millennial scale fluctuations of the european ice sheet at the end of the last glacial and their potential impact on global climate abstract reconstructing northern hemisphere ice sheet oscillations and meltwater routing to the ocean is important to better understand the mechanisms behind abrupt climate changes to date research efforts have mainly focused on the north american laurentide ice sheets lis leaving the potential role of the european ice sheet eis and of the scandinavian ice sheet sis in particular largely unexplored using neodymium isotopes in detrital sediments deposited off the channel river we provide a continuous and well dated record for the evolution of the eis southern margin through the end of the last glacial period and during the deglaciation our results reveal that the evolution of eis margins was accompanied with substantial ice recession especially of the sis and simultaneous release of meltwater to the north atlantic these events occurred both in the course of the eis to its lgm position i e during heinrich stadial hs 3 and hs2 31 29 ka and 26 23 ka respectively and during the deglaciation i e at 22 ka 20 19 ka and from 18 2 0 2 to 16 7 0 2 ka that corresponds to the first part of hs1 the deglaciation was discontinuous in character and similar in timing to that of the southern lis margin with moderate ice sheet retreat from 22 5 0 2 ka in the baltic lowlands as soon as the northern summer insolation increase from 23 ka and an acceleration of the margin retreat thereafter from 20 ka importantly our results show that eis retreat events and release of meltwater to the north atlantic during the deglaciation coincide with amoc destabilisation and interhemispheric climate changes they thus suggest that the eis together with the lis could have played a critical role in the climatic reorganization that accompanied the last deglaciation finally our data suggest that meltwater discharges to the north atlantic produced by large scale recession of continental parts of northern hemisphere ice sheets during hs could have been a possible source for the oceanic perturbations i e amoc shutdown responsible for the marine based ice stream purge cycle or so called he s that punctuate the last glacial period

a review of glacial geomorphology and chronology in northern spain timing and regional variability during the last glacial cycle abstract in this paper we synthesize the research in glacial geomorphology and geochronology in northern spain with special attention to the evidence of local glacier maximum extent earlier than the global lgm of mis 2 18 21 ka bp more accurate models of glacier evolution have been defined based on limnogeological geochronological and geomorphological data in the pyrenees osl optically stimulated luminescence surface exposure and radiocarbon dating techniques have identified end moraines and fluvial terraces corresponding to mis 6 about 170 ka and even to mis 8 about 260 ka and also established the timing of the last local glacial maxima as prior to global lgm mis 4 ca 50 70 ka during the global lgm a smaller re advance occurred but glaciers reached different extents in the central and the eastern pyrenees in nw iberia radiocarbon and osl techniques point to local glacial maximum prior to ca 26 ka 38 ka and probably synchronous with 45 ka although some bias might have been introduced by the dating procedures this review demonstrates that in both regions the local maximum extent occurred prior to the global lgm the asynchronies between the glacial maxima chronologies in the different mountain ranges of northern spain suggest that local climate factors exert a strong control on mountain glacier dynamics

cosmic ray labeling of erosion surfaces in situ nuclide production rates and erosion models a number of in situ cosmogenic radionuclides and stable nuclides have been measured in natural exposed rock surfaces with a view to study their in situ production and rock erosion rates 1 the in situ radionuclides can be used for a high resolution tomography of the erosional history of an exposed surface two stable nuclides 3he 21ne and five radionuclides 10be 26al 36cl 14c 39ar having half lives in the range of 300 1 5 106 yr half life are measurable in many rock types a prerequisite for the application of the in situ nuclides for the study of erosional histories of surfaces is a knowledge of their production rates under different irradiation conditions altitude latitude irradiation geometry and shielding relative nuclide production rates can be determined fairly accurately using the extensive available data on cosmic ray neutrons 2 absolute nuclide production rates cannot generally be predicted with any accuracy because of lack of data on excitation functions of nuclides unless some normalization is possible as was done in the case of several cosmic ray produced isotopes in the atmosphere 3 based on a recent natural calibration experiment in which erosion free surfaces exposed to cosmic radiation for 11 000 yrs were sampled the absolute production rates of 10be and 26al in quartz have been accurately estimated for mountain altitudes in sierra nevada 4 the absolute production rates of 10be and 26al in quartz can therefore be estimated fairly accurately for any given latitude and altitude some measurements of 14c in rocks of low erosion rate 5 similarly allow an estimate of its production rate attempts made to measure the in situ production rates of 3he in rocks have not yet led to a convergent production rate in view of the importance of knowing the production rates of isotopes of he ne and ar i present here theoretical estimates of their production rates based on available cross section data i discuss the information that can be extracted from the study of the in situ nuclides in rocks useful parameters characterizing the exposure history of a rock surface are 1 the effective surface exposure age and 2 the time averaged erosion rate the implications of these parameters for single and multiple nuclide studies are discussed in terms of the erosion models considered

luminescence dating of proglacial sediments from the eastern alps the potential of optically stimulated luminescence osl for dating proglacial deposits is tested here at three last glacial key sites in the eastern alps this was undertaken using both sand sized feldspar and quartz grains as well as fine silt sized material the samples reveal rather poor luminescence intensities of the investigated quartz grains and it is also clearly demonstrated that several of the deposits were incompletely bleached prior to deposition bleaching experiments were carried out and different approaches for extracting the aliquots where the osl was completely bleached prior to burial were tested applying different osl measurement techniques and analytical procedures we investigated which approach was most appropriate for dating known age proglacial sediments best results were achieved using single aliquot regenerative dose methodology on coarse grain quartz and feldspar samples in combination with the approach of preusser et al 2007 luminescence dating of proglacial sediments from switzerland boreas in press for ed calculation

glacial landforms and their paleoclimatic significance in sierra de guadarrama central iberian peninsula abstract this paper investigates the glacial evolution on the east face of pico de penalara 40 51 n 3 57 w 2428 m the highest elevation of sierra de guadarrama in the center of the iberian peninsula the geomorphologic stability of glacial landforms and permanence of snow cover were examined and 18 samples were selected for dating with cosmogenic isotope 36cl from moraine formations in four well differentiated phases as well as from a pre glacial periglacial blockfield and a glacial threshold near the headwall the results show the synchrony between the last glacial maximum lgm advance and most results obtained recently by cosmogenic dating in southern europe within the mis marine isotope stage 2 stadial but earlier than the global lgm i e between 25 and 19 ka bp there was slow glacial retreat with minor re advances between 19 and 16 ka and rapid deglaciation from 16 ka this paper presents initial results still pending confirmation for the minimum age of the periglacial summit block formation around 80 ka for the existence of moraine formations older than the last advance and for the existence of glaciers during the younger dryas stadial to explain the synchrony between two moraine formations at different altitudes this paper formulates the hypothesis of the secondary moraine evidenced in currently existing glaciers similar to those which existed on penalara

simulation of snow shielding corrections for cosmogenic nuclide surface exposure studies abstract snow cover reduces cosmogenic nuclide production rates in bedrock corrections for snow cover can be more than 10 in mountainous mid latitude regions where many glacial chronologies have been constructed using cosmogenic nuclide surface dating of landforms most published snow corrections use historic climate data of limited duration that are not likely to reflect adequately the full range of snow conditions over the time of exposure we present a model for describing the impact of snow burial on long term exposure histories of landforms the model applies an energy balance approach to snowpack evolution and incorporates both historic and long term climate proxy data attenuation of cosmogenic fast neutrons is modeled alternatively as a simple exponential decrease with increased shielding or as a thin surface layer with constant production followed by an exponential decrease with increasing depth the choice of attenuation model has little effect on the modeled results for the cairngorms but will have a more significant effect in regions characterized by thinner less dense snowpacks spatial variability in snow cover is modeled as a function of elevation only ignoring local variability in snow accumulation as a result of slope aspect wind redistribution and local topography thus model results reveal general spatial and temporal trends in snow shielding effects rather than site specific corrections applications to data from the cairngorm mountains of scotland show that the constant plus exponential cpe production rate depth profile reduces but does not eliminate snow shielding effects under present day conditions snow at 900 m in the cairngorm mountains reduces average production rates by 6 using the cpe profile and 9 with the exponential profile ep long term climate simulations from 15 5 ka through today produce larger snow shielding effects mainly because they predict an increased proportion of precipitation as snowfall during the younger dryas at 900 m this long term simulation reduces average cosmogenic isotope production rates by 12 cpe and 14 ep these results indicate that snow shielding corrections based on historic climate records may be a potential source of systematic error in midlatitude mountainous regions

