a glacio isostatic facies model and amino acid stratigraphy for late quaternary events in spitsbergen and the arctic strong early holocene crustal uplift over the spitsbergen archipelago reflects disappearance of an ice mass centred just north east of the archipelago and which decayed rapidly just after 10 000 bp after a maximum extension between 12 600 and 10 000 bp from the lithofacies distributions associated with these events a glacio isostatic facies model can be defined which combined with analyses of amino acid racemization provides a valuable stratigraphic method for correlating pre holocene glacio isostatic events these are correlated with events in greenland and both are contrasted with weichselian glacial events at the southern margins of the two great northern hemisphere ice sheets and with contemporary water mass changes in the north atlantic and norwegian sea the geographical variation in glacier response through time is explained by three principal climatic circulation patterns

the late weichselian glacial maximum on western spitsbergen inferred from offshore sediment cores abstract the late weichselian glacial history of the continental shelf off western spitsbergen is discussed based on acoustic sub bottom records and sediment cores the outer part of isfjorden and the inner shelf to the west of this fjord are characterized by a thin veneer 10 20 m of glacigenic sediments and absence of ice marginal features towards the outer shelf the sediment thickness increases significantly and exceeds 500 m at the shelf edge possible moraine complexes were identified in this outer part sediment cores from the inner shelf sampled a firm diamicton interpreted as till beneath soft glaciomarine sediments radiocarbon dates on shells from the clay resting directly on the till suggest an age of around 12 500 yrs b p for the base of the marine sequence we argue that grounded ice covered the sites shortly before in contrast to suggestions that the fjords and coast were partly ice free during the late weischselian we conclude that the ice must have reached out onto the continental shelf

continuous monitoring of snowpack dynamics in alpine terrain by aboveground neutron sensing the characteristics of an aboveground cosmic ray neutron sensor crns are evaluated for monitoring a mountain snowpack in the austrian alps from march 2014 to june 2016 neutron counts were compared to continuous point scale snow depth sd and snow water equivalent swe measurements from an automatic weather station with a maximum swe of 600 mm april 2014 several spatially distributed terrestrial laser scanning tls based sd and swe maps were additionally used a strong nonlinear correlation is found for both sd and swe the representative footprint of the crns is in the range of 230 270 m in contrast to previous studies suggesting signal saturation at around 100 mm of swe no complete signal saturation was observed these results imply that crns could be transferred into an unprecedented method for continuous detection of spatially averaged sd and swe for alpine snowpacks though with sensitivity decreasing with increasing swe while initially different functions were found for accumulation and melting season conditions this could be resolved by accounting for a limited measurement depth this depth limit is in the range of 200 mm of swe for dense snowpacks with high liquid water contents and associated snow density values around 450 kg m 3 and above in contrast to prior studies with shallow snowpacks interannual transferability of the results is very high regardless of presnowfall soil moisture conditions this underlines the unexpectedly high potential of crns to close the gap between point scale measurements hydrological models and remote sensing of the cryosphere in alpine terrain

late weichselian glacier retreat in kongsfjorden west spitsbergen svalbard the chronology of late weichselian to holocene deglaciation of kongsfjorden west spitsbergen has been reconstructed based on the geomorphic and stratigraphic record of ice retreat relative sea level relationships and 14c dating of associated marine organic materials the seaward extent of glacial drift and fjord bathymetry constrain a secure reconstruction for the ice sheet near the mouth of the fjord at ca 13 000 yr b p but do not rule out the possibility that more extensive glaciation was achieved earlier during the late weichselian regional shoreline relations rates of emergence and radiocarbon dating of foraminifera deposited just above till indicate that deglaciation occurred in two steps one beginning during or just prior to the late weichselian marine limit phase at 13 000 12 000 yr b p and another beginning at 10 000 9500 yr b p the fjord was completely deglaciated by 9440 130 yr b p a period of stable relative sea level began 10 700 yr b p and ended between 10 000 and 9500 yr b p which we take to indicate renewed glacial loading during the younger dryas glacier readvance within kongsfjorden at this time was diminutive suggesting that most of the younger dryas ice sheet growth was confined to the eastern part of the archipelago and or to the barents shelf the two step deglaciation of kongsfjorden occurred during intervals of accelerated global ice sheet melting and rapid oceanic and atmospheric warming in more temperate latitudes of the circum atlantic region this coincidence most likely resulted from contemporaneous increases in the poleward transport of oceanic heat

