous we also find that regional seawater 18o is significantly influenced by the paleobathymetry and the resolution of oceanic gateways boundary conditions that are not well known for the past our simulation of cretaceous seawater 18o has major implications for oxygen isotope paleothermometry we conclude that conventional assumptions of past seawater 18o may lead to an overestimate of cretaceous sea surface temperatures especially at middle and high latitudes

the chronology of holocene alluvial sediments from the wetterau germany provided by optical and 14c dating holocene floodplain chronologies are often hard to establish the principal limitation being the scarc ity of organic remains in the present study optical dating of flood loam was carried out in

human and climate impact on catchment development during the holocene geul river the netherlands interest in the holocene development of small to medium sized river catchments in western and central europe in relation to changes in land use and climate has increased over the past years in this study we reconstruct the holocene landscape development and fluvial dynamics of the geul river the netherlands and the main forcing mechanisms of environmental change field studies were carried out and we used osl and 14c dating methods to reconstruct the holocene valley development our study shows that 2 periods of deforestation during the roman period and the high middle ages led to severe soil erosion and increased floodplain sedimentation in the catchment of the geul river possibly combined with periods of increased wetness during the high middle ages alluvial fans have been active since the roman deforestation phase our results show that the geul catchment is highly sensitive to changes in land use

estimates of fault dimensions for small earthquakes using stopping phases we propose a new method to estimate the fault dimensions of small earthquakes based on stopping phases without assuming a rupture velocity we detected two high frequency stopping phases being the hilbert transforms of each other for several earthquakes at two local stations during an earthquake swarm at the eastern offshore of ito in the izu peninsula japan which started on march 2 1997 if we assume the geometry of fault to be circular we can determine relative locations of nearest and farthest edges of the circular fault employing the difference of arrival times between these two stopping phases applying this method to several small earthquakes in the swarm we succeeded in estimating the fault dimensions of these earthquakes we also could determine the fault plane from two nodal planes by comparing the fault radii obtained at individual station

phases of soil erosion derived colluviation in the loess hills of south germany in south germany soil erosion is as old as farming and dates back to early neolithic times its sedimentary products form thick colluvial and alluvial sediment bodies in all drainage basins numerous local studies exist but the extrapolation of findings from local case studies to a regional scale has been problematic here a graphical approach is used for frequency analysis of existing data a frequency distribution for optical dates on colluvial sediments from the beginning of agriculture until 1200 ad was constructed by 1 representing the optical ages by gaussian distributions and 2 summing all the single curves the resulting graph clearly shows phases of increased colluviation during periods of stronger human impact a first significant increase occurred during the bronze age during the iron age roman period and at around 800 ad distinct maxima appear in the distribution and highest frequencies are present towards the end of the analysed period at around 1100 ad conclusions that can be drawn from such an approach are limited by sampling bias and other factors but for the analysed period and on a regional and long term scale colluviation seems to have been mainly triggered by intensity of land use climatic fluctuations are of only secondary importance rainfall events that were sufficiently erosive to produce colluvial sediments occurred throughout the agricultural periods the limiting factor for colluvium production was sensitivity of the landscape to erosion and this is a result of land use d 2002 elsevier science b v all rights reserved

holocene alluvial sediment storage in a small river catchment in the loess area of central belgium abstract soil erosion and sediment deposition widely affect landscape development particularly in erosion prone areas with loess derived soils nevertheless until now few attempts were made to quantify soil losses and sediment storage over long centennial or millennial timescales in this study the holocene alluvial sediment storage in a small river catchment 52 km2 of the belgian loess belt is estimated and a preliminary sediment budget for the catchment is presented in the valley of the nethen river c 13 km long a detailed survey of the alluvial sediment archive was conducted hand augerings and percussion drillings were made along cross valley transects at 12 locations in the catchment ams 14c dating of peat samples provided a temporal framework for the interpretation of the cores results show that the thickness of holocene sediment deposits in the nethen valley is 4 to 6 m which corresponds to a total clastic sediment mass of 14 106 t stored in the valley bottom three alluvial units could be distinguished and associated with deposition phases from 9600 to 2900 b c 2900 b c to a d 1000 and a d 1000 to present in contrast to the older sediments units 1 and 2 deposits from the last 1000 year unit 3 contain little organic matter they are seldom intercalated with peat layers and devoid of tufa unit 3 reaches a thickness of c 2 m thereby representing 50 of the holocene sediment mass stored in the alluvial plain the mean sedimentation rate in the alluvial plain for this last phase is 26 t ha 1 a 1 which is about tenfold larger than the sedimentation rates calculated for the older holocene sediment units sediment supply towards the alluvial plain has therefore increased tremendously since medieval times these results are in contrast to dating results obtained for colluvial sediments in a nearby dry valley within the catchment of the nethen where soil erosion and sediment deposition started in the early iron age and was already substantial during the roman age this means that there is a time lag of about one millennium between the onset of high sedimentation rates in the upstream area and high deposition rates in the alluvial plain this is probably caused by a change in coupling sediment connectivity between the plateau slopes and rivers as soil erosion proceeds first the dry zero order valleys in the catchment act as sediment traps and only after these are filled sediment reaches the floodplains the preliminary sediment budget for the nethen catchment illustrates that 50 of the sediment that was eroded during the holocene was stored in colluvial deposits which are mainly located on footslopes and in dry valley bottoms another 29 of the sediment mass is stored in the alluvial plain

preservation potential for late quaternary river alluvium valley sequences of late quaternary alluvial units reflect alluvial preservation as well as alluvial production factors effects of lateral channel migration incision aggradation and channel stability on preservation potential are explored and then considered in the light of 14 available data sets cartographically dated and model data based on lateral channel migration well mapped and dated late quaternary valley unit surveys and composite age frequency plots for dated alluvial units and flood sediments despite much expectable variation between sites and the complex effects of river activity combinations a common characteristic of the data sets examined is the significance of preservation factors lateral migration tends to eliminate older units as it creates new alluvial deposits whereas incision may lead to the preferential preservation of older units beyond the incision slot aggradational environments are likely to preserve more complete records although simultaneous lateral migration may eliminate possibly repeatedly the upper parts of alluvial units the common pattern of inset and incised streams within pleistocene and early holocene fills or bedrock gives finite extent to later units within narrowing valleys so that development of new valley floor units is necessarily at the expense of reprocessing earlier ones floods associated with both slack water deposits and berms are also responsible for the removal of accessible earlier materials thus limiting the preserved record of earlier events in light of these censoring effects of river activities the sequence of preserved late quaternary units within uk sequences is reconsidered it is concluded that preservation potential factors have led to spatial and temporal bias in the alluvial record and that both here and elsewhere preservation potential needs to be considered systematically alongside variable sedimentation resulting from allogenic environmental factors when interpreting the alluvial archive copyright 2003 john wiley sons ltd journal of quaternary science

classification and mapping of anthropogenic landforms on cultivated hillslopes using dems and soil thickness data example from the sw parisian basin france this study focuses on linear anthropogenic landforms of decametric width on cultivated hillslopes and their relations to soil thickness variability the 16 ha study area shows a rolling topography supported by cretaceous chalk of the sw parisian basin france two types of landforms were identified lynchets similar to those described as soil terraces occurring on downslope field parts in other contexts and undulations linear convex landforms that cut across fields accurate dem construction and a detailed soil thickness survey were performed all over the study area soil samples were classified considering their location on specific types of anthropogenic landforms the classification tree ct method was applied to assess whether lynchets and undulations can be discriminated through morphometric attributes slope curvature profile curvature and planform curvature and soil thickness ctsoil or through morphometric attributes only cttopo the ct application establishes predictive classification models to map the spatial distribution of lynchets and undulations over the whole study area the validation results of the ctsoil and cttopo applications show model efficiencies of 83 and 67 respectively both models performed well for lynchets errors arise mainly from difficulties in unequivocally discriminating gently convex undulations and undifferentiated surfaces especially when soil thickness is not accounted for mean values of soil thickness are 1 08 0 62 and 0 45 m in lynchets undulations and undifferentiated areas respectively the general shape of the thickened soil is characteristic to each type of anthropogenic landform multi temporal mapping of field border networks shows that undulations are linked to borders that were removed during the latest land consolidation lynchets are associated with current field borders lynchets and undulations which cover 39 of the study area define topographic indicators of human induced soil accumulations the method involves perspectives for efficiently mapping and quantifying the anthropogenically modified spatial variability of soil thickness on agricultural hillsides

environmental changes during the holocene climatic optimum in central europe human impact and natural causes abstract the priority programme changes of the geo biosphere aimed to reconstruct the environmental history of central europe with emphasis on the time interval from 9000 to 5500 cal bp time slice ii coinciding with the holocene climatic optimum during this period the onset of human activities such as settlement agriculture and animal husbandry caused environmental changes studies of different landscape units in germany were carried out to identify these anthropogenically induced changes and to distinguish them from natural effects on the environmental system the investigated archives included laminated lake sediments fluvial sediments colluvia and soils speleothems peat and coastal sediments the different archives were examined using refined research methods including a variety of sedimentary and geochemical analyses together with pollen analysis and dating methods for the establishment of a reliable chronology the results of the various research groups are summarised and critically discussed based on these results the climatic optimum can be subdivided into three periods 1 the early atlantic from 9000 to 7500 cal bp with negligible human impact and stable environmental conditions 2 the late atlantic during early and middle neolithic from 7500 to 6300 cal bp with pollen evidence for vegetation changes but only negligible changes detectable in other proxy records and 3 the late atlantic during the younger neolithic jungneolithikum after 6300 cal bp with human impact observed in many archives and proxy records especially in the pollen record but also in lacustrine and fluvial sediments during the whole climatic optimum natural causes such as minor shifts of temperature did not induce substantial environmental changes though some changes such as temporary droughts may have facilitated and amplified the observed human impact

spatio temporally variable response of fluvial systems to late pleistocene climate change a case study from central germany abstract the change of the earth s climate and anthropogenic forcing challenge catchment management as the deliberate use of the fluvial system s natural resources depends to some extent on the predictability of the system s variable sensitivity to external impacts the alluvial history of the wetter valley in central germany provides an example of the occurrence of a spatio temporally variable catchment sensitivity to the late pleistocene climate change empirical models that are based on sediment flux controls such as sediment supply transport capacity and gradient serve to explain differential floodplain construction during the early younger dryas the large scale basin upland morphology caused localised divergent cooling impacts and vegetation changes which generated reach scale variable sediment transport system states in the wetter valley the spatial arrangement of reach scale variable response is ascribed to the tectonically driven morphological configuration of the wetter catchment the crucial amplification of differential floodplain construction can be assigned to the spatially variable availability of a surplus of laacher see tephra particles in manner of a pulsed sediment input the ubiquitous tephra cover was previously deposited by the laacher see volcano event in the upper allerod thus the reach scale variable response during the early younger dryas can be deemed to have been climatically triggered but superimposed by an internally driven specific upstream catchment response the documented processes of late quaternary alluviation in the wetter valley imply the need for whole catchment approaches the latter are a prerequisite to reveal the occurrence and causalities of variable fluvial response in relation to external impacts that interact with internal morphological controls this is seen to be crucial to achieve an improved predictability of future environmental change in fluvial landscapes

