late weichselian and holocene sedimentary palaeoenvironment and glacial activity in the high arctic van keulenfjorden spitsbergen high arctic fjords for example van keulenfjorden on spitsbergen provide valuable palaeoenvironmental archives as they typically contain landforms and sediment sequences that document past changes in glacial activity with high temporal resolution van keulenfjorden was covered with a grounded glacier during the last glacial and it was deglaciated between c 11 8 and 11 3 cal ka bp the retreat of the ice front accelerated from approximately 80 to 190 m a during the deglaciation the maximum late holocene glacier extent occurred after surge like advances of the glacier nathorstbreen between 2790 and 2610 cal yr bp i e during a period with the coldest climatic conditions on svalbard this maximum extent was reached approximately 2600 years earlier than inferred for most fjords on svalbard suggesting that surge like glacier advances on svalbard can occur under variable climatic conditions the time interval between the advances of nathorstbreen around 2 7 ka bp was approximately 100 150 years this is comparable to the last and only historically known quiescent phase of nathorstbreen of c 120 years between the late 19th century and the most recent surge from 2003 to 2012

a 5500 year oxygen isotope record of high arctic environmental change from southern spitsbergen the oxygen isotope composition of chironomid head capsules in a sediment core spanning the past 5500 years from lake svartvatnet in southern spitsbergen was used to reconstruct the oxygen isotope composition of lake water 18olw and local precipitation the 18olw values display shifts from the baseline variability consistent with the timing of recognized historical climatic episodes such as the roman warm period the dark ages cold period and the little ice age the highest values of the record ca 3 above modern 18olw values occur at ca 1900 1800 cal yr bp three negative excursions increasing in intensity toward the present at 3400 3200 1250 1100 and 350 50 cal yr bp are tentatively linked to roughly synchronous episodes of increased glacier activity and general cold spells around the northern north atlantic their manifestation in the svartvatnet 18olw record not only testify to the sensitivity and potential of high arctic lacustrine 18ochir records in tracking terrestrial climate ev

holocene glacier advances in the headwaters of sredniaya avacha kamchatka russia abstract holocene glacial deposits in sredniya avacha headwaters are subdivided into three age groups events a b and c based upon geomorphic features tephrochronology and lichenometry tephras of opala volcano 1400 1500 yr b p ksudach volcano 1700 1800 and 6000 yr b p and zavaritskiy volcano 2800 yr b p are used as stratigraphic markers rhizocarpon geographicum l dc and rhizocarpon section alpicola growth curves are established using tephrochronologically dated and historical surfaces the age of event a pre hypsitermal moraines is constrained by an age of 6000 yr b p for overlying ksudach 2 tephra and an age of 7200 lichenometric l yr b p event b neoglaciation had a multiple nature with the most prominent advances at 4300 3500 3300 2800 2600 2100 1800 1400 and 1300 1100 l yr b p the culmination occurred before 2800 yr b p as suggested by a date for zavaritskiy volcano tephra found on the glacial and outwash deposits less extensive glacier advances of event c little ice age occurred at 800 600 500 200 180 110 and 90 40 l yr b p the ela depression was 200 250 100 150 30 70 m during the culmination of events a b and c respectively

over 400 previously undocumented svalbard surge type glaciers identified abstract identifying glaciers that exhibit surge type behavior is important when using evidence of ice front fluctuations as a proxy for reconstructing past climate oscillations this study identifies previously undocumented surge type glaciers in svalbard based on the presence of crevasse squeeze ridges in glacier forelands crevasse squeeze ridges are landforms suggested to be unique to surging glacier land systems estimates vary greatly as to the actual percentage of surge type glaciers in svalbard and consequently their distribution pattern is poorly understood a detailed survey of recent 2008 2012 high resolution aerial imagery from toposvalbard provided by the norwegian polar institute allowed for a survey of all the glacier forelands in svalbard before our study 277 individual glaciers in svalbard have been documented to exhibit surge behavior by using crevasse squeeze ridges as indicators of surge behavior we have identified 431 additional glaciers that have surged we suggest that this is a modest value as the unique surge landforms were not visible in approximately one third of the forelands with documented surge histories limits to the crevasse squeeze ridge technique are presented and potential controlling factors for crevasse squeeze ridge formation preservation are discussed

formal ratification of the quaternary system period and the pleistocene series epoch with a base at 2 58 ma in june 2009 the executive committee of the international union of geological sciences iugs formally ratified a proposal by the international commission on stratigraphy to lower the base of the quaternary system period to the global stratotype section and point gssp of the gelasian stage age at monte san nicola sicily italy the gelasian until then had been the uppermost stage of the pliocene series epoch the base of the gelasian corresponds to marine isotope stage 103 and has an astronomically tuned age of 2 58 ma a proposal that the base of the pleistocene series epoch be lowered to coincide with that of the quaternary the gelasian gssp was also accepted by the iugs executive committee the gssp at vrica calabria italy which had hitherto defined the basal boundary of both the quaternary and the pleistocene remains available as the base of the calabrian stage age now the second stage of the revised pleistocene in ratifying these proposals the iugs has acknowledged the distinctive qualities of the quaternary by reaffirming it as a full system period correctly complied with the hierarchical requirements of the geological timescale by lowering the base of the pleistocene to that of the quaternary and fully respected the historical and widespread current usage of both the terms quaternary and pleistocene copyright 2009 john wiley sons ltd

tectonic and lithologic controls on bedrock channel profiles and processes in coastal california 1 recent theoretical models suggest that topographic characteristics of bedrock channels are products of interactions among tectonics substrate resistance and the climatically modulated erosive ability of the river the degree to which these factors influence the form of channel profiles is poorly quantified at present here we investigate bedrock channels developed across the southern flank of the santa ynez mountains california uniform climate and systematic variations in lithology and rock uplift rate along the range allow comparison of channel morphology between 1 channels eroding rocks of uniform and nonuniform strength and 2 channels experiencing differences in tectonic forcing we combine field observations surveys and analysis of digital data to determine topographic and hydraulic characteristics of bedrock channels at a constant rock uplift rate streams flowing from resistant to less resistant bedrock exhibit highly concave profiles and increased gradients along lower reaches relative to channels developed in uniform bedrock these effects are interpreted as responses to 1 an increase in substrate resistance to channel incision in the upper reaches and 2 transport limited gradients along lower reaches comparisons of channels developed across uniform lithology but experiencing an approximately sevenfold difference in rock uplift rate reveal an approximately twofold increase in gradient and an approximately threefold decrease in width in this landscape the combined channel adjustments of gradient and width are consistent with a fluvial incision model in which channel incision rate is linearly proportional to mean bed shear stress

scandinavian glacial and climatic fluctuations during the holocene abstract historical documents and lichenometric studies give a detailed picture of the little ice age in scandinavia there was a large advance in norway which has been dated at a few places to 1750 small readvances during the retreat occurred around a d 1780 1810 1840 1850 1850 1870 1890 1910 and 1930 in sweden most of these advances have been recognized and in addition extensive advances are dated by lichenometry to around a d 1600 1650 and 1700 1720 soils buried beneath moraines often yield radiocarbon dates that are much too old methods dependent on these must therefore be used with care evidence for pre little ice age advances are often considered equivocal the most reliable information is probably provided by studies of lacustrine sediments combining information from all sources the most significant pre little ice age glacier advances most likely occurred in 7 5 5 1 4 5 3 2 2 8 2 2 1 9 and 1 5 1 1 radiocarbon ka bp advances that were less extensive or for which there is less evidence occurred around 6300 5600 2500 940 600 560 and 380 bp

holocene glacial and climatic variations on spitsbergen svalbard holocene glacial and climatic variations have been inferred from investigations of sediment cores from the proglacial lake linnevatnet western spitsbergen a low content of glacially derived coal absence of regular laminations and a slow sedimentation rate in the lower part of the lacustrine sediments indicate that the former glaciers that existed within the catchment area during the last ice age melted quickly away as a result of the younger dryas holocene warming and during the next 6000 years there were no glaciers in the valley increasing coal content incipient laminations and rising sedimentation rates indicate that the glacier linnebreen started to form 4000 5000 years ago probably as a response to the late holocene cooling the holocene maximum extent of the glacier occurred during the little ice age starting with a pronounced ice advance in the thirteenth or fourteenth century a well dated core from billefjorden which is assumed to reflect glacial fluctuations in the inner part of the i