changes in biological production in the mixed water region mwr of the northwestern north pacific during the last 27 kyr abstract piston core pc6 40 n 143 e provides the first record of biological production and alkenone sea surface temperature sst in the mixed water region mwr off sanriku japan in the northwestern north pacific over the last 27 kyr biogenic opal content was low until the early holocene and rapidly increased at 6 calendar kiloyears before present cal kyr bp low biological production in the mwr resulted from the reduced duration of the phytoplankton bloom during the glacial period 27 18 cal kyr bp and from nutrient depletion especially silica during the deglaciation 15 9 5 cal kyr bp in spite of the decreased amount of nutrients in the oyashio water biological production increased in the late holocene 6 cal kyr bp present the data revealed that nutrients supplied from deeper levels by eddies played an important role in biological production in the mwr contrary to the conventional concept that the oyashio current has controlled productivity in this region alkenone sst during the glacial period was on average 13 6 c which is close to the modern sst 14 6 c in june but this timing is not consistent with the climap results 13 4 14 3 c in august this result indicates that alkenone sst recorded not late spring but summer temperatures owing to a bloom shift caused by surface water cooling during the last glacial period alkenone sst was even lower during the deglaciation than during the lgm and reached a minimum 9 4 c at 14 0 cal kyr bp 15 n was very high during the deglaciation implying that nutrients in the euphotic zone were depleted around the core site nutrient stress probably had a physiological impact on coccolithophorids and resulted in the apparent minimum alkenone sst these findings indicate that the reconstruction of sst by alkenones can sometimes be very complex and possibly misleading

foraminiferal isotope anomalies from northwestern pacific marginal sediments 1 we evaluated the influence of methane release from methane hydrate reservoirs in the northwestern pacific continental margin on stable isotope values we analyzed stable isotopes of foraminifera from a piston core collected at 1066 m water depth off eastern hokkaido northern japan carbon isotope signals indicated that planktonic and benthic foraminifera in several glacial sediment layers in the core were highly depleted in 13c both the planktonic and benthic foraminiferal 13c values ranged from about 10 to 2 most foraminiferal tests in these horizons were brown as a result of postdepositional alteration foraminiferal oxygen isotopes fluctuated abnormally in the glacial sediment layers showing small about 0 5 positive shifts relative to normal glacial values we attributed the positive shifts to authigenic carbonate formation in the foraminiferal tests the authigenic carbonates have formed when rising methane from methane hydrate in the sediment became oxidized as it came in contact with dissolved sulfate near the seafloor episodic methane release events may be associated with great plate boundary earthquakes with epicenters near the coring site

automated determination of snow water equivalent by acoustic reflectometry snow water equivalent swe is commonly determined using gravimetric and depth measurement techniques previous research has demonstrated the ability to determine swe from the propagation and reflection of acoustic waves despite the advantages of the acoustic technique it has not been adapted so that swe can be determined in an automated fashion this paper presents a new technique for determining swe by the application of acoustics a maximum length sequence was used as the input to the layered snowpack system signal processing of the reflected wave and a recursive algorithm was used to model the sound pressure wave as it passed through the snowpack embedded systems were designed to implement the signal processing and calculations so that swe could be quickly determined at a field location the systems were deployed at sites near whitehorse yt and at sites in the rocky mountains of alberta canada comparisons were made between swe estimated by the acoustic technique and swe determined by gravimetric sampling these comparisons demonstrated that the acoustic swe measurement performed with the embedded systems and the new signal processing technique can provide swe estimates that are of comparable accuracy to swe calculated from gravimetric samples