the late antiquity environmental crisis in emilia region po river plain northern italy geoarchaeological evidence and paleoclimatic considerations abstract for about four decades in italy local scientific literature has occasionally dealt with fluvial avulsions suggesting they should be considered as genetically linked to a peculiar climatic worsening that occurred in the late 6th century ad the so called paul the deacon deluge research performed by the soprintendenza per i beni archeologici dell emilia romagna over the last few years has allowed better definition of the timing of a more articulated alluvial history mainly concerning the roman imperial age and late antiquity 1st 6th century ad the main stratigraphic details of fourteen selected archaeological excavation sites eleven recently surveyed and three reviewed from the literature performed in the cities of modena bologna and related surroundings have been summarized eleven 14 c dates ranging between the years 130 ad and 810 ad allowed us to chronologically delimit a first framework for the riverbed network behaviour during ancient times in the central part of the region the alluvial process appeared to be continuous throughout the time span examined the fan trench was the most sensitive reach of the river system it started to aggrade during the 4th century ad during the 5th century ad and probably after the end of the 6th century ad a number of avulsions occurred this indicates that the fluvial system was in a metastable equilibrium whose behavioural threshold was finally overcome hence the importance of the supposed year 589 ad crisis the deluge appears to be less than previously supposed the riverbed aggradation became evident immediately after the roman empire s economic and demographic crisis of the 3rd century ad and it was probably due to the loss of the land preservation systems in the mountain catchment areas the long duration of the aggradation phase suggests that more than one human settlement phase in the minor catchment areas and or a minor climatic worsening pulse probably occurred during the 5th century ad the starting of the aggradation also coincided with the end of the petit maclu 1 high level phase of the european lakes notwithstanding this the climate s role as a forcing co factor can still be hard to evaluate positively due to the lack of local proxy data

interplay between climatic tectonic and anthropogenic forcing in the lower rhine graben the roer river the roer is a small river which drains the rhenish shield and confluences with the meuse river up to now the geological climatological biostratigraphical and pedological setting of the roer valley were not sufficiently integrated to disentangle the effects of external forcing factors on the roer river in this study we perform a detailed and integrated reconstruction of the fluvial morphology and palaeogeography of the roer river in order to determine responses to combined climatic tectonic and anthropogenic forcing factors the roer river has formed five terrace levels since the weichselian late pleniglacial fluvial planform of the roer river was predominantly climate controlled during the lateglacial and early holocene reach to reach variations in river terrace formation and fluvial planform change occur due to variations in tectonic setting subsurface geology base level fluctuations and the confluence with tributary systems differential subsidence by active faulting in the roer valley graben during the early lateglacial caused a preferential usage of the down tilt channels of the up to then double channel belt systems in the roer valley this preferred channel avulsion towards a fault zone leaving an underfit system on the up tilted side and the clustering of holocene roer channels along that fault zone meet the criteria for a lateral response of the roer river to a tectonic forcing anthropogenic influences in the form of deforestation and land use changes during the late holocene are responsible for the formation of a final terrace level and overbank sediments 2019 elsevier b v

grain size of fine grained windblown sediment a powerful proxy for process identification abstract dust transport by the wind is not a uniform process but may occur in different modes according to source area conditions and transport height and distance subsequently these differences are expressed in terms of grain size and fluxes of the aeolian deposits transport distances may vary from several tens of meters to thousands of kilometers while the height accordingly may vary from meters to more than thousand meters a relation with grain size distributions may be established on the base of type occurrences of different loess facies three main loess populations and several subpopulations of primary windblown origin may be defined according to their grain size dominated by fine sand to very coarse silt silt and very fine silt to clay respectively each of them reflects a specific aeolian process and transport conditions it follows that the grain size distribution of a loess deposit is an excellent proxy for the reconstruction of aeolian processes and wind circulation patterns apart from primary pure wind deposition loess may also be affected by secondary post depositional processes examples are settling of loess particles in a lacustrine setting and reworking by rivers or surface runoff although the primary loess characteristics are maintained reworking processes leave also their imprint in the grain size distribution as a useful tool for secondary process identification

gplates building a virtual earth through deep time gplates is an open source cross platform plate tectonic geographic information system enabling the interactive manipulation of plate tectonic reconstructions and the visualization of geodata through geological time gplates allows the building of topological plate models representing the mosaic of evolving plate boundary networks through time useful for computing plate velocity fields as surface boundary conditions for mantle convection models and for investigating physical and chemical exchanges of material between the surface and the deep earth along tectonic plate boundaries the ability of gplates to visualize subsurface 3 d scalar fields together with traditional geological surface data enables researchers to analyze their relationships through geological time in a common plate tectonic reference frame to achieve this a hierarchical cube map framework is used for rendering reconstructed surface raster data to support the rendering of subsurface 3 d scalar fields using graphics hardware accelerated ray tracing techniques gplates enables the construction of plate deformation zones regions combining extension compression and shearing that accommodate the relative motion between rigid blocks users can explore how strain rates stretching shortening factors and crustal thickness evolve through space and time and interactively update the kinematics associated with deformation where data sets described by geometries points lines or polygons fall within deformation regions the deformation can be applied to these geometries together these tools allow users to build virtual earth models that quantitatively describe continental assembly fragmentation and dispersal and are interoperable with many other mapping and modeling tools enabling applications in tectonics geodynamics basin evolution orogenesis deep earth resource exploration paleobiology paleoceanography and paleoclimate

high sea surface temperatures during the early cretaceous epoch the early cretaceous epoch about 145 100 million years ago is generally thought of as a greenhouse period with high atmospheric co2 concentrations1 and high global mean temperatures2 but evidence for episodes of cooler conditions and even transient glaciations has been proposed3 4 5 6 7 8 9 here we present sea surface temperature records spanning the period from 142 to 128 million years ago berriasian barremian ages from low and mid latitudes reconstructed using the tex86 palaeotemperature proxy during this period we find sea surface temperatures exceeding 32 c at 15 20 n and averaging 26 c at 53 s these temperatures substantially exceed modern temperatures at equivalent latitudes and are incompatible with the notion of consistently cooler conditions in the earliest cretaceous moreover we find little variability in the sea surface temperature records even during the valanginian carbon isotope excursion 138 135 million years ago which was thought to be associated with marked temperature fluctuations5 we conclude that the earliest cretaceous was characterized by a warm stable climate with a lower meridional temperature gradient than today

revised geology age and vertebrate diversity of the dinosaur bearing griman creek formation cenomanian lightning ridge new south wales australia abstract the mid cretaceous griman creek formation gcf which crops out near the town of lightning ridge in the surat basin of north central new south wales australia is noteworthy for its opalised vertebrate fauna the fossil assemblage comprises remains of aspidorhynchid teleosts lamniform chondrichthyans dipnoans chelid and possible meiolaniform turtles leptocleidid like and possible elasmosaurid plesiosaurians anhanguerian pterosaurs titanosauriform sauropods megaraptoran theropods ankylosaurians several forms of non iguanodontian and iguanodontian ornithopods crocodylomorphs enantiornithine birds and stem and true monotremes making it one of the most diverse mid cretaceous terrestrial vertebrate faunas in australia a detailed stratigraphic survey of twenty subterranean opal mines provides new information on the geology age and palaeoenvironment of the main fossil bearing beds vertebrate remains derive from the finch clay facies laterally extensive but discontinuous lenses of claystone that likely accumulated relatively rapidly in near coastal but freshwater embayments i e lagoonal conditions and probably represent a single roughly contemporaneous fauna u pb age dating of detrital zircons extracted from a distinct layer of volcanogenic claystone immediately overlying one of the opalised fossil bearing layers yields a maximum depositional age of 100 2 96 6 ma these new dates confirm an early to mid cenomanian age for the fauna rather than albian as has been reported previously the gcf at lightning ridge is therefore equivalent to the middle part of the winton formation queensland and several million years older than the sauropod dominated fauna at winton

morphological control on sedimentation rates and patterns of delta floodplains in the swiss alps abstract glacially overdeepened alpine valleys and their perialpine lakes are very effective sedimentary sinks that include landforms as alluvial fans fan deltas and deltas the sedimentary archives of these landforms can provide long sedimentary records of erosion and aggradation processes in a catchment focusing on longer time series is vital to improve the conventional instrument based models of sediment transfer as longer time series record the effective low frequency sediment discharges triggered by high magnitude floods the research reported here combines statigraphical analysis of the sedimentary records of two lake deltas in the bernese alps with geostatistical modeling of the sedimentation storage of delta plain deposits from the three dimensional sediment storage model the sedimentary environments and aggradation dynamics of the aare and the lutschine rivers were reconstructed in 500 year time slices over the last 2500 years the spatial distributions of the aggradation rates of the two deltas show similar trends with decreasing downstream rates from delta apex to the delta front at lake brienz which is related to the adaption of the river s longitudinal profile to the pleistocene overdeepened valley morphology local modification of this trend was detected at narrowing of the valley floor caused by landslides the quantification of delta plain sediment volumes provides evidence that aggradation processes have decreased aare or remained nearly stable lutschine in the delta plains during the last 1500 years despite the strong human impact in the form of land use this decrease and the possible compensation of major human induced catchment erosion may be attributed to a more or less efficient regulation of the river channels during the last millennium which transferred the sediment load into lake brienz the sediment volumes obtained and the historical progradation of delta lobes support the previous hypothesis of the connectivity from source headwater catchments to sink perialpine lakes in the main valleys of the bernese alps the results of our study provide new insight into the quantitative estimation of sediment storage for geomorphic process modeling and into the evolution of alpine deltas during the late holocene

barremian cenomanian palaeotemperatures for australian seas based on new oxygen isotope data from belemnite rostra oxygen isotope ratio 18o data are presented for 55 belemnite rostra specimens of late aptian albian age from the great artesian basin of eastern australia and of late barremian early cenomanian age from the carnarvon basin of western australia the belemnites were carefully screened for diagenesis by means of catholuminescence and trace element geochemistry the 18o record for the carnarvon basin palaeolatitude 40 s is interpreted to show a long term warming trend from 10 c in the aptian to a maximum of 15 c in the cenomanian shorter term fluctuations in the mid albian are also apparent data from the great artesian basin palaeolatitude 40 55 s show a wider 18o range which is attributed to the epeiric sea context of this sample set the larger range in 18o is interpreted to reflect differing water mass characteristics due possibly to a combination of variable freshwater dilution seasonal temperature fluctuations and isotopic exchange between seawater and pyroclastic sediment within the epeiric sea nevertheless the aptian albian 18o trends are still comparable to those obtained for the carnarvon basin the inferred palaeotemperature trends for the australian sedimentary basins are consistent with records from other regions and demonstrate that broadly synchronous palaeotemperature variations can be recognised on a global scale during the cretaceous although our data do indeed show cool temperatures within the aptian and the albian reaching a low of 10 c these estimates are somewhat warmer than those based on glendonite genesis however the exact position of the glendonite bearing and dropstone rich parts of the bulldog shale is poorly constrained with respect to our isotope data and the warmest temperatures were of late albian and early cenomanian age however to conform to greenhouse warmth and equability and to achieve parity with other palaeotemperature records the 18oseawater estimate of 1 0 that is generally used for cretaceous oceans in an ice free world needs to be adjusted to a slightly higher value

