holocene glacial activity and climatic variations in the swiss alps reconstructing a continuous record from proglacial lake sediments cores recovered from proglacial lake silvaplana swiss alps were investigated to examine the influence of holocene glaciers on lacustrine sedimentation during times of glacial activity in the catchment the sedimentation in the lake is dominated by the input of silt and clay sized material delivered by glacial meltwaters the deposition of fine grained material and the formation of varves reflect the existence of glaciers in the catchment and can therefore be used for the reconstruction of glacial history sedimentation rates are up to nine times higher in the varved than in the non varved sediments indicating significantly higher erosion rates under glaciated catchment conditions glacial varves were deposited in lake silvaplana during glacial retreat in the latest pleistocene and early holocene until 9400bp non varved deposits having a higher organic content and coarser grain sizes accumulated at lower rates when glacial activity was absent or negligible within the catchment between 9400 and 3300 bp

tracking holocene glacial and high altitude alpine environments fluctuations from minerogenic and organic markers in proglacial lake sediments lake blanc huez western french alps holocene palaeoenvironmental evolution and glacial fluctuations at high altitude in the western french alps are reconstructed based on a multiproxy approach within lake blanc huez 2550 m a s l drainage basin the combination of seismic profiling 3 5 khz piston coring and radiocarbon dating in proglacial lacustrine sediments together with a detailed organic analysis of autochthonous and allochthonous supply allows documenting the evolution of glacier activity during the holocene over the last 9700 years the holocene lake record has a bimodal pattern whose transition is progressive and occurring between 5400 and 4700 cal bp during the early holocene the organic lacustrine facies reflects reduced glacial activity in the catchment this major glacial retreat seems to result from solar forcing and high summer insolation after 5400 cal bp lacustrine sedimentation is marked by the gradual increase both of minerogenic supply and soil erosion suggesting a progressive transition to wetter climatic conditions this climate change is synchronous both from the gradual decrease of summer insolation and the gradual reorganization of oceanic and atmospheric circulations characterizing the beginning of the neoglacial period both colder temperature and humid climate induced significant glacier advance since 4700 cal bp over this global trend three periods are particularly associated with higher runoff processes and higher soil erosion interpreted as wetter time intervals resulting from enhanced northern westerlies regimes across the north atlantic and western europe they are dated from 8700 to 7000 4700 to 2500 and 1200 to 200 cal bp these wetter phases drastically contrast with periods of reduced glacial activities dated from the early bronze age ca 3870 3770 cal bp the iron age ca 2220 2150 cal bp the roman period ca ad115 330 and the medieval warm period ca ad760 1160 in addition these dryer periods are associated with mining activities at high altitude

the effect of geomorphological setting on holocene lake sediment variability northern swedish lapland the effect of geomorphological setting on holocene lake sediment variability northern swedish lapland

interhemispheric synchrony of late glacial climatic instability as recorded in proglacial lake mascardi argentina several high resolution continental records have been reported recently in sites in south america but the extent to which climatic variations were synchronous between the northern and southern hemispheres during the late glacial holocene transition and the causes of the climatic changes remain open questions previous investigations indicated that east of the andes the middle and high latitudes of south america warmed uniformly and rapidly from 13 000 14c yr bp with no indication of subsequent climate fluctuations equivalent for example to the younger dryas cooling here we present a multiproxy continuous record radiocarbon dated by accelerated mass spectroscopy from proglacial lake mascardi in argentina the results show that unstable climatic conditions comparable to those described from records obtained in the northern hemisphere dominated the late glacial holocene transition in argentina at this latitude furthermore a significant advance of the tronador ice cap which feeds lake mascardi occurred during the younger dryas chronozone this instability suggests a step wise climatic history reflecting a global rather than regional forcing mechanism the lake mascardi record therefore provides strong support for the hypothesis that ocean atmosphere interaction rather than global ocean circulation alone governed interhemispheric climate teleconnections during the last deglaciation 1997 john wiley sons ltd

spatial and temporal variations in electrical conductivity in a pro glacial stream system resultats d observations spatio temporelle de la conductivite electrique en ete 1978 et 1981 du systeme d ecoulement proglaciaire du glacier de tsidjiore nouve valais suisse des cycles d echantillonnage a 12 h 24 h et 48 h montrent l existence de cycles diurnes et de caracteristiques de complementarite entre les periodes d ablation entre plusieurs jours ou de jour en jour

the rhone glacier was smaller than today for most of the holocene we present the development and application of the novel in situ cosmogenic 14 c 10 be chronometer to recently exposed proglacial bedrock of the rhone glacier switzerland results show that during the holocene the glacier was smaller than today for 6500 2000 yr and larger than today for 4500 2000 yr this pattern is consistent with limited data from other techniques for glaciers in the alps and scandinavia but in contrast to glaciers from the southern alps of new zealand emphasizing the high sensitivity of large mountain glaciers to small climate changes the 14 c 10 be chronometer also shows that abrasion rates beneath the rhone glacier increased with ice speed

younger dryas and holocene glacier fluctuations and equilibrium line altitude variations in the jostedalsbre region western norway reconstructed younger dryas 11000 10000 y bp valley and cirque glaciers west of the jostedalsbre ice cap suggest an equilibrium line altitude ela depression of 450 50 m compared to the present level the mid preboreal 9500 200 y bp deglaciation was characterized by vertical wastage indicating that the ela was above the summit plateaus during the erdalen event 9100 200 y bp marginal moraines were formed up to 1 km beyond the little ice age lia moraines which lie in front of the present valley outlet glaciers of the jostedalsbre ice cap the average ela lowering during this event is calculated to 325 m below the modern level lithostratigraphic and paleobotanical studies show that the hypsithermal ca 8000 6000 y bp ela was about 450 m higher than at present as a result jostedalsbreen probably disappeared entirely during that period the glacier reformed about 5300 y bp the ela intersected the modern mean equilibrium line altitude five times from ca 2600 y bp to the present the outlet valley glaciers reached their maximum neoglacial extent during the lia in the mid 18th century when the ela was depressed 100 150 m below the present level

lake level fluctuations at lake bourget eastern france around 4500 3500 cal a bp and their palaeoclimatic and archaeological implications on the basis of sedimentological analysis of two cores taken at chatillon lake le bourget northern french pre alps and well dated by radiocarbon dates in addition to tree ring dates obtained from an archaeological layer this paper presents a high resolution lake level record for the period 45003500 cal a bp the collected data provide evidence of a complex palaeohydrological climatic oscillation spanning the ca 43003850 cal bp time interval with major lake level maxima at ca 4200 and 40503850 cal a bp separated by a lowering episode around 4100 cal a bp the lake level highstands observed at chatillon between 4300 and 3850 cal bp appear to be synchronous with i a major flooding period recorded in deep cores from the large lakes le bourget and bodensee and ii glacier advance and tree line decline in the alps such wetter and cooler climatic conditions in west central europe around 4000 cal a bp may have been a nonlinear response to decrease and seasonal changes in insolation they may also provide a possible explanation for the general abandonment of prehistoric lake dwellings north of the alps between 4360 and 3750 cal a bp