quaternary evolution of the ploucnice river system bohemian massif based on fluvial deposits dated with optically stimulated luminescence and in situ produced cosmogenic nuclides abstract the ploucnice river system located in the central bohemian massif is draining an area almost not covered by continental ice sheets but instead archiving the fluvial deposits the fluvial style changes from a high energy braided to a long bend meandering river in the upper terrace levels 36 to 29 m above present floodplain the middle terrace levels 22 to 14 m above present floodplain indicate a fluvial style changing from a high to medium energy braided river in the lower terrace levels 13 to 5 m above present floodplain the terrace deposits indicate high energy braided to long bend meandering river environments to provide greater details on the timing of fluvial terrace formation this study applied 26al and 10be isochron burial and optically stimulated luminescence osl dating methods to terraces of the ploucnice river system terrace fluvial infills are dated with isochron burial dating in relative altitude 34 29 and 14 m above present floodplain apf whereas terrace accumulations in relative altitude 19 12 and 6 m apf are dated with osl because of differences in age results between the two dating methods we propose two different evolution models the first is based on isochron burial and osl dating and the second model is on osl dating results only the time span represented by the river terraces remains unclear and varies from eburonian to weichselian 1680 to 56 ka or from saalian to weichselian 138 to 56 ka with the estimation of the highest terrace 248 ka respectively the former river evolution model is based on tectonic activity at least since 1000 ka morphotectonic analysis recognized new lineaments of which the general direction corresponds with the main direction of the oh e fault zone ne to ene striking and lu ice fault zone nw striking based on dated terrace ages of 1153 123 ka at 14 m apf and 138 21 ka at 19 m above present floodplain we propose a normal fault being active from at least 1153 ka the second river evolution model assumes possible remobilization of clasts analyzed by isochron burial dating before their final deposition from three osl ages we calculated a mean incision rate and estimated an age of upper terrace levels at 34 m apf to be 248 38 ka saalian age as remobilization of clasts in high energy fluvial and glaciofluvial environments is very likely age determination is challenging nevertheless we interpret the terrace record in the ploucnice river system as a product of quaternary climatic changes influenced by tectonic processes

the martian hemispheric dichotomy may be due to a giant impact mars is divided into two fundamentally different geological provinces of approximately hemispherical extent1 3 the more southerly province is heavily cratered contains relatively old geological units and superficially resembles the lunar and mercurian highlands the northern province is relatively lightly cratered and contains younger geological units including extensive plains volcanic edifices and volcanic calderas except for the tharsis and elysium regions and other large volcanoes most of the younger northern province consists of lowlands which lie an average of 3 km below the highlands lowlands occupy about one third of mars they are separated from the highlands by a distinct scarp or by a sloping transitional zone as much as 700km wide in which highland materials have been disrupted and partly replaced by lowland deposits fig 1 the transition is characterized by a variety of landforms unknown on other planets the highlands and lowlands are in isostatic equilibrium across the transitional zone4 no generally accepted explanation for the cause of the highland lowland dichotomy has been proposed although thinning of the lithosph re in the northern hemisphere by internal processes has been suggested5 large impacts which were a feature of early solar system history have also been suggested as an important cause of such early planetary surface heterogeneities3 6 7 subcircular lowlands such as argyre chryse hellas and isidis planitia and the plains south of tharsis occupy previously recognized impact basins8 10 we propose here that the largest expanse of lowlands also results from formation of a large impact basin early in mars history that has profoundly shaped the planet s surface

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

late weichselian and holocene sedimentary environments and ice rafting in isfjorden spitsbergen abstract multi proxy analyses of two sediment cores from central isfjorden were used to reconstruct the glacial history in central spitsbergen during the late weichselian and the holocene and to relate iceberg rafting and sea ice rafting to climatic and oceanographic changes in the north atlantic region a basal till was deposited beneath an ice stream prior to 12 700 cal years bp calendar years before the present several tidewater glaciers influenced the sedimentary environment during the younger dryas and probably already during the allerod the younger dryas cooling might be reflected by enhanced sea ice formation and suspension settling as well as reduced iceberg rafting the final deglaciation was dominated by intense iceberg rafting it terminated around 11 200 cal years bp optimum holocene climatic and oceanographic conditions with significantly reduced ice rafting occurred between c 11 200 and 9000 cal years bp ice rafting occurred almost exclusively from icebergs after 10 200 cal years bp the icebergs most probably originated from tidewater glaciers on east spitsbergen indicating the presence of a strong east west temperature gradient at this time an increase of iceberg rafting around 9000 cal years bp followed by enhanced sea ice rafting reflects the onset of a general cooling in the western barents sea svalbard region comparatively intense rafting from icebergs and sea ice between 9000 and 4000 cal years bp is related to this cooling a general reduction in ice rafting after 4000 cal years bp is most probably the result of the enhanced formation of shore fast and or more permanent sea ice cover reducing the drift of icebergs and sea ice in the fjord the results indicate that the palaeoenvironmental conditions on central spitsbergen to a large degree depended on the oceanographic conditions in the western barents sea and west off spitsbergen however climatic trends affecting greenland and the entire north atlantic region can also be identified

the changing extent of marine terminating glaciers and ice caps in northeastern svalbard since the little ice age from marine geophysical records climate warming in svalbard since the end of the little ice age early in the 20th century has reduced glacier extent in the archipelago previous attempts to reconstruct little ice age glacier

rock uplift rates in south africa from isochron burial dating of fluvial and marine terraces the high plateau of southern africa is considered to be either uplifting due to mantle driven dynamic topography or to have been stable since mesozoic rifting to address this debate we determined rock uplift in south africa from the long term incision rate of the sundays river near port elizabeth and from an uplifted marine terrace near durban we dated the terraces with cosmogenic 26 al and 10 be using both isochron and simple burial dating methods we find that the sundays river has incised at 16 1 1 3 m m y for the past 4 m y and the marine terrace yields a rock uplift rate of 9 4 2 2 m m y these results are inconsistent with rapid neogene uplift

submarine glacial landforms and sedimentary environments in vaigattbogen northeastern spitsbergen abstract vaigattbogen is located in northern svalbard the area is currently affected by several tidewater glaciers this study uses multibeam sub bottom acoustic data and four sediment cores to reconstruct the late weichselian and holocene glacial history in vaigattbogen during the last glacial ice flowed northwards through vaigattbogen and fed into the hinlopen strait ice stream streamlined bedforms indicate relatively fast ice flow and their increasing elongation ratios towards the north suggest increasing flow velocities de geer moraines in the shallower parts of vaigattbogen imply that multiple halts and or re advances interrupted the ice retreat in these areas a sediment core suggests that the north basin deglaciated prior to 9 1 cal ka bp in the south basin two large moraine ridges and networks of crevasse squeeze ridges suggest that at least two surge type advances occurred during the holocene the hinlopenbreen glacier surged in the early 1970s and deposited the inner r 2 of the two large moraine ridges radiocarbon ages from a sediment core recovered from the crest of the outer r 1 ridge yield a basal age of 2 6 cal ka bp however the core did not sample subglacial diamict and the age of the ridge could be anything between 2 6 cal ka bp and early holocene the r 1 ridge formed prior to the little ice age lia implying that more than one tidewater glacier has experienced a pre lia surge on the east coast of spitsbergen suggesting that surging during the holocene was a regional phenomenon the r 1 ridge is double crested with small crevasse squeeze ridges between the crests suggesting that more than one surge type advance occurred during the holocene reaching approximately the same location data from eastern svalbard indicate differences in surge landform assemblages suggesting that different mechanisms could have governed surge cycles throughout the holocene

the geomorphic imprint of glacier surges into open marine waters examples from eastern svalbard abstract seafloor morphology beyond nine tidewater glaciers terminating in open marine settings in eastern svalbard has been investigated using multibeam swath bathymetry historical information on tidewater glacier fluctuations over the past century or so shows that the seafloor offshore has been exposed only recently most glaciers have been observed to surge or have looped surface moraines indicating past surges during these ice advances and subsequent retreat a well preserved submarine landform assemblage has been produced a subglacial landforms include overridden moraine ridges mega scale glacial lineations msgls other streamlined lineations elongate drumlins and medial moraines small ridges forming a complex boxwork or rhombohedral pattern and meltwater related eskers and channels b ice marginal landforms include large terminal moraines with debris flow lobes on their outer flanks and indentations on their inner sides small transverse retreat moraines and crater like kettle holes c glacimarine features include iceberg ploughmarks and an otherwise relatively smooth sedimentary seafloor produced by fine grained debris rain out a schematic plan view landform assemblage model for tidewater glaciers advancing into open marine settings is developed arcuate terminal moraines marking the ice advance limit provide a distinctive component submarine basin s exposed inside these moraine ridges when ice retreats contain suites of individual landforms produced subglacially and ice marginally with a consistent order of timing of deposition and stratigraphic superposition the new schematic model is compared with earlier models based on submarine landforms associated with surges in the more topographically constrained setting of spitsbergen fjords differences include i the overall arcuate shape of the open marine assemblage ii the indented ice proximal sides of terminal moraine ridges iii the fan shaped pattern of streamlined lineations iv crater like kettle holes at the inner lateral margins of many submarine basins v prominent systems of eskers and channels modern glaciological analogues from ongoing surges of ice caps in eastern svalbard and severnaya zemlya provide contemporary observations of ice advance into open marine settings including heavily crevassed ice lobes with finger like termini