asynchronous holocene colluvial and alluvial aggradation a matter of hydrosedimentary connectivity based on optically stimulated luminescence osl and radiocarbon dating we establish chronologies of colluviation and alluviation in different floodplain sections of the northwestern wetterau loess basin germany similar to some other european valley floors holocene floodplain aggradation is marked by two important breaks 1 a millennial scale delay between the neolithic agricultural colluviation and floodplain aggradation in loess catchments agricultural colluviation started at about 7000 cal bp and anthropogenic floodplain aggradation only at about 2200 200 cal bp 2 a centennial scale variability in a temporary rise in rates of anthropogenic floodplain aggradation up to 3 6 1 7 mm yr during the high middle ages in directly neighbouring reaches independent archaeologic historic and vegetation records document distinct agricultural histories of hillsides and floodplains and highlight the importance of hydrosedimentary connectivity as compared with land use intensity the late iron age

changes in sediment flux and storage within a fluvial system some examples from the rhine catchment the rhine river system can look back on a long history of human impact whereas significant anthropogenic changes to the river channel started only 200 years ago the impacts of land use have been felt for more than 7500 years here we review results from several case studies and show how land use change and climate impacts have transformed the fluvial system we focus on changes in sediment delivery pathways and slope channel coupling and show that these vary in time and depend on the magnitude of a rainfall event these changes must be accounted for when trying to use sediments as archives of land use change and climatic impacts on fluvial systems for example human impact is recorded in slope deposits only as long as rainfall intensity and runoff generation do not exceed the threshold for gullying similarly climatic impacts are only recorded in alluvium when both the landscape is rendered sensitive by human activities e g deforestation and rainfall thresholds for gullying are exceeded copyright 2003 john wiley sons ltd

grain size characterization of reworked fine grained aeolian deposits abstract after a previous review of the grain size characteristics of in situ primary fine grained aeolian deposits reworked secondary aeolian deposits as modified in lacustrine environments and by alluvial and pedogenic processes are discussed in this paper as a reference the grain size characteristics of primary loess deposits are shortly described commonly pedogenesis and weathering of primary loess may lead to clay neoformation and thus to an enrichment in grain diameters of 4 8 m a size which is comparable to the fine background loess remarkably the modal grain size values of primary loess are preserved after re deposition in lakes and floodplains but secondary lacustrine settings show a very characteristic admixture with a clayey population of 1 2 5 m diameter due to the process of settling in standing water similarly alluvial settings show often an addition with coarse grained sediment supplied by previously eroded sediment however floodplain settings show also often the presence of pools and other depressions which behave similarly to lacustrine environments as a result alluvial secondary loess sediments are characterized by the poorest grain size sorting when compared with the other secondary loess and primary loess despite the characteristic texture of each of these deposits grain size characteristics of the described individual sediment categories are not always fully diagnostic and thus grain size analysis should be complemented by other information as sedimentary structures and fauna or flora to reliably reconstruct the sedimentary processes and environments

revealing the pace of river landscape evolution during the quaternary recent developments in numerical dating methods during the last twenty years several technical developments have considerably intensified the use of numerical dating methods for the quaternary the study of fluvial archives has greatly benefited from these enhancements opening new dating horizons for a range of archives at distinct time scales and thereby providing new insights into previously unanswered questions in this contribution we separately present the state of the art of five numerical dating methods that are frequently used in the fluvial context radiocarbon luminescence electron spin resonance esr 230th u and terrestrial cosmogenic nuclides tcn dating we focus on the major recent developments for each technique that are most relevant for new dating applications in diverse fluvial environments and on explaining these for non specialists therefore essential information and precautions about sampling strategies in the field and or laboratory procedures are provided for each method new and important implications for chronological reconstructions of quaternary fluvial landscapes are discussed and where necessary exemplified by key case studies a clear statement of the current technical limitations of these methods is included and forthcoming developments which might possibly open new horizons for dating fluvial archives in the near future are summarised

slip history of the 1994 sanriku haruka oki japan earthquake deduced from strong motion data abstract we analyzed the seismic waves of the 1994 sanriku haruka oki earthquake m w 7 7 which occurred in the aftershock area of the 1968 tokachi oki earthquake m w 8 2 applying a multiple time window inversion scheme to near source strong motion data we obtained a detailed spatiotemporal rupture process and compared it with that of the tokachi oki earthquake the fault geometry is constructed based on the aftershock distribution the obtained rupture model is consistent with the cmt solution even for a non double couple component the total seismic moment is 4 0 10 20 n m large slips are concentrated in three asperities the first asperity centers about 40 km south and 50 km west from the hypocenter with a maximum slip of 4 4 m the second one centers about 60 km west from the hypocenter with a maximum slip of 2 2 m and the third one lies about 110 km west from the hypocenter with a maximum slip of 2 6 m the obtained moment rate and the duration on the first and second asperities are lower and much longer than those on the third asperity respectively the first asperity does not overlap with an area of large slip during the tokachi oki earthquake but the second or third seem to overlap with or be adjacent to the asperity of the tokachi oki earthquake our inversion result also shows an abrupt change of the rupture velocity from 1 8 to 3 0 km sec at the central part of the fault plane a difference of the seismic coupling between the oceanic and the continental lithospheres at the trenchward side and at the landward side of the 143 e meridian seems to affect the rupture process of this earthquake

climate forcing of fluvial system development an evolution of ideas starting from traditional ideas on the climatic steering of fluvial system dynamics it appears that there are different kinds of climatic influences on system dynamics they vary from direct climatic forcing like peak precipitation to indirect like permafrost and partial forcing like vegetation vegetation or its absence and not directly climate is considered as the main cause of fluvial incision or deposition during temperate or cold periods however other external factors than climate and non climatic factors such as local basin characteristics like subsoil lithology and relief express their effects on the fluvial systems by their role in the energy balance of the river catchment finally internal factors in fluvial system evolution like thresholds and response time should not be neglected

the holocene fluvial chronology of spain evidence from a newly compiled radiocarbon database abstract a critical analysis of 74 radiocarbon dates selected from a total of 102 published and unpublished dates from holocene fluvial environments in spain has identified a number of periods of increased fluvial activity in spain namely 11 170 10 230 9630 8785 7980 6860 5800 4800 3880 3085 2895 1820 1300 0 cal bp the latter period reflecting sustained fluvial response to increased human impact the radiocarbon samples were classified according to type of depositional environment a alluvial overbank b flood basin c alluvial channel gravels d fluvio torrential deposits and e slackwater flood deposits palaeofloods dates from slackwater flood deposits indicated at least five phases of increased frequency of large magnitude floods during the holocene 10 855 10 230 9530 8780 2880 2430 975 790 and 520 265 cal yr bp flood basin type deposition occurred from 7980 to 4830 cal yr bp the main clusters of dates from alluvial floodplain deposits occurred at 2750 2150 and 930 520 cal yr bp the record is discussed in relation to other palaeoenvironmental archives including pollen records of holocene vegetation change and palaeoclimatic proxies such as the north atlantic drift ice record comparison with the latter indicates that major holocene flooding coincided with cold climate phases during 9530 9280 2880 2430 and 520 265 cal yr bp a cooling phase at 10 855 10 230 and warming phases at 9030 8780 and 975 790 cal yr bp

floodplain architecture of an actively meandering river the ploucnice river the czech republic as revealed by the distribution of pollution and electrical resistivity tomography abstract the aim of this study was to describe the floodplain architecture of the ploucnice river a naturally meandering river in the czech republic using manual drill coring the element analysis of sediments and electrical resistivity tomography ert the ploucnice river has received diffuse pollution since the early twentieth century mainly pb followed by a prominent temporally well defined pollution pulse from uranium mining in the 1970s and 1980s mainly u and 226ra the pollution created a chemostratigraphic temporal framework for overbank fines we used geographical information systems gis to describe the channel s dynamics and visualise fluvial landforms we sampled and analysed the finest floodplain sediments in the top 1 to 2 m of the floodplain fill silty and sandy deposits and we used ert to visualise bodies of coarser and deeper strata at depths down to 3 m several limits of ert imaging have been found by a comparison of the resistivity domains with lithological descriptions of the cores several decimetre thick strata were not revealed they are below the spatial resolution of that method and humidity affected the results that were obtained in the topmost strata the space for deposition of fluvial sediments in the ploucnice river is being created by 1 natural lateral shifts in the channel up to 0 5 m year 2 meander loop development and cutoffs at the timescale of decades to centuries and spatial scale of up to 1 4 of the floodplain width and 3 more substantial reorganisation of the channel structure by avulsions probably at the timescale of centuries these processes continuously create space for the deposition of overbank fines on the top of former point bars and in swales and abandoned channels as a consequence of the speed of the channel shifts at least 80 of the fine grained top of the floodplain fill overbank fines was reworked over approximately three centuries

a jurassic ornithischian dinosaur from siberia with both feathers and scales middle jurassic to early cretaceous deposits from northeastern china have yielded varied theropod dinosaurs bearing feathers filamentous integumentary structures have also been described in ornithischian dinosaurs but whether these filaments can be regarded as part of the evolutionary lineage toward feathers remains controversial here we describe a new basal neornithischian dinosaur from the jurassic of siberia with small scales around the distal hindlimb larger imbricated scales around the tail monofilaments around the head and the thorax and more complex featherlike structures around the humerus the femur and the tibia the discovery of these branched integumentary structures outside theropods suggests that featherlike structures coexisted with scales and were potentially widespread among the entire dinosaur clade feathers may thus have been present in the earliest dinosaurs

variability in fluvial geomorphic response to anthropogenic disturbance abstract humans have greatly impacted the processes and intensities of erosion sediment transport and storage since the introduction of agriculture in many regions around the world accelerated floodplain sedimentation can be related to increases in human pressure on the environment however the relation between the intensity of anthropogenic disturbance and the magnitude of change in fluvial sediment dynamics is not straightforward and often non linear here we review a number of case studies from contrasting environmental settings in the european loess belt the eastern mediterranean mountain ranges and the eastern usa detailed field based sediment archive studies and sediment budgets covering time periods ranging from 200 to over 5000 year as well as the use of pollen and sediment provenance techniques show that no overarching concept of changes in floodplain sedimentation following anthropogenic disturbance can be established slope channel dis connectivity controls the existence of thresholds or tipping points that need to be crossed before significant changes in downstream sediment dynamics are recorded following human impact this coupling can be related to characteristics of human pressure such as its duration intensity and spatial patterns but also to the geomorphic and tectonic setting furthermore internal feedback mechanisms such as those between erosion and soil thickness further complicate the story all these factors controlling the propagation of sediment from eroding hillslopes to river channels vary between regions hence only unique patterns of fluvial geomorphic response can be identified as a result unravelling the human impact from current day sediment archives and predicting the impact of future human disturbances on fluvial sediment dynamics remain a major challenge this has important implications for interpreting contemporary sediment yields as well as downstream sediment records in large floodplains deltas and the marine environment in terms of changes in the drivers of environmental change