chironomid response to environmental drivers during the holocene in a shallow treeline lake in northwestern fennoscandia the significance of different environmental drivers for the chironomid compositional changes during the holocene was assessed using partial redundancy analysis these drivers included pollen inferred mean july air temperature vegetation cover as pollen percentages diatom inferred water ph and total organic carbon toc and sediment properties as loss on iginition loi variance partitioning showed that on the holocene timescale chironomid assemblages were significantly responding to changes in betula percentages this is explained by the co occurring response of chironomids to the holocene climatic development which has also been responsible for the development of vegetation in the catchment however during the very early holocene period from 10 500 cal yr bp to 8300 cal yr bp chironomids were responding more directly to the changes in water quality ie ph during the latter part of the holocene no environmental variable appeared to be significant in explaining the variation in chironomid assemblages this may be due to the underestimation of the actual water toc by the diatom based toc model however for the latter part of the holocene from 5000 cal yr bp to the present the importance of limnological changes attributed to the development of marginal mires on the midges is evident our study shows that factors other than climate may have had more direct influence on the chironomid abundances at certain time periods although these factors are probably indirectly connected to climate through catchment processes more understanding of the catchment mediated climate effects on lake ecology and chironomids in high latitudes is needed in addition to careful site selection in order to better understand the environmental reconstructions

holocene glacier fluctuations a global overview of glacier advances and retreats grouped by regions and by millennia for the holocene is compiled from previous studies the reconstructions of glacier fluctuations are based on 1 mapping and dating moraines defined by 14 c tcn osl lichenometry and tree rings discontinuous records time series and 2 sediments from proglacial lakes and speleothems continuous records time series using 189 continuous and discontinuous time series the long term trends and centennial fluctuations of glaciers were compared to trends in the recession of northern and mountain tree lines and with orbital solar and volcanic studies to examine the likely forcing factors that drove the changes recorded a general trend of increasing glacier size from the earlyemid holocene to the late holocene in the extra tropical areas of the northern hemisphere nh is related to overall summer temperature forced by orbitally controlled insolation the glaciers in new zealand and in the tropical andes also appear to follow the orbital trend i e they were decreasing from the early holocene to the present in contrast glacier fluctuations in some monsoonal areas of asia and southern south america generally did not follow the orbital trends but fluctuated at a higher frequency possibly triggered by distinct teleconnections patterns during the neoglacial advances clustered at 4 4e4 2 ka 3 8e3 4 ka 3 3e2 8 ka 2 6 ka 2 3e2 1 ka 1 5e1 4 ka 1 2e1 0 ka 0 7e0 5 ka corresponding to general cooling periods in the north atlantic some of these episodes coincide with multidecadal periods of low solar activity but it is unclear what mechanism might link small changes in irradiance to widespread glacier fluctuations explosive volcanism may have played a role in some periods of glacier advances such as around 1 7e1 6 ka coinciding with the taupo volcanic eruption at 232 5 ce but the record of explosive volcanism is poorly known through the holocene the compilation of ages suggests that there is no single mechanism driving glacier fluctuations on a global scale multidecadal variations of solar and volcanic activity supported by positive feedbacks in the climate system may have played a critical role in holocene glaciation but further research on such linkages is needed the rate and the global character of glacier retreat in the 20th through early 21st centuries appears unusual in the context of holocene glaciation though the retreating glaciers in most parts of the northern hemisphere are still larger today than they were in the early and or mid holocene the current retreat

holocene optimum events inferred from subglacial sediments at tschierva glacier eastern swiss alps abstract this study investigates the subglacial sedimentary archive at tschierva glacier eastern swiss alps subfossil wood remains found at the retreating glacier tongue indicate that their emergence results from recent transport from an upvalley basin a confluence basin like structure was found to exist by georadar measurements underneath the present glacier in combination with high resolution age determinations based on dendrochronology and radiocarbon dating it is implied that a retreated tschierva glacier allowed vegetation growth and sediment accumulation in that basin three periods of glacier recession were detected which occurred around 9200 cal yr bp from 7450 to 6650 cal yr bp and from 6200 to 5650 cal yr bp these periods are called holocene optimum events hoe accordingly an equilibrium line rise 220 m compared to the reference period from 1960 to 1985 was inferred from digital elevation models of former glacier extents since glacier mass balance depends on summer june july august temperature and precipitation an equilibrium line altitude ela rise of 220 m implies a summer temperature increase of about 1 8 c assuming unchanged precipitation during the dated hoe alternative calculations point to probable temperature increase in a broad interval between 1 0 c taking into account a precipitation change of 250 mm a to 2 5 c with 250 mm a precipitation change supporting earlier paleotemperature estimates it is proposed that higher mean summer insolation caused a stronger seasonality during the mid holocene as compared to late holocene conditions

reconstructing holocene glacier activity at langfjordjokelen arctic norway using multi proxy fingerprinting of distal glacier fed lake sediments abstract late glacial and holocene glacier fluctuations are important indicators of climate variability in the northern polar region and contain knowledge vital to understanding and predicting present and future climate changes however there still is a lack of robustly dated terrestrial climate records from arctic norway here we present a high resolution relative glacier activity record covering the past 10 000 cal a bp from the northern outlet of the langfjordjokelen ice cap in arctic norway this record is reconstructed from detailed geomorphic mapping multi proxy sedimentary fingerprinting and analyses of distal glacier fed lake sediments we used principal component analysis to characterize sediments of glacial origin and trace them in a chain of downstream lakes of the variability in the sediment record of the uppermost lake jokelvatnet 73 can be explained by the first principal component axis and tied directly to upstream glacier erosion whereas the glacial signal becomes weaker in the more distal lakes store rundvatnet and storvatnet magnetic susceptibility and titanium count rates were found to be the most suitable indicators of holocene glacier activity in the distal glacier fed lakes the complete deglaciation of the valley of sor tverrfjorddalen occurred 10 000 cal a bp followed by a reduced or absent glacier during the holocene thermal optimum the langfjordjokelen ice cap reformed with the onset of the neoglacial 4100 cal a bp and the gradually increasing glacier activity culminated at the end of the little ice age in the early 20th century over the past 2000 cal a bp the record reflects frequent high amplitude glacier fluctuations periods of reduced glacier activity were centered around 1880 1600 1250 and 950 cal a bp while intervals of increased glacier activity occurred around 1680 1090 440 and 25 cal a bp the large scale holocene glacier activity of the langfjordjokelen ice cap is consistent with regional temperature proxy reconstructions and glacier variability across norway long term changes in the extent of the northern outlet of the langfjordjokelen ice cap largely followed trends in regional summer temperatures whereas winter season atmospheric variability may have triggered decadal scale glacial fluctuations and generally affected the amplitude of glacier events

decadal scale autumn temperature reconstruction back to ad 1580 inferred from the varved sediments of lake silvaplana southeastern swiss alps a quantitative high resolution autumn september november temperature reconstruction for the southeastern swiss alps back to ad 1580 is presented here we used the annually resolved biogenic silic

holocene climatic change in swedish lapland inferred from an oxygen isotope record of lacustrine biogenic silica holocene climatic variability was studied in a 9500 year lake sediment sequence from the abisko region in swedish lapland using the oxygen isotope ratio in diatom biogenic silica d 18 osi oxygen and hydrogen isotope ratios of waters from the abisko area suggest that in this region the evaporative flux is small and the isotopic composition of most lakes reflects that of the local precipitation the hydrological setting of the region and sensitivity analysis of isotopic response to changing climatic parameters such as humidity inflow and evaporation show that the downcore diatom d18osi record is primarily controlled by changes in the summer isotopic composition of the lake water the overall 3 5 depletion in d 18 osi since the early holocene is interpreted as an increase in the influence of the arctic polar continental air mass that carries depleted precipitation we estimate that this change is associated with a 2 5 4 c cooling that has occurred since the early holocene in general the diatom d 18 osi record resembles the average annual air temperature reconstructed for the greenland ice core gisp2 especially during the past 4000 years with a pronounced cooling starting at 2000 years bp