timing of last deglaciation in the cantabrian mountains iberian peninsula north atlantic region based on in situ produced 10 be exposure dating abstract the last glacial termination led to major changes in ice sheet coverage that disrupted global patterns of atmosphere and ocean circulation paleoclimate records from iberia suggest that westerly episodes played a key role in driving heterogeneous climate in the north atlantic region we used 10be cosmic ray exposure cre dating to explore the glacier response of small mountain glaciers ca 5 km2 that developed on the northern slope of the cantabrian mountains iberian peninsula an area directly under the influence of the atlantic westerly winds we analyzed twenty boulders from three moraines and one rock glacier arranged as a recessional sequence preserved between 1150 and 1540 m above sea level a s l in the monasterio valley redes natural park results complement previous chronologic data based on radiocarbon and optically stimulated luminescence from the monasterio valley which suggest a local glacial maximum local gm prior to 33 ka bp and a long standing glacier advance at 24 ka coeval to the global last glacial maximum lgm resultant 10be cre ages suggest a progressive retreat and thinning of the monasterio glacier over the time interval 18 1 16 7 ka this response is coeval with the heinrich stadial 1 an extremely cold and dry climate episode initiated by a weakening of the atlantic meridional overturning circulation amoc glacier recession continued through the bolling allerod period as indicate the minimum exposure ages obtained from a cirque moraine and a rock glacier nested within this moraine which yielded ages of 14 0 and 13 0 ka respectively together they suggest that the monasterio glacier experienced a gradual transition from glacier to rock glacier activity as the amoc started to strengthen again glacial evidence ascribable to the younger dryas cooling was not dated in the monasterio valley but might have occurred at higher elevations than evidence dated in this work the evolution of former glaciers documented in the monasterio valley seems consistent with previous 10be chronologies reported in other mountain ranges of the iberian peninsula which have been recalculated according to a common production rate and scaling scheme however the re evaluation of published 10be chronologies has highlighted the fact that glacial evidence previously ascribed to the younger dryas might be more limited than previously thought and the need for additional studies to characterized the extent of glaciers during the younger dryas cooling

position of the polar front along the western iberian margin during key cold episodes of the last 45 ka 1 this paper documents the migration of the polar front pf over the iberian margin during some of the cold climatic extremes of the last 45 ka it is based on a compilation of robust and coherent paleohydrological proxies obtained from eleven cores distributed between 36 and 42 n planktonic 18o globigerina bulloides ice rafted detritus concentrations and the relative abundance of the polar foraminifera neogloboquadrina pachyderma sinistral were used to track the pf position these three data sets compared from core to core show a consistent evolution of the sea surface paleohydrology along the iberian margin over the last 45 ka we focused on five time slices representative of cold periods under distinct paleoenvironmental forcings the 8 2 ka event and the younger dryas two recent cold events occurring within high values of summer insolation heinrich events 1 and 4 reflecting major episodes of massive iceberg discharges into the north atlantic and the last glacial maximum typifying the highest ice volume accumulated in the northern hemisphere for each event we generated schematic maps mirroring past sea surface hydrological conditions the maps revealed that the polar front presence along the iberian margin was restricted to heinrich events the sea surface conditions during the last glacial maximum were close to those at present day except for the northern sites which briefly experienced subarctic conditions

northern iberian abrupt climate change dynamics during the last glacial cycle a view from lacustrine sediments abstract we present a palaeoclimatic reconstruction of the last glacial cycle in iberia ca 120 000 11 600 cal yrs bp based on multi proxy reconstructions from lake sediments with robust chronologies and with a particular focus on abrupt climate changes the selected lake sequences provide an integrated approach from northern iberia exploring temperature conditions humidity variations and land sea comparisons during the most relevant climate transitions of the last glacial period thus we present evidence that demonstrates i cold but relatively humid conditions during the transition from mis 5 to mis 4 which prevailed until ca 60 000 cal yrs bp in northern iberia ii a general tendency towards greater aridity during mis 4 and mis 3 ca 60 000 to 23 500 cal yrs bp punctuated by abrupt climate changes related to heinrich events he iii a complex highly variable climate during mis 2 23 500 to 14 600 cal yrs bp with the mystery interval mi 18 500 to 14 600 cal yrs bp and not the global last glacial maximum lgm 23 000 to 19 000 cal yrs bp as the coldest and most arid period the last glacial transition starts in synchrony with greenland ice records at 14 600 cal yrs bp but the temperature increase was not so abrupt in the iberian records and the highest humidity was attained during the allerod gi 1a to gi 1c and not during the bolling gi 1e period the younger dryas event gs 1 is discernible in northern iberian lake records as a cold and dry interval although iberian vegetation records present a geographically variable signal for this interval perhaps related to vegetation resilience

timing of glaciation during the last glacial cycle evaluating the concept of a global last glacial maximum lgm abstract it has long been known that mountain glaciers and continental ice sheets around the globe reached their respective maximum extent at different times during the last glacial cycle often well before the global last glacial maximum lgm c 23 19 ka which is formally defined by peaks in global sea level and marine oxygen isotope records however there is increasing evidence from around the world that it was not only mountain glaciers which were asynchronous with the global lgm but also some regions of the large continental glaciers the barents kara ice sheet in northern eurasia together with a majority of ice masses throughout asia and australasia reached their maximum early in the last glacial cycle a few thousand years before the global lgm period the east antarctic ice sheet also reached its maximum extent several millennia before the global lgm in numerous mountainous regions at high mid and low latitudes across the world glaciers reached their maximum extent before marine isotope stage mis 2 in mis 5 4 and 3 this is in contrast to most sectors of the laurentide ice sheet the cordilleran ice sheet the se sector of the fennoscandinavian ice sheet and the alpine ice sheet in central europe which appear to have reached their maximum close to the global lgm in mis 2 the diachronous maximum extents of both mountain glaciers and continental ice sheets during the last glacial cycle means that the term and acronym last glacial maximum lgm has limited chronostratigraphical meaning when correlating glacial deposits and landforms

a multiple dating method approach applied to the sanabria lake moraine complex nw iberian peninsula sw europe new evidence in the nw region of the iberian peninsula w42 n6 w of a glacial advance coeval with the global last glacial maximum lgm of the marine isotope stage 2 has been identified through a dataset of exposure ages based on 23 10 be concentration measurements carried out on boulder samples taken from a set of latero frontal moraines results span the interval 19 2e15 4 10 be ka matching the last deglaciation period when iberia experienced the coldest and driest conditions of the last 25 ka and are consistent with lateglacial chronologies established in other mountain regions from sw europe the extent of the lgm stade identified in this work is similar to the local maximum ice extent stade recorded and dated as prior to 33 ka using radiocarbon and optically stimulated luminescence this work showcases how multiple dating approaches and detailed geomorphological mapping are required to reconstruct realistic palaeoglacier evolution models

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

from gullies to mountain belts a review of sediment budgets at various scales this paper reviews the state of the art in the concept as well as in the application of sediment budgets in sedimentary research sediments are a product of mass dispersal at the earth surface and take part in global cycles sediment budgets aim at quantifying this mass transfer based on the principle of mass conservation and are the key to determine ancient fluxes of solid matter at the earth surface this involves fundamental questions about the interplay of uplift climate and denudation in mountain belts and transfer of sediments from the continents to the oceans as well as applied issues such as soil and gully erosion reservoir siltation and coastal protection first after introducing basic concepts relevant scales and methodologies the different components of quaternary routing systems from erosion in headwaters river systems glacial and paraglacial systems lakes deltas estuaries coasts shelves epicontinental seas and deep sea fans are discussed in terms of their sediment budget most suitable are sedimentologically closed or semi closed depositional environments e g alluvial fans lakes deltas and deep sea fans in a second step the dynamics of passive active and collisional tectonic settings and sediment budgets in related sedimentary basins are explored and new concepts of sediment portioning at large geodynamic scales are introduced ancient routing systems are more or less incomplete and may be intensively fragmented or destroyed in active tectonic settings in terms of sedimentary basin types rifts intracontinental and epicontinental settings are preferred objects of sediment budgets because of their persistence and relatively simple overall sedimentary architecture however closing basins such as foreland forearc retroarc piggy back and wedge top basins may provide excellent snapshots of orogenic sediment fluxes in a third step the large long lived routing systems of the amazon the ganges brahmaputra and the rhine are reviewed for each system estimates of either sediment volumes mass or sediment fluxes of continental and marine subsystems have been compiled in order to receive a complete routing in terms of mass conservation for specific time periods since the late glacial maximum as well as the cenozoic following lessons can be taken from these case studies i depositional centers and fluxes show strong shifts in space and time and call for caution when simply looking at subsystems ii the response times of these large systems are within the milankovich time interval thus lower than predicted from diffusion models iii cyclic routing of sediments in continental basins is much more dominated by climate human control than by eustacy and iv at long time scales ultimate sinks win over intermittent storage it is concluded from this review that the quantitative understanding of global sediment cycling over historic and geologic time and its response to allogenic forcing is still in its infancy and further research is needed towards a holistic view of sediment routing systems at various temporal and spatial scales and their coupling with global biogeochemical cycles this includes i to better determine response times of large routing systems by linking quaternary with cenozoic sediment budgets and continental with marine sub systems ii to combine advanced provenance techniques with sediment budgets in order to reconstruct ancient systems iii to study sediment partitioning at the basin scale iv to reconcile continental supply dominated sequence stratigraphy with the eustatic dominated marine concept and iv to account for non actualism of ancient systems with respect to their erosion and transport mode in particular during glaciations and pronounced arid intervals glacial and eolian sediment routing may cross over hydrologic boundaries of drainage basins thus challenging the principle of mass conservation