late weichselian and holocene relative sea level history of broggerhalvoya spitsbergen abstract radiocarbon dated whalebones from raised beaches record a relative sea level history for broggerhalvoya western spitsbergen that suggest a two step deglaciation on svalbard at the end of the late weichselian glaciation the late weichselian marine limit was reached at about 13 000 yr b p and was followed by relatively slow emergence until about 10 000 yr b p either in response to ice unloading in the barents sea initial retreat of local fjord glaciers or some combination of the two rare whale skeletons dating between 13 000 and 10 000 yr b p indicate that the norwegian sea was at least seasonally ice free during that interval deglaciation of spitsbergen is recorded by the rapid emergence of broggerhalvoya after 10 000 yr b p this was followed by a transgression during the mid holocene here named the talavera transgression and another in modern times raised beach morphologies suggest striking differences in nearshore depositional processes before and after 10 000 yr b p that are probably related to changes in the rate of uplift and in sea ice conditions

debris flow recurrence periods and multi temporal observations of colluvial fan evolution in central spitsbergen svalbard abstract fan shaped accumulations of debris flow deposits are common landforms in polar regions such as svalbard although depositional processes in these environments are of high interest to climate as well as mars analog research several parameters e g debris flow recurrence periods remain poorly constrained here we present an investigation based on remote sensing as well as in situ data of a 0 4 km2 large colluvial fan in hanaskogdalen central spitsbergen we analyzed high resolution satellite and aerial images covering five decades from 1961 to 2014 and correlated them with lichenometric dating as well as meteorological data image analyses and lichenometry deliver consistent results and show that the recurrence period of large debris flows 400 m3 is about 5 to 10 years with smaller flows averaging at two per year in the period from 2008 to 2013 while this is up to two orders of magnitude shorter than previous estimates for svalbard 80 to 500 years we found the average volume of 220 m3 per individual flow to be similar to previous estimates for the region image data also reveal that an avulsion took place between 1961 and 1976 when the active part of the fan moved from its eastern to its western portion a case study of the effects of a light rain event 5 mm day in the rainy summer of 2013 which triggered a large debris flow further shows that even light precipitation can trigger major flows this is made possible by multiple light rain events or gradual snow melt pre saturating the permafrost ground and has to be taken into account when predicting the likelihood of potentially hazardous mass wasting in polar regions furthermore our findings imply a current net deposition rate on the colluvial fan of 480 m3 year which is slightly less than the integrated net deposition rate of 576 to 720 m3 year resulting from the current fan volume divided by the 12 500 to 10 000 years since the onset of fan build up after the area s deglaciation however the actual deposition rate which should increase in a warmer climate including more rain cannot be constrained due to effects like ongoing toe cutting of the debris fan and some flows only causing internal redistributions

a comparison of seismic and radar methods to establish the thickness and density of glacier snow cover we show that geophysical methods offer an effective means of quantifying snow thickness and density opportunistic efficient but non optimized seismic refraction and ground penetrating radar gpr

polygon pattern geomorphometry on svalbard norway and western utopia planitia mars using high resolution stereo remote sensing data abstract polygonal systems formed by thermal contraction cracking are complex landscape features widespread in terrestrial periglacial regions the manner in which cracking occurs is controlled by various environmental factors and determines dimension shape and orientation of polygons analogous small scale features are ubiquitous in martian mid and high latitudes and they are also inferred to originate from thermal contraction cracking we studied the geomorphometry of polygonally patterned ground on svalbard to draw a terrestrial analogy to small scale polygonal structures in scalloped terrain in martian mid latitudes we performed a comparative quantitative terrain analysis based on high resolution stereo remote sensing data hrsc ax and hirise in combination with terrestrial field data and multivariate statistics to determine the relationship of polygon geomorphometry to local environmental conditions results show that polygonal structures on svalbard and in utopia planitia on mars are similar with respect to their size and shape a comparable thermal contraction cracking genesis is likely polygon evolution however is strongly related to regional and local landscape dynamics individual polygon dimensions and orthogonality vary according to age thermal contraction cracking activity and local subsurface conditions based on these findings the effects of specific past and current environmental conditions on polygon formation on mars must be considered on both earth and mars the smallest polygons represent young recently active low centered polygons that formed in fine grained ice rich material small low centered martian polygons show the closest analogy to terrestrial low centered ice wedge polygons the formation of composite wedges could have occurred as a result of local geomorphological conditions during past martian orbital configurations larger polygons reflect past climate conditions on both earth and mars the present degradation of these polygons depends on relief and topographical situation on svalbard the thawing of ice wedges degrades high centered polygons in contrast the present appearance of polygons in utopia planitia is primarily the result of contemporary dry degradation processes