late holocene flooding records from the floodplain deposits of the yugu river south korea abstract predicting responses of regional hydrological cycles to global warming requires an understanding of past hydrological events on various timescales this study investigated the variability of flooding as recorded in fluvial floodplain deposits the percentage of sand sized material in two cores collected from the floodplain of the yugu river one of the tributaries of the keum river central south korea has been tested as a proxy for the occurrence and magnitude of past flooding the sand fraction of the floodplain deposits in cores kl28 and kl29 which record deposition over the last 3500 years varied on multicentury timescales and suggests several past episodes of higher frequency large floods these clusters of large floods seem to correlate well with northern hemisphere temperature anomalies and suggest that more frequent large floods occurred during the medieval warm period mwp than during the little ice age lia the occurrence of more frequent large floods on the keum river tributary may have been driven by intensified northerly winds over east asia and resultant moisture convergence over korea and or a weakened thermal gradient between the tropical ocean and asian continent furthermore the centennial scale changes in the sand fraction of the floodplain deposits were partly similar to remote el nino southern oscillation enso activity implying a possible link between flooding in central south korea and enso activity this study has demonstrated that floodplain deposits have much potential for recording paleofloods though floodplains can be and quite often are very complex places in terms of their depositional history in regions where natural lakes suitable for the study of paleohydrology and paleoclimate are lacking well controlled time series data for the sand content at multiple sites in fluvial floodplains may be used to understand paleoflooding and extreme precipitation variability in the past

geoarchaeological records in temperate european river valleys quantifying the resource assessing its potential and managing its future throughout the quaternary episodes of glaciation and associated low sea level have resulted in the connection of the terrestrial landmasses of britain and mainland europe the river systems that established themselves across these newly emergent land surfaces of the coastal plain would have created important migration corridors for both animals and humans a point corroborated by the affinity of palaeolithic remains across britain and europe technological developments within the last decade have allowed these now submerged valley floors and adjacent terrestrial landscapes associated with the last cold stage and early and middle parts of the current holocene interglacial to be explored and their archaeological legacies unravelled providing geoarchaeologists with an opportunity to contribute to major cultural debates however in order to maximize knowledge it is essential that geoarchaeologists working within river valleys across both britain and the european continent are addressing similar research questions by collecting data using comparable methodologies this paper reviews the approach taken in different regions and provides a baseline assessment to allow the development of a coherent european wide framework for alluvial geoarchaeology and geoprospection particularly with respect to the holocene record

spatio temporal evolution of the choisille river southern parisian basin france during the weichselian and the holocene as a record of climate trend and human activity in north western europe abstract the morpho sedimentary evolution of the choisille floodplain lowland river catchment 288 km2 a tributary of the river loire in the south western parisian basin was studied through 61 core drillings along eight transects and a geophysical survey located in four stretches of the river stretches a and b correspond to two sub catchments and stretches c and d are in the main valley sixty 14c and four osl datings were obtained and sediments were analysed on seven reference cores eight phases of evolution differing markedly from the evolution of more northern areas in the parisian basin and north western europe were identified from spatio temporal distribution of nine lithological facies the deepest incision phase 1 occurred during the first part of the weichselian followed by the deposition of a gravelly sandy unit phase 2 during the middle pleniglacial which was deeply incised phase 3 probably during the bolling from the allerod up to the last third of the boreal phase 4 sedimentation was continuously dominated by peaty deposits with no evidence of either increased hydraulic energy during the younger dryas or of incision during the lateglacial holocene transition this trend seems to reflect the specificity of the south western parisian basin climate from the late weichselian up to the end of the boreal due to the influence of the atlantic ocean compared to more northern areas where the climate was more continental the downstream incision trend during the last third of the boreal up to the subatlantic phases 5 and 6 indicates a sharp increase in precipitation and vegetation cover the lack of peaty sediments widespread in north western europe and also of precipitated carbonates frequent in the parisian basin seems to be due to local physiographic characteristics the main part of the sediment filling which is principally silty and retrograde began during the subatlantic phase 7 and 8 as a result of deforestation of the plateaux for crop farming high human induced sediment yield and storage concealed the possible impacts of climate change on fluvial dynamics lithological facies change from phase 7 to 8 can only indicate the autogenic morphological evolution of the floodplain in accretion the non univocal upstream downstream variation in the start of phase 7 shows that sediment yield varied in space and time in the catchment particularly in relation to the agricultural potential of the different areas this observation could be used to testify human induced sedimentation in other catchments

sensitivity of west and central european river systems to environmental changes during the holocene a review abstract sediment deposition in floodplains is an essential part of the sediment dynamics of a catchment these sediment dynamics can vary largely on a holocene time scale under the influence of driving forces such as land use and climatic variations in this paper we review the holocene floodplain sediment deposition history of rivers in west and central europe with special attention to the influence of climate and land use variability during the early holocene preboreal to atlantic period most floodplains were rather stable with limited floodplain aggradation after this initial phase of relative stability sedimentation rates increase during the middle and late holocene with often the most important deposition phase during the last 1000 to 2000 a the start of the increase in sedimentation varies spatially with an earlier start in the west france germany then in the east poland belarus ukraine while there are also local differences between regions which are settled early e g loess regions compared to later settled regions the sedimentation history of most floodplains can be linked to the local land use history while influence of climatic variations on floodplain aggradation is often reported to be of minor importance processes related to bedload are often reported to be more influenced by climatic events relationships between the driving forces and the sediment history are mainly based on synchronicity and there is seldom proof for a direct causal relationship future research should focus on a system based approach integrating the floodplain deposition in the entire sediment dynamics which includes also erosion colluvial deposition and export main research questions that need further attention include integration of system based concepts like landscape connectivity and buffering effects and also the assessment of the individual contribution of land use changes and climatologic variations on the sediment dynamics detailed sediment budget studies combined with modeling studies can make an important contribution to the understanding of floodplain sediment dynamics

acoustic emission events interpreted in terms of source directivity during inversion for the source mechanisms of laboratory acoustic emission events relatively high misfit values expressed as the rms of the inverted equations were observed our experiment was performed on westerly granite a processed set of data consisting of 2405 acoustic emission events was used and a semi homogeneous velocity model was considered a correction for sensor radiation patterns and individual sensor constants was taken into account and an acausal attenuation model was assumed source mechanisms were inverted for the moment tensor the application of a more sophisticated medium model improved inversion quality only for some events introducing the source directivity a standard approach for earthquakes with magnitudes larger than approximately 4 increased the number of successfully inverted events directivity was introduced using a haskell source model optionally unilateral and bilateral versions of the source were considered lower values of rms for the haskell source model were considered to justify the directivity approach this formalism enables us to select the preferable fault from the two nodal planes within the fault plane solution the rupture directions were observed to tend to the dip direction of the preferred fault they were found to be preferably subparallel to slip directions for acoustic emissions with a significant dc component the source time functions retrieved from the seismograms are in agreement with finite source theory

geochemical tools for the stratigraphic correlation of floodplain deposits of the morava river in stražnicke pomoravi czech republic from the last millennium article i nfo the floodplain of the morava river in stra nicke pomoravi south east moravia czech republic contains a very valuable record of regional environmental change which goes back to several thousand years its interpretation has been limited by poor stratigraphic correlation and dating of the sediments we present a geochemical solution to this challenge we studied 8 outcrops of floodplain deposits from 4 localities along a 6 km long part of the current meander belt of the morava river in stra nicke pomoravi using geochemical proxy analyses magnetic susceptibility measurements 14 c dating of wood remnants and sediment micromorphology the proxy methods are based on elemental analysis edxrf and analysis of the cation exchange capacity of clay minerals granulometric analyses provided the basis for lithological and facies assignment of the sediments our geochemical and mineralogical interpretations have further been tested by microstratigraphically studying the optical properties of the fine fraction horizons older than about 3 centuries were 14

impact of mediaeval agriculture on the alluvium in the san river headwaters polish eastern carpathians abstract an abrupt change in sedimentary processes occurs in the alluvium of the san river headwaters in the bieszczady mountains polish eastern carpathians older gravels are overlain with a sharp boundary by an extensive cover of sand and silt which is enriched in wood debris partly burned at the base the spatial distribution of the fine grained alluvium the wood debris composition and radiocarbon ages are best explained by a relatively sudden onset of deforestation and cultivation of the valley bottom and slopes in the middle of the second millennium this corresponds well with palynological archaeological and historical data on the agricultural colonisation of the valley

isotopic analysis of coexisting late jurassic fish otoliths and molluscs implications for upper ocean water temperature estimates ophosphate of fi sh teeth are abstract the 18 o compositions of well preserved jurassic fi sh otoliths from wootton bassett uk provide upper ocean paleotemperatures that are comparable with those derived from the iso topic analysis of fitooth phosphates providing independent scrutiny of such paleotempera tures 18 o otolith temperatures in excess of 30 c also rival temperatures associated with the middle cretaceous thermal maximum the negative carbon isotopes of the otoliths may point to a freshwater infl uence and potentially migratory nature of the fi sh however given the large departures from equilibrium fractionation toward more negative carbon values reported from modern marine fi sh we consider our temperature interpretations to be robust and representa tive of the marine depositional environment depleted 13 c values we believe suggest that the otoliths examined in this study belong to fiwith high metabolic rates

scale linkage and contingency effects of field scale and hillslope scale controls of long term soil erosion anthropogeomorphic sediment flux in agricultural loess watersheds of southern germany abstract agricultural landscapes with a millennial scale history of cultivation are common in many loess areas of central europe over time patterns of erosion and sedimentation have been continually modified via the variable imposition of anthropogenic discontinuities and linkages on fragmented hillslope sediment cascades which eventually caused the complicated soilscape pattern these field records challenge topographically oriented models of hillslope erosion and simple predictions of longer term change of spatial soilscape by cultivation activities a thorough understanding how soilscape patterns form in the long term however is essential to develop spatial concepts of the sediment budget particularly for the spatial modeling of anthropogenic hillslope sediment flux using gis in this study i used extensive datasets of anthropogenic soil truncation and burial in a typical undulating loess watershed in southern germany 10 km2 wetterau basin n of frankfurt a m spatial soilscape properties and historic sediment flux as caused by cultivation over seven millennia were evaluated by these data the soilscape pattern on the low gradient hillslopes of the study area was found to be marked by a statistical near random pattern of varying depth thickness of truncation and overthickened burial moreover it was shown that truncation and burial had developed independently from each other and did not correlate with either hillslope gradient or downslope curvature hence in the field any combination of few nearly preserved severely truncated or completely removed soil profiles with either no some or a thick sediment cover is present thereby lacking an obvious spatial pattern here i suggest putting long term change of the soilscape into a contextual anthropogeomorphic systems perspective that accommodates components of human induced soil erosion operating at different spatial scales to interpret the longer term spatial consequences at the hillslope system level in the study area system scale linkages are marked by the spatial intersection of a finer scaled managed field system with a broader hillslope scale framework of natural erosion controls in the low gradient study area field borders exert control over the spatial reference of soil erosion and sedimentation sites over time this brought about a growing historical and spatial contingency change to the soilscape because of arbitrary spatial changes of the field system which are inherent in its socio agricultural maintenance thus the very low gradient and low erosivity setting of the study area have singled out the agency of human induced spatial and connectivity controls and contingency for long term spatial hillslope sediment flux although these findings may be less true for different settings they allow for deriving a generic conceptual model of the linkages between natural and anthropogenic subsystems to interpret the effects of long term human induced sediment flux accordingly the resulting balance between on hillslope net storage and net delivery to streams is scaling with basic physiographic properties of erosivity and sedimentation as well as the degree of anthropogenic hillslope fragmentation for loess areas in europe variable fields are fundamental anthropogeomorphic units that determine appropriate system scaling for historic sediment flux analysis and constrain retrodiction and prediction of changing fluxes at a point and a time at watershed scales methodical implications address adequate sampling strategies to record soilscape change as a result of which a critical review of the applicability of the catena concept to long cultivated hillslopes in central europe was included finally the suggested refined generic model of long term human controlled sediment flux involves a number of research opportunities particularly for linking modeling approaches to long term field records of cultivation related change in the soilscape