an early advance of glaciers on mount akdag sw turkey before the global last glacial maximum insights from cosmogenic nuclides and glacier modeling abstract for the first time in turkey we report an early advance of glaciers before the broadly defined global last glacial maximum lgm forty one moraine boulders from three glacial valleys on mount akdag 36 54 n 29 57 e 3016 m southwest coast of turkey were dated with cosmogenic 36 cl valleys on the north side of the mountain were filled with few km long glaciers that terminated at elevations of about 2000 m above sea level a s l the pre lgm glaciations reached their maximum positions 2150 m a s l by 35 1 2 5 ka ago 1 ka 1000 calendar years the glaciers readvanced during the global lgm and reached their farthest locations 2050 m a s l by around 21 7 1 2 ka ago later glaciers retreated and shortly stabilized during the lateglacial at around 15 1 0 9 ka ago using the glacier modeling and paleoclimate proxies from the eastern mediterranean we estimated that if temperatures during the lgm were 8 11 c colder than modern which is suggested by paleotemperature proxies from the region precipitation was up to two times more than that of today previous estimates on southwest coast of turkey indicate a similar precipitation value while central turkey requires drier conditions implying regional heterogeneity on lgm climates in turkey

exposure age chronology of the last glaciation in the eastern pyrenees abstract we present a chronology of ice recession in the eastern pyrenees based on in situ produced 10be data obtained from the tet paleoglacier complex the sampling strategy is based on the relative chronology provided by a detailed geomorphological map of glacial landforms results indicate that the last maximum ice advance occurred late i e during marine isotope stage 2 compared to the chronology currently established for the rest of the pyrenees despite debatable evidence for a glacial readvance during the oldest dryas stade ice cap melt out was rapid residual cirque glaciers having disappeared by the allerod interstade this is consistent both with north atlantic excursions established by the greenland ice cores and paleoenvironmental data for the region the rapid response of the east pyrenean ice cap to temperature variations is primarily linked to its small size compared to larger pyrenean ice fields to the dry mediterranean climate and to topography related nonlinearities in which a small vertical rise in equilibrium line altitude generates a large change in ice mass possible sources of age uncertainty are discussed in the context of sampling design for single nuclide 10be dating of landform sequences in formerly glaciated landscapes

middle and late pleistocene glaciations in the campo felice basin central apennines italy the present paper refers to research conducted in the tectonic karst depression of campo felice in the central apennines italy in which glacial alluvial and lacustrine sediments have been preserved stratigraphic interpretations of sediments underlying the campo felice plain are based on evidence obtained from nine continuous core boreholes the boreholes reach a depth of 120 m and provide evidence of five sedimentation cycles separated by erosion surfaces each cycle is interpreted as an initial response to a mainly warm stage characterized by low energy alluvial and colluvial deposition pedogenesis and limited episodes of marsh formation in turn a mainly cold stage follows during which a lake formed and glaciers developed and expanded leading to deposition of glacial and fluvioglacial deposits the chronological framework is established by eleven accelerator mass spectrometer 14c ages and three 39ar 40ar ages on leucites from interbedded tephra layers these age determinations indicate five glacial advances that respectively occurred during marine oxygen isotope stages 2 3 4 6 10 and 14

mountain glaciation and paleoclimate reconstruction in the picos de europa iberian peninsula sw europe abstract geomorphic mapping and stratigraphic analysis of a lake core document the late quaternary glacial history of the central and eastern massifs of the picos de europa northwestern spain the distribution of glacial deposits indicates that at their most advanced positions glaciers occupied 9 1 km2 extended as far as 7 km down valley and had an estimated equilibrium line altitude ela ranging between 1666 and 1722 m radiocarbon dating of sediment deposited in a lake dammed by moraines of this advance show that the maximum glacial extent was prior to 35 280 440 cal yr bp this advance was followed by two subsequent but less extensive late pleistocene advances recorded by multiple moraines flanking both massifs and sedimentary characteristics in the lake deposits the last recognized glacial episode is the 19th century maximum extent of small little ice age glaciers in the highest cirques above 2200 m

too young or too old evaluating cosmogenic exposure dating based on an analysis of compiled boulder exposure ages cosmogenic exposure dating has greatly enhanced our ability to define glacial chronologies spanning several global cold periods and glacial boulder exposure ages are now routinely used to constrai

sequence and chronology of the cuerpo de hombre paleoglacier iberian central system during the last glacial cycle abstract the cuerpo de hombre paleoglacier occupies the upper sector of the cuerpo de hombre river basin located on the northwest slope of the sierra de bejar mountains iberian central system at the stage of the maximum ice extent during the last glacial cycle this paleoglacier was one of the longest tongues emerging from the sierra de bejar plateau glacier the study of the morphostratigraphic succession and the geometric and genetic relations between the geomorphological indicators of this paleoglacier has revealed its evolutionary sequence during the last glacial cycle the comparison between this sequence and the one previously established by a regional evolutionary pattern shows that although they both coincide in general terms some stages substages of this pattern must be corrected or more clearly defined the absolute chronology of the different stages was obtained using terrestrial cosmogenic nuclides 10 be the maximum ice extent of cuerpo de hombre paleoglacier has been dated to 25 0 ka mis2 and concurrent with the lgm this chronology coincides with date obtained for other paleoglaciers in the iberian central system but is slightly more modern than the regional chronology estimated as most likely for the maximum ice extent in these areas subsequent to reaching the maximum extent the glacier had a retreat minimum age 20 6 ka followed by another stage of expansion or readvance after which it stabilised until the start of the deglaciation stage 17 8 ka in all previous work the deglaciation stages in the iberian central system have been described as one continuous recession process however in the cuerpo de hombre paleoglacier all the data point to stabilisations of considerable magnitude and particularly to another stage of readvance of the glacier based on its chronology minimum age 11 1 ka and its evolutionary significance this new readvance has been correlated with the older dryas stadial finally the evolutionary context marked by the indicators and its chronology confirm that the whole of the late glacial sequence identified in cuerpo de hombre can be correlated with the traditionally established in northern europe climatic periods or stadials and interstadials oldest dryas bolling older dryas allerod younger dryas the minimum ages obtained for the cold periods stadials in this sequence in the cuerpo de hombre paleoglacier are respectively 17 5 ka 13 9 ka and 11 1 ka this complete sequence of the late glacial period including the stadials older and younger dryas had not been previously identified in any of the paleoglaciers in the iberian central system

snow shielding factors for cosmogenic nuclide dating inferred from monte carlo neutron transport simulations abstract conventional formulations of changes in cosmogenic nuclide production rates with snow cover are based on a mass shielding approach which neglects the role of neutron moderation by hydrogen this approach can produce erroneous correction factors and add to the uncertainty of the calculated cosmogenic exposure ages we use a monte carlo particle transport model to simulate fluxes of secondary cosmic ray neutrons near the surface of the earth and vary surface snow depth to show changes in neutron fluxes above rock or soil surface to correspond with shielding factors for spallation and low energy neutron capture neutron fluxes are partitioned into high energy epithermal and thermal components the results suggest that high energy neutrons are attenuated by snow cover at a significantly higher rate shorter attenuation length than indicated by the commonly used mass shielding formulation as thermal and epithermal neutrons derive from the moderation of high energy neutrons the presence of a strong moderator such as hydrogen in snow increases the thermal neutron flux both within the snow layer and above it this means that low energy production rates are affected by snow cover in a manner inconsistent with the mass shielding approach and those formulations cannot be used to compute snow correction factors for nuclides produced by thermal neutrons additionally as above ground low energy neutron fluxes vary with snow cover as a result of reduced diffusion from the ground low energy neutron fluxes are affected by snow even if the snow is at some distance from the site where measurements are made

a northern lead in the orbital band north south phasing of ice age events abstract re analysis of existing data sets shows that they are fully consistent with northern insolation control of ice age cycles and do not provide strong support for alternate models invoking tropical or southern controls the coldest time of the last 100 ka in central greenland was nearly synchronous with the minimum in summer insolation about 24 ka bp thousand years before 1950 approximately one third of the total termination i warming since then was achieved over the almost 10 ka before the abrupt warming into the bolling which some workers have interpreted as the start of the warming southern warming as recorded in the byrd station antarctica ice isotopic record lagged northern warming co2 rise was roughly synchronous with southern warming methane rise may have been delayed a little as was sea level rise and the change in the isotopic composition of atmospheric oxygen was delayed significantly the data for the extrema just before termination ii are consistent with occurrence of the same phasing as for termination i but with somewhat different progression of the two terminations once initiated perhaps because of differences in the forcing