postglacial uplift and relative sea level changes in finnmark northern norway abstract the outer coast of finnmark in northern norway is where the former fennoscandian and barents sea ice sheets coalesced this key area for isostatic modelling and deglaciation history of the ice sheets has abundant raised shorelines but only a few existing radiocarbon dates constrain their chronology here we present three holocene sea level curves based on radiocarbon dated deposits from isolation basins at the outermost coast of finnmark located at the islands soroya and rolvsoya and at the nordkinn peninsula we analysed animal and plant remains in the basin deposits to identify the transitions between marine and lacustrine sediments terrestrial plant fragments from these transitions were then radiocarbon dated radiocarbon dated mollusk shells and marine macroalgae from the lowermost deposits in several basins suggest that the first land at the outer coast became ice free around 14 600 cal yr bp we find that the gradients of the shorelines are much lower than elsewhere along the norwegian coast because of substantial uplift of the barents sea also the anomalously high elevation of the marine limit in the region can be attributed to uplift of the adjacent seafloor after the younger dryas the coast emerged 1 6 1 0 cm per year until about 9500 9000 cal yr bp between 9000 and 7000 cal yr bp relative sea level rose 2 4 m and several of the studied lakes became submerged at the outermost locality rolvsoya relative sea level was stable at the transgression highstand for more than 3000 years between ca 8000 and 5000 cal yr bp deposits in five of the studied lakes were disturbed by the storegga tsunami ca 8200 8100 cal yr bp

vibroseis deconvolution a comparison of cross correlation and frequency domain sweep deconvolution ideally traditional vibroseis processing produces a band limited zero phase klauder wavelet through cross correlation of the sweep with the recorded signal an alternative wavelet processing method involves deconvolving the sweep from the recorded vibroseis trace this deconvolution can be achieved through frequency domain division we compare and contrast the advantages and disadvantages of sweep deconvolution versus cross correlation on synthetic and real data

late weichselian iceberg surface melt and sediment production from the eurasian ice sheet results from numerical ice sheet modelling abstract results from a numerical ice sheet model were matched with geological evidence detailing the extent and timing of the late weichselian ice sheet in the eurasian arctic through simple adjustments in the model s environmental inputs the numerical model predicts the spatial and temporal variation in 1 subglacial sediment transport and deposition 2 rates of iceberg calving and 3 rates of supraglacial melting over the past 30 000 yr the ice sheet is characterised by a series of ice streams occupying bathymetric troughs in the barents sea and west of norway which act as sources for glacial sediment build up and iceberg production our model indicates that significant volumes of sediment are deposited over the bear island fan 3000 km 3 in 12 000 yr franz victoria trough fan 500 km 3 in 8000 yr and a series of smaller fans west of norway which combine to yield 4000 km 3 in 12 000 yr the norwegian channel ice stream operated for only 4000 yr during which time 400 km 3 of sediments were deposited on the adjacent fan the ice sheet experienced two major periods of iceberg production where the rate of calving increased by 50 at about 15 000 and 12 500 yr ago however the time dependent response of iceberg calving to sea level rise for individual ice streams is shown to be more complicated than the generalised ice sheet response the marine portions of the ice sheet decayed after 15 000 yr ago resulting in several embayments at the mouths of bathymetric troughs a second pulse of enhanced iceberg calving at 12 500 yr ago caused further decay of the marine ice sheet and the ice margin retreated back to the shorelines of island archipelagos in the northern barents sea ice loss through surface melting was restricted mostly to the southern margin of the ice sheet