quaternary river terraces in england forms sediments and processes abstract flights of quaternary river terraces in south and east england have common characteristics involving low gradient planed or irregular bedrock surfaces and single or multi storey gravel deposits rather than depending on warm cold or cold warm transitions it is suggested that bedrock planation working depths of gravel and later stage relatively shallow aggradations are all dominantly of cold climate origin basal sediments show active incorporation of plucked and periglacially shattered materials whilst super incumbent units incorporating up catchment and slope derived materials demonstrate later cold stage sediment influx and consequent cessation of active bedrock erosion channel activity effecting both planation and deposition are reviewed together with the detailed sedimentology of gravelly sediments which show evidence of both autogenic processes bar migration channel switching and infilling and truncation of upper sedimentation units cold climate indicators turbation ice wedge casts and frozen block transport and specifically for the last glacial interglacial cycle varying sediment flux as climates changed both interglacial and transitional activities are believed to be of lesser morphological significance whilst prior uplift is taken as enabling rather than being a generator of terrace within the timescale of a glacial interglacial cycle variations within cold stage climates varying sediment influx and channel belt bedrock erosion are stressed as dominating mid catchment and mid latitude quaternary terracing at the glacial interglacial scale

glacier hydrology in svalbard norwegian high arctic abstract progress in glacier hydrology has focused on temperate glaciers although partly or wholly non temperate glaciers are found in many parts of the world and significant areas of former ice sheets were probably non temperate it has usually been assumed that drainage from non temperate glaciers consists of relatively dilute and invariable supraglacial runoff in this paper the hydrology of glaciers in the high arctic archipelago of svalbard is examined variations in the thermal regimes of glaciers and their implications for drainage are first addressed results from svalbard concerning meltwater discharge and storage and solute and suspended sediment dynamics are then reviewed in general meltwater penetration of non temperate ice is limited and drainage from non temperate glaciers in svalbard has many of the characteristics of sub aerial drainage however it would be erroneous to view this drainage simply as dilute supraglacial runoff as significant material transport occurs in suspension and solution furthermore twentieth century climate change has probably led to changes in the thermal regimes of some svalbard glaciers such that relict drainage structures are sometimes observed while meltwater yields are augmented by runoff which can be attributed to the loss of mass from glaciers at large spatial scales turbid plumes observed at the marine margins of polythermal ice caps indicate that meltwater can be routed subglacially through non temperate ice

the island of amsterdamoya a key site for studying past climate in the arctic archipelago of svalbard abstract this paper introduces a series of articles assembled in a special issue that explore holocene climate evolution as recorded in lakes on the island of amsterdamoya on the westernmost fringe of the arctic svalbard archipelago due to its location near the interface of oceanic and atmospheric systems sourced from arctic and atlantic regions amsterdamoya is a key site for recording the terrestrial response to marine and atmospheric changes we employed multi proxy approaches on lake sediments integrating physical biogeochemical and isotopic analyses to infer past changes in temperature precipitation and glacier activity the results comprise a series of quantitative holocene length paleoclimate reconstructions that reveal different aspects of past climate change each of the four papers addresses various facets of the holocene climate history of north western svalbard including a reconstruction of the annabreen glacier based on the sedimentology of the distal glacier fed lake gjoavatnet a reconstruction of changing hydrologic conditions based on sedimentology and stratigraphy in lake hakluytvatnet reconstruction of summer temperature based on alkenone paleothermometry from lakes hakluytvatnet and hajeren and a hydrogen isotope based hydrological reconstruction from lake hakluytvatnet we also present high resolution paleomagnetic secular variation data from the same lake which document important regional magnetic field variations and demonstrate the potential for use in synchronizing holocene sedimentary records in the arctic the paleoclimate picture that emerges is one of early holocene warmth from ca 10 5 ka bp interrupted by transient cooling ca 10 8ka bp and followed by cooling that mostly manifested as two stepwise events ca 7 and 4 ka bp the past 4ka were characterized by dynamic glaciers and summer temperature fluctuations decoupled from the declining summer insolation

sensitivity to long term climate change of subpermafrost groundwater systems in svalbard deep subpermafrost aquifers are highly climate dependent with the permafrost as an aquitard preventing groundwater recharge and discharge a study from the high arctic island of spitsbergen svalbard shows that during a glacial to interglacial phase both the permafrost and the glacier regime will respond to climatic changes and a glacier fed groundwater flow system will vary accordingly a full glaciation results in the melting of permafrost and groundwater can flow through pores and fracture systems in the rocks and sediments below the temperate zones of glaciers these groundwater flow systems will mainly be localized to fjords and valleys and form low lying terrestrial springs when the relative sea level drops during deglaciation due to glacio isostatic rise during an interglaciation permafrost develops and thickens and the groundwater recharge and discharge areas will thereby be gradually reduced to a minimum reached at the warmest part of an interglaciation an already frozen spring system cannot reopen before the permafrost melts only groundwater springs related to permanently warm based glacial ice will persist into the next glaciation during a new glaciation flow systems that terminated during the previous interglaciation may become revitalized if overridden by warm based ice causing permafrost thawing

bedrock channel adjustment to tectonic forcing implications for predicting river incision rates we present detailed data of channel morphology for a river undergoing a transient response to active normal faulting where excellent constraints exist on spatial and temporal variations in fault slip rates we show that traditional hydraulic scaling laws break down in this situation and that channel widths become decoupled from drainage area upstream of the fault unit stream powers are 4 times higher than those predicted by current scaling paradigms and imply that incision rates for rivers responding to active tectonics may be significantly higher than those heretofore modeled the loss of hydraulic scaling cannot be explained by increasing channel roughness and is an intrinsic response to tectonic forcing we show that channel aspect ratio is a strongly nonlinear function of local slope and demonstrate that fault induced adjustment of channel geometries has reset hillslope gradients the results give new insight into how rivers maintain their course in the face of tectonic uplift and illustrate the first order control the fluvial system exerts on the locus and magnitude of sediment supply to basins

statistical analysis of brepollen bathymetry as a key to determine average depths on a glacier foreland abstract the study demonstrates the usefulness of statistical analysis to classify valleys because of the influence of the glaciers that formed them as well as to determine the average depth at their cross section parallel to the glacier front moreover the usefulness of the analysis of shape of the histogram of depth the value of skewness and kurtosis and the relation between the average median and mode of depths to classify valleys is shown the statistical analysis of the normalized shape of the valley cross sections allowed establishment of the relation between the measured depth the location of the measurements and the average depth of the valley cross sections

the importance of independent chronology in integrating records of past climate change for the 60 8 ka intimate time interval this paper provides a brief overview of the most common dating techniques applied in palaeoclimate and palaeoenvironmental studies including four radiometric and isotopic dating methods radiocarbon 230th disequilibrium luminescence cosmogenic nuclides and two incremental methods based on layer counting ice layer varves for each method concise background information about the fundamental principles and methodological approaches is provided we concentrate on the time interval of focus for the intimate integrating ice core marine and terrestrial records community 60 8 ka this dating guide addresses palaeoclimatologists who aim at interpretation of their often regional and local proxy time series in a wider spatial context and therefore have to rely on correlation with proxy records obtained from different archives from various regions for this reason we especially emphasise scientific approaches for harmonising chronologies for sophisticated and robust proxy data integration in this respect up to date age modelling techniques are presented as well as tools for linking records by age equivalence including tephrochronology cosmogenic 10be and palaeomagnetic variations finally to avoid inadequate documentation of chronologies and assure reliable correlation of proxy time series this paper provides recommendations for minimum standards of uncertainty and age datum reporting

chronology of holocene glaciation central brooks range alaska the central brooks range was glacierized in the highest north facing cirques during late middle to late holocene neoglacial time this neoglaciation involved at least 5 major cirque glacier expansions of similar magnitude as based on lichenometric mapping of more than 50 glaciers and radiocarbon dates directly associated with 5 moraines initial stabilization of debris covered glaciers took place by early holocene time but evidently no moraines formed during this interval few morainal ridges are preserved that date from the older expansions but they have been lichenometrically dated 20 age reliability to 3 separate intervals 4400 3500 and 2900 yr b p twelve morainal complexes have ridges indicative of glacial advance that lichenometrically date at 1800 500 yr b p relict lichens that are now emerging undisturbed from beneath a receding glacier toe imply that this time was one of prolonged recession in at least some parts of the brooks range however radiocarbon analysis of dead moss at this same site dates a subsequent neoglacial advance across the cirque floor at 1120 180 yr b p our data suggest that for the past 1 100 yr cirque glaciers have been continuously in more extended positions than they are today during this glaciologically favorable interval the last two major advances occurred at 800 150 and 390 90 yr b p a d 1410 1600 glaciers across the central brooks range stayed close to their maxima until a d 1640 1750 historical photographs and lichenometry show that retreat was most rapid after a d 1870 and decelerated after the mid 1900s recession from this most recent neoglacial maximum has amounted to 150 700 m and continues at present the cirque glacier advances were accompanied by equilibrium line altitude ela depressions of 100 to 200 m below levels maintained in the late 1970s environmental lapse rate estimates and 1977 1981 glaciologic meteorologic measurements suggest that summer air temperatures accompanying neoglacial maxima were respectively 1 c or 3 to 4 c cooler than those of the late 1970s across the central brooks range the neoglacial maxima elas rise northeastward and northward from 2 to 5 m km 1