chronology of glaciations in the cantabrian mountains nw iberia during the last glacial cycle based on in situ produced 10be abstract the mountain ranges of the iberian peninsula preserve a valuable record of past glaciations that may help reconstruct past atmospheric circulation patterns in response to cooling events in the north atlantic ocean available chronologies for the glacial record of the cantabrian mountains which are mainly based on radiocarbon and luminescence dating of glacial related sediments suggest that glaciers recorded their glacial maximum gm during mis 3 and experienced a later last glacial maximum lgm advance this lgm extent is not established yet preventing a fair correlation with available cosmic ray exposure cre based chronologies for the glacial record of the pyrenees and the sistema central we present a glacial reconstruction and a 10 be cre chronology for the porma valley in the southern slope of the central cantabrian mountains glacial evidence at the lowest altitudes correspond to erratic boulders and composite moraines whose minimum 10 be cre age of 113 9 7 1 ka suggests that glaciers were at their maximum extent during mis 5d most likely in response to the minima in summertime insolation of the last glacial cycle recessional moraines preserved within the glacial maximum limits allow the assessment of subsequent glacier advances or stagnations the most remarkable advance took place prior to 55 7 4 0 ka probably at the end of mis 4 consistently with minimum radiocarbon ages previously reported for lacustrine glacial related deposits in the cantabrian mountains a limited number of 10 be cre ages from a composite moraine suggest a possible advance of the porma glacier coeval with the global lgm the glacier front attributed to the lgm would be placed within the margins of the previous gm like in the western pyrenees erratic boulders perched on an ice moulded bedrock surface provided a mean 10 be cre age of 17 7 1 0 ka suggesting that part of the recessional moraine sequence corresponds to minor advances or stagnations of the glacier fronts during the lateglacial period this recessional response is consistent with deglacial chronologies previously established in the pyrenees and the sistema central and correlates with the coldest and driest conditions of mis 2 according to lacustrine records finally a relict rock glacier provided a mean 10 be cre age of 15 7 0 8 ka for movement cessation of its toe indicating that periglacial conditions prevailed at least until the end of heinrich stadial 1 mystery interval

a combined morphometric sedimentary gis and modelling analysis of flooding and debris flow hazard on a composite alluvial fan caveside tasmania abstract two episodes of intense flooding and sediment movement occurred in the westmorland stream alluvial system near caveside australia in january 2011 and june 2016 the events were investigated in order to better understand the drivers and functioning of this composite alluvial system on a larger scale so as to provide awareness of the potential hazard from future flood and debris flow events a novel combination of methods was employed including field surveys catchment morphometry gis mapping from lidar and aerial imagery and hydraulic modelling using riverflow 2d software both events were initiated by extreme rainfall events

morphometric controls and geomorphic responses on fans in the southern alps new zealand morphometric variables associated with 41 debris ow and 18 uvial fans and their basins in the southern alps of new zealand are examined the results show statistically signi cant differences in the area maximum elevation relief and ruggedness melton s r of the basin and the area gradient and apex and toe elevations of the fan between debris ow and uvial sites concavity of the fan longitudinal pro le also differs between the two fan types although this could not be tested statistically most of these morphometric differences re ect differences in processes and environmental controls on them discriminant analysis indicates that basin area and fan gradient best differentiate the two fan types by process moderately strong correlations exist on both debris ow and uvial fans between basin area or melton s r and fan area correlations between basin area or melton s r and fan gradient are generally weaker the results of this study also indicate that on debris ow prone fans the fan gradient and basin melton s r have lower thresholds which overlap little with upper thresholds associated with basins where only stream ow reaches the fan these thresholds may therefore have value in preliminary morphometric assessments of debris ow hazard on fans in the southern alps copyright 2004 john wiley sons ltd

stratigraphic and sedimentological observations from seismic data across the chicxulub impact basin seismic data across the offshore half of the chicxulub impact crater reveal a 145 kmdiameter post impact basin to be a thickening of tertiary sediment which thickens by 0 7 sec from the basin margin to the basin center the basin existed long after the impact and was gradually infilled to its current flat surface a suite of seismic horizons within the impact basin have been picked on four reflection lines across the crater they reveal that the western and northwestern parts of the impact basin were filled first subsequently there was a dramatic change in the depositional environment indicated by an unconformable surface that can be mapped across the entire basin a prograding shelf sequence downlaps onto this unconformity in the eastern basin the seismic stratigraphic relationships suggest a marine regression with sedimentation becoming gradually more passive as sediments fill the eastern part of the impact basin the central and northeastern parts of the basin are filled last the onshore hole yaxcopoil 1 yax 1 which was drilled on the flanks of the southern basin has been projected onto the offshore seismic data to the west of the crater center using dates obtained from this onshore well and regional data approximate ages have been placed on the most significant horizons in the offshore seismic data our preliminary interpretation is that the western and northwestern basins were almost entirely filled by 40 ma and that the marine regression observed in the eastern basin is early miocene in age offshore seismic stratigraphic analyses and onshore data within yax 1 suggest that the early paleocene is highly attenuated across the impact basin the mesozoic section appears to be 1 km thicker offshore than onshore we calculate that given this offshore thickening the volume of mesozoic rocks that have been excavated melted or vaporized during impact is around 15 larger than expected from calculations that assume the offshore thickness is equal to that onshore this has significant consequences for any environmental calculations the current offset between the k t boundary outside and inside the crater is 700 m however infilling of basins with sediments is usually accompanied by subsidence and immediately following the impact the difference would have been smaller we calculate the original topographic offset on the k t boundary to have been between 450 and 700 m which is in agreement with depthdiameter scaling laws for a mixed target

the last glacial termination a major puzzle of paleoclimatology is why after a long interval of cooling climate each late quaternary ice age ended with a relatively short warming leg called a termination we here offer a comprehensive hypothesis of how earth emerged from the last global ice age a prerequisite was the growth of very large northern hemisphere ice sheets whose subsequent collapse created stadial conditions that disrupted global patterns of ocean and atmospheric circulation the southern hemisphere westerlies shifted poleward during each northern stadial producing pulses of ocean upwelling and warming that together accounted for much of the termination in the southern ocean and antarctica rising atmospheric co2 during southern upwelling pulses augmented warming during the last termination in both polar hemispheres

maximum extent of late pleistocene glaciers and last deglaciation of la cerdanya mountains southeastern pyrenees abstract this paper examines glacial evolution in the la pera and malniu cirques and aranser la llosa and duran valleys in the cerdanya massifs on the south facing slopes of the eastern pyrenees a geomorphologic analysis and dating of moraine boulders glacially polished bedrock and rock glacier blocks were carried out by means of cosmogenic 36cl surface exposure dating the maximum ice advance was contemporary with the last glacial maximum at 23 ka ago and it was of greater or only slightly lesser magnitude than for previous quaternary advances the termini of glaciers remained close to maximum positions with minor advances and retreats until 18 17 ka when the glacial tongues disappeared from the valleys depending on the previous topography these glaciers left behind a single polygenic moraine in the case of confined valleys or multiple moraines next to each other in the case of flat more open areas a final glacial advance is detected during the oldest dryas close to the cirque headwalls and the glaciers finally disappeared during the bolling interstadial the glaciers were then replaced by rock glaciers whose front immediately became inactive although their activity continued near their source area until the early holocene

chronology of the last glacial cycle in the european alps chronological data for glacier advances in the european alps between the last interglacial eemian and the holocene are summarised 115 to 11 ka during this time glaciers were most extensive extending tens of kilometres out onto the forelands between 30 and 18 ka that is synchronous with the global ice volume maximum of marine isotope stage mis 2 evidence for ice expanding to just past the mountain front for an earlier major glacier advance comes from swiss sites where advances have been luminescence dated to mis 5d 100 ka and mis 4 70 ka up to now no such evidence has been found in the eastern alps by 18 ka more than 80 of the late wurmian ice volume had gone subsequently glaciers readvanced reaching into the upper reaches of the main valleys during the lateglacial gschnitz stadial which likely occurred around 17 ka with final moraine stabilisation no later than 15 4 ka the link of the egesen stadial with the younger dryas climate deterioration is supported by exposure ages from four sites as well as minimum limiting radiocarbon dates from bogs within former glacier tongue areas key questions on the spatial and temporal variability of ice extents throughout the last glacial cycle have yet to be answered copyright 2008 john wiley sons ltd