post glacial relative sea level history of northwestern spitsbergen svalbard the late weichselian and holocene raised beach sequences on northwestern spitsbergen provide a detailed record of sea level oscillations during the last deglacial hemicycle initial emergence commenced at 13 ka coincident with local deglaciation and until 10 5 ka was characterized by a relative slow rate of emergence 1 5 to 5 m ka interrupted by minor stillstands or transgressions associated with possible glacier re advances the orientation of paleo spits and the paucity of whale remains at the late weichselian marinelimit indicate that the prevailing westerly fetch was dampened by a semi permanent sea ice cover allowing long shore drift to predominate a period of accelerated emergence 15 to 30 m ka between 10 5 and 9 ka is correlative with rapid deglaciation of fiords the middle and late holocene is characterized by two brief transgressions one between 6 5 and 5 0 ka that did not exceed 7 m asl and a present probable slow rise in sea level that commenced 2 to 1 ka the strandline tilts in northwestern spitsbergen and the pattern and rate of emergence on svalbard indicate that the maximum glacier loads during the late weichselian were centered on nordaustlandet and on the central and eastern part of the archipelago northwestern and southwestern spitsbergen were marginal to glacial loading and were deglaciated early 13 ka which is presently incompatible with maximum ice sheet extent and the timing and position of deglacial margins recently reconstructed for the barents sea and svalbard mountain ranges and large fiords probably confined major outlet glaciers to the central part of the archipelago preventing inundation of much of western spitsbergen by an inferred large ice sheet based in eastern svalbard and the barents sea

aminostratigraphy of european marine interglacial deposits molluscan fossils collected from shallow water marine sediment across nw europe and nearby arctic regions have been analysed for the extent of isoleucine epimerization dl ratio in indigenous protein residues the dl ratios confirm that essentially all classical eemian sites from nw europe are of the same age and are correlative with the type locality near amersfoort in the netherlands shells from interglacial marine sediment beneath the type weichselian till in poland also correlate with the type eemian site dl ratios in holsteinian marine shells 0 29 are substantially higher than in their eemian counterparts 0 17 late cromerian shells yield even higher ratios 0 46 dl ratios in late glacial shells 0 06 and middle weichselian shells 0 09 permit differentiation from modern 0 01 and last interglacial material based on the position of the matuyama brunhes boundary and the differences in dl ratios the eemian must correlate with isotope substage 5e whereas the holsteinian is most likely substage 7c possibly stage 9 but certainly younger than stage 11 intra saalian warm periods may be terrestrial equivalents of the younger substages of stage 7 extensive pre eemian marine sediments along the sw coast of denmark previously correlated with the holsteinian are shown to be of late cromerian age the underlying till there is the first widespread evidence of a pre elsterian till in nw europe dl ratios in molluscs from last interglacial sites along the arctic coast of the ussr the arctic islands and eastern greenland are substantially lower than in their european counterparts due to their low thermal histories the combined mid and high latitude data are used to develop a predictive model for the expected dl ratio in any of several moderate epimerization rate taxa for last interglacial sites with mean temperatures between 20 and 15 c not all sites could be unambiguously assigned to an established interglacial the fjosanger norway and margareteberg sweden sites previously thought to be eemian yield dl ratios higher than in secure nearby eemian material it is yet unresolved whether these are aberrant sites or if they predate the last interglacial in situ shoreline deposits encountered in borings in sw belgium and in exposures on the belgium coastal plain contain molluscs that yield dl ratios intermediate between secure eemian and late weichselian ratios raising the possibility that a late stage 5 high sea level event attained near modern levels in the southern north sea basin resolution of these uncertainties is the focus of future work

the last interglacial glacial cycle in fennoscandia abstract the climate and glacier fluctuations during the last interglacial glacial cycle in fennoscandia seem to correspond roughly in time with the climate fluctuations recorded in france germany holland however the climate in fennoscandia was considerably colder and the coldest phases are recorded as periods with glacier fluctuations admittedly the exact age and amplitudes of some fluctuations are still much debated

the last glacial maximum on spitsbergen svalbard most scientists have concluded previously that the west coast of spitsbergen svalbard remained ice free during the late weichselian between 25 000 and 10 000 yr b p we conclude that the glaciation was more extensive terraces that were postulated to have been ice free are covered by a thin late weichselian till sudden drop in the marine limit and basal radiocarbon dates of raised glaciomarine sediments demonstrates that the glaciers in the main fjords isfjorden and van mijenfjorden terminated west outside of the fjord mouths basal radiocarbon dates from glaciomarine clay above till in cores from the continental shelf west of spitsbergen yielded ages of about 12 500 yr b p from which we conclude that the ice extended to the shelf edge based on the extent of amino acid diagenesis in radiocarbon dated molluscs the duration of the maximum extension of the late weichselian glaciation was short certainly less than 10 000 years during the ice free period preceding that glaciation at least back to 40 000 yr b p the glaciers on svalbard were not significantly larger than at present as shown by marine deposits close to the glacier snouts many radiocarbon dates place deglaciation of the outer coast at about 12 500 yr b p at about 10 000 yr b p the rest of the archipelago rapidly became ice free