a new asymptotic method for the modeling of near field accelerograms we study high frequency radiation from a dislocation model of rupture propagation at the earthquake source we demonstrate that in this case all the radiation emanates from the rupture front and by a change of variables that at any instant of time the high frequency waves reaching an observer come from a line on the fault plane that we call isochrone an asymptotic approximation to near source velocity and acceleration is obtained that involves a simple integration along the isochrones for every time step it is shown that wave front discontinuities critical or stopping phases are radiated every time an isochrone becomes tangent to a barrier this leads to what we call the critical ray approximation which is given in a closed form the previous results are compared with discrete wavenumber synthetics obtained by bouchon 1982 for the gilroy 6 recording of the coyote lake earthquake of 1980 the fit between the asymptotic and full numerical method is extremely good the critical ray approximation permits the identification of different phases in bouchon s synthetics and the prediction of the behavior of the signal in the vicinity of their arrival time

change in the frequency of extreme events as the indicator of climatic change in the holocene in fluvial systems abstract the transformation of natural systems of climatic origin in the holocene may be realised by a change in the type of extreme events or by a change in their frequency or by both the rapid warming at the younger dryas preboreal transition exemplifies a parallel drop in frequency and a change in the type of events several wetter phases of the holocene are characterised by rises in frequency of various types of extreme rainfalls the fragmentary records of events in the fluvial and slope systems coincide with smoothed variations in stable ecosystems and shifts of ecotonal zones such as tree line and lake levels

responses of the upriver valley sediment to holocene environmental changes in the paju area of korea abstract multidisciplinary paleoproxy data from five sedimentary cores uj 03 06 07 10 and 12 recovered from the broad flat upriver valley in the paju area of korea are presented twelve ams radiocarbon dates from cores uj 03 and 12 provided a high resolution holocene record for the sedimentary sequence ranging from about 8000 ybp to the present from 6400 to 4400 14 c ybp 7100 5000 cal ybp the sediments were dominantly poorly sorted medium to coarse sands containing angular to subangular pebbles suggesting that the materials were locally derived the increased abundance of coarse grained sediment was attributed to intensified rainfall during the mid holocene despite the dense regional vegetational cover this period probably corresponded to the holocene climate optimum in the korean peninsula total organic carbon toc values showed a marked increase from 4400 to 2100 14 c ybp 5000 2200 cal ybp which coincided with an observed decrease in particle size i e a decrease in sand content these changes indicated the onset of paludification on the silty or sandy valley bottom contemporaneously relative abundances of pinus and herbaceous pollen increased and the east asian summer monsoon became weakened several intermittent depositional layers were observed ranging from 2100 14 c ybp 2200 cal ybp to the present which contained a high concentration of rootlets sand or clay particles these types of recurring sedimentation events are attributable to climatic shifts and or human impacts such as timber harvest and land clearing the upriver valley catchment was probably sensitive to flash floods due to poorly vegetated slopes accelerating rates of erosion as a consequence of land use change this research indicates that the response of a valley system such as that in paju to climate or human induced environmental changes can vary greatly on local and regional scales

past hydrological events reflected in holocene history of polish rivers abstract a database of 335 radiocarbon dates from holocene fluvial sediments in poland has been compiled each sample is characterized by 25 parameters all samples were grouped into one of 7 regions characterized by hydrological regime and one of 8 depositional environments statistical analysis was used to enhance the palaeoenvironmental data and 17 phases may be distinguished 10 of which have a distinct sharp peak abandoned paleochannels 149 dates clearly reflect the major wetter phases of the holocene an opposite picture is presented by overbank aggradation 86 dates connected mainly with expansion of agriculture preliminary correlations are made on peat bog records changes in vegetation lake water level rates calcareous tufa and speleothems growth landslides phases and debris flow phases these show many convergences explained by climatic fluctuations during the holocene

anatomy of sinosauropteryx prima from liaoning northeastern china a spectacular pair of sinosauropteryx skeletons from jurassic cretaceous strata of liaoning in northeastern china attracted worldwide notoriety in 1996 as the first dinosaurs covered with feather l

river terraces as a response to climatic forcing formation processes sedimentary characteristics and sites for human occupation abstract climate impact on the fluvial processes led to morphological and sedimentological differentiation of a terrace this diversity in the fluvial environment determined how people could adapt to the river although the climatic impact on development and initiation of river terraces seems to be well accepted a number of pertinent questions disturb this simplicity for instance the exact terrace development within a climate cycle is still under debate different kinds of terraces and their sedimentary successions may originate either from aggradation incision or lateral migration is there a typical sedimentary succession below terraces what is the genetic origin of each sedimentary layer what are the relative ages of those layers and erosion phases within a climate driven erosion aggradation cycle the variability in staircase preservation in relation to climatic cyclicity is analysed in three scenarios specific scenarios depend essentially on the preservation of the fluvial deposits dating from the warm periods finally a preliminary inventory is presented of the most favourable sites for human occupation in fluvial valleys as derived from a random selection of archaeological findings generally human occupation in that morphological position seems to be linked with at least temporarily dry conditions climatic conditions do not seem to play the major role the termination of a settlement may have been due to increased risks of flooding apart from other than natural fluvio environmental reasons

fluvial history of the northern upper rhine river southwestern germany during the lateglacial and holocene times abstract three time slices were focused on reconstruction of the lateglacial and holocene landscape evolution in the northern upper rhine rift valley the fluvial history of the northern upper rhine river during the last 15 000 years is characterised by repeated rapid changes of fluvial morphodynamics and sedimentation conditions in consequence the floodplain of the rhine river may be subdivided into three different meander generations which differ mainly on morphological lithological and pedogenetical criteria using complementary dating techniques pollen irsl ams 14c a detailed chronology was obtained for the floodplain sediments e g overbank deposits peat bogs aeolian dune sands of the rhine river and its tributary the neckar river bergstrasen necker while the latter became completely abandoned during the younger dryas period the rhine river probably started meandering at the onset of the allerod period and most likely continued its meandering pattern since the lateglacial the change from the oldest meander generation to the older meander generation occurred during the late phase of the atlantic period however the timing of the onset of the younger meander generation is not known in detail at present probably it started to develop in the late subboreal period or at the transition from the subboreal to the subatlantic period

influence of oceanic anoxic events on the evolution of mid cretaceous radiolaria in the north atlantic and western tethys abstract mid cretaceous aptian turonian extinction radiation events of radiolaria from the north atlantic and western tethys are summarized in relation to oceanic anoxic events oae from investigations of radiolarian faunas black shales and stable carbon isotopes extinction and radiation events of radiolaria can be observed from the late early aptian the earliest albian the latest albian and the cenomanian turonian boundary these events correlate well with organic carbon rich sediments that contain type ii kerogen and show positive 13c excursions they correspond to the oceanic anoxic events oae in the early aptian oae 1a selli level early albian oae 1b late albian oae 1d and latest cenomanian oae 2 bonarelli level detailed investigations of the two most significant events the selli and the bonarelli level in the umbria marche basin of central italy show that extinctions coincide with the first occurrence of marine black shales type ii kerogen and the most prominent rise of 13corg values stepwise extinctions and continuous radiations precede and follow the events similar patterns are evident for the oae 1b and 1d black shales dominated by terrestrial organic matter type iii kerogen e g oae 1c are not characterized by isotopic excursions or by radiolarian extinction radiation events contemporaneous drowning events documented from carbonate platforms around the investigated basins provide a link to a model where flooding of lowlands and leaching of nutrients during a relative rise of sea level lead to an increased productivity and an expansion of the oxygen minimum zone omz because of the loss of deep habitats deeper dwelling forms become extinct shallower dwelling radiolarians survive a narrowing of the omz during highstands and relative sea level falls together with a coupled decrease of the nutrient supply leads to the development of new niches and therefore to radiation

an inversion method to analyze rupture processes of small earthquakes using stopping phases 1 we propose a method to obtain source parameters most importantly the rupture velocity of small earthquakes on the basis of stopping phases it is assumed that a rupture begins at one focus of an ellipse and spreads radially at a constant rupture velocity on the fault surface eventually terminating on the elliptical boundary this model allows us to investigate a wide variety of rupture configurations ranging from a circular to a unilaterally propagating rupture in this model we find that two high frequency stopping phases hilbert transformations of each other are radiated and that the difference in arrival times between the two stopping phases is dependent on the average value of the rupture velocity the radius of the major semiaxes of the ellipse and its ellipticity these parameters can be estimated by a nonlinear least squares inversion method we perform simulation tests which allow us to detect a hilbert transform pair whose arrival times coincide with ones predicted by an assumed source model from noisy data these simulation tests show that our inversion method is useful since our method does not require an a priori assumption of the average rupture velocity the orientation of the fault plane and the circular crack model it provides us with a tool for estimating accurate source dimensions as well as rupture processes of small earthquakes

high frequency seismic radiation from a buried circular fault summary we propose a simplified method for the calculation of near field accelerograms it is based upon the hypothesis that in the course of dynamic faulting the dominating part of the seismic radiation is emitted by the rupture front as the rupture moves smoothly it radiates continuously generating the low frequency part of the field high frequency waves are produced by jumps in the rupture velocity and abrupt changes in the stress intensity factor the wave front discontinuities created in this fashion are evaluated by asymptotic methods and may be propagated away from the source by ray theoretical methods we apply our technique to the evaluation of asymptotic near field accelerograms for a circular fault buried in a half space the agreement with numerical accelerograms calculated by full wave theory is very satisfactory two problems are given particular emphasis 1 the phase shifts introduced by focusing and 2 a simpler method based on dislocation theory is proposed for the calculation of the radiation coefficients from a discontinuously moving rupture front

the temporal and spatial quantification of holocene sediment dynamics in a meso scale catchment in northern bavaria germany the aufsess river catchment 97 km2 in northern bavaria germany is studied to establish a holocene sediment budget and to investigate the sediment dynamics since the early times of farming in the third millennium bce the temporal characterization of the sediment dynamics is based on an intensive dating program with 73 osl and 14 14c ages to estimate soil erosion and deposition colluvial and alluvial archives are investigated in the field by piling and trenching supported by laboratory analyses the sediment budget shows that 58 of these sediments are stored as colluvium in on and foot slope positions 9 are stored as alluvium in the floodplains and 33 are exported from the aufsess river catchment colluviation starts in the end neolithic c 3100 bce while first indicators of soil erosion derived alluviation is recorded c 2 3 ka later the pattern of sedimentation rates also displays differences between the colluvial and alluvial system with a distinct increase in the middle ages c 1000 c