timing of glaciation in the mediterranean mountains during the last cold stage recent research in the mountains of the mediterranean has attempted to establish the timing of the maximum extent of glaciers during the last cold stage several dating methods have been utilised and new dating frameworks have emerged in key areas in several places multiple dating techniques radiocarbon optically stimulated luminescence u series applied to glacial and associ ated sediments suggest that local glacier maxima preceded the global last glacial maximum lgm ca 18 14 c ka bp 21 cal ka bp by at least several thousand years studies in spain the pyrenees the maritime alps and turkey utilising cosmogenic isotope analyses 10 be and 36 cl have yielded glacial geochronologies with maxima that correlate closely with the marine isotope record of ice volume and the global lgm in some cases the use of different geochronological techniques has led to conflicting evidence for the timing of the local last glacier maxima in the same area from a palaeoclimate perspective glacier climate reconstructions for the local last glacier maxima in the mountains of central italy northern greece and western turkey indicate that climate was wet and cold in italy and greece the local glacier maxima preceded the driest part of the last cold stage as indicated by palaeoecological records by several thousand years for western turkey however recent cosmo genic exposure ages combined with glacier modelling suggest a local last glacier maximum charac terised by cold and wet conditions coinciding with the global lgm the available evidence indicates that a dichotomy is emerging not only in our understanding of the timing of glaciation across the mediterranean but also in the palaeoclimatic interpretations derived from glacial and palaeoecolo gical records copyright 2008 john wiley sons ltd

radiocarbon dating reservoir effects and calibration abstract we summarize how radiocarbon measurements are made using accelerator mass spectrometry we also discuss some complications inherent in the radiocarbon dating method when calibrating radiocarbon dates to calendar dates for example measurements of radiocarbon 14c in some types of materials are complicated by a reservoir effect caused by an apparent age of the source reservoir that differs from the contemporary atmospheric surface 14c value in other cases mobile carbon sources in nature can produce mixed sources of carbon we explore these effects and discuss their possible implications for 14c measurements and how we can deal with them

a stratigraphical basis for the last glacial maximum lgm abstract the last glacial maximum lgm is widely used to refer to the episode when global ice volume last reached its maximum and associated sea levels were at their lowest however the boundaries of the interval are ill defined and the term and acronym have no formal stratigraphical basis this is despite a previous proposal to define it as a chronozone in the marine records on the basis of oxygen isotopes and sea levels spanning the interval 23 19 or 24 18 ka and centred on 21 ka in terrestrial records the lgm is poorly represented since many sequences show a diachronous response to global climate changes during the last glacial cycle for example glaciers and ice sheets reached their maximum extents at widely differing times in different places in fact most terrestrial records display spatial variation in response to global climate fluctuations and changes recorded on land are often diachronous asynchronous or both leading to difficulties in global correlation however variations in the global hydrological system during glacial cycles are recorded by atmospheric dust flux and this provides a signal of terrestrial changes whilst regional dust accumulation is recorded in loess deposits global dust flux is best recorded in high resolution polar ice core records providing an opportunity to define the lgm on land and establish a clear stratigraphical basis for its definition on this basis one option is to define the global lgm as an event between the top end of greenland interstadial 3 and the base onset of greenland interstadial 2 spanning the interval 27 540 23 340 ka greenland stadial 3 this corresponds closely to the peak dust concentration in both the greenland and antarctic ice cores and to records of the global sea level minima this suggests that this definition includes not just the coldest and driest part of the last glacial cycle but also the peak in global ice volume the later part of the lgm event is marked by heinrich event 2 which reflects the onset of the collapse of the laurentide at c 24 ka together with other ice sheets in the north atlantic region a longer and later span for the lgm may be desirable although defining this in chronostratigraphical terms is problematic whichever formal definition is chosen this requires the contribution of the wider quaternary community

timing of pleistocene glaciations in the high atlas morocco new 10be and 36cl exposure ages abstract this paper presents data from 42 new samples yielding late pleistocene cosmogenic 10be and 36cl exposure ages of moraine boulders across a series of glaciated valleys in the toubkal massif 4167 m a s l high atlas morocco this represents the first comprehensive pleistocene glacial chronology in north africa and one of the largest datasets from the mediterranean region the timing of these glacier advances has major implications for understanding the influence of atlantic depressions on moisture supply to north africa and the mediterranean basin during the pleistocene the oldest and lowest moraines which span elevations from 1900 to 2400 m a s l indicate that the maximum glacier advance occurred from mis 5 to 3 with a combined mean 10be and 36cl age of 50 2 19 5 ka 1 sd n 12 7 outliers the next moraine units up valley at higher elevations 2200 2600 m a s l yielded exposure ages close to the global last glacial maximum lgm with a combined mean 10be and 36cl age of 22 0 4 9 ka 1 sd n 9 7 outliers the youngest exposure ages are from moraines that were emplaced during the younger dryas with a combined mean 10be and 36cl age of 12 3 0 9 ka 1 sd n 7 no outliers and are found in cirques at the highest elevations ranging from 2900 to 3300 m a s l from moraines predating the younger dryas a large number of young outliers are spread evenly between 6 and 13 ka suggesting a continuing process of exhumation or repositioning of boulders during the early to mid holocene this attests to active seismic processes and possibly intense erosion during this period

late pleistocene climate of the northern iberian peninsula new insights from palaeoglaciers at fuentes carrionas cantabrian mountains

constraining the age of superimposed glacial records in mountain environments with multiple dating methods cantabrian mountains iberian peninsula abstract numerous cases of timing differences between glacier advances recorded in mountain environments have been documented over the last decade usually suggesting potential age conflicts between the different dating techniques the frequent use of a single technique to date numerically a given glacial sequence makes it difficult to address to what extent age differences can be an artifact related to biased numerical age results or a paleoclimate signature here we present a new set of 43 numerical ages based on three dating techniques 10be surface exposure dating radiocarbon and optically stimulated luminescence that complement the chronology of pleistocene glacial advances in the porma valley in the central cantabrian mountains of spain results compliment previous chronologies in the area supporting an important glacial advance during marine isotope stage 3 stage iia 56 ka that culminated with the last glacial maximum advance stage iib 33 24 ka of mis 2 in response to increased rainfall and solar insolation minima glacier fronts reached elevations as low as 1130 m a s l possibly without overriding evidence related to the previous pleistocene glacial maximum extent glacier recession in the cantabrian mountains started at 21 20 ka ago after the global lgm we suggest that the recession was initiated by increased insolation followed by hyper cool and dry conditions during heinrich stadial 1 in response to meltwater discharges in the north atlantic

palaeoenvironmental studies in nw iberia cantabrian range vegetation history and synthetic approach of the last deglaciation phases in the western mediterranean abstract at the north western limit of the mediterranean basin in the mediterranean oceanic transition zone the multidisciplinary study of two palaeolakes villaseca and la mata province of leon provides data on the last deglaciation the juxtaglacial lakes were formed during a deglaciation phase of the last cold stage weichselian wurm estimated from the regional and pyrenean chronological data between circa 48 ka and 32 ka ka 1000 years ago their drainage occurred circa 17 ka and 15 ka respectively during the definitive glacial retreat phases these results provide evidence for a glacial maximum extension preceding the global last glacial maximum lgm and an early deglaciation comparisons with the pyrenean data show that in the most important glacial basins of the pyrenean cantabrian range glaciers were still present at middle elevation circa 18 20 ka the final deglaciation did not happen until around 16 ka during the period 48 13 3 ka along the pyrenean cantabrian range three stages can be distinguished in the deglacial processes between circa 48 and 32 ka the deglacial retreats were contemporaneous with d o events 12 to 6 between circa 32 ka and 18 ka major sedimentary modifications were rare two of them are synchronous with d o 4 and 3 a glacial readvance also occurred during this period along the pyrenean cantabrian range between 18 and 17 ka major sedimentary changes and an increase in the 18o records of the ngrip ice core record are synchronous between 15 and 13 3 ka glacial retreats and sedimentary changes are synchronous with the climatic improvement observed from the end of the oldest dryas to the end of the bolling allerod period these correspondencies suggest relationships between the deglacial processes in the western mediterranean and the palaeoenvironmental events in the north atlantic region during the last glacial interglacial transition during the full glacial period the pollen data indicates dominant steppic environments the oldest dryas was not a constant cooling phase and from around 15 5 ka the pollen data indicates a slight warming during the holocene until circa 2040 cal bp mixed oak forests developed and pine was a prominent component of the cantabrian landscape then the forests were destroyed due to mining agriculture and fire and this favoured the extension of heathland

maximum glacial advance and deglaciation of the pinar valley sierra de gredos central spain and its significance in the mediterranean context abstract pinar valley is located on the north side of galana peak 40 15 21 n 5 18 00 w 2564 m a s l sierra de gredos in the center of the iberian peninsula surface exposure ages based on the in situ accumulation of 36 cl were obtained from six moraine boulders and from three bedrock outcrops to investigate the timing of both the last local glacial maximum and the deglaciation the oldest moraines which probably overrode older glacial deposits are coeval to the global last glacial maximum subsequently the pinar glacier underwent minor pulsations close to its maximum position followed by general glacier retreat after 17 16 ka small cirque glaciers probably remained during the terminal pleistocene but they had completely disappeared by 10 ka