acoustic waveform inversion with application to seasonal snow covers the amplitude and waveform shape of atmospheric acoustic pulses propagating horizontally over a seasonal snow cover are profoundly changed by the air forced into the snow pores as the pulses move over the surface this interaction greatly reduces the pulse amplitude and elongates the waveform compared to propagation above other ground surfaces to investigate variations in snow cover effects acoustic pulses were recorded while propagating horizontally over 11 different naturally occurring snow covers during two winters two inversion procedures were developed to automatically match the observed waveforms by varying the snow cover parameters in theoretical calculations a simple frequency domain technique to match the dominant frequency of the measured waveform suffered from multiple solutions and poor waveform matching while a time domain minimization method gave unique solutions and excellent waveform agreement results show that the effective flow resistivity and depth of the snow are the parameters controlling waveform shape with the pore shape factor ratio of secondary importance inversion estimates gave flow resistivities ranging from 11 to 29 kn s m 4 except for two late season cases where values of 60 and 140 were determined compared to 345 for the vegetation covered site in the summer acoustically determined snow depths agreed with the measured values in all but one case when the depth to a snow layer interface instead of the total snow depth was determined except for newly fallen snow the pore shape factor ratio values clustered near two values that appear to correspond to wet 1 0 or dry 0 8 snow

amino acid geochronology resolution and precision in carbonate fossils changes in indigenous proteins preserved in carbonate skeletons can be used to estimate the time elapsed since death of the organism racemization the most widely used reaction in amino acid geochronology refers to the inversion of l amino acids to their d configuration for the protein amino acid l isoleucine racemization occurs about only one of the two chiral carbon atoms this reaction epimerization proceeds from an initial dl ratio near zero to an equilibrium ratio of about 1 30 the reaction rate is controlled primarily by temperature and to a lesser degree by the nature of the proteins themselves a variable related to taxonomy and the extent of protein degradation analyzing monospecific samples minimizes the taxonomic variable the resolving power of dl ratios as relative age indices is a function of the reaction rate degree of natural variability and analytical uncertainty natural variability is defined as the spread in ratios in five well preserved shells of the same age from a single stratum and is primarily related to taxonomy it can range from 20 or more in taxa of low reliability to 1 in taxa of greatest integrity 5 to 10 is to be expected analytical uncertainty within a single laboratory is relatively insignificant amounting to no more than 2 but interlaboratory comparisons suggest caution in comparing ratios determined at different laboratories or by different techniques sampling appropriate portions of a shell is essential to minimize variability in dl ratios site temperature exerts the greatest control on reaction rate hence resolving power for tropical sites 25 c age differences 1 ka can be resolved within the holocene and ca 5 to 10 ka for older samples as the rate decreases equilibrium is attained after 150 to 300 ka the reaction rate is substantially lower at mid latitude sites ca 10 c where equilibrium requires about 2 ma and resolution within the last glacial cycle is no better than 10 to 20 ka arctic sites 10 c show almost no measurable racemization within the holocene and in extreme cases even within the last 100 ka equilibrium is not attained in 10 ma the extent of amino acid racemization epimerization in carbonate fossils provides chronological information for the critical time period beyond radiocarbon dating dl ratios can be used directly as relative age indices and with suitable calibration can provide reasonable estimates of absolute age and or effective diagenetic temperature improving the accuracy of racemization based age estimates requires a better understanding of racemization kinetics in carbonate systems