ams radiocarbon dating of organic poor lake sediment an example from linnevatnet spitsbergen svalbard ams radiocarbon dating of specific organic fractions is used to evaluate sources of errors in dating of organic poor lake sediment from linnevatnet a proglacial arctic lake dates on un differentiated bulk organic matter are much too old because of contamination from detrital coal attempts to remove coal from other organic matter were only partially successful a consequence of the wide grain size distribution of the coal even if coal contamination is fully removed the bulk of the remaining organic matter is of aquatic origin and is unsuitable for 14c dating because the lake waters are depleted in 14 c due to dissolution of carbonate minerals terrestrial plant macrofossils provide the only reliable material to date the lake sediment however this material is present in sufficient quantity for ams radiocarbon dating only in cores proximal to the main inlet streams paired dates on terrestrial plants and aquatic insects from the same core level and paired dates on modern aquatic and terrestrial vege

new faunal and isotopic evidence on the late weichselian holocene oceanographic changes in the norwegian sea downcore studies of planktonic and benthonic foraminifera and 18o and 13c in the planktonic foraminifer neogloboquadrina pachyderma sin in two piston cores from the southern part of the norwegian sea suggest large changes in the oceanic circulation pattern at the end of oxygenisotope stage 2 and in the early part of stage 1 prior to oxygen isotope termination ia 16 000 13 000 yr b p an isolated watermass with lower oxygen content and temperature warmer than today existed below a low salinity ice covered surface layer in the norwegian sea close to termination ia well oxygenated deep water probably with positive temperatures was introduced this deep water which must have had physical and or chemical parameters different from those of present deep water in the norwegian sea could have been introduced from the north atlantic or been formed within the basin by another mechanism than that which forms the present deep water of the norwegian sea a seasonal ice cover in the southern part of the norwegian sea is proposed for the period between termination ia and the beginning of ib close to 10 000 yr b p the present situation with strong influx of warm atlantic surface water and deep water formation by surface cooling was established at termination ib

review of the neotectonics of the eastern turkish armenian plateau by geomorphic analysis of digital elevation model imagery digital elevation model dem images provide synoptic views of the earth s surface allowing the analysis of landforms of still active tectonic and volcanic structures at regional scale a dem at 250 m pixel size constitutes regional scale data particularly efficient to investigate the late miocene quaternary deformation of the eastern turkish armenian plateau in the arabian eurasian area of convergence geomorphic analysis of the dem image associated with review of fault plane solutions of earthquakes show that faults are mostly strike slip with small vertical component here we show that the orientations of the tectonic and volcanic structures fit with a tectonic regime characterized by n s shortening and e w lengthening consistent with westward escape of anatolia perpendicular to the direction of the arabia eurasia shortening the uniform uplift of the plateau the predominance of strike slip faulting the lack of major thrusts and the occurrence of normal faults do not support a model of going on crustal thickening due to intracontinental convergence on the contrary our observations can be better interpreted in terms of lithospheric thinning and mantle upwelling related to gravity escape of anatolia

rapid late pleistocene incision of atlantic passive margin river gorges the direct and secondary effects of rapidly changing climate caused large rivers draining the atlantic passive margin to incise quickly into bedrock beginning about 35 000 years ago measured in samples from bedrock fluvial terraces 10 beryllium shows that both the susquehanna and potomac rivers incised 10 to 20 meter deep gorges along steep convex lower reaches during the last glacial cycle this short lived pulse of unusually rapid down cutting ended by 13 000 to 14 000 years ago the timing and rate of downcutting are similar on the glaciated susquehanna and unglaciated potomac rivers indicating that regional changes not simply glacial meltwater initiated incision

quaternary downcutting rate of the new river virginia measured from differential decay of cosmogenic 26al and 10be in cave deposited alluvium the concentrations of the cosmogenic radionuclides sup 26 al and sup 10 be in quartz can be used to date sediment burial here we use sup 26 al and sup 10 be in cave deposited river sediment to infer the time of sediment emplacement sediment burial dates from a vertical sequence of caves along the new river constrain its quaternary downcutting rate to 27 3 4 5 m m y and may provide evidence of regional tectonic tilt 32 refs 3 figs 1 tab

mild little ice age and unprecedented recent warmth in an 1800 year lake sediment record from svalbard the arctic region is subject to a great amplitude of climate variability and is currently undergoing large scale changes due in part to anthropogenic global warming accurate projections of future change depend on anticipating the response of the arctic climate system to forcing and understanding how the response to human forcing will interact with natural climate variations the svalbard archipelago occupies an important location for studying patterns and causes of arctic climate variability however available paleoclimate records from svalbard are of restricted use due to limitations of existing climate proxies here we present a sub decadal to multidecadal scale record of summer temperature for the past 1800 yr from lake sediments of kongressvatnet on west spitsbergen svalbard based on the first instrumental calibration of the alkenone paleothermometer the age model for the high arctic lake sediments is based on 210 pb plutonium activity and the first application of tephrochronology to lake sediments in this region we find that the summer warmth of the past 50 yr recorded in both the instrumental and alkenone records was unmatched in west spitsbergen in the course of the past 1800 yr including during the medieval climate anomaly and that summers during the little ice age lia of the 18 th and 19 th centuries on svalbard were not particularly cold even though glaciers occupied their maximum holocene extent our results suggest that increased wintertime precipitation rather than cold temperatures was responsible for lia glaciations on svalbard and that increased heat transport into the arctic via the west spitsbergen current began ca a d 1600

examination of surface exposure ages of antarctic moraines using in situ produced 10be and 26al concentrations of 10be t12 1 5 106 y and 26a1 t12 0 72 106 y have been determined by accelerator mass spectrometry ams in a suite of quartz samples taken from sandstone boulders in several moraines in arena valley a dry valley adjacent to the taylor glacier in the quatermain mountains southern victoria land east antarctica these isotopes are produced in surficial quartz by cosmic ray spallation of o and si the concentrations in these samples ranged from 6 1 105 to 3 0 107 at g 1 for 10be and from 9 4 106 to 1 2 108 at g 1 for 26a1 depending upon the extent of exposure at the surface analyses of 10be in several samples from a single moraine at altitudes ranging from 1300 to 1650 m permitted an estimation of the air attenuation pathlength of cosmic ray neutrons the value of 142 96 41 g cm 2 is consistent with other published values production rates of 17 6 4 at g 1 y 1 for 10be and 113 54 16 at g 1 y 1 for 26a1 at 1300 m and 87 s and a 26al 10be production ratio of 6 5 1 3 1 3 were calculated from the data these values correspond to sea level production rates at high geomagnetic latitude of 6 4 at g 1 y 1 and 41 7 at g 1 y 1 for 10be and 26a1 respectively consistent with determinations based on 11 ky glacially polished surfaces in the sierra nevada in california these production rates imply exposure ages for the various moraines ranging from 50 ky to 2 5 my in accordance with other geological evidence the 10be and 26al ages of these rocks compare favorably with those found using a similar dating method based on in situ production of 3he examination of the 3he concentrations in conjunction with the present data set yields an estimate of 3he production of 230 8540 at g 1 y 1 corresponding to 85 31 15 at g 1 y 1 at sea level this is lower than previously reported values of 240 60 at g 1 y 1 and 190 at g 1 y 1 scaled to sea level and high geomagnetic latitude based respectively on volcanic flows less than 2000 years old at low latitude and samples collected from 14 400 year old volcanic flows this discrepancy is likely due to diffusive losses which may become significant up to 50 for surface exposure ages on the order of 2 0 my nevertheless the general correlations among the three isotopes suggest that 3he does not suffer gross losses through diffusion