pattern and forcing of northern hemisphere glacier variations during the last millennium time series depicting mountain glacier fluctuations in the alps display generally similar patterns over the last two centuries as do chronologies of glacier variations for the same interval from elsewhere in the northern hemisphere episodes of glacier advance consistently are associated with intervals of high average volcanic aerosol production as inferred from acidity variations in a greenland ice core advances occur whenever acidity levels rise sharply from background values to reach concentrations 1 2 equiv h kg above background a phase lag of about 10 15 yr equivalent to reported response lags of alpine glacier termini separates the beginning of acidity increases from the beginning of subsequent ice advances a similar relationship but based on limited and less reliable historical data and on lichenometric ages is found for the preceding 2 centuries calibrated radiocarbon dates related to advances of non calving and non surging glaciers during the earlier part of the little ice age display a comparable consistent pattern an interval of reduced acidity values between about 1090 and 1230 a d correlates with a time of inferred glacier contraction during the medieval optimum the observed close relation between noothern hemisphere glacier fluctuations and variations in greenland ice core acidity suggests that sulfur rich aerosols generated by volcanic eruptions are a primary forcing mechanism of glacier fluctuations and therefore of climate on a decadal scale the amount of surface cooling attributable to individual large eruptions or to episodes of eruptions is simlar to the probable average temperature reduction during culminations of little ice age alacier advances ca 0 5 1 2 c as inferred from depression of equilibrium line altitudes

changes in distal sedimentation regime of the rhone delta system controlled by subaquatic channels lake geneva switzerland france abstract seismic reflection profiles combined with sediment cores reveal centennial changes in the proximal and distal sedimentation regime in the rhone river delta system lake geneva which is dominated by sublacustrine channels from detailed analyses of the thickness distribution of depositional units and the occurrence of turbidites at least two shifts of the primarily active sublacustrine channels are inferred for the past 1500 years the first northward shift is dated at 1480 20 cal ad and was likely linked to a centennial flood in the swiss rhone valley that occurred in 1469 ad and acted either as a direct cause or as a preconditioning factor favoring the shifting a shift back southward in 1720 90 cal ad may have been caused either by long term human impact related to the first embankment constructions on the rhone river or by a natural event such as the 1755 ad brig earthquake or the centennial flood of 1640 ad another important change in the sedimentation regime occurs in 1775 125 cal ad when the onset of rhone turbidite deposition is recorded in the distal sediments this relative progradation of the rhone turbidites is certainly due to the disconnection of the vieux rhone branch before 1826 and the subsequent first rhone river correction starting in 1863 that led to the present single active rhone subaquatic channel

sedimentary evidence of landscape and climate history since the end of mis 3 in the krkonose mountains czech republic abstract a sedimentary core recovered from the cirque basin of labsk d l valley 1039 m a s l in the krkonose mountains reflects the environmental history for approximately the last 30 000 years analyses of magnetic susceptibility carbon content pollen assemblages and macrofossil data in a 15 m thick sediment sequence provide the first continuous record of lateglacial and holocene vegetation history in sudetes region of the czech republic the succession of sedimentary units in the lower part of the core suggests that the cirque was ice free before the onset of the last glaciation at the beginning of marine isotope stage 2 highly variable climate prevailed during this period with cold conditions culminating about 18 cal ka bp cold climates persisted until the lateglacial period evidenced by an identified warming and subsequent cooling event correlated with the younger dryas period sparse treeless vegetation dominated in the catchment area at that time the sequence of interrupted thinly laminated silts reflects the retreat and temporary readvance of a local glacier in the cirque during 12 5 10 8 cal ka bp subsequently the alpine treeline ecotone gradually shifted above the cirque floor palaeoclimatic conditions in the early holocene fluctuated strongly whereas since 5 1 cal ka bp conditions have been more stable pollen based climate reconstructions suggest significant cooling at around 9 8 9 3 7 7 7 5 and 4 0 3 3 cal ka bp spruce forests have dominated the site since 5 0 cal ka bp when the vegetation became similar to the modern one two phases of increased sedimentation were identified within the holocene culminating about 9 2 7 5 cal ka bp and 5 8 5 5 cal ka bp sediment yield was as high as 2 4 mm yr 1 during the period reflecting environmental changes during the atlantic sub boreal transition

holocene vegetation history and quantitative climate reconstructions in a high elevation oceanic district of the italian alps evidence for a middle to late holocene precipitation increase abstract we reconstructed the vegetation and climate history during the last 10 ka in a high elevation sedimentary record armentarga peat bog 2345 m asl on the southern flank of the european alps through the study of paleoecological and sedimentary proxies we included a specific elevational transect of modern pollen accumulation rates for timberline forming trees and shrubs alnus viridis pinus sylvestris mugo pinus cembra quantitative reconstructions of july temperature and annual precipitation were obtained by applying numerical transfer functions built on an extensive pollen climate calibration set from the european alps changes in elevational vegetation arrangement were primarily driven by phases of precipitation increase and to a lesser extent by millennial scale temperature changes already known from glacier timberline chironomids and speleothem records at alpine scale changes in pollen inferred annual precipitation occurred in three main steps an early holocene moderately humid phase is mirrored by the early spread of alnus viridis dwarf forests precipitation started to increase at 6 2 ka cal bp a further prominent step forward at the middle to late holocene transition led to the high values of snowfall and runoff characterizing today s oceanic elevational climates of the outer italian alps this change led to timberline depression and grassland expansion locally human impact was weak at the late neolithic bronze age transition this event correlates with lake level oscillations in the northern mediterranean borderlands suggesting intensification of southern air masses conveyed by tyrrhenian cyclones towards windward districts

correlation of alaskan varve thickness with climatic parameters and use in paleoclimatic reconstruction the thickness of varves in the sediments of skilak lake alaska are correlated with the mean annual temperature r 0 574 inversely correlated with the mean annual cumulative snowfall r 0 794 and not correlated with the mean annual precipitation r 0 202 of the southern alaska climatological division for the years 1907 1934 a d varve thickness in skilak lake is sensitive to annual temperature and snowfall because skilak glacier the dominant source of sediment for skilak lake is sensitive to these climatic parameters trends of varve thickness are well correlated with trends of mean annual cumulative snowfall r 0 902 of the southern alaska climatological division and with trends of mean annual temperature of the southern r 0 831 and northern r 0 786 alaska climatological divisions trends of varve thickness also correlate with trends of annual temperature in seattle and north head washington r 0 632 and 0 850 respectively comparisons of trends of varve thickness with trends of annual temperature in california oregon and washington suggest no widespread regional correlation trends of annual snowfall in the southern alaska climatological division and trends of annual temperature in the southern and northern alaska climatological divisions are reconstructed for the years 1700 1906 a d climatic reconstructions on the basis of varve thickness in skilak lake utilize equations derived from the regression of series of smoothed climatological data on series of smoothed varve thickness reconstruction of trends of mean annual cunulative snowfall in the southern alaska climatological division suggests that snowfall during the 1700s and 1800s was much greater than that during the early and mid 1900s the periods 1770 1790 and 1890 1906 show marked decreases in the mean annual snowfall reconstructed trends of the annual temperature of the northern and southern alaska climatological divisions suggest that annual temperatures during the 1700s and 1800s were lower than those of the early and mid 1900s two periods of relatively high annual temperatures coincide with the periods of low annual snowfall thus determined

la icp ms u pb dating of carboniferous ash layers in the cantabrian zone n spain stratigraphic implications seven centimetre thick volcanic ash fall layers interbedded within the thick carboniferous successions of the cantabrian zone in northern spain were dated by u pb zircon laser ablation inductively coupled plasma mass spectrometry across an interval ranging from visean to kasimovian thus covering most of the carboniferous period all these ash layers occur in fossiliferous successions allowing us to insert the radiometric data within a well constrained biostratigraphic framework considering the analytical uncertainty the obtained ages match the ages inferred from the conodont biostratigraphy established in the mississippian succession which hosts the oldest two ash layers visean in age and the fusuline and mega and microflora data from the strata hosting the moscovian and kasimovian westphalian stephanian tonsteins the age of a langsettian tonstein along with data provided by several papers stating that in the cantabrian zone langsettian floras were contemporaneous with lowermost moscovian fusulines suggest that langsettian floras could have been younger in spain than in other areas our absolute ages provide new constraints not only for the correlation of the carboniferous successions of the cantabrian zone with time equivalent reference successions in other parts of the world but also for calibrating the carboniferous global chronostratigraphic units based on marine fossils with the west european regional units supplementary material stratigraphic position and biostratigraphic information on the studied ash fall layers analytical methods and geochronological results are available at https doi org 10 6084 m9 figshare c 3768701