late quaternary glacial phases in the iberian peninsula abstract the only glaciers existing today in the iberian peninsula are small features located in the pyrenees though their number and extension has undergone significant changes over the late quaternary the wide range of glacial landforms and deposits distributed across different iberian ranges suggests the occurrence of several past periods with larger glacial systems the objective of this research is to summarize the current knowledge on the spatial and temporal patterns of glacial activity in the iberian mountains during the late quaternary to this purpose the chronological framework was divided in six periods glaciations prior to the last glacial cycle middle pleistocene last glacial cycle late pleistocene termination 1 holocene little ice age lia and present day the data were geographically divided considering the mountain systems where glacial evidence exists pyrenees cantabrian range nw ranges central range iberian range and sierra nevada during quaternary cold stages ice accumulated in the head valleys of these mountain ranges and glaciers flowed down valleys in all cases glaciers remained confined within the mountain systems and did not reach the surrounding lowlands depending on the combination of temperatures and moisture conditions more or less ice was stored in some ranges there is evidence of middle pleistocene glaciations one potentially correlating with marine isotope stage mis 12 and another correlating with mis 6 with glaciation dated to ca 130 170 ka however most of the glacial records correspond to the last glacial cycle and subsequent termination the maximum glacial expansion of this last pleistocene glaciation stage occurred well before the global last glacial maximum lgm between 30 and 60 ka in the cantabrian mountains and pyrenees at ca 30 ka in sierra nevada and nw ranges and almost synchronously to the lgm in the central range and iberian range a massive glacial retreat occurred in all ranges at 19 20 ka but the long term deglaciation process was interrupted by cold intervals such as the oldest and younger dryas which favoured glacial expansion in the highest mountains temperature increase recorded during the holocene conditioned the melting of glaciers which only reappeared in the highest massifs during the coldest periods such as the lia however post lia warming led to glacier disappearance in the cantabrian mountains sierra nevada and most massifs of the pyrenees together with an accelerated shrinkage of the small glaciers still existing in this range at elevations near 3000 m

luminescence dating applications in geomorphological research abstract chronological control remains critical to the interpretation of environmental change and to establishing long term rates of geomorphological processes radiocarbon dating will continue to be the central technique for age assessment of carbon bearing sediments deposited in the last ca 40 ka but alternative absolute dating strategies are required for older or non carbon bearing sediments they include uranium series dating of precipitated sediments k ar and ar ar dating of primary volcanic materials and cosmogenic isotopic dating of surface exposure ages an additional family of methods collectively termed luminescence techniques is increasingly providing a basis for the age assessment of detrital sedimentary deposits these methods directly date the deposition of detrital mineral grains typically quartz and feldspar and have been demonstrated to provide accurate deposition chronologies for up to 800 ka although 150 ka is more typical in the past decade a subset of luminescence techniques which employ optical sample stimulation methods called optical dating has made it possible to date samples from a much wider range of depositional systems given that the methods directly date sedimentation they allow direct assessment of depositional dynamism in numerous terrestrial and subaqueous including marine sedimentary systems and have demonstrated particular potential in the elucidation of chronologies from aeolian dune and loess fluvial colluvial coastal and volcaniclastic environments this paper provides a summary of the principles of the luminescence especially optical dating methods and shows how recent developments specifically single aliquot dating procedures have dramatically enhanced the scope and potential of the method the luminescence techniques are increasingly being incorporated into a wide range of geomorphological studies which seek to establish the nature of landscape changes over the past interglacial glacial cycle and beyond

the glacial history of the pindus mountains greece abstract geomorphological evidence for pleistocene glaciation has been mapped in the pindus mountains of northwest greece and the chronology of glaciation in this area has been established through soil profile analysis and u series dating of secondary carbonates calcite formed within glacial deposits three glacial stages are evident in the sedimentological and geomorphological records the earliest and most extensive recorded glaciation predates 350 000 yr b p and was characterized by extensive valley glaciers and ice fields a more recent glaciation occurred before the last interglacial and was characterized by glaciers that reached midvalley positions the last phase of glaciation in greece is recorded by small cirque glacier moraines and relict periglacial rock glaciers the glacial and periglacial sequence on mount tymphi has been used in conjunction with a reference parastratotype the long lacustrine sequence at ioannina to provide a chronostratigraphical framework for cold stage deposits in g

last glacial maximum and deglaciation of sierra de gredos central iberian peninsula abstract the study area is located in the sierra de gredos a portion of the sistema central range of central spain specifically in the gredos gorge on the north side of pico almanzor 2596 masl where glacial forms are present down to an altitude of 1410 m 10 km from the headwall this paper presents cosmogenic 36 cl surface exposure dates of four closely spaced lateral moraine ridges within the area of maximum advance of the ancient glacier 8 km from the headwall and two glacially polished bedrock thresholds 3 and 5 km from the headwall the dates are overall coherent and indicate a maximum advance at 26 24 ka subsequently the glacier front stabilized around its maximum position for 3 ka with small scale fluctuations resulting in small closely spaced moraines ridges glacier recession began after 21 ka accelerating sharply by 16 ka the glacier had probably disappeared from the gredos gorge by 15 ka there are no traces of older or more recent moraines than those dated in this study these results are in agreement with the well known late pleistocene climatic evolution of the northern atlantic and with the glacial chronology of the alps and other mediterranean mountains however the gredos gorge has no geomorphic evidence of the younger dryas cold event probably because of the low altitude and southern character of these mountains

gis morphometric indicators for the analysis of sediment dynamics in mountain basins watershed management and headwater reconstruction programs require a reliable knowledge of sediment dynamics geographical information systems gis provide the framework for the implementation of different complex techniques for the assessment of shallow landsliding and erosion processes in mountain basins this paper presents some morphometric indicators aimed at erosion and sediment delivery analysis the proposed indicators can be easily derived from medium to fine resolution digital elevation models dem applications conducted in eastern italian alps have shown the adequateness of the proposed approach to address erosion and sediment related problems the analysis considered the classification of sediment source areas with regard to their activity the comparison between drainage basins having different morphological characteristics and the topographic control on sediment transport capacity with a particular attention to the identification of channel reaches characterised by a low sediment transport capacity

contrasting impacts of dansgaard oeschger events over a western european latitudinal transect modulated by orbital parameters abstract terrestrial and marine proxies pollen planktic and benthic foraminiferal oxygen isotopes alkenone and foraminifer derived sea surface temperatures ssts ice rafted debris from images deep sea cores md95 2042 and su81 18 37 n 10 w md99 2331 and md03 2697 42 n 9 w and md04 2845 45 n 5 w show that western european and offshore environments were strongly affected by dansgaard oeschger d o and heinrich h events we concentrate here on latitudinal variability in the forest cover extent and composition of western europe during the succession of d o events showing new pollen records for core md04 2845 and for marine isotopic stages mis 3 and 4 of core md99 2331 in general cold ssts characteristic of greenland stadials were contemporaneous with the expansion of semi desert or steppic vegetation while greenland interstadials were synchronous with the expansion of forest our data reveal that the amplitude of atlantic and mediterranean forest expansions differs for any given d o warming during the glacial period 74 18 ka in the western mediterranean d o 16 17 and d o 8 and 7 corresponding to minima in precession were associated with strong expansion of forest cover contrasting with weak expansion of forest cover during d o 14 and 12 the opposite pattern is revealed at the atlantic sites further north the strongest greenland warmings are recorded for d o 19 11 and 8 this contrasting latitudinal climatic scenario is compared with other northern hemisphere records revealing similarities between the mediterranean climate and the asian monsoon regime which may relate to a summer atmospheric teleconnection between the two regions comparable to the present day situation parallels between mediterranean climate enhancement and peaks in global methane ch 4 during the last glacial period suggest a significant role of monsoon activity in determining ch 4 emission from wetlands

environmental evolution in the picos de europa cantabrian mountains sw europe since the last glaciation abstract the western massif of the picos de europa latitude 43 n longitude 4 5 w includes some of the highest peaks in the cantabrian mountains this massif was heavily glaciated during the last glaciation though the post glacial environmental evolution is still poorly understood using a complementary geomorphological and sedimentological approach we have reconstructed the environmental events occurred in this massif since the last pleistocene glaciation the geomorphological distribution of glacial landforms suggests the occurrence of four main glacial stages maximum glacial advance glacial expansion after the maximum advance late glacial and little ice age moreover a 5 4 m long sedimentary sequence was retrieved from the karstic depression of belbin providing a continuous record of the paleoenvironmental conditions in this area since the last glaciation until nowadays this section suggests that the maximum glacial expansion occurred at a minimum age of 37 2 ka cal bp significantly prior to the global last glacial maximum subsequently periglacial processes prevailed in the mid lands of the massif until glaciers expanded between 22 5 and 18 7 ka cal bp following the melting of the glaciers a shallow lake appeared in the belbin depression lake sediments do not show evidence of a cold stage during the late glacial when moraine systems formed at higher locations the terrestrification of this lake started at 8 ka cal bp and the area turned into grassland at 4 9 ka cal bp the existence of charcoal particles in the sediments of belbin sequence reveals the onset of human occupation in the massif through the use of fire activity for grazing purposes finally the presence of moraines inside the highest northern cirques shows evidence of the last glacial phase that occurred during the little ice age cold event since then the warming climate has led to the melting of these glaciers and periglacial processes prevail in the high lands of the massif