natural change and human impact in a present day fluvial catchment the geul river southern netherlands abstract the geul river has a long history of channel straightening and bank protection but also has several natural meandering parts in addition some formerly fixed or protected stretches of the river have been allowed to meander freely since 1988 therefore it represents an ideal case for evaluating the contribution of human interference to the intrinsic evolution of the river in this paper we compare the response of selected not protected reaches of the present day river to different human modifications the river banks were labelled as stable unstable or erosive as might be expected stretches with a high sinuosity have a high percentage of erosive and unstable bank length while low sinuosity stretches experience hardly any erosion the amount of lateral erosion and sedimentation in natural situations is compared with that in situations with different bank protection and stabilization types erosion rates may locally attain up to 2 m per year detailed grain size analysis of point bar sections enable distinction of successive fining up sequences vertical aggradation rates within the point bars are up to 0 15 m yr 1 the highest rates are found in the youngest point bars collectively the results of this study show that when bank protection is removed the freely meandering river creates its own specific ecosystems and retention capacity increases such a return to natural environmental and ecological conditions is in accordance with the objectives of the european water framework directive

heavy metal contamination in overbank sediments of the geul river east belgium its relation to former pb zn mining activities overbank sediments of the geul river east belgium are highly contaminated by the heavy metals pb zn and cd due to former pb zn mining activities in the drainage basin geochemical variations in vertical overbank sediment profiles sampled 1 km north of the mine tailings of plombieres allow metal fluxes back to the 17th century to be reconstructed the vertical profiles are subdivided into three major units corresponding to different industrial periods based on sedimentological criteria as well as on the distribution of contaminants alluvial sediments with the highest heavy metal concentrations correspond to the major period of mining activity of the 19th century the fact that zn mining at the la calamine open mine started before large scale mining of the pbs zns subsurface exploitations is reflected in the vertical profiles by an increase in zn content before a marked increase in pb and cu the regional extent of contamination in the alluvial deposits was evaluated on the basis of the geochemical analysis of sediments at depths of the 0 20 cm and 80 100 cm most of the upper samples are extremely contaminated significant local variations in heavy metal concentration in the lower samples are interpreted in terms of which overbank sediment horizon has been sampled at a depth of 80 100 cm this indicates that blind sampling of overbank sediments to characterize the degree of contamination in shallow boreholes can give very erratic results

source parameters and rupture velocities of microearthquakes in western nagano japan determined using stopping phases we use an inversion method based on stopping phases imanishi and takeo 2002 to estimate the source dimension ellipticity and rupture velocity of microearthquakes and investigate the scaling relationships between source parameters we studied 25 earthquakes ranging in size from m 1 3 to m 2 7 that occurred between may and august 1999 at the western nagano prefecture japan which is characterized by a high rate of shallow earthquakes the data consist of seismograms recorded in an 800 m borehole and at 46 surface and 2 shallow borehole seismic stations whose spacing is a few kilometers these data were recorded with a sampling frequency of 10 khz in particular the 800 m borehole data provide a wide frequency bandwidth with greatly reduced ground noise and coda wave amplitudes compared with surface recordings high frequency stopping phases appear in the body waves in hilbert transform pairs and are readily detected on seismograms recorded in the 800 m borehole after correcting both borehole and surface data for attenuation we also measure the rise time which is defined as the interval from the arrival time of the direct wave to the timing of the maximum amplitude in the displacement pulse the differential time of the stopping phases and the rise times were used to obtain source parameters we found that several microearthquakes propagated unilaterally suggesting that all microearthquakes cannot be modeled as a simple circular crack model static stress drops range from approximately 0 1 to 2 mpa and do not vary with seismic moment it seems that the breakdown in stress drop scaling seen in previous studies using surface data is simply an artifact of attenuation in the crust the average value of rupture velocity does not depend on earthquake size and is similar to those reported for moderate and large earthquakes it is likely that earthquakes are self similar over a wide range of earthquake size and that the dynamics of small and large earthquakes are similar

alluvial and colluvial sediment storage in the geul river catchment the netherlands combining field and modelling data to construct a late holocene sediment budget abstract we used a combined approach of a two dimensional erosion and hillslope sediment delivery model watem sedem and detailed geomorphological reconstructions to quantify the different components in a sediment budget for the geul river catchment southern netherlands since the high middle ages hillslope erosion and colluvium deposition were calculated using the model while floodplain storage was estimated using field data our results show that more than 80 of the total sediment production in the catchment has been stored as colluvium mostly generated by hillslope erosion while almost 13 is stored in the floodplain since the high middle ages this situation resembles a capacity limited system model results for the period prior to the high middle ages with a nearly completely forested catchment show that far less sediment was generated and that most of the sediments were directly transported to the main river valleys or out of the catchment a supply limited system geomorphological analysis of a large alluvial fan shows the sensitivity of the study area to changes in the percentage of arable land our combined field data modeling study presents an elegant method to calculate a catchment sediment budget for a longer period and is able to identify and quantify the most important sediment storage elements furthermore it provides a valuable tool to calculate a sediment budget while only limited dated fluvial sediment sequences are available

comparison of laser grain size analysis with pipette and sieve analysis a solution for the underestimation of the clay fraction classically the grain size of soil and sediment samples is determined by the sieve method for the coarse fractions and by the pipette method based on the stokes sedimentation rates for the fine fractions results from the two methods are compared with results from laser diffraction size analysis which is based on the forward scattering of monochromatic coherent light from a point of view of laboratory efficiency the laser sizing technique is far superior accuracy and reproducibility are shown by measurements on certified materials it appears that laser grain size measurements of certified materials correspond very well with the certificated measurements tests were also done on a set of randomly selected sediments of fluvial aeolian and lacustrine origin except for the 2 m clay fraction there is a coarsening of the mean diameter of one to two size classes 0 25 caused by the non sphericity of the particles the platy form of the clay particles induces considerable differences eight size classes between pipette and laser measurements the 2 m grain size defined by the pipette method corresponds with a grain size of 8 m defined by the laser particle sizer for the studied sediments using a higher grain size level for the clay fraction when laser analysis is applied enables workers in the geological and environmental field to compare classical pipette analysis with a laser sizing technique

a polar dinosaur feather assemblage from australia abstract exceptionally preserved mesozoic feathered dinosaur fossils including birds are famous but recognized from only very few localities worldwide and are especially rare in the southern hemisphere here we report an assemblage of non avian and avian dinosaur feathers from an early cretaceous polar around 70 s environment in what is now southeastern australia the recovered remains incorporate small 10 30 mm long basal paravian like tufted body feathers open vaned contour feathers and asymmetrical bird like wing feathers that possess high angled barbs with possible remnants of barbicels amongst the geologically oldest observed to date such morphological diversity augments scant skeletal evidence for a range of insulated non avian theropods and birds inhabiting extreme southern high latitude settings during the mesozoic although some of these fossil feathers exhibit what may be residual patterning most are uniformly toned and preserve rod shaped microbodies as well as densely packed microbody imprints on the barbules that are structurally consistent with eumelanosomes geochemical analysis detected no identifiable residual biomolecules which we suspect were lost via hydrolysis and oxidization during diagenesis and weathering nevertheless an originally dark pigmentation can be reasonably inferred from these melanic traces which like the coloured feathers of modern birds might have facilitated crypsis visual communication and or thermoregulation in a cold polar habitat

a guide to phanerozoic cold polar climates from high latitude ice rafting in the cretaceous the high latitude extent of warm climate indicators at certain times in earth history has been considered as evidence that the globe was ice free for long intervals despite theoretical considerations and results from numerical modelling experiments1 2 indicating that this was unlikely one of the warmest periods the cretaceous displays faunal and floral evidence for cool temperate to sub tropical conditions very near to the poles however our studies of lower cretaceous mudstones of central australia that contain outsized exotic blocks have led to the conclusion that the blocks were emplaced by ice rafting implying that high latitude ice was present at sea level strata of a similar origin of mid jurassic to mid cretaceous age occur on other continents that were positioned between 65 and 78 palaeolatitude indeed there is a record of high latitude ice rafting throughout the phanerozoic suggesting that ice was present on earth for much of its history and that ice free conditions could have been at most only episodic over the past 600 myr

the 1992 nicaragua earthquake a slow tsunami earthquake associated with subducted sediments the 1992 nicaragua earthquake was a tsunami earthquake that is it generated tsunamis disproportionately large for its surface wave magnitude m s the moment magnitude m w determined from long period 250 s surface waves was 7 6 significantly larger than the 20 s m s of 7 this m s m w disparity is also characteristic of tsunami earthquakes the nicaragua earthquake is the first tsunami earthquake to be captured by modern broadband seismic networks allowing us to present here seismograms of sufficiently high quality to make inferences about the rupture mechanisms we conclude that the nicaragua earthquake was a slow thrust earthquake which occurred on the subduction interface between the cocos and north american plates and because of the absence of sediments on the trench floor offshore of nicaragua the slip propagated up dip all the way to the ocean bottom exciting large tsunamis the occurrence of slip on a plate interface filled with soft subducted sediments caused the rupture process to be slower than in ordinary subduction zone thrust earthquakes our results reinforce the idea that tsunami warning systems using long period 100 s waves are necessary to reduce the hazard from this type of earthquake

human induced overbank sedimentation in the foreland of the eastern sudety mountains analysis of a 2 3 m thick vertical sequence of fine grained overbank alluvial sediments on the foreland of the eastern sudety mountains reveals that these sediments resulted from human land use changes following the holocene climatic amelioration the first farmers and breeders migrating northward from the danube basin crossed the limit of the sudety carpathians and settled the loess covered glubczyce plateau about 7000 years ago the farming and breeding tribes of early bronze age created the compact settlement structure of the lusitian culture here about 1600 1300 years bc the first forest clearance began at this time slavic settlements existed here in early medieval times from at least the 6th and 7th centuries onwards later economic expansion of the opole duchy and increased population density up to 20 30 persons km2 caused an increase in soil erosion and flood amplitudes investigation of small radius palaeomeander infills adjacent to the main channels indicates that fossilization of organic material that filled these palaeochannels started in early medieval times due to more frequent flood waves and an increased rate of overbank sedimentation in channel undercuts older alluvia have well developed cambic gleyo fluvisols while younger homogenous alluvia do not have traces of soil processes analysis of heavy metal concentrations in older and younger deposits indicates very similar concentrations of cadmium copper lead and zinc this indicates that the source of these alluvia was the transfer of sediments from the mainly deforested part of the drainage basin therefore since at least early medieval times and possibly even earlier the glubczyce plateau has been a deforested region despite the mountainous character of the headwater area of rivers in the eastern sudety foreland sediment transfer from sub mountainous loess covered uplands induced by human activity is clearly marked in the granulometric and geochemical properties of the vertical sequences of overbank deposits copyright 2002 john wiley sons ltd