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

environmental change during the holocene in western china on a millennial timescale recent data on the evolution of the inland lakes loess palaeosol sequences and glacier variations in western china are briefly reviewed the lake history shows three distinct stages in the holocene i e low water levels before 7500 bp a stage of expansion during the climatic optimum between 7500 and 3500 bp and contraction after 3500 bp three stages wooded grassland mixed woodland wooded grassland becoming steppe also appear indicated by the holocene loess palaeosol sequence in the lanzhou region the optimal period for soil development being between 7500 and 3500 bp there were seven periods of glacier advance the continental glaciers advanced at about 8300 5700 4000 and 400 bp in northwestern china and the maritime glaciers advanced at about 3000 2000 1000 and 200 bp it is suggested that the climatic changes show two periodicities during the holocene namely at intervals of about 2500 and 1000 years

silver and lead in high altitude lake sediments proxies for climate changes and human activities abstract high altitude lake sediments are often used as archives for environmental changes and their chemical and isotopic compositions provide significant constraints on natural and anthropogenic long term changes that have occurred in their catchment area here trace element concentrations and pb isotopes are presented for two sedimentary cores from lake blanc huez in the french alps to trace the impact of climate changes and human activities over the holocene lead and ag contents are very high and clearly dominated by input from a pb ag vein located a few meters from the lakeshore a vein that also buffers the pb isotopes mining of this vein in medieval times is recorded in the corresponding lake sediments with high ag content coupled with high pb u ratio these chemical characteristics can be used to constrain the major holocene climate changes significant advances of glaciers next to the lake produced sediments with ag and pb concentration peaks and high pb u ratios due to accelerated erosion of the pb ag vein similar to the effects of the medieval mining in contrast reduced glacier activity led to the formation of organic rich sediments with high u and as contents and low pb u ratios more generally the observed combination of chemical changes could be used elsewhere to decipher environmental changes over long periods of time

how stable are twentieth century calibration models a high resolution summer temperature reconstruction for the eastern swiss alps back to ad 1580 derived from proglacial varved sediments we found a significant positive correlation between local summer air temperature may september and the annual sediment mass accumulation rate mar in lake silvaplana 46 n 9 e 1800 m a s l during the twentieth century r 0 69 p 0 001 for decadal smoothed series sediment trap data 2001 2005 confirm this relation with exceptionally high particle yields during the hottest summer of the last 140 years in 2003 on this base we developed a decadal scale summer temperature reconstruction back to ad 1580 surprisingly the comparison of our reconstruction with two other independent regional summer temperature reconstructions based on tree rings and documentary data revealed a significant negative correlation for the pre 1900 data ie late little ice age this demonstrates that the correlation between mar and summer temperature is not stable in time and the actualistic principle does not apply in this case we suggest that different climatic regimes modern little ice age lead to changing state conditions in the catchment and thus to considerably different sediment transport mechanisms therefore we calibrated our mar data with gridded early instrumental temperature series from ad 1760 1880 r 0 48 p 0 01 for decadal smoothed series to properly reconstruct the late lia climatic conditions we found exceptionally low temperatures between ad 1580 and 1610 0 75 c below twentieth century mean and during the late maunder minimum from ad 1680 to 1710 0 5 c below twentieth century mean in general summer temperatures did not experience major negative departures from the twentieth century mean during the late little ice age this compares well with the two existing independent regional reconstructions suggesting that the lia in the alps was mainly a phenomenon of the cold season

constant denudation rates in a high alpine catchment for the last 6 kyrs terrestrial cosmogenic nuclides tcn have widely been used as proxies in determining denudation rates in catchments most studies were limited to samples from modern active streams thus little is known about the magnitude and causes of tcn variability on millennial time scales in this work we present a 6 kyrs long high resolution record of 10be concentrations n 18 which were measured in sediment cores from an alluvial fan delta at the outlet of the fedoz valley in the swiss alps this record is paired with a three year time series n 4 of 10be measured in sediment from the active stream currently feeding this fan delta the temporal trend in the 10be concentrations after correction for postdepositional production of 10be was found to be overall constant and in good agreement with the modern river 10be concentration the calculated mean catchment wide denudation rate amounts to 0 73 0 18 mm yr this fairly constant level of 10be concentrations can be caused by a constant denudation rate over time within the catchment or alternatively by a buffered signal in this contribution we suggest that the large alluvial floodplain in the fedoz valley may act as an efficient buffer on holocene time scales in which sediments with different 10be signatures are mixed therefore presumable variations in the 10be signals derived from changes in denudation under a fluctuating holocene climate are only poorly transferred to the catchment outlet and not recorded in the 10be record however despite the absence of high frequency signals we propose that the buffered and averaged 10be signal could be meaningfully and faithfully interpreted in terms of long term catchment averaged denudation rate our study suggests that alluvial buffers play an important role in regulating the 10be signal exported by some alpine settings that needs to be taken into account and further investigated this article is protected by copyright all rights reserved

nonmigrating semidiurnal and diurnal tides at 95 km based on wind measurements from the high resolution doppler imager on uars 1 for more than a decade derived results from the high resolution doppler imager hrdi on uars have provided an enormous amount of new and invaluable information on the global variability of atmospheric winds these and other results have given added impetus to theoretical modeling efforts until recent years the large majority of investigations have focused on migrating tides and now more results on nonmigrating tides have become available we provide new results for semidiurnal and diurnal nonmigrating tides based on data from hrdi at 95 km much of these results have not been obtained before and they are substantially different from those that have been previously reported our amplitudes are usually significantly larger with more periodicities in both day of year and latitude than results that have previously appeared in the literature we also find components up to longitude wave number 3 that are significant and have not been presented before and that traveling components of larger longitude wave numbers 4 5 and 6 can reach several m s in amplitude we compare our results with earlier results based on hrdi measurements and from selected models