holocene cirque glacier activity in western spitsbergen svalbard sediment records from proglacial linnevatnet holocene glacial variations of a presently ice free cirque in western spitsbergen are inferred from sediment records from the proglacial lake linnevatnet glaciation is indicated in the core records by increased intensity of laminae derived from the cirque inflow and by increase in sediment accumulation rate radiocarbon ages on terrestrial plant macrofossils limit the onset of glaciation in the cirque to within the last six centuries no evidence for earlier glaciation is recognized in the core records indicating that the threshold for glaciation in the cirque was not reached during prior neoglacial advances local climate events favouring glacier expan sion were either of greater magnitude or of longer duration during the little ice age than at any other time during the holocene

upper cenozoic fluvial history in the bohemian massif abstract two periods of fluvial development are identified in the bohemian massif bm uplands during the upper cenozoic the first lower miocene period is characterised by large unterraced gravel bodies up to 100 m thick filling overdeepened valleys or forming nowadays highly fragmented spreads upon plateaux and interfluves for the second upper pliocene holocene period a diverse style of deposition is typical the sedimentation is discontinuous and all types of continental sediments show repeated breaks in deposition this type of deposition is believed to be driven by the very essence of this time span i e climatically controlled alternation of erosion and accumulation phases because the uplands of the bm remained ice free and higher relief ensured repeated down cutting whenever the environment permitted the river valleys preserve complete records of the entire younger period the progressive series of incisions each of which is followed by an aggradation phase resulted in the formation of stairway like terrace sequences starting some 120 150 m above the rivers the onset of a new style of fluvial deposition together with the origin of a new drainage pattern is dated approximately to the gauss matuyama palaeomagnetic reversal this corresponds in central europe with the start of deposition of loess and formation of complex quaternary type sequences of slope sediments in uplands and can be taken to indicate a new geological era these changes may be therefore taken as support for the lowering of the quaternary tertiary erathem boundary

atlantic water advection to the eastern fram strait multiproxy evidence for late holocene variability a multiproxy data set of an ams radiocarbon dated 46 cm long sediment core from the continental margin off western svalbard reveals multidecadal climatic variability during the past two millennia investigation of planktic and benthic stable isotopes planktic foraminiferal fauna and lithogenic parameters aims to unveil the atlantic water advection to the eastern fram strait by intensity temperatures and salinities atlantic water has been continuously present at the site over the last 2 000 years superimposed on the increase in sea ice icebergs a strengthened intensity of atlantic water inflow and seasonal ice free conditions were detected at 1000 to 1200 ad during the well known medieval climate anomaly mca however temperatures of the mca never exceeded those of the 20th century since 1400 ad significantly higher portions of ice rafted debris and high planktic foraminifer fluxes suggest that the site was located in the region of a seasonal highly fluctuating sea ice margin a sharp reduction in planktic foraminifer fluxes around 800 ad and after 1730 ad indicates cool summer conditions with major influence of sea ice icebergs high amounts of the subpolar planktic foraminifer species turborotalia quinqueloba in size fraction 150 250 m indicate strengthened atlantic water inflow to the eastern fram strait already after 1860 ad nevertheless surface conditions stayed cold well into the 20th century indicated by low planktic foraminiferal fluxes most likely at the beginning of the 20th century cold conditions of the terminating little ice age period persisted at the surface whereas warm and saline atlantic water already strengthened hereby subsiding below the cold upper mixed layer surface sediments with high abundances of subpolar planktic foraminifers indicate a strong inflow of atlantic water providing seasonal ice free conditions in the eastern fram strait during the last few decades

timing of european fluvial terrace formation and incision rates constrained by cosmogenic nuclide dating abstract age constraints of late cenozoic fluvial terraces are important for addressing surface process questions related to the incision rates of rivers or tectonic and climate controls on denudation and sedimentation unfortunately absolute age constraints of fluvial terraces are not always possible and many previous studies have often dated terraces with relative age constraints that do not allow for robust interpretations of incision rates and timing of terrace formation however in situ produced cosmogenic nuclides allow absolute age determination and hence incision rates of fluvial deposits back to 5 ma here we present cosmogenic depth profile dating and isochron burial dating of four different river systems in europe spanning 12 of latitude we do this to determine river incision rates and spatial variations in the timing of terrace formation isochron burial age constraints of four selected terraces from the vltava river czech republic range between 1 00 0 21 to 1 99 0 45 ma an isochron burial age derived for the allier river central france is 2 00 0 17 ma five terrace levels from the esla river nw spain were dated between 0 08 0 04 0 01 ma and 0 59 0 13 0 20 ma with depth profile dating the latter age agrees with an isochron burial age of 0 52 0 20 ma two terrace levels from the guadalquivir river sw spain were dated by depth profile dating to 0 09 0 03 0 02 ma and 0 09 0 04 0 03 ma the one terrace level from the guadalquivir river dated by isochron burial dating resulted in an age of 1 79 0 18 ma results indicate that the cosmogenic nuclide based ages are generally older than ages derived from previous relative age constraints leading to a factor 2 3 lower incision rates than previous work furthermore the timing of terrace formation over this latitudinal range is somewhat obscured by uncertainties associated with dating older terraces and not clearly synchronous with global climate variations

holocene glacial history of svalbard status perspectives and challenges abstract we synthesize the current understanding of glacier activity on svalbard from the end of the late pleistocene 12 000 yrs before present to the end of the little ice age c 1920 ad our glacier history is derived from the svalhola database the first compilation of holocene geochronology for svalbard and the surrounding waters including over 1 800 radiocarbon terrestrial cosmogenic nuclide and optically stimulated luminescence ages data have been categorized by geological setting uniformly re calibrated quality assessed and ultimately used to constrain glacier fluctuations deglaciation ice free conditions glacier re advances and ice marginal positions we advance existing knowledge by mapping the extent and distribution of ice cover during the holocene glacial maximum and the glacial minimum as well as present retreat rates and percentages within early holocene fjord systems throughout the holocene svalbard glaciers have responded to a varying combination of climatic environmental and dynamic driving factors which influence both the extent and behavior of ice margins we discuss the complexities of glacier systems and their dynamics in response to changes in climate this review provides a holistic state of the art of holocene glaciers on svalbard suitable for orienting future works which address gaps in our current knowledge

production of cosmogenic radionuclides at great depth a multi element approach abstract for the last two decades in situ produced cosmogenic nuclides are increasingly applied in earth sciences to quantify surface processes in parallel significant reduction of the analytical uncertainties linked to advances in accelerator mass spectrometry ams allows more precise measurements however among all the published works on cosmogenic nuclides only few studies are dedicated to a better understanding of their production systematic or to a better constrain of the physical parameters involved in their production thus an approach to investigate in situ produced cosmogenic nuclides 10 be 26 al and 36 cl along a single 11 meter long core drilled from the surface and composed of carbonates and quartzose conglomerates has been launched these measurements have been used to quantify muon induced productions based on natural samples for each studied nuclide contrary to the current most oftenly used calculation of muon induced production parameters which are based on irradiation experiments at discrete energies productions based on natural samples are considering the entire energy range of particles reaching the ground surface the evolution of 36 cl concentrations with depth needs to agree with those parameters deduced from 10 be and 26 al data this is optimized when considering a fast muon induced 36 cl production contribution and a spallation production rate at sea level high latitude slhl of 42 0 2 0 atoms 36 cl g ca 1 a 1 1 sigma uncertainty

structure and origin of holocene cold events abstract the present interglacial the holocene spans the period of the last 11 700 years it has sustained the growth and development of modern society the millennial scale decreasing solar insolation in the northern hemisphere summer lead to northern hemisphere cooling a southern shift of the intertropical convergence zone itcz and a weakening of the northern hemisphere summer monsoon systems on the multidecadal to multicentury scale periods of more stable and warmer climate were interrupted by several cold relapses at least in the northern hemisphere extra tropical area based on carefully selected 10 000 year long time series of temperature and humidity precipitation as well as reconstructions of glacier advances the spatiotemporal pattern of six cold relapses during the last 10 000 years was analysed and presented in form of a holocene climate atlas hoclat see http www oeschger unibe ch research projects holocene atlas a clear cyclicity was not found and the spatiotemporal variability of temperature and humidity precipitation during the six specific cold events 8200 6300 4700 2700 1550 and 550 years bp was very high different dynamical processes such as meltwater flux into the north atlantic low solar activity explosive volcanic eruptions and fluctuations of the thermohaline circulation likely played a major role in addition internal dynamics in the north atlantic and pacific area including their complex interaction were likely involved