research history on glacial geomorphology and geochronology of the cantabrian mountains north iberia 43 42 n 7 2 w abstract the study of glacial geomorphology in the cantabrian mountains a mountain range that extends 460 km along the northern coast of the iberian peninsula sw europe started late in the 19th century and continues nowadays with a growing number of research papers however the number and timing of glaciations remains poorly understood partially due to the still limited number of numerical ages its southerly location and proximity to the atlantic ocean make this mountain range potentially sensitive to past climate fluctuations this work updates the glacial knowledge evolution for the whole range from the queixa invernadoiro massif to the basque mountains reviewing i the history of glacial research since the late 19th century ii the methodological approaches applied to reconstruct both the spatial extent and timing of past glacial stages and iii the main geomorphological and geochronological evidence reported until date including glacial features attributed to the last glacial cycle last 120 ka and previous glaciations according to current knowledge glaciers extended over the cantabrian mountains covering a total area of 3150 km2 showing asymmetric development conditioned by variations of the topographic configuration and moisture supply along the range available geochronology based on radiocarbon optically stimulated luminescence and terrestrial cosmogenic nuclides suggests the occurrence of at least 2 glacial advances during the last glacial cycle i a glacial maximum stage that took place at a minimum age of 36 45 ka marine isotope stage 3 and ii a second glacial advance at 19 23 ka mis 2 in some areas the extent of the glacier tongues during the second glacial advance was comparable to previous glacial maximum and was followed by glacial retreat conditions with formation of recessional moraines asynchronous glacial maximum conditions have been reported only for the castro valnera mis 4 3 numerical ages and queixa invernadoiro mis 6 1 numerical age massifs until now finally geomorphological evidence reported in picos de europa has been attributed to prior glaciations and correlated to cold conditions recorded during mis 12 and mis 22 based on a very limited number of numerical ages

small isolated glacial catchments as priority targets for cosmogenic surface exposure dating of pleistocene climate fluctuations southeastern pyrenees a new 10 be data set from a small glacial catchment in the pyrenees confirms almost full glacier extent during marine isotope stage mis 2 extends the oldest cosmogenic exposure ages of moraines in this mountain range to mis 5 and constrains paleoclimate reconstructions in the mediterranean region it also illustrates the advantageous conditions for the long term preservation of terminal moraines provided by small low gradient glacier catchments that did not merge with compound ice masses even during glacial maxima these small gently sloping and isolated glacier catchments are proposed as priority targets for terrestrial cosmogenic nuclide dating of peak pleistocene glacier advances providing scope for greater accuracy in interregional paleoclimatic correlations

the last deglaciation of the southeastern sector of the scandinavian ice sheet the scandinavian ice sheet sis was an important component of the global ice sheet system during the last glaciation but the timing of its growth to or retreat from its maximum extent remains poorly known we used 115 cosmogenic beryllium 10 ages and 70 radiocarbon ages to constrain the timing of three substantial ice margin fluctuations of the sis between 25 000 and 12 000 years before the present the age of initial deglaciation indicates that the sis may have contributed to an abrupt rise in global sea level subsequent ice margin fluctuations identify opposite mass balance responses to north atlantic climate change indicating differing ice sheet sensitivities to mean climate state

paired 26al and 10be exposure ages from lundy new evidence for the extent and timing of devensian glaciation in the southern british isles lundy lies in a strategic geographical position for understanding the glacial history of the british isles the island bears evidence of glaciation largely in the form of ice moulded bedrock and glaciallytransported boulders e an unusual occurrence this far south in the british isles irish sea ice penetrated the western bristol channel overriding lundy from the northwest during the last phase of glaciation in this area the results of paired terrestrial cosmogenic nuclide analyses 26al 10be constrain the timing of this extensive glaciation and provide for the first time an age for the exposure of lundy granite following deglaciation the results from nine paired samples yield 26al 10be exposure ages of 31 4e48 8 ka 10be and 31 7e60 0 ka 26al this challenges the view that any glaciation this far south must belong to middle pleistocene glaciations such as the anglian stage c 480e420 ka and a devensian age for the last glaciation is consistent with findings from the isles of scilly further south however the findings suggest early mid devensian marine isotope stage mis 4e3 glaciation of lundy it also implies that the island was exposed or covered for a short time by non erosive cold based ice at the global last glacial maximum lgm during mis 2 26e21 ka the potential exposure of the island throughout mis 2 contrasts with the evidence from the isles of scilly and the celtic sea which were glaciated at the lgm

late pleistocene and holocene glaciation in the pyrenees a critical review and new evidence from 10be exposure ages south central pyrenees a compilation and a critical assessment of the 14c data set available show that the chronology of glacial events in the pyrenees is not well constrained after reviewing the literature on glacial reconstruction we suggest a simplified subdivision of the pyrenean last glacial cycle record into last pleniglacial deglaciation and neoglacial to improve the numerical glacial chronology we provide 10be surface exposure ages for 5 glacial erosion surfaces 9 moraines and 2 erratics in the upper noguera ribagorcana valley south central pyrenees published corrected 14c data and new 10be exposure ages indicate that the major phase of moraine building recorded in this valley during the last pleniglacial probably occurred after 25 ka bp this age calls in question the generally accepted hypothesis of a very early deglaciation of the pyrenees ca 70 40 ka bp and strongly suggests that the pyrenees could have been in pleniglacial conditions during the last glacial maximum lgm however we do not exclude the possibility that the maximum glacier extent during the last glacial cycle had taken place much earlier than the lgm as indicated by some published u th ams 14c and osl data we suggest that pleniglacial conditions could have taken place during a longer 30 20 ka period than generally assumed and that the last pleniglacial could include several glacier fluctuations recorded irregularly in different valleys with a last major glacier readvance taking place around the lgm in addition the deglaciation is represented by a series of moraines deposited between ca 13 7 0 9 and 10 1 0 6 ka this moraine series indicates a highly variable climatic pattern that is partly correlated with greenland stadial 1 the younger dryas and suggests that the deglaciation could have continued into the early holocene

first 36cl cosmogenic moraine geochronology of the dinaric mountain karst velež and crvanj mountains of bosnia and herzegovina abstract this article presents the first attempt to date moraines in the dinaric mountain karst using cosmogenic 36cl surface exposure dating technique twenty samples were collected from moraine boulders from two sets of the lowest and largest lateral moraines on the vele 1965 m asl and crvanj mountains 1920 m asl in bosnia and herzegovina the dated lateral terminal moraine complexes spanning elevations from 980 to 1350 m asl are up to 2 7 km long and rise more than 100 m above the valley floor the moraine boulders yielded 36cl ages spanning from oldest dryas for vele 14 9 1 1 ka to younger dryas for crvanj 11 9 0 9 ka considering the average age of the two oldest samples from each lateral moraine as the most representative time of moraine emplacement the dated moraines mark the largest extent of glaciers in both study areas which have been reconstructed to 28 km2 for vele and 24 km2 for crvanj having a mean equilibrium line altitude at 1388 m and 1541 m respectively under modern precipitation values which account for 2000 mm the temperature depression between 8 and 10 c is required to sustain the palaeoglaciers with reconstructed equilibrium line altitudes glaciers of similar size with such low equilibrium line altitudes during the lateglacial have not been reported until now for the balkan peninsula it is very likely that the boulder ages reflect complex exhumation and denudation histories which at this point do not allow obtaining more precise moraine chronologies for the study areas nevertheless this article delivers new data on the extent and timing of quaternary glaciations in the mediterranean mountains where records of glacier fluctuations seem to be asynchronous amongst different areas it is clear that dating moraines with cosmogenic 36cl surface exposure dating in carbonate lithologies in areas of high precipitation like the dinaric karst remains challenging