megaturbidite deposits in the holocene basin fill of lake como southern alps italy abstract for the first time limnogeological investigations have been carried out in lake como the deepest lake of the alps combining a bathymetric survey multibeam simrad 3000 with a high resolution seismic reflection study single channel 3 5 khz sub bottom profiler and a coring campaign gravity corer this data set enables detailed characterization of the sedimentary subsurface in the western branch of the lake the como branch which has a typical fjord morphology this paper focuses on the deepest part of the como branch argegno basin in which up to 3 5 m thick turbidite deposits are identified the basin fill of the como branch is characterized by well layered draping and onlapping pelagic sediments that are locally affected by creeping and that are intercalated with mass wasting deposits in particular with two large debris flow deposits evolving into megaturbidites in the deepest part of the basin the multibeam data together with the acoustic facies distributions and the volumes of these two major sedimentary deposits mt1 3 106 m3 and mt2 10 5 106 m3 indicate that they resulted from large slides at the northern tip of the como branch along the steep slopes of a sub lacustrine plateau the estimated ages of these events around the mid 12th mt1 and early 6th mt2 centuries are extrapolated from mean sedimentation rates based on radiocarbon 14c and radionuclide 137cs analyses from short cores in the argegno basin possible trigger mechanisms leading to these catastrophic events in the como branch include a combination of steep slope overloading with significant lake level fluctuations related to holocene climate change and or earthquake shaking the tentative age assignment places the age of both major mass movements near two other events mt1 near the occurrence of a major earthquake in the po plain in 1222 ad intensity ix mcs macroseismically derived magnitude 6 2 and mt2 near a megaturbidite triggered in 700 ad in a proglacial lake in southeastern switzerland blass a anselmetti f grosjean m sturm m 2005 the last 1300 years of environmental history in the sediments of lake sils engadine switzerland eclogae geologicae helvetiae 98 319 332 since dangerous tsunami like waves seiches can be generated by large sub aqueous landslides leading to such megaturbidites in this fjord like basin future studies are required 1 to constrain the age of these catastrophic events 2 to document the stabilities of the steep slopes in the como branch 3 to assess the expected frequency of such catastrophic events and 4 to model the propagation of large waves in the como branch and their potential damage along the highly populated lake shore

climatic variability in the northwestern alps france as evidenced by 600 years of terrigenous sedimentation in lake le bourget cores recovered from periglacial lake le bourget deep basin northwestern alps were investigated to examine the ine uence of the little ice age lia on terrigenous lacustrine sedimentation growing glaciers in the regional watershed induced catastrophic rhone river e oods and major undere ow deposits in the deep basin during the early e fteenth the sixteenth and the mid eighteenth centuries the lia is characterized by a decrease in deposition from intere ows from ad 1550 to 1740 and an increase in deposition from undere ows from ad 1550 to 1800 on one hand spectral analyses of the laminations in intere ow deposits reveal 4 5 years cyclicities from ad 1440 to 1550 as well as 7 8 and 13 14 years cyclicities from ad 1740 to 1870 on the other hand spectral analyses of a clay mineral ratio ree ecting undere ow deposits highlight 45 50 years cyclicities from ad 1550 to 1800 these pluriannual decadal and pluridecadal periods are typical of the north atlantic oscillation nao a nao like period in our data would be a consequence of periodical variations in rainfall and snow accumulation during late autumn and winter over lake le bourget s watershed

frequency and intensity of high altitude floods over the last 3 5 ka in northwestern french alps lake anterne in central western europe several studies have shown that colder holocene periods such as the little ice age also correspond to wet periods however in mountain areas which are highly sensitive to erosion processes and where precipitation events can be localized past evolution of hydrological activity might be more complicated to assess these past hydrological changes a paleolimnological approach was applied on a 13 4 m long sediment core taken in alpine lake anterne 2063 m asl and representing the last 3 5 ka lake sedimentation is mainly composed of ood deposits triggered by precipitation events sedimentological and geochemical analyses show that oods were more frequent during cold periods while high intensity ood events occurred preferentially during warmer periods in mild temperature conditions both ood patterns are present this underlines the complex relationship between ood hazards and climatic change in mountain areas during the warmer and or dryer times of the end of iron age and the roman period both the frequency and intensity of oods increased this is interpreted as an effect of human induced clearing for grazing activities and reveals that anthropogenic interferences must be taken into account when reconstructing climatic signals from natural archives

varve studies at hector lake alberta canada and the relationship between glacial activity and sedimentation glacial lake sedimentary records from hector lake in banff national park alberta are examined with the aim of clarifying the relationship between glacial activity and outwash sedimentation rhythmic couplets in lake bottom sediments provide a method for accurate documentation and dating of recent sedimentation chronology as analysis of 137cs content indicates that the couplets are of annual periodicity i e varves a comparison of sedimentation rate records with recent regional glacial history indicates that high sedimentation rates of one to a few decades duration occur either during and immediately following periods of moraine deposition ie maximum ice stands or during periods of rapid ice recession comparison of sedimentary records with somewhat longer term glacial and vegetation records indicates that sedimentation rate variations of several centuries duration closely parallel changes in upvalley ice extent over this time scale high sedimentation rates occur during periods of relatively increased ice extent low rates during periods of reduced ice extent within this general pattern however sedimentation rates may remain very high for nearly a century following maximum ice stands due to the exposure of unstable glaciogenic deposits to fluvial reworking during ice recession

holocene temperature variations at a high altitude site in the eastern alps a chironomid record from schwarzsee ob solden austria few well dated quantitative holocene temperature reconstructions exist from high altitude sites in the central eastern alps here we present a chironomid based quantitative reconstruction of mean july air temperatures tjuly throughout the holocene for a remote high mountain lake schwarzsee ob solden situated above the treeline at 2796 m a s l in the austrian alps applying a chironomid temperature inference model developed from lakes of the alpine region to a high resolution chironomid record from the lake provides evidence for early holocene ca 10000 8600 cal yr bp tjuly of up to 8 5 c i e 4 c above the modern 1977 2006 mean july temperature the reconstruction reveals the so called 8 2 ka cold event centered at ca 8250 8000 cal yr bp with temperatures ca 3 c below the early holocene thermal maximum rather warm ca 6 c and productive conditions prevailed during ca 7900 4500 cal yr bp the chironomid record suggests a climate transition between ca 5200 and 4500 cal yr bp to cooler tjuly a distinct cooling trend is evident from ca 4500 until ca 2500 cal yr bp thereafter the study site experienced its coldest conditions around 4 c or less throughout the rest of the holocene with the exception of the warming trend during the late 20th century beside other factors the northern hemisphere summer insolation seems to be the major driving force for the long term trends in tjuly at high altitudes in the eastern alps due to the extreme location of the lake and the limited temperature range represented by the applied calibration data set the chironomid based temperature reconstruction fails to track phases of the late holocene climatic history with tjuly cooler than 4 c further chironomid based palaeoclimate model and down core studies are required to address this problem provide more realistic tjuly estimates from undisturbed high altitude lakes in the alps and extract a reliable regional temperature signal

reconstruction of last glacial to early holocene monsoon variability from relict lake sediments of the higher central himalaya uttrakhand india abstract proglacial lake sediments at goting in the higher central himalaya were analyzed to reconstruct the summer monsoon variability during the last glacial to early holocene sedimentary structures high resolution mineral magnetic and geochemical data suggest that the lacustrine environment experienced fluctuating monsoonal conditions optically stimulated luminescence osl dating indicates that the lake sedimentation occurred before 25 ka and continued after 13 ka during this period goting basin witnessed moderate to strengthened monsoon conditions around 25 ka 23 5 ka 22 5 ka 22 ka 18 ka 17 ka 16 5 ka and after14 5 13 ka the last glacial phase ended with the deposition of outwash gravel dated at 11 ka indicating glacial retreat and the onset of holocene condition additionally centennial scale fluctuations between 16 5 ka and 12 7 ka in the magnetic and geochemical data are seen a close correspondence at the millennial scale between our data and that of continental and marine records from the indian sub continent suggests that goting basin responded to periods of strengthened monsoon during the last glacial to early holocene we attribute the millennial scale monsoon variability to climatic instability in higher northern latitudes however centennial scale abrupt changes are attributed to the result of albedo changes on the himalaya and tibetan plateau

paleoclimatic inferences from glacial fluctuations on svalbard during the last 20 000 years the climate history of western spitsbergen svalbard is deduced from variations of glaciers during the last 20 000 years a major depression of the regional equilibrium line altitude ela occurred during the late weichselian glacial maximum 18000 13000y ago when low summer temperatures may have caused year round snow accumulation on the ground this rapid expansion of the glaciers also indicates nearby moisture sources suggesting partly open conditions in the norwegian sea during the summers a rapid glacial retreat around 13 000 12 500 y bp was caused by a sudden warming during the younger dryas the ela along the extreme western coast of spitsbergen was not significantly lower than at present in contrast to fennoscandia the british isles and the alps there is no evidence for readvance of local glaciers during younger dryas on western spitsbergen this difference is attributed to a much dryer climate on spitsbergen and probably only slight changes in sea surface temperatures in addition summer melting in this high arctic area is more sensitive to orbitally increased insolation around 10 000 y bp another rapid warming occurred and during early and mid holocene the summer temperatures were significantly higher than at present a temperature decline during the late holocene caused regrowth of the glaciers which reached their maximum holocene position during the last century