an isochron method for cosmogenic nuclide dating of buried soils and sediments we describe an improved method for dating buried paleosols using measurements of the cosmic ray produced radionuclides 10be and 26al in quartz grains and apply it to a sequence of intercalated tills and paleosols in central missouri usa that record plio pleistocene advances of the laurentide ice sheet a buried paleosol implies a period of surface exposure and nuclide accumulation followed by burial and a halt to nuclide production if the paleosol is formed in a sedimentary unit such as till this unit may also have been emplaced with unknown 26al and 10be concentrations inherited from past surface exposure if the inherited nuclide concentrations are the same at all depths in the soil as is true for well mixed sediments such as till then the 26al and 10be concentrations at different depths in the paleosol will show a linear relationship the slope of this line depends on the duration of burial of the paleosol but not on the inherited nuclide concentrations or on the sample depths thus one can date strata overlying buried paleosols by measuring 26al and 10be at multiple depths in the paleosol and calculating the burial age of the paleosol from the resulting isochron we focus on applying this approach to till paleosol sequences but the basic idea of forming an 26al 10be burial isochron with a set of samples that share the same burial age but differ in other aspects of their exposure history applies to other stratigraphic settings as well the method yields ages for four tills in missouri that are stratigraphically consistent agree with paleomagnetic age constraints and show that ice advanced into missouri near 1 25 ma near 0 8 ma and twice between ca 0 4 and 0 2 ma

hydroclimate variability of high arctic svalbard during the holocene inferred from hydrogen isotopes of leaf waxes abstract the response of the arctic hydrologic cycle to global warming includes changes in precipitation patterns and moisture availability associated with variable sea ice extent and modes of atmospheric circulation reconstructions of past hydroclimate changes help constrain the natural range of these systems identify the manners in which they respond to different forcing mechanisms and reveal their connections to other components of the climate system all of which lead to a better understanding of present and future changes here we examine hydroclimate changes during the holocene in the high arctic archipelago of svalbard by reconstructing the isotopic composition of precipitation we measured the hydrogen isotopic composition d values of leaf wax compounds n alkanes c 25 c 31 in a sediment core from lake hakluytvatnet on the island of amsterdamoya northwest spitsbergen we interpret d values of mid chain c 25 and long chain c 29 c 31 length n alkanes to represent changes in the isotopic composition of lake water and precipitation over the last 12 9 ka after deglaciation of the catchment water supply became restricted and the lake experienced significant evaporative isotopic enrichment indicating warmer conditions from 12 8 to 7 5 ka the isotope values suggest an increase in the delivery of moisture from warmer sub polar air masses between 12 8 and 9 5 ka followed by generally warm but unstable conditions between 9 5 and 7 5 ka possibly indicating a response to meltwater forcing sedimentary evidence indicates a hiatus in deposition c 7 5 5 0 ka likely as a result of desiccation of the lake at c 5 0 ka lacustrine sedimentation resumed and over the last 5 ka there was a progressive increase in the influence of polar air masses and colder conditions which culminated in an abrupt shift to colder conditions at c 1 8 ka this late holocene cooling ended c 0 18 ka when isotopic data indicate warmer conditions and greater influence of moisture derived from lower latitudes

recent high arctic glacial sediment redistribution a process perspective using airborne lidar abstract progressive glacier thinning retreat and mass loss in the high arctic is increasingly exposing forefield sediments to processes of mobilisation and redistribution in this paper we quantify forefield sediment redistribution at midtre lovenbreen svalbard using repeat light detection and ranging lidar surveys conducted in 2003 and 2005 in combination with field based observations average surface lowering of the forefield over the observation period identified from lidar surveys is 0 05 ma 1 and two primary areas of sediment reworking are identified active fluvial incision of proglacial streams by 2 m and lateral moraine downwasting of similar magnitude multivariate analysis of fluvial and climatological field data indicates that observed forefield sediment mobilisation is driven primarily by discharge forcing but with contributions from thermoerosive processes and stochastic autogenic sediment supply during the period of observation disparity between sediment loss in forefield fluvial systems as calculated from lidar data 3000 4000 103 kg and monitoring of fluvial sediment load 1600 3500 103 kg suggests the likely presence of significant quantities of buried ice beneath a thick debris mantle as evidenced by field observations relatively uniform lowering of the moraine crest identified from our repeat lidar surveys indicates thermoerosion of an ice core however simple debris layer thickness modelling indicates an increase in variation of debris layer thickness at lower elevations providing support for the assertion that moraine disintegration is driven by complex combinations of both thermal and mechanical processes this study demonstrates the viability of using lidar in conjunction with field monitoring to better understand sedimentary deglaciation dynamics and processes and also highlights the significance of forefield areas in controlling the sediment yield from deglaciating catchments

a general model of paraglacial landscape response a unifying attribute of all forms of paraglacial response is that deglaciation results in the exposure of unstable or metastable sediment sources that are subsequently tapped by a wide variety of processes over a wide range of timescales the paraglacial period in different geomorphological contexts is therefore con ditioned by two variables glacially conditioned sediment release and rate of sediment reworking under steady state conditions the latter may be approximated by an exhaustion model in which sediment yield is related to the amount of remaining available sediment by a negative exponential function this model offers an approximation for the behaviour of primary paraglacial systems in which glacigenic sediment sources are not replenished the long term behaviour of secondary primarily uvial paraglacial systems in which sediment inputs include both in situ and reworked glacigenic sediment appears intrinsically more complex but consistent with an exhaustion model if initial sediment avai

reconstruction of glacier variability from lake sediments reveals dynamic holocene climate in svalbard abstract the arctic is warming faster than anywhere else on earth holocene proxy time series are increasingly used to put this amplified response in perspective by understanding arctic climate processes beyond the instrumental period however available datasets are scarce unevenly distributed and often of coarse resolution glaciers are sensitive recorders of climate shifts and variations in rock flour production transfer this signal to the lacustrine sediment archives of downstream lakes here we present the first full holocene record of continuous glacier variability on svalbard from glacier fed lake hajeren this reconstruction is based on an undisturbed lake sediment core that covers the entire holocene and resolves variability on centennial scales owing to 26 dating points a toolbox of physical geochemical xrf and magnetic proxies in combination with multivariate statistics has allowed us to fingerprint glacier activity in addition to other processes affecting the sediment record evidence from variations in sediment density validated by changes in ti concentrations reveal glaciers remained present in the catchment following deglaciation prior to 11 300 cal bp culminating in a holocene maximum between 9 6 and 9 5 ka cal bp correspondence with freshwater pulses from hudson strait suggests that early holocene glacier advances were driven by the melting laurentide ice sheet lis we find that glaciers disappeared from the catchment between 7 4 and 6 7 ka cal bp following a late hypsithermal glacier reformation around 4250 cal bp marks the onset of the neoglacial supporting previous findings between 3380 and 3230 cal bp we find evidence for a previously unreported centennial scale glacier advance both events are concurrent with well documented episodes of north atlantic cooling we argue that this brief forcing created suitable conditions for glaciers to reform in the catchment against a background of gradual orbital cooling these findings highlight the climate sensitivity of the small glaciers studied which rapidly responded to climate shifts the start of prolonged neoglacial glacier activity commenced during the little ice age lia around 700 cal bp in agreement with reported advances from other glaciers on svalbard in conclusion this study proposes a three stage holocene climate history of svalbard successively driven by lis meltwater pulses episodic atlantic cooling and declining summer insolation

late holocene glacier activity at inner hornsund and scottbreen southern svalbard new 10be dating on two late holocene maximum moraines on the treskelen peninsula and at scottbreen svalbard improve constraints on the timing and character of holocene glacial activity in this region average moraine ages of 1 9 0 3 ka n 4 on the treskelen peninsula and 1 7 0 1 ka n 5 on scottbreen indicate the timing of a glacial culmination the age of moraine abandonment at treskelen and scottbreen correlates with snowline lowering and glacier expansion between 2 0 and 1 5 ka observed elsewhere on svalbard both scottbreen and the glaciers near treskelen have surged in the instrumental record like many glaciers across svalbard yet the age relation between our possible surge related moraines and other glacier records leads us to hypothesize that on centennial and longer timescales climate forcing outweighs surge dynamics which exerts a stronger control on glacier length on centennial timescales at our study sites

long term wind erosion on mars abstract wind erosion and deposition are powerful agents of surface change on mars erosion is sensitive to the atmospheric density so feedback between orbit variations and atmospheric density can enhance the sensitivity of erosion rates to orbital parameters we use statistics derived from a 1 gyr integration of the spin axis of mars coupled with runs of the nasa ames 3 d general circulation model gcm at a variety of orbital conditions and pressures to explore this feedback we find that wind erosion in the gcm is associated with two factors baroclinic zone winds and strong cross equator solstice flows both of these factors are influenced by topography producing an asymmetry in the erosion pattern between the north and the south the erosion model averaged over 1 gyr produces potential erosion rates of 1 7 10 5 m yr 1 in the north and 1 0 10 5 m yr 1 in the south which increase by an order of magnitude in an early 28 mbar atmosphere the stability of these potential erosion patterns over geological time indicates that the lowland regions of mars are continuously eroded and that wind is capable of revealing ancient sedimentary deposits or eroding substantial deposits that may have otherwise been preserved