quaternary glacial evolution in the central cantabrian mountains northern spain abstract the glacial evolution of the cantabrian mountains is not well known previous studies have focused on the extent of the glacial maximum and the presence of younger features in several massifs recently efforts have been made to date glacial periods particularly the glacial maximum this work presents a reconstruction of the glacial evolution in the cantabrian mountains providing data on the environmental characteristics and timing of the different stages from the quaternary glacial maximum to the little ice age the study area covers 3000 km 2 between the 4 58 w and 3 34 w and includes eleven massifs of the central area of the cantabrian mountains the selected sectors have an atlantic and atlantic mediterranean transitional climate and include the highest massifs above 2600 m and low altitude glacierised massifs lower than 2000 m glacial extent and evolution have been reconstructed on the basis of detailed geomorphological and morphostratigraphic mapping the equilibrium line altitude palaeo ela has been estimated for the different stages of each tongue the ela has been assessed by the aar and modified kurowski methods and altitude methods have been considered a numerical chronological framework is proposed using 17 ams radiocarbon and one osl data obtained in lake and bog deposits from three massifs four main glacial stages have been differentiated between 38 000 bp and the little ice age they correspond to different cold environments and the number of glacial stages varies from one to four among the different massifs conclusions are analysed in the context of the quaternary glacial evolution of other iberian mountains

last glacial maximum and lateglacial in the polish high tatra mountains revised deglaciation chronology based on the 10 be exposure age dating abstract deglaciation chronology of the polish high tatra mountains has been reconstructed based on 10 be exposure age dating fifty seven rock samples were collected from boulders located on the terminal and lateral moraines that limit the horizontal extent of the lgm and the lateglacial glaciers in the biala woda and sucha woda catchments the uncertainty weighted mean age of 21 5 2 5 ka obtained for the maximum terminal moraine in the sucha woda valley indicates that the oldest preserved moraines were formed during the global lgm the age population ranges between 15 1 1 0 and 28 3 2 0 ka and suggests that glaciers reached their maximum position lgm i as early as 28 25 ka and the final stabilization of the form occurred much later possibly after melting of buried dead ice the younger glacial oscillation lgm ii occurred no later than 20 5 ka and is represented by well preserved termino lateral moraine systems in the panszczyca valley the first lateglacial stage lg1 in the study area is documented in the rybi potok valley at the rp1 moraine 1300 m a s l which was stable at around 16 6 0 3 ka the younger lg2 stage has no defined absolute age however it is constrained between 16 5 and 15 5 ka by the timing of the lg3 stage this cold event is represented by well formed moraines in the roztoka piec stawow polskich rybi potok and panszczyca valleys of which exposure age indicates their deposition between 15 0 0 5 and 15 6 0 1 ka the lg1 lg2 and lg3 stages likely occurred during the oldest dryas cold stage greenland stadial 2 1a related to the north atlantic cooling heinrich event 1 the youngest glacial oscillation is evidenced by moraines in the pusta and panszczyca valleys these moraines are composed of very large granitic blocks of which exposure ages often exhibit isotope inheritance this is reflected by the youngest p3 moraine in the panszczyca valley with a mean age of deposition close to the lgm the r4 moraine system in the pusta valley however indicates two oscillations phases that occurred at around 13 ka and correlates well with the timing of rp5 moraine formation in the za mnichem valley the lg4 stage is related to the climate cooling during the younger dryas greenland stadial 1 lgm elas reconstructed for the biala woda and sucha woda panszczyca glaciers were located at 1460 1480 m a s l during the oldest dryas stages the ela in the high tatras rose from 1600 to 1650 m a s l in the rybi potok valley and from 1700 to 1800 m a s l in the roztoka piec stawow polskich valley the younger dryas ela depending on glacier s exposition was located between 1950 and 2000 m a s l climate modelling results show that the lgm glaciers maximum advance could have advanced in the high tatras when the mean annual temperature was lower than today by 11 12 c and precipitation was reduced by 40 60 during the lateglacial stages the temperature decrease in the study area changed from 10 c during the oldest dryas to 6 c during the younger dryas and precipitation lowering decreased from 50 to 30 or even 10 respectively compare to modern conditions

a new hierarchical bayesian approach to analyse environmental and climatic influences on debris flow occurrence abstract how can debris flow occurrences be modelled at regional scale and take both environmental and climatic conditions into account and of the two which has the most influence on debris flow activity in this paper we try to answer these questions with an innovative bayesian hierarchical probabilistic model that simultaneously accounts for how debris flows respond to environmental and climatic variables in it full decomposition of space and time effects in occurrence probabilities is assumed revealing an environmental and a climatic trend shared by all years catchments respectively clearly distinguished from residual random effects the resulting regional and annual occurrence probabilities evaluated as functions of the covariates make it possible to weight the respective contribution of the different terms and more generally to check the model performances at different spatio temporal scales after suitable validation the model can be used to make predictions at undocumented sites and could be used in further studies for predictions under future climate conditions also the bayesian paradigm easily copes with missing data thus making it possible to account for events that may have been missed during surveys as a case study we extract 124 debris flow event triggered between 1970 and 2005 in 27 catchments located in the french alps from the french national natural hazard survey and model their variability of occurrence considering environmental and climatic predictors at the same time we document the environmental characteristics of each debris flow catchment morphometry lithology land cover and the presence of permafrost we also compute 15 climate variables including mean temperature and precipitation between may and october and the number of rainy days with daily cumulative rainfall greater than 10 15 20 25 30 40 mm day 1 application of our model shows that the combination of environmental and climatic predictors explained 77 of the overall variability of debris flow occurrences in this data set occurrence probabilities depend mainly on climatic variables which explain 44 of the overall variability through the number of rainy days and maximum daily temperature this important time component in the variability of overall debris flow occurrence is shown to be responsible for a significant increase in debris flow activity between 1970 and 2005 at regional scale environmental variables which account for 33 of the overall variability includes mostly the morphometric variables of the debris flow catchments

pleistocene ice caps on the coastal mountains of the adriatic sea ice caps once covered large areas of mount orjen 1894 m on the adriatic coast of montenegro bosnia herzegovina croatia the largest ice cap covered an area of c 165 km2 and reached a maximum ice thickness of c 450 m in some areas reaching down to 500 m above modern sea level u series dating of secondary carbonates within moraines indicates that the most extensive glaciation occurred during the middle pleistocene correlating with a major phase of glaciation in greece to the south during mis 12 c 480 430 ka later less extensive glaciations are also recorded in the cirques and valleys and correlate with glaciations during mis 6 190 130 ka and mis 5d 2 110 11 7 ka each phase of glaciation would have required large amounts of snow accumulation under modern precipitation values which at c 5000 mm are some of the highest in europe mean annual temperatures would need to be only c 5 6 c lower in order to form similar sized glaciers today a mean annual temperature depression of 12 13 c would still require 1000 mm of snow accumulation water equivalent to balance ablation suggesting sustained moisture supply during pleistocene cold stages such sustained precipitation supply during pleistocene cold stages is likely to have been facilitated by major temperature contrasts between the european landmass and the mediterranean sea which are likely to have sustained lee side vortices to the south of the alps in the gulf of genoa and adriatic sea forming weak moisture bearing depressions which tracked across the eastern adriatic coastal mountains large ice caps on the dinaric alps would have blocked the inland penetration of these depressions resulting in much drier conditions in the balkan interior creating favourable conditions for the deposition of thick accumulations of loess the last glaciers on orjen formed during the younger dryas 12 9 11 7 ka and confirm the influence of north atlantic ocean circulation on pleistocene climate change in this part of the mediterranean

palaeogeography and 10be exposure age chronology of middle and late pleistocene glacier systems in the northern pyrenees implications for reconstructing regional palaeoclimates abstract we present constraints on the chronology palaeogeography and palaeoclimatic implications for western europe of middle and late pleistocene glaciation in the ariege catchment north eastern pyrenees based on 37 cosmogenic 10 be exposure ages obtained from moraines and glacially scoured bedrock exposures we have dated six regional glacial stades the chronology emphasises several conclusions that are new to the region i in the pyrenees the global lgm occurred several thousands of years after the maximum ice extent of the wurmian glaciation ii almost full glacier extent occurred again during the global lgm but only in the eastern pyrenees iii valley glaciers such as in the ariege trunk valley attained lengths of 25 km during the oldest dryas stadial the cosmogenic exposure ages additionally provide the first direct evidence of 10 km scale fluctuations of ice front positions during the late pleistocene glacial cycle probably at the time of marine isotope stage 3 as well as rare insights into middle pleistocene ice margin positions compared with existing evidence of glacial palaeogeography in other catchments of the pyrenan range the data also reveal a sharp contrast in relative ice extent between the glacierized catchments of the eastern pyrenees ariege carol malniu tet where wurmian mie and lgm ice fronts reached similar positions and the rest of the range where ice fronts at the time of the mis 2 and global lgm palaeotemperature minima lagged far behind the wurmian mie terminal moraines we ascribe this non uniform behaviour among catchments to non uniform palaeoclimatic conditions along the strike of the pyrenees a range of palaeoenvironmental proxies reviewed in the literature highlight a sharp difference in sea surface temperatures between the warmer western mediterranean and the cooler bay of biscay the consequences of such an e w temperature gradient on weather patterns during the global lgm are compatible with a strengthening of mediterranean low pressure systems particularly the semi permanent balearic low generating greater precipitation over the eastern pyrenees compared to atlantic weather systems further west