7200 years of rhone river flooding activity in lake le bourget france a high resolution sediment record of nw alps hydrology magnetic susceptibility ms was measured with high resolution 5 mm on a 9 m long 14c dated core from lake le bourget savoie france spanning the last 7200 years the strong correlation r 0 85 of the ms with the silicate borne suite of elements si al fe mg k and anti correlation with the carbonate content r 0 87 allows it to be used as a proxy for the fluctuations of the abundance of riverborne clastic fraction versus authigenic carbonates in sediment as the rhone is the only river bringing a significant amount of silicate minerals to the coring site the ms downstream is interpreted as a proxy of the rhone suspended load discharge in lake le bourget this is confirmed over the last 3000 years by the good match with the evolution of hydrological activity of the rhone as it is known through geomorphological studies of well dated archaeological sites over the last 7200 years the record is consistent with the regional record of lake water level fluctuations while the intensity of the ms

recent glacier variations and volcanic eruptions the injection of volcanic dust and gases into the atmosphere during major eruptions has been advanced to explain short term variations of climate1 4 a calculated global cooling of 1k during episodes of intense volcanic activity3 could lead to a snowline depression sufficient to cause glacier advances equivalent to those of the last several centuries the hypothesis would therefore be strengthened if a close relationship could be demonstrated between global volcanicity and the pattern of recent glacier variations glacier activity in the northern hemisphere during much of the past 100 yr shows a lack of synchrony with that in the southern hemisphere but in each hemisphere the sequence of glacier variations matches the acidity record in polar ice cores and the frequency of volcanic eruptions in successive latitude belts this suggests that glaciers fluctuate in response to atmospheric build up of volcanic aerosols produced during large eruptions and that explosive volcanism may therefore be a major factor in modulating climate on the decadal scale

stacking of discontinuous regional palaeoclimate records chironomid based summer temperatures from the alpine region since multi site reconstructions are less affected by site specific climatic effects and artefacts regional palaeotemperature reconstructions based on a number of sites can provide more robust estimates of centennial to millennial scale temperature trends than individual site specific records furthermore reconstructions based on multiple records are necessary for developing continuous climate records over time scales longer than covered by individual sequences here we present a procedure for developing such reconstructions based on relatively short centuries to millennia discontinuously sampled records as are typically developed when using biotic proxies in lake sediments for temperature reconstruction the approach includes an altitudinal correction of temperatures an interpolation of individual records to equal time intervals a stacking procedure for sections of the interval of interest that have the same records available as well as a splicing procedure to link the individual stacked records into a continuous reconstruction variations in the final stacked and spliced reconstruction are driven by variations in the individual records whereas the absolute temperature values are determined by the stacked segment based on the largest number of records with numerical simulations based on the ngrip 18o record we demonstrate that the interpolation and stacking procedure provides an approximation of a smoothed palaeoclimate record if based on a sufficient number of discontinuously sampled records finally we provide an example of a stacked and spliced palaeotemperature reconstruction 15000 90 calibrated 14c yr bp based on six chironomid records from the northern and central swiss alps and eastern france to discuss the potential and limitations of this approach

holocene glaciation of alaska and adjoining yukon territory canada abstract holocene glacial fluctuations between arctic central interior and southern maritime alaska are broadly synchronous this synchrony is evident from a review of work in 11 study areas with varying numbers of glaciers 3 100 glacier types subpolar cirque temperate valley tidewater surging and dating methodologies the pattern is temporally and spatially consistent with vegetation data and generally with climatic deteriorations culminating in the little ice age early holocene glacial advances are confirmed for 7 6 5 8 lichen ka bp at 4 of 97 glaciers in the brooks range advances also occurred by 5 85 and 5 7 ka bp at separate glacier tongues in the northern alaska range at least by 6 5 ka bp in lituya bay and possibly also in the malaspina and aleutian islands areas a sharp increase in glacier activity began by 4 4 ka bp in the arctic and glacier bay areas and by about 3 ka bp major glacier advances probably were initiated or well underway throughout alaska during holocene glacial maxima ice filled glacier and lituya bays as well as fjords of prince william sound and massive moraines buried forests in the northeastern st elias mountains area minor recession is recorded directly or implied in most of alaska about 2 ka bp or locally through the following millennium subsequently distinct but locally weak advances occurred by about 1 2 ka bp in most areas again followed by intervals of glacier recession most pervasive and ubiquitous were the little ice age advances initiated about 700 bp these generally culminated in two major advances between about 400 and 50 bp in the arctic those of a d 1600 dominated those of the late 1800s in the gulf of alaska those of the middle 1700s or late 1800s dominated large scale asynchronous advances and retreats of calving tidewater glaciers have been recorded during the twentieth century but most such movements are only indirectly related to climate

on the current state of lake sediment palaeomagnetic research summary it is now possible to obtain high quality records of geomagnetic secular variations in the direction though not the magnitude of the ancient field type curves are presented for four regions namely north america west europe argentina and australia constructed by fitting cubic splines to data stacked from numbers of cores of post glacial sediments ways in which the results can be used to investigate the grosser properties of the ancient field are discussed

long period geomagnetic secular variations since 12 000 yr bp a comparison of secular variation records of the geomagnetic field inclination obtained from palaeomagnetic studies of european and north american post glacial and late glacial sediments suggests that geomagnetic westward drift has persisted through the past 12 000 yr between 12 000 and 2 500 yr bp the overall average drift rate was between 0 14 and 0 16 deg yr 1 at 2 500 yr bp it is tentatively suggested that the drift rate increased and rose to a maximum of nearly 0 5 deg yr 1 before decreasing to historically observed values of 0 25 deg yr 1

varve formation and the climatic record in an alpine proglacial lake calibrating annually laminated sediments against hydrological and meteorological data processes leading to the formation of varves in proglacial oeschinensee switzerland are investigated the aim is to calibrate annually laminated sediments of the last three decades against hydrological and meteorological instrumental data results from water samples and sediment traps show that the suspended sediment in the lake is mainly distributed by underflows during the time of the largest sediment input from may to mid august this leads to the deposition of the basal silt layers of the varves settling of fine grained suspension from interflows dominates sedimentation between august and october forming the final layer of fine grained material at the end of the annual deposition cycle the median grain size at the top of the varves is always below 5 m and thus defines the varve boundaries varve thickness is a function of the annual discharge of suspended load from the catchment this is supported by evidence from hydrological and meteorological data compiled for a glaciated catchment loetschen