observations of low frequency acoustic to seismic coupling in the summer and winter experiments were conducted at a site in northern vermont to investigate low energy acoustic to seismic coupling in the 5 to 500 hz frequency band for propagation distances between 1 and 274 m pistol shots were used as the source of the acoustic waves with geophones and microphones serving as the receivers the strongest coupling into the ground occurred as the air wave passed with measured ratios of about 7 and 6 10 6 m s 1 pa 1 in the summer and winter respectively compressional waves induced in the ground immediately under the source were observed as first arrivals since they travel at the higher subsurface seismic wave velocity but their amplitudes were one to two orders of magnitude lower than those of the later arriving air wave a comparison of the summer and winter recordings revealed a number of effects caused by the introduction of a 0 25 m thick snow cover the peak amplitude of the seismic arrival induced by the passage of the acoustic wave was more strongly attenuated in the winter wi

numerical modeling of the late weichselian svalbard barents sea ice sheet abstract previous reconstructions of the ice cover of the svalbard barents sea region during the late weichselian have ranged from small ice masses on svalbard to complete inundation of the barents shelf region by an ice sheet several kilometers thick we have used a time dependent finite difference numerical model to undertake a new glaciological reconstruction for the svalbard barents sea ice sheet over the last 30 000 yr the numerical model requires environmental forcing functions in the form of air temperature and precipitation and their behavior with respect to altitude together with sea level change and an iceberg calving relation ice buildup on svalbard is calculated to have begun 28 000 yr ago and maximum dimensions were reached by 20 000 yr ago covering svalbard and the northwestern barents sea with a center of mass 1 3 km thick around eastern svalbard decay was complete by about 10 000 yr ago the margin of the modeled ice sheet at its maximum is in good agreement with observed sea floor morphological features but there are discrepancies in timing between the modeled ice sheet decay and i a dated meltwater spike in fram strait and ii the observed rebound curves for svalbard an inverse approach was used to predict ice sheet decay and it was found that increasing the rate of iceberg calving within the model produces a deglaciation some 2000 yr earlier which is compatible with these two independent datasets the reconstruction is also compatible with geological evidence on the isostatic response of bjornoya close to the southern limit of the ice sheet and seismically observed deposits interpreted to be ice proximal facies located in the northwestern barents sea our time dependent model reconstructions of the svalbard barents sea ice sheet indicate ice cover over only the northwestern barents sea during the late weichselian but this does not preclude the presence of ice derived from fennoscandia and the kara sea region elsewhere in the barents sea

submarine landforms and glacimarine sedimentary processes in lomfjorden east spitsbergen understanding the role of fjords in modulating the long term interaction between ice sheets and glaciers with the surrounding ocean requires the investigation of glacigenic landform and sediment archives in svalbard there is a wealth of data from fjords in west spitsbergen that constrains the glacial history of this sector of the svalbard barents sea ice sheet sbis since the last glacial maximum lgm and the nature and timing of subsequent ice retreat in contrast however very little is known about the glacial history of fjords in east spitsbergen this paper combines multibeam swath bathymetry sub bottom profiles lithological data and radiocarbon dates from lomfjorden svalbard to provide the first insights into the dynamics of tidewater glaciers and associated glacimarine sedimentary processes in a northeast spitsbergen fjord at the lgm a fast flowing ice stream drained the sbis through lomfjorden serving as a tributary to a south north flowing ice stream in hinlopenstretet ice advance is recorded by streamlined bedrock glacial lineations and drumlins a radiocarbon date of 9 7 ka bp from the outer fjord provides a minimum date for retreat of this ice stream and suggests that lomfjorden was ice free earlier than fjords in west spitsbergen ice retreat occurred in a slow and step wise manner indicated by the presence of recessional moraines and de geer moraines by 4 5 ka bp the local tidewater glaciers had probably retreated inland of their present positions the limited extent of glacigenic landform assemblages in front of these glaciers implies that any holocene re advances were probably restricted the principal sedimentary processes during deglaciation were suspension settling from meltwater causing deposition of weakly stratified bioturbated mud in ice distal settings at rates of 0 02 0 08 cm a 1 and gravitational mass flows forming sandy turbidites in ice proximal areas iceberg ploughmarks and ice rafted debris provide evidence for the presence of large icebergs during deglaciation our data suggest an early and extensive deglaciation in east spitsbergen fjords and show that previous reconstructions of the extent of the sbis need to be revised as new data emerges from east spitsbergen the data confirm that tidewater glaciers from different regions of spitsbergen behaved differently since the lgm and that variations in landform sediment assemblages occur even within geographically adjacent fjords