probability of moraine survival in a succession of glacial advances emplacement of glacial moraines normally results in obliteration of any older moraines deposited by less extensive glacial advances a process we call obliterative overlap a probability analysis of the likely impact of obliterative overlap on the completeness of the glacial record assumes that moraines were deposited at various distances from their glacial source areas randomly over time assuming randomness and obliterative overlap after 10 glacial episodes the most likely number of surviving moraines is only three the record of the pleistocene is in agreement with the probability analysis the 10 glaciations during the past 0 9 m y inferred from the deep sea record resulted in moraine sequences in which only two or three different aged moraine belts can generally be distinguished

a topographically forced asymmetry in the martian circulation and climate large seasonal and hemispheric asymmetries in the martian climate system are generally ascribed to variations in solar heating associated with orbital eccentricity as the orbital elements slowly change over a period of 10 4 years characteristics of the climate such as dustiness and the vigour of atmospheric circulation are thought to vary as should asymmetries in the climate for example the deposition of water ice at the northern versus the southern pole such orbitally driven climate change might be responsible for the observed layering in mars polar deposits by modulating deposition of dust and water ice most current theories assume that climate asymmetries completely reverse as the angular distance between equinox and perihelion changes by 180 here we describe a major climate mechanism that will not precess in this way we show that mars global north south elevation difference forces a dominant southern summer hadley circulation that is independent of perihelion timing the hadley circulation a tropical overturning cell responsible for trade winds largely controls interhemispheric transport of water and the bulk dustiness of the atmosphere the topography therefore imprints a strong handedness on climate with water ice and the active formation of polar layered deposits more likely in the north

holocene moraine chronology spitsbergen svalbard lichenometric evidence for multiple neoglacial advances in the arctic late holocene neoglacial moraines occurring within 1 or 2 km of present glacier margins are prominent features in the forefields of spitsbergen glaciers little ice age moraines are typically the most extensive and best preserved moraines of older holocene advances are much less common where observed older moraines occur as moraine remnants and provide irrefutable evidence of earlier neoglacial advances the fragmentary moraine record indicates two little ice age advances and two older neoglacial advances lichenometry provides calibrated ages for periods of moraine stabilization the oldest moraines stabilized by ca 1500 years ago and a second group of moraines stabilized by ca 1000 years ago little ice age moraines were deposited during two periods an early group of moraines stabilized ca 650 years ago and a later group during the last several centuries the proposed moraine chronology compares well with other proxy climate records on spitsbergen and with moraine records from areas borde

glacier fluctuations during the past 2000 years abstract a global compilation of glacier advances and retreats for the past two millennia grouped by 17 regions excluding antarctica highlights the nature of glacier fluctuations during the late holocene the dataset includes 275 time series of glacier fluctuations based on historical tree ring lake sediment radiocarbon and terrestrial cosmogenic nuclide data the most detailed and reliable series for individual glaciers and regional compilations are compared with summer temperature and when available winter precipitation reconstructions the most important parameters for glacier mass balance in many cases major glacier advances correlate with multi decadal periods of decreased summer temperature in a few cases such as in arctic alaska and western canada some glacier advances occurred during relatively warm wet times the timing and scale of glacier fluctuations over the past two millennia varies greatly from region to region however the number of glacier advances shows a clear pattern for the high mid and low latitudes and hence points to common forcing factors acting at the global scale globally during the first millennium ce glaciers were smaller than between the advances in 13th to early 20th centuries ce the precise extent of glacier retreat in the first millennium is not well defined however the most conservative estimates indicate that during the 1st and 2nd centuries in some regions glaciers were smaller than at the end of 20th early 21st centuries other periods of glacier retreat are identified regionally during the 5th and 8th centuries in the european alps in the 3rd 6th and 9th centuries in norway during the 10th 13th centuries in southern alaska and in the 18th century in spitsbergen however no single period of common global glacier retreat of centennial duration except for the past century has yet been identified in contrast the view that the little ice age was a period of global glacier expansion beginning in the 13th century or earlier and reaching a maximum in 17th 19th centuries is supported by our data the pattern of glacier variations in the past two millennia corresponds with cooling in reconstructed temperature records at the continental and hemispheric scales the number of glacier advances also broadly matches periods showing high volcanic activity and low solar irradiance over the past two millennia although the resolution of most glacier chronologies is not enough for robust statistical correlations glacier retreat in the past 100 150 years corresponds to the anthropogenic global temperature increase many questions concerning the relative strength of forcing factors that drove glacier variations in the past 2 ka still remain

10be surface exposure ages on the late pleistocene and holocene history of linnebreen on svalbard abstract arctic glaciers were sensitive to past changes in high latitude winter precipitation and summer temperature here we develop a late pleistocene to holocene history for linnebreen linne glacier in western svalbard using 10 be surface exposure ages on isolated erratic and moraine boulders we show that linnebreen had separated from the larger ice sheet over svalbard and was retreating up valley around the start of the younger dryas cold period we attribute this retreat during a cold period on svalbard to moisture starvation of linnebreen from advanced sea ice and or elevated shortwave boreal summer insolation that overwhelmed any reduction in sensible heat after an ice free period during the early to middle holocene linnebreen reformed sometime after 4 6 0 2 ka and was at a position roughly equivalent to its little ice age lia maximum extent before it began to retreat at 1 6 0 2 ka comparison with calibrated 14 c dates from three other glaciers could suggest that this period of ice retreat at 1 6 ka could be regional in extent linnebreen occupied the pre lia moraine when there was an increased ratio of cold arctic sourced relative to warm atlantic sourced waters around svalbard and advanced sea ice the retreat of linnebreen at 1 6 ka was concurrent with the increased presence of warm atlantic waters around svalbard and attendant sea ice retreat these coincident changes in ocean temperatures sea ice extent and linnebreen moraine age could imply a climatic forcing of the pre lia advance and retreat of linnebreen summer temperatures rather than changes in precipitation would then be dominant in driving ice retreat although the possibility of stochastic glacier margin variability cannot be excluded our data therefore suggest that linnebreen may have responded differently to past changes in sea ice extent that could depend on the background climate state deglacial climate vs late holocene climate which highlights the complexity in climatic controls on arctic glaciers

stream terrace genesis implications for soil development genesis of three distinct types of stream terraces can be understood through application of the concepts of tectonically induced downcutting base level of erosion complex response threshold of critical power diachronous and synchronous response times and static and dynamic equilibrium climatic and tectonic stream terraces are major terraces below which flights of minor complex response degradation terraces can form these three types of terraces can be summarized by describing a downcutting aggradation renewed downcutting sequence for streams with gravell bedload by tectonically induced downcutting streams degrade to achieve and maintain a dynamic equilibrium longitudinal profile at the base level of erosion lateral erosion bevels bedrock beneath active channels to create major straths that are the fundamental tectonic stream terrace landform aggradation events record brief reversals of long term tectonically induced downcutting because they raise active channels they may be considered as major the result of climatic perturbations or minor the result of complex response model types of perturbations climatically controlled aggradation followed by degradation leaves an aggradation surface this type of fill terrace tread is the fundamental climatic stream terrace landform aggradation surfaces may be buried by subsequent episodes of deposition unless intervening tectonically induced downcutting is sufficient for younger aggradation surfaces to form below older surfaces raising of the active channel by either tectonic uplift or by climatically induced aggradation provides the vertical space for degradation terraces to form first in alluvial fill and then in underlying bedrock along tectonically active streams these are complex response terraces because they result from interactions of dependent variables within a given fluvial system pauses in degradation to a new base level of erosion and or minor episodes of backfilling lead to formation of complex response fill cut and strath or of fill terraces fill cut terraces are formed in alluvium they are complex response terraces because they are higher than the base level of erosion good exposures and dating are needed to distinguish static equilibrium complex response minor strath terraces from dynamic equilibrium tectonic major straths strath terraces may be regarded as complex response terraces where degradation rates between times terrace tread formation exceed the long term uplift rate for the reach based on ages and positions of tectonic terraces late quaternary global climatic changes control aggradation events and even the times of cutting of major tectonic straths because the base level of erosion can not be attained during times of climatically driven aggradation degradation events most terrace soils form on treads of climatic and complex response terraces aggradation surfaces may provide an ideal flight of terraces on which to study a soils chronosequence each aggradation event is recorded by a single relict soil where tectonically induced downcutting is sufficient to provide clear altitudinal separation of the terrace treads multiple paleosols are typical of tectonically stable regions where younger aggradation events spread alluvium over treads of older climatic terraces pedons on a climatic terrace in a small fluvial system commonly are roughly synchronous variations of soil properties that can be attributed to temporal differences will be minor compared to altitudinally controlled climatic factors climatic terraces of adjacent watersheds also should be roughly synchronous correlatable variations of soil properties that can be attributed to temporal differences will be minor compared to lithologic and climatic factors between different watersheds such generalizations may not apply to basins with sufficient relief that geomorphic responses to climatic changes occur at different and overlapping times and to large rivers whose widely separated reaches are characterized by different response times to climatic perturbations soils on climatic terraces of distant watershedswill not be synchronous if their respective aggradation events occur during full glacial times and interglacial times soils on some complex response terraces may be diachronous within a given fluvial system and typically are diachronous between watersheds