lake sediment record of the geomagnetic secular variation in britain during holocene times summary a palaeomagnetic record of the geomagnetic secular variation during the last 10000 years has been obtained from 10 cores of sediment from loch lomond scotland lake windermere north england and llyn geirionydd north wales a time scale is provided by 30 radiocarbon age determinations and pollen analyses on several of the cores the main swings and much fine detail of both declination and inclination records repeat well between cores and between lakes and the overall record is much more detailed than previous european records the new record shows that neither declination nor inclination swings have been periodic over the past 10000 years but that the main swings have become progressively shorter in duration during that time each swing is characterized by fine detail which enables use of the record as a secondary method of dating other european sediments the motion of the geomagnetic vector has been predominantly clockwise throughout the time period spanned but confirms a period of anticlockwise motion from 1100 to 600 bp first discovered by british archaeomagnetic investigations the record agrees with british and czechoslovakian archaeomagnetic records but not with japanese archaeomagnetic or north american lake sediment records this suggests that the secular changes are controlled by local growing and decaying drifting sources rather than by wobbling of the main geomagnetic dipole

late holocene nao and oceanic forcing on high altitude proglacial sedimentation lake bramant western french alps comparison of glacially derived clastic inputs in high altitude proglacial lake bramant western french alps with measured north atlantic oscillation winter naow index reveals an inverse correlation between ad 1884 and 1968 at the pluridecadal timescale 20 25 years this reflects periodical variations in snow accumulation over lake bramant catchment area partly influencing the glacier mass balance in the watershed further comparisons with reconstructed naow index since ad 1500 highlight spatial and temporal variations of the pluridecadal naow influence on this alpine climate especially at the end of the little ice age in addition wavelet analysis of continuous proxies of clastic sedimentation over the last 4150 years indicates significant pluridecadal variability at frequencies compatible with the nao 30 years while periods centered at 60 70 years could also be linked to the north atlantic ocean atmosphere internal variability atlantic multidecadal oscillation amo the influence of the n

use of lacustrine sedimentary sequences as indicators of holocene glacial history banff national park alberta canada abstract bottom sediments from three lakes in the canadian rocky mountains were examined with the aim of evaluating the usefulness of downvalley sediment studies in reconstruction of holocene glacial histories analyses of organic carbon and carbonate contents of core sediments provide information on changing sedimentation rate and changing relative importance of glacial and non glacial sediment sources sedimentary histories of the three lakes are similar suggesting that they record regional glacial climatic forcing rather than localized events and thus that they may be useful in reconstructing holocene glacial history lacustrine sediments indicate a period of high sedimentation rates and relatively large glacial sediment contribution prior to 7500 7000 yr b p with much reduced rates and decreased glacial sediment contribution between about 6000 and 4000 yr b p possibly interrupted by a brief period of increased glacial sediment output shortly after 5000 yr b p sometime after 4000 yr b p sedimentation rates and glacial sediment output began to rise again reaching approximately present levels by 2750 2650 yr b p and have not since returned to low mid holocene levels in detail over the last 3000 yr there is some indication of a slight decrease in sedimentation rate for more than 1000 yr after about 2200 yr b p sedimentation rates and glacial sediment input into all three lakes rose between about 900 and 750 yr b p and have remained very high since if the lake sediments are interpreted as a proxy record of upvalley glacial activity they allow the development of a glacial chronology which is at once generally consistent with and more complete and easily datable than the surficial glacial record

reconstruction of holocene glacier history from distal sources glaciofluvial stream bank mires and a glaciolacustrine sediment core near sota saeter breheimen southern norway this study attempts to reconstruct the holocene glacier history of breheimen southern norway from four stream bank mire sites and a downstream lake sediment core near sota saeter based on lithostr

what were the primary forcing mechanisms of high frequency holocene climate and glacier variations a compilation of holocene glacial advances throughout the world is compared with summer solar insolation integrated over the northern hemisphere and the magnitudes of global acid fallout from volcanic eruptions north of 20 s estimated from the acidity signal of annual ice layers in the crete and camp century ice cores in greenland correlation analysis between glacial advances versus volcanic eruptions yielded a correlation coefficient of r 0 71 a climatic forcing curve solar insolation and volcanic eruptions weighted 1 1 versus glacial advances increased the correlation coefficient to r 0 90 this suggests that the combined effect of volcanic aerosols and orbital related northern hemisphere summer insolation may have been the primary forcing mechanism of worldwide climate and glacier fluctuations throughout the holocene

neoglacial glacier fluctuations in the canadian rockies abstract the little ice age was the most extensive neoglacial glacier advance in the canadian rockies evidence of earlier less extensive neoglacial glacier advances is based on wood recovered from several glacier forefields wood flushed out of athabasca glacier 7550 8230 yr b p three dates and dome glacier 6120 6380 yr b p two dates indicates that forests occurred upvalley of present glacier termini during the hypsithermal detrital logs from peyto 14 dates saskatchewan 3 dates robson 3 dates and yoho 1 date glaciers plus in situ slumps at peyto and robson glaciers have yielded 14 c dates between 2490 and 3300 yr b p 12 dates between 2800 and 2990 this wood is derived from sources at or upvalley from present glacier termini and represents forests overridden by glaciers between ca 3100 and 2500 yr b p treeline was higher than present immediately prior to this advance this advance which did not extend beyond the little ice age maximum position is designated the peyto advance and correlated with the tiedemann advance in western british columbia earliest little ice age advances at peyto and robson glaciers are dated ca 800 600 yr b p at positions ca 500 m upvalley from little ice age limits

late holocene glacier reconstruction reveals retreat behind present limits and two stage little ice age on subantarctic south georgia observational data show that climate in the southern ocean region is rapidly changing however past the instrumental period our understanding of climate variability in the region is limited by a scarcity of highresolution palaeoclimate records alpine glaciers present on many southern ocean islands may provide such data because changes in their mass balance extent and erosion rates often mark a response to climate shifts rock flour the fine grained fraction of the glacial erosion process is suspended in meltwater streams and transferred into the sediments of downstream lakes continuously recording glacier variations here we utilize this relationship to present a reconstruction of the late holocene glacier history of subantarctic south georgia using sediments from the glacier fed middle hamberg lake to fingerprint a glacial erosion size signal we used titanium counts validated against changes in sediment density and grain size allowing a continuous reconstruction of glacier variations over the past similar to 1250 years together with local moraine evidence and supporting evidence from other southern hemisphere glaciers on new zealand and in patagonia our findings reveal a series of consecutively diminishing late holocene advances in addition to a glacier maximum before 1250 cal a bp these include a twostage litle ice age with advances around 300 and 120 cal a bp in line with evidence from southern patagonia in addition we present evidence for an unreported retreat behind present limits around 500 cal bp

holocene glaciation of the central sierra nevada california abstract sediment cores from two bedrock dammed lakes in north fork big pine creek sierra nevada california preserve the most detailed and complete record of holocene glaciation yet recovered in the region the lakes are fed by outwash from the palisade glacier the largest 1 3 km 2 and presumably longest lived glacier in the range and capture essentially all of the rock flour it produces distinct late holocene matthes and late pleistocene recess peak moraines lie between the modern glacier and the lakes the lakes have therefore received continuous sedimentation from the basin since the retreat of the tioga glacier last glacial maximum and capture rock flour related to all post lgm advances a total of eight long cores up to 5 5 m sediment depth and one short surface sediment short core preserve a coherent record of fluctuating rock flour flux to the lakes through the holocene age constraints on rock flour spikes in first and second lakes based on 31 14c dated macrofossils indicate holocene glaciation began 3200 cal yr b p followed by a possible glacier maximum at 2800 cal yr b p and four distinct glacier maxima at 2200 1600 700 and 250 170 cal yr b p the most recent maximum being the largest reconstruction of the equilibrium line altitudes ela associated with each distinct advance recorded in the moraines recess peak matthes and modern indicates ela depressions relative to modern of 250 m and 90 m for recess peak and matthes advances respectively these differences represent decreases in summer temperatures of 1 7 2 8 c recess peak and 0 2 2 matthes and increases in winter precipitation of 22 34 cm snow water equivalent s w e recess peak and 3 26 cm s w e matthes compared to modern conditions although small these changes are significant and similar to those noted in the cascade range to the north and represent a significant departure from historical climate trends in the region