spatial and temporal distribution of slip for the 1992 landers california earthquake we have determined a source rupture model for the 1992 landers earthquake m w 7 2 compatible with multiple data sets spanning a frequency range from zero to 0 5 hz geodetic survey displacements near field and regional strong motions broadband teleseismic waveforms and surface offset measurements have been used explicitly to constrain both the spatial and temporal slip variations along the model fault surface our fault parameterization involves a variable slip multiple segment finite fault model which treats the diverse data sets in a self consistent manner allowing them to be inverted both independently and in unison the high quality data available for the landers earthquake provide an unprecedented opportunity for direct comparison of rupture models determined from independent data sets that sample both a wide frequency range and a diverse spatial station orientation with respect to the earthquake slip and radiation pattern in all models consistent features include the following 1 similar overall dislocation patterns and amplitudes with seismic moments of 7 to 8 10 26 dyne cm seismic potency of 2 3 to 2 7 km 3 2 very heterogeneous unilateral strike slip distributed over a fault length of 65 km and over a width of at least 15 km though slip is limited to shallower regions in some areas 3 a total rupture duration of 24 sec and an average rupture velocity of 2 7 km sec and 4 substantial variations of slip with depth relative to measured surface offsets the extended rupture length and duration of the landers earthquake also allowed imaging of the propagating rupture front with better resolution than for those of prior shorter duration strike slip events our imaging allows visualization of the rupture evolution including local differences in slip durations and variations in rupture velocity rupture velocity decreases markedly at shallow depths as well as near regions of slip transfer from one fault segment to the next as rupture propagates northwestward along the multiply segmented fault length the rupture front slows as it reaches the northern limit of the johnson valley landers faults where slip is transferred to the southern homestead valley fault an abrupt acceleration is apparent following the transfer this process is repeated and is more pronounced as slip is again passed from the northern homestead valley fault to the emerson fault although the largest surface offsets were observed at the northern end of the rupture our modeling indicates that substantial rupture was also relatively shallow less than 10 km in this region

low productivity and slow deep water circulation in mid cretaceous oceans paleofertility estimates are derived from organic carbon accumulation rates determined in nonbioturbated mid cretaceous deep sea deposits using organic carbon preservation factors observed in laminated sediments from anoxic holocene environments the estimated mid cretaceous primary production rates are as much as an order of magnitude lower than those measured in today s oceans an evaluation of dissolved oxygen budgets using a simple oceanic circulation model indicates very low deep water renewal rates in mid cretaceous oceans 28 references 2 tables 4 figures

past hydrological events reflected in the holocene fluvial record of europe abstract a comprehensive database of radiocarbon dated fluvial units in great britain poland and spain has been compiled to investigate the relationship between environmental change flooding and holocene river dynamics following the methodology recently developed by macklin and lewin macklin m g lewin j 2003 river sediments great floods and centennial scale holocene climate change journal of quaternary science 18 101 105 radiocarbon dates in fluvial sequences that coincide with a modification in sedimentation rate or style have been highlighted allowing geomorphologically significant changes in holocene river activity to be identified data analysis has been undertaken at both national and sub national scales and on catchments of different size type and land use history multiple phases of higher flood frequency characterized by accelerated erosion and sediment deposition on floodplains are recognized and compared with a range of climate proxies the relative and varying roles of climate and land use on river dynamics are considered and the value of the database for reconstructing past hydrological events as well as for predicting river response to future environmental change is assessed

southern polar forests the early cretaceous floras of victoria and their palaeoclimatic significance abstract a diverse fossil flora including cryptogams pteridosperms cycadales bennettitales ginkgoales coniferales and angiosperms occurs in early cretaceous fluvial and lacustrine strata in the otway and gippsland basins in southern victoria both evergreens e g araucarians cycads ferns and deciduous or semi deciduous forms e g certain pteridosperms and ginkgoales seem to have been represented certain ferns ginkgos and conifers grew to a large size overall the assemblages are typical of early cretaceous floras the associated fauna includes dinosaurs hypsilophodontids allosaurs lepidosaurs chelonians birds fish including the lungfish ceratodus and insects the evidence of the biota as a whole suggests a warm to cool temperate relatively equable climate of moderate seasonality with no widespread winter freezing the complex mesozoic apparent polar wander path apw indicated for australia places victoria in high to polar palaeolatitudes ca 70 85 s during the early cretaceous this apw path is supported by paths for other gondwana continents the existence of the victorian early cretaceous forest and biotic communities through polar nights of about two to five months duration is difficult to accept evergreen species would have required relative equability of light whatever the temperature the dinosaurs foliage throughout the year and the lungfish warm to temperate conditions without freezing in view of the consistency of mesozoic palaeomagnetic results for gondwanaland and the enigmatic presence of mesozoic and early cenozoic fossil floras and faunas in very high northern palaeolatitudes the possibility of a reduced obliquity of the ecliptic in mesozoic early cenozoic time should be considered

extreme polar warmth during the cretaceous greenhouse paradox of the late turonian δ18o record at deep sea drilling project site 511 1 oxygen isotope data for upper turonian planktonic foraminifera at deep sea drilling project site 511 falkland plateau 60 s paleolatitude exhibit an 2 excursion to values as low as 4 66 vienna peedee belemnite standard pdb coincident with the warmest tropical temperature estimates yet obtained for the open ocean the lowest planktonic foraminifer 1 8 o values suggest that the upper ocean was as warm as 30 32 c this is an extraordinary temperature for 60 s latitude but is consistent with temperatures estimated from apparently coeval mollusc 1 8 o from nearby james ross island 65 s paleolatitude glassy textural preservation a well defined depth distribution in site 511 planktonics low sediment burial temperature 32 c and lack of evidence of highly depleted pore waters argue against diagenesis even solid state diffusion as the cause of the very depleted planktonic values the lack of change in benthic foraminifer 1 8 o suggests brackish water capping as the mechanism for the low planktonic 1 8 o values however mixing ratio calculations show that the amount of freshwater required to produce a 2 shift in ambient water would drive a 7 psu decrease in salinity the abundance and diversity of planktonic foraminifera and nannofossils high planktonic benthic ratios and the appearance of keeled foraminifera argue against lower than normal marine salinities isotope calculations and climate models indicate that we cannot call upon more depleted freshwater 1 8 o to explain this record without more late turonian data especially from outside the south atlantic basin we can currently only speculate on possible causes of this paradoxical record from the core of the cretaceous greenhouse

fluvial response to climatic and anthropogenic forcing in the moselle drainage basin ne france during historical periods evidence from osl dating the aim of this paper is to study a low energy fluvial system response to natural and anthropogenic forcing during the last two millennia in contrast with longer timescales holocene to quaternary historical sedimentary archives are sparse in such systems which are typically characterized by the predominance of erosion compared with aggradation we studied three main sections in the moselle valley northeastern france by a multi proxy approach combining morphology sedimentology archaeological evidence historical archives and dating the geochronological framework was based on optically stimulated luminescence osl and validated by independent age control the exposed sediments were allocated to different historical periods from roman period to present the first results show that in contrast with many other fluvial systems the moselle and its tributaries did not experience major changes during historical periods climatic changes such as the little ice age had a minor influence on floodplain aggradation e g in grain size or sedimentation rates in the moselle valley and were only able to affect the fluvial style this provides evidence that the reworking of sediments is the main fluvial process at short timescales in the valley floors of the moselle catchment in contrast anthropogenic forcing seems important not only during recent centuries but also since roman times this is suggested by the case study of the metz mazelle section where significant headward erosion and sedimentation were recognized and may be related to human occupation the results therefore point to a need for increasing geoarchaeological and geochronological research in the moselle catchment and similar low energy fluvial systems such research is actually essential to improve the knowledge of the fluvial response to environmental changes during the historical periods and to recognize the respective influence of natural variability and human forcing copyright 2012 john wiley sons ltd

the history of soil erosion and fluvial deposits in small catchments of central europe deciphering the long term interaction between humans and the environment a review abstract during the last few decades many case studies focused on the dynamics of fluvial systems in response to hillslope erosion land use impact and climate changes this paper will review the current state of knowledge of the dynamics of past soil erosion and gullying in small catchments

water mass characteristics in the cenomanian us western interior seaway as indicated by stable isotopes of calcareous organisms abstract stable oxygen isotopes taken from taxon specific planktic foraminifera are potential sources of water mass density proxy data and paleoclimate information material suitable for stable isotope analysis is uncommon in the middle to late cenomanian strata of the western interior of the usa however well preserved material from 17 correlative horizons at five localities across se montana and ne wyoming has provided an opportunity to obtain reliable 18 o data from foraminiferal samples fine fraction carbonate e g calcareous nannofossils and inoceramid prisms with the exception of inoceramids which for a benthic organism have stable isotopic compositions resembling surface dwelling calcareous organisms these data indicate that the water column was vertically stratified and water masses were anomalously depleted in 18 o within samples planktic and benthic foraminifera display strong vertical gradients in 18 o and 13 c of several per mil the vertical gradient of 18 o ranges from more negative nearer the sea surface to less negative at the sea floor with a gradient of about 4 this implies less saline warmer waters near the surface with increasingly more saline colder waters with depth this isotopic distribution indicates a stably stratified water column at least seasonally in addition a persistent vertical carbon isotope gradient of 2 3 suggests a strong nutrient gradient that if mixed would result in high surface water fertility preservation of high amounts of organic carbon in the sediments corroborates this inference although the water column was stratified overall the nutrients necessary to promote high productivity were clearly renewed at least seasonally nutrient renewal could have been achieved by 1 winter cooling of the upper layer allowing deeper seasonal mixing with nutrient rich deep waters 2 seasonal shallowing of the pycnocline into the photic zone 3 entrainment and decomposition of organic matter at the previously proposed frontal convergence 4 upwelling of nutrient rich deep waters along the previously proposed oceanic front or 5 mixing of shelf waters with more oceanic waters across an oceanic front

the impact of land use and climate change on late holocene and future suspended sediment yield of the meuse catchment abstract in this study we investigate the relative importance of changes in land use and climate on suspended sediment yield sy on millennial timescales in the meuse basin we use a spatially distributed soil erosion and sediment delivery model watem sedem to simulate sy in three time periods 4000 3000 bp minimal anthropogenic influence 1000 2000 ad includes land use and climate change and the 21st century changes in climate are based on climate model output ecbilt clio vecode for the 21st century the model is forced according to two emission scenarios of the intergovernmental panel on climate change ipcc namely the sres scenarios a2 and b1 these scenarios lie towards the higher and lower end of the full ipcc scenario range respectively for 4000 3000 bp the basin is assumed to be almost fully forested for 1000 2000 ad land use is reconstructed using corine data historical sources and land use modelling and for the 21st century land use is based on the european land use change project eururalis whilst rainfall erosivity increases by only 3 between 4000 3000 bp and 1000 2000 ad sy increases from ca 92 000 mg a 1 to ca 306 000 mg a 1 this model prediction is in agreement with the limited regional multi proxy data available our simulations show that almost all of this increase is due to the conversion of forest to agricultural land over the period 1000 1900 ad sy shows a significant increasing trend with a peak of ca 388 000 mg a 1 in the 19th century due to continuing deforestation in the 20th century reforestation and rapid urbanisation result in a decrease to ca 281 000 mg a 1 sensitivity analyses show that although land use change acts as the primary control on long term changes in sy the sensitivity of sy to changes in climate increases as the percentage of deforested land increases for the 21st century the results are highly sensitive to the scenarios used due to relatively large increases in rainfall erosivity sy increases by 12 compared to the 20th century according to scenario a2 or by 8 according to b1 however the associated land use change scenarios cause decreases in sy by 26 a2 and 46 b1 the net effect is thus a decrease of sy this study highlights the potentially significant efficacy of land use planning as a tool to mitigate the negative effects of soil erosion and sediment delivery to rivers