the effect of snow on vehicle generated seismic signatures vehicle generated seismograms recorded under summer and winter conditions at fort devens ma are analyzed and compared the appearance and frequency content of the recorded ground motion change dramatically from summer to winter when a 0 7 m thick snow layer is present the snow layer causes a 10 db reduction in the amplitude of the acoustically coupled signal relative to the signal generated where the vehicle contacted the ground a magnitude squared coherence analysis and a simple wiener prediction model of the acoustic transmission near the observation point reinforce this conclusion

late cenozoic environments in the barents sea we examine the paleoceanography and paleogeography of the barents sea during the late cenozoic glacial regime by seismostratigraphy and core analysis during the smaller glaciations which probably dominated the first period of the glaciogenic regime approximately 2 5 0 8 ma glaciomarine processes with sediment influx from the adjacent mainland prevailed the barents sea has been covered by grounded ice sheets several five to 10 times during the late cenozoic we speculate that these glaciations occurred during the last 0 8 ma during these larger glaciations the margin of the ice sheet expanded to the shelf edge and the continental shelf break and slope acted as a depocenter and prograded rapidly frequent sediment gravity flows accumulated on the lower continental slope during interglacials the barents sea was converted to a starved continental margin most of the barents sea was glaciated during the maximum of the last glaciation 19 16 ka a two stepped deglaciation 16 to 13 ka and 13 to 10 ka occurred incipient atlantic water reached the western areas about 13 ka and totally replaced the arctic water by 10 ka these paleoceanographic events were delayed in the eastern barents sea

determining snow water equivalent by acoustic sounding the possibility of determining snow water equivalent swe by the use of an acoustic impulse was assessed at two field locations in saskatchewan and british columbia canada these sites represent cold windswept prairie and temperate deep mountain snowcovers a continuous frequency swept acoustic wave was sent into the snowpack and received signal processing was then subsequently used to estimate the depth and density of each snow layer by a recursive relationship involving frequency modulated continuous wave fmcw radar and seismological techniques from this method it is also shown that the tortuosity of snow can be estimated data collected by gravimetric sampling was used as comparison to the swe values determined by the use of acoustic sounding the results showed that for the saskatchewan sites the correlation between the measured and the modeled values of swe was 0 86 whereas at the british columbia sites the correlation was 0 78 the difference in the correlations was interpreted as being due to additional acoustic measurement error at the british columbia sites caused by higher liquid water contents and more layers in the snowpack the measured and the modeled swe for saskatchewan snowpacks with high liquid water contents were found to be weakly associated with correlations of 0 30 the acoustically determined values of tortuosity were close to unity 1 which is in agreement with the values characteristic of snow as a porous substance further research is necessary to determine whether this technique can be applied to snow in other environmental conditions copyright 2007 john wiley sons ltd

arctic rockwall retreat rates estimated using laboratory calibrated ert measurements of talus cones in longyeardalen svalbard holocene rockwall retreat rates quantify integral values of rock slope erosion and talus cone evolution here we investigate holocene rockwall retreat of exposed arctic sandstone cliffs in longyear

paleoceanographic evolution of the sw svalbard margin 76 n since 20 000 14c yr bp abstract two cores from the southwestern shelf and slope of storfjorden svalbard taken at 389 m and 1485 m water depth have been analyzed for benthic and planktic foraminifera oxygen isotopes and ice rafted debris the results show that over the last 20 000 yr atlantic water has been continuously present on the southwestern svalbard shelf however from 15 000 to 10 000 14c yr bp comprising the heinrich event h1 interval the bolling allerod interstades and the younger dryas stade it flowed as a subsurface water mass below a layer of polar surface water in the benthic environment the shift to interglacial conditions occurred at 10 000 14c yr bp due to the presence of a thin upper layer of polar water surface conditions remained cold until ca 9000 14c yr bp when the warm atlantic water finally appeared at the surface neither extensive sea ice cover nor large inputs of meltwater stopped the inflow of atlantic water its warm core was merely submerged below the cold polar surface water