erosion under climate and human pressures an alpine lake sediment perspective we review the scientific efforts over the last decades to reconstruct erosion from continuous alpine lake sediment records we focused both on methodological issues showing the growing importance of non destructive high resolution approaches xrf core scanner as well as progresses in the understanding of processes leading to the creation of an erosion signal in lakes we distinguish continuous records from event records both provide complementary information but need to be studied with different approaches continuous regionally relevant records proved to be particularly pertinent to document regional erosion patterns throughout the holocene in particular applying the source to sink approach event based approaches demonstrated and took advantage of the strong non linearity of sediment transport in high altitude catchment areas this led to flood frequency and intensity reconstructions highlighting the influence of climate change upon flood dynamics in the mountain the combination of different record types both in terms of location high vs low elevation sedimentology high vs low terrigenous contribution and significance local vs regional is one of the main outputs of this paper it allows the establishment of comprehensive histories of nw french alps erosion but also and consequently soil dynamics and hydrological patterns throughout the holocene we also discuss the influence of glacier dynamics one of the major agents of erosion in the alps a major feature is the growing human influence upon erosion at a local scale since at least the middle of the bronze age 3500 cal bp however and according to the regional record from lake bourget only few periods of rising erosion at local scales generated a regional record that can be discriminated from wetter climatic periods among them the period between 200 bce and 400 ad appeared to be marked by a generalised rise in human triggered erosion at local scales in the northern french alps this review highlights the importance of modern high resolution and interdisciplinary studies of lake sediments in order to better understand the complex relationships between humans climate and the earth system in general we strongly argue that regional integration of data is now required to move a step further such an integration is easier with cost and time effective methods as well as after a better definition of approaches and their limits this should lead to a stronger collaboration between paleo data producers and modellers in the near future

abrupt onset of the little ice age triggered by volcanism and sustained by sea ice ocean feedbacks 1 northern hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes however the causes of superposed century scale cold summer anomalies of which the little ice age lia is the most extreme remain debated largely because the natural forcings are either weak or in the case of volcanism short lived here we present precisely dated records of ice cap growth from arctic canada and iceland showing that lia summer cold and ice growth began abruptly between 1275 and 1300 ad followed by a substantial intensification 1430 1455 ad intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium a transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times and that cold summers can be maintained by sea ice ocean feedbacks long after volcanic aerosols are removed our results suggest that the onset of the lia can be linked to an unusual 50 year long episode with four large sulfur rich explosive eruptions each with global sulfate loading 60 tg the persistence of cold summers is best explained by consequent sea ice ocean feedbacks during a hemispheric summer insolation minimum large changes in solar irradiance are not required

one thousand seven hundred years of interaction between glacial activity and flood frequency in proglacial lake muzelle western french alps local glacial fluctuations and flood occurrences were investigated in the sediment sequence of proglacial lake muzelle based on geochemical analysis and organic matter content established using loss on ignition and reflectance spectroscopy we identified six periods of increased glacial activity over the last 1700 yr each is in accordance with records from reference glaciers in the alps a total of 255 graded layers were identified and interpreted as flood deposits most of these occurred during glacial advances such as the little ice age period and exhibit thicker deposits characterized by an increase in the fine grain size fraction fine sediment produced by glacial activity is transported to the proglacial lake during heavy rainfall events the excess of glacial flour during these periods seems to increase the watershed s tendency to produce flood deposits in the lake sediment suggesting a strong influence of the glacier on flood reconstruction records thus both flood frequency and intensity which is estimated based on layer thickness as a proxy cannot be used in reconstruction of past extreme events because of their variability there is a need to take into account changes in sediment supply in proglacial areas that could preclude satisfactory interpretation of floods in terms of past climate variability

the biomarker record of lake albano central italy implications for holocene aquatic system response to environmental change abstract a study of lipid biomarkers in predominantly laminated organic carbon rich sediments in lake albano central italy has been used to reconstruct changes in the aquatic system variations and changes in the lake catchment area during the holocene biomarkers of aquatic organic matter such as dinosterol isoarborinol tetrahymanol diplopterol and diploptene reflect two major changes in the mixing behaviour and the biological assemblages of lake albano at around 6 5 and 3 8 ky bp respectively biomarkers for higher land plants such as friedelin long chain n alkanes amyrenone and amyrenone display different distribution patterns indicating changes in the lake s catchment at 6 5 and 5 0 ky bp resulting from soil erosion and changes in the local vegetation analogously the recognised changes in the water column structure and biological components are coherent with previous reconstructions based on independent parameters the new data highlight the importance of multiproxy studies to better characterize palaeoenvironmental changes that are in turn the first step towards elucidating their trigger mechanisms i e climate vs human induced

palaeoenvironmental and palaeoseismic implications of a 3700 year sedimentary record from proglacial lake barrancs maladeta massif central pyrenees spain abstract a multidisciplinary study including sedimentological mineral magnetic and palaeobotanical techniques applied to a sediment core recovered from proglacial lake barrancs in the seismically active maladeta massif has provided the basis for documenting environmental changes and palaeoseismic activity in the central pyrenees for the last ca 3700 yr lake barrancs is located downstream of the tempestats and barrancs cirque glaciers and sedimentation is dominated by clastic input corresponding to seasonal changes in sediment supply slow fine particle settling during the winter and sediment loaded homopycnal flows during the warm season triggered by snow melting and glacier outwash have resulted in deposition of rhythmites composed of clays silts and sands the predominance of finer grained sediments and the low concentration of relatively finer magnetite grains suggest that glacier activity was very small if not absent before ca a d 350 their replacement by coarser grained sediments and the overall increased but highly oscillating concentrations of relatively coarser magnetite grains in the uppermost 4 3 m of the record suggest the onset of glacial activity and enhanced snow melting in the catchment of lake barrancs after a d 350 we suggest that this onset of glacial and enhanced snow melt activity was driven by a complex balance between winter precipitation and annual mean temperatures among other climatic variables peat layers suggest two dramatic lake level drops at a d 300 and a d 450 when lake barrancs was drained the mechanisms for such extreme hydrological events are not clear changes in the precipitation evaporation ratio cannot account for such desiccation events dam failure is unlikely since there are no geomorphological evidence of breaching processes geomorphological and structural evidence demonstrates active faulting since formation of lake barrancs and reactivation during earthquake shaking based on this we propose an alternative explanation for the desiccation events that involves the draining of the lake through pre existing fractures opened by earthquakes further studies in lake barrancs and other lakes from the maladeta massif are necessary to validate the hypotheses presented here concerning the response of glacial and snow melt activity to climate variability and the palaeoseismic record of the central pyrenees

disequilibrium of holocene sediment yield in glaciated british columbia it is generally supposed that specific sediment yield the quantity of sediment passing a monitored river cross section per unit area drained upstream of that section declines as the area drained increases1 3 part of the sediment mobilized from the land surface is supposed to go back into storage at field edges and on footslopes and floodplains in contrast we show here that data from british columbian rivers reveal a pattern of increasing specific sediment yield at all spatial scales up to 3 104 km2 this results from the dominance of secondary remobilization of quaternary sediments along river valleys over primary denudation of the land surface the result controverts the conventional model which has been derived from studies of small highly disturbed agricultural catch ments the rivers are still responding to the last glaciation giving a landscape relaxation time greater than 10 kyr this holds pro found implications for geomorphological theory and for studies of erosion