influence of inherited topography on the holocene sedimentary evolution of coastal systems an example from arno coastal plain tuscany italy abstract understanding the relative control exerted by autogenic factors such as changes in sediment supply local subsidence and inherited topography is of crucial interest for a thorough comprehension of the sedimentary evolution of late quaternary coastal systems through an example from the arno coastal plain in tuscany we show to what extent sedimentation of the holocene succession even after the time of maximum marine ingression was influenced by the presence of a buried 5 7 km wide incised valley system generated by the arno river during the late pleistocene in response to the last glacial sea level fall a prominent stratigraphic marker locally known as pancone ca 5 15 m thick made up of extremely soft and homogeneous organic rich clays is reported from the upper 20 30 m of the mid holocene succession buried beneath the arno coastal plain high resolution stratigraphy integrated with microfossil investigations enables detailed facies characterization and mapping of this marker horizon at proximal most locations pancone consists of thin lagoonal deposits sandwiched between backswamp clays around the city of pisa and at more distal locations this stratigraphic marker is made up almost entirely of lagoonal clays with lateral transition to backswamp deposits the development of pancone was triggered by an abrupt transgressive pulse that led to the ultimate flooding of the arno paleovalley this transgressive event occurred shortly after a widespread episode of sub aerial exposure and climate deterioration related to the 8200 yr bp cold event confinement of the mid holocene pancone lagoon into an area formerly occupied by the post glacial arno incised valley system along with transition to backswamp facies in coincidence of the former interfluves is interpreted to reflect the higher compaction of the less indurated valley fill relative to the adjacent stiff pleistocene substratum the local increase in land subsidence contributed to the prolonged persistence of a 6 km wide lagoonal system encompassing the peak of holocene transgression and the early phases of decelerated sea level rise up to ca 6000 cal yr bp the arno coastal plain thus offers a good illustration of how inherited topography due to the presence of formerly active incised valleys may influence the holocene evolution of coastal plains favoring local development and preservation of topographic lows

paleoflooding reconstruction from holocene levee deposits in the lower meuse valley the netherlands this study investigates the holocene levee deposits and paleoflooding history of the lower meuse in the netherlands based on archeological investigations and sedimentary analyses grain size end member modelling magnetic susceptibility and thermogravimetric analyses the levee on the left bank in the study area near ooijen contains a continuous sedimentary record in the nw downstream part the archeological evidence and sedimentary results including a grain size based flood energy index lfei indicate that the lower meuse experienced a quiescent flooding period and low sedimentation rates during the mid late mesolithic when the levee was low and human influence was minor deposition during the mesolithic shows a fining upward trend and a highly developed soil containing abundant artefacts during the neolithic and bronze age the flooding intensity was low but gradually increased to a moderate level probably because of deforestation and increased runoff limited bronze age findings may reflect decreased human activity because of the increased flooding starting from the iron age the meuse experienced a generally enhanced flooding regime which is reflected by erosion and coarsened sedimentation in the iron age and roman period the high peak discharges during the iron age may have re opened a low lying paleochannel near to the levee during the intensified floods this general increasing trend is interrupted by the lower flooding phase in the early middle ages dark ages from the middle to the late middle ages the floods intensified again the coarsening deposition and higher sedimentation rates since the iron age resulted from increased floods and higher sediment supply by deforestation and soil erosion the findings of this study agree with a recent paleoflood reconstruction for the lower meuse by using a floodplain archive implying that levee sediment records have potential in paleohydrological studies if the completeness of the record and chronological information is guaranteed 2019 elsevier b v

holocene floodplain deposition and scale effects in a typical european upland catchment a case study from the ambleve catchment ardennes belgium this study quantifies holocene alluvial sediment deposition in the belgian ambleve catchment 1080 km2 situated in the ardennes uplands an extended coring data set is used for a quantitative description and a quantification of the alluvial depositions the floodplains fall into three main types the upper and lower floodplains and the steep reaches total holocene alluvial sediment deposition amounts to 32 tg or 0 029 tg km2 dating of sediments using iron slag as tracer shows that on average 42 of contemporary storage was accumulated during the last 600 years radiocarbon dating of fluvial deposits at eight sites in the catchment confirms that the majority of the sediment is relatively recent the increased sedimentation rates for this period are related to anthropogenic land use possibly enhanced by climatic variations a fluvial sediment budget was constructed for this 600 yr time period and shows that export from the catchment has about the same importance as storage in the floodplains while la

holocene changes in flooding frequency in south korea and their linkage to centennial to millennial scale el nino southern oscillation activity to trace past changes in flooding frequency we investigated fluvial sediments in the middle reach of the nakdong river south korea sediments with larger grain size lower total organic carbon percentage and depleted 13 c values in the recovered sediment cores were interpreted as periods of more frequent flooding patterns of decreased long term flooding frequency and vegetation changes during the early to late holocene were similar to the decreasing regional summer monsoon intensity multicentennial frequent flooding periods in the study area 2900 3400 cal yr bp 3600 3900 cal yr bp 4600 5300 cal yr bp and 5800 6400 cal yr bp corresponded to stronger el nino southern oscillation enso activity periods based on previous studies showing that high frequency tropical typhoon driven coastal inundation along the western coast of japan during the middle to late holocene was coupled with stronger enso activity it is likely that the observed centennial to millennial scale flood frequency change in south korea was influenced mainly by changes in the genesis and tracks of tropical typhoons at centennial to millennial time scales this suggests that the centennial to millennial scale hydrologic changes in east asia were linked to the remote atmospheric oceanic circulation changes represented by an enso like pattern

timescales climate and river development abstract in the long term glacial interglacial sequences river development follows general climatic evolution however at the scale of one cold warm cycle it appears that the geomorphological effect of river activity is best expressed at times of climatic change such periods of pronounced fluvial action last only a short time in more detail the internal evolution in a drainage basin after a climatic event results in a delayed response of the morphology and sedimentation pattern finally on the shortest timescale local thresholds may play a decisive role in the reactions of river systems it is concluded that the relation between fluvial development and climate is not a simple one but is fundamentally dependant on the timescale

human induced prehistoric soil buried in the flood plain of svratka river czech republic the natural setting and prehistoric human activity on holocene floodplains in central europe is a compelling issue from several points of view this environment presents an important sedimentary ar

the black floodplain soil in the amoneburger becken germany a lower holocene marker horizon and indicator of an upper atlantic to subboreal dry period in central europe abstract in many sediment profiles of central european floodplains a black horizon is found between late glacial and middle to upper holocene sediments this horizon is rich in clay and humic material and is referred to as black floodplain soil bfs its widespread occurrence in the amoneburger becken near marburg hessen provides some new insights into the period and circumstances of its development as a polygenetic formation the bfs is of special importance for paleoecological and archeological research it was probably supplied with clay and humic substances from the surrounding terrestrial chernozemic soils and therefore it also has to be regarded as a sediment it developed mainly in the boreal and atlantic periods but did not gain its final characteristics until a following dry period which led to a lowering of the ground water table and widespread illuviation in the floodplains even in former lacustrine deposits

cenomanian palaeotemperatures derived from the oxygen isotopic composition of brachiopods and belemnites evaluation of cretaceous palaeotemperature proxies sixty low magnesium calcite samples from cenomanian articulate brachiopods belemnites and oysters from the epicontinental shelf sea of europe were geochemically and microscopically studied in order to evaluate their preservation and potential as carriers of palaeoenvironmental information the sampled localities in northern spain germany and southern england cover the transition between subtropical 25 30 n and temperate 33 38 n climates mean cenomanian salinity adjusted palaeotemperatures of diagenetically unaltered terebratulid and rhynchonellid brachiopods are 25 5 1 3 c in spain and 19 4 1 9 c in southern england the resulting low to mid latitude meridional temperature gradient of 0 7 c per degree latitude is similar to the gradient today and suggests modern heat transport values for cenomanian low latitudes oxygen isotopic composition of unaltered specimens of the upper cenomanian belemnite praeactinocamax plenus mean 0 2 is enriched in 18o by 1 in comparison to brachiopod shells correspondingly upper cenomanian palaeotemperatures derived from belemnite calcite 13 0 1 3 c underestimate modelled mid latitude sea surface temperatures by 6 c since p plenus occurs as boreal pulse fauna during a short interval in the late cenomanian its heavy oxygen isotopic composition can be attributed either to migration from a cooler and or deeper water mass or to unknown vital effects

the role of biogeography and ecology on the isotope signature of cuttlefishes cephalopoda sepiidae and the impact on belemnite studies abstract calcitic belemnite guards are often used for temperature reconstructions of ancient seawater by using oxygen isotope thermometry these geochemical studies discuss diagenesis and vital effects but neglect ecological or biogeographic effects on the isotope signature to estimate the impact of seasonal temperature variations short term salinity changes and biogeography on the isotope signals we compare the 18o and 13c signals of ten cuttlebones with local water temperatures the cuttlebones aragonitic internal shells come from five different species of recent cuttlefish sepiidae sepia sp from seven different regions north sea baltic sea mediterranean red sea angola north australia and tasmania all analysed specimens reflect the temperature characteristics of their habitat perfectly the 18o signal and calculated temperatures follow annual temperature changes of up to 15 c the 13c values show no clear pattern and are thought to be controlled by vital effects freshwater influence is recognizable in the negative 18o and 13c values of the baltic sea specimen although sudden short term salinity changes are not reflected by the signatures

surprisingly small increase of the sedimentation rate in the floodplain of morava river in the stražnice area czech republic in the last 1300 years abstract sediment profiles from the floodplain of morava river in the czech republic have been collected from exposed river banks 4 6 m long sections and cores 2 4 m deep and investigated using a set of geochemical proxies validated by granulometry and conventional geochemical analysis outlined in our previous paper the work was conducted to evaluate the increase in sedimentation rate during medieval and modern time periods correlation of sediments along the current channel belt allows identification of two most important synchronous changes in the channel structure over the past 1300 years in the 13th century and at the end of the 16th century these changes could be related to central european climatic extremes rather than to land cover land use practises analysis of the pollen record in peaty deposits at the floodplain edge allows excluded dramatic deforestation in medieval times maps of the area from the last five centuries revealed direct and indirect signs of past avulsions and clearly show how the original multichannel system was transformed into a single meandering channel in the early 20th century the extrapolated aggradation rate net vertical accretion of floodplain fines except for levee sediments increased from 0 2 0 3 cm year in 700 ad to 0 3 0 4 cm year in 2000 ad depending on the grain size of the sediment this is the smallest yet reported enhancement of siliclastic deposition although morava river watershed has been intensively used for agriculture and its land cover has changed in a manner similar to west and central european rivers