controls on dryland mountain landscape development along the nw saharan desert margin insights from quaternary river terrace sequences dades river south central high atlas morocco abstract this study documents river terraces from upstream reaches of the dades river a major fluvial system draining the south central high atlas mountains terraces occur as straths with bedrock bases positioned at 10 m altitudinal intervals up to 40 m t1 t5 above the valley floor becoming less common between 50 and 140 m the rock strength stratigraphy and structure of the mountain belt influences terrace distribution terraces are absent in river gorges of structurally thickened limestone whilst well developed laterally continuous terraces t1 t4 form along wide valleys occupying syncline structures dominated by weaker interbedded limestone mudstone terrace staircases develop in confined canyons associated with weaker lithologies and influence from structural dip and stratigraphic configuration terraces comprise a bedrock erosion surface overlain by fluvial conglomerates rare overbank sands and colluvium this sequence with some osl irsl age control suggests terrace formation over a 100 ka climate cycle with valley floor aggradation during full glacials and incision during glacial interglacial transitions this integrates with other archives e g lakes glaciers dunes appearing typical of landscape development along the nw saharan margin south of the high atlas and similar to patterns in the western southern mediterranean the 100 ka climate cycle relationship suggests that the terrace sequence documents late middle pleistocene landscape development consistent altitudinal spacing of terraces and their distribution throughout the orogen suggests sustained base level lowering linked to uplift exhumation of the high atlas low incision rates 1 and general absence of terrace deformation suggests dominance of isostatically driven base level lowering with relief generation being early pleistocene or older

quaternary fans and terraces in the khumbu himal south of mount everest their characteristics age and formation large fans and terraces are frequent in the khumbu himal within the high himalayan valleys south of mt everest these features are composed of massive matrix and clast supported diamicts that were formed from both hyperconcentrated flows and coarse grained debris flows cosmogenic radionuclide crn exposure ages for boulders on fans and terraces indicate that periods of fan and terrace formation occurred at c 16 c 12 c 8 c 4 and c 1 5 ka and are broadly coincident with the timing of glaciation in the region the dating precision is insufficient to resolve whether the surfaces formed before during or after the correlated glacial advance however the sedimentology and morphostratigraphic and geomorphological relationships suggest that fan and terrace sedimentation in this part of the himalaya primarily occurs during glacier retreat and is thus paraglacial in origin furthermore modern glacial lake outburst floods and their associated deposits are common in the khumbu himal as the result of glacial retreat during historical times we therefore suggest that late quaternary and holocene fan and terrace formation and sediment transfer are probably linked to temporal changes in discharge and sediment load caused by glacier oscillations responding to climate change the timing of major sedimentation events in this region can be correlated with fans and terraces in other parts of the himalaya suggesting that major sedimentation throughout the himalaya is synchronous and tied to regional climatic oscillations bedrock incision rates calculated from strath terrace ages average c 3 9 mm a 1 suggesting that the overall rate of incision is set by regional uplift

dating sediment burial with in situ produced cosmogenic nuclides theory techniques and limitations abstract dating sediment burial over million year time scales is crucial in many areas of the earth sciences and archeology but is often difficult using traditional techniques sediment burial can be dated by the radioactive decay of cosmogenic nuclides provided that the sediment was exposed to cosmic rays prior to burial dating calculations are straightforward if sediment is buried deeply and rapidly enough to prevent cosmogenic nuclide production after burial however the analysis can be complicated by postburial production if sediment is insufficiently shielded from secondary cosmic ray nucleons and muons this paper discusses how buried sediments can be dated over timescales up to 5 myr using 26 al and 10 be in quartz

magnitude and frequency in proglacial rivers a geomorphological and sedimentological perspective abstract proglacial fluvial sedimentary systems receive water from a variety of sources and have variable discharges with a range of magnitudes and frequencies little attention has been paid to how these various magnitude and frequency regimes interact to produce a distinctive sedimentary record in modern and ancient proglacial environments this paper reviews the concept of magnitude and frequency in relation to proglacial fluvial systems from a geomorphic and sedimentary perspective rather than a hydrological or statistical perspective the nature of the meltwater inputs can be characterised as low magnitude high frequency primarily controlled by ablation inputs from the source glacier or high magnitude low frequency primarily controlled by exceptional inputs the most important high magnitude low frequency inputs are catastrophic outburst floods often referred to by the term jokulhlaup icelandic for glacier burst glacier surges are an additional form of cyclical variation impacting the proglacial environment which briefly alter the volumes and patterns of meltwater input the sedimentary consequences of low magnitude high frequency discharges are related to frequent variations in stage the greater directional variability that sediment will record and the increased significance of channel confluence sedimentation in contrast the most significant characteristics of high magnitude low frequency flooding include the presence of large flood bars and mid channel jokulhlaup bars hyperconcentrated flows large gravel dunes and the formation of ice block kettle hole structures and rip up clasts glacier surges result in a redistribution of low magnitude high frequency processes and products across the glacier margin and small floods may occur at the surge termination criteria for distinguishing magnitude and frequency regimes in the proglacial environment are identified based on these major characteristics studies of quaternary proglacial fluvial sediments are used to determine how the interaction of the various magnitude and frequency regimes might produce a distinctive sedimentary record consideration of sandur architecture and stratigraphy shows that the main controls on the sedimentary record of proglacial regions are the discharge magnitude and frequency regime sediment supply the pattern of glacier advance or retreat and proglacial topography a model of sandur development is suggested which shows how discharge magnitude and frequency in combination with sandur incision and aggradation controlled by glacier advance and retreat can control sandur stratigraphy

arctic holocene glacier fluctuations reconstructed from lake sediments at mitrahalvoya spitsbergen the arctic region has experienced a significantly larger warming during the last decades compared to the rest of the world and model simulations indicate a continued amplification of future global warming in the polar regions a better understanding of natural climate variability in the arctic is much needed to provide a better context for the observed warming trend by utilising proxy data it is possible to obtain palaeoclimatic records beyond the range of instrumental observations which increase our understanding of long term arctic climate change here a continuous record of past changes in equilibriumline altitude ela has been reconstructed for the alpine glacier karlbreen located on the northwest coast of spitsbergen 79 n based on sediment analyses from a distal glacier fed lake a multivariate statistical analysis suggests that the concentration of geochemical elements ti si and k in the lake sediments together with the physical parameter dry bulk density dbd reflect changes in the amount of inorganic detrital input to klosa which is closely linked to the size and ela of the upstream glacier karlbreen a linear regression model based on historically documented glacier extents was used to calculate continuous ela changes back to 3500 cal yr bp from about 9200 to 3500 cal yr bp the sedimentary record indicates that karlbreen was very small or had completely melted away karlbreen was probably close to its maximum holocene extent several times during the neoglacial first around 1700 cal yr bp then later at 225 and 135 cal yr bp an ice cored moraine system in front of karlbreen extends well into the main basin of klosa and it is difficult to explain how this moraine could have formed without disturbing the sedimentary record in the lake e g through slumping events the sedimentary record in klosa is continuous and undisturbed over the past 6700 years suggesting that the outermost moraine formed prior to this time and that it most likely survived the holocene thermal maximum on svalbard

climatically controlled river terrace staircases a worldwide quaternary phenomenon a comparison of fluvial terrace sequences from around the world based on data collected as part of international geoscience programme igcp project no 449 has revealed significant patterns river terraces provide important records of uplift which is essential for their formation and of landscape evolution their cyclic formation however almost invariably seems to have been a response to climatic fluctuation sequences in the european core area of igcp 449 which has the longest and most extensive research history have been used as templates for worldwide comparison there is evidence for a global acceleration of uplift at the time of and perhaps in response to the mid pleistocene revolution when climatic fluctuation switched to 100 kyr milankovitch cycles terraces formed prior to this generally consist of wide aggradational sheets that probably each represent formation over several 41 kyr cycles subsequently river valleys became more steeply entrenched and terraces formed in response to the stronger 100 kyr climatic forcing in many cases at approximately one per cycle this paper uses the new data resource to explore differences between records in different climate zones between sequences with variable numbers of middle late pleistocene terraces and between systems in which the all important incision event has occurred in different parts of climatic cycles key records discussed include european examples from the rhine thames somme dniester dnieper don volga and aguas from asia the gediz turkey and orontes syria from north america the south platte and colorado from south africa the vaal and sundays from australia the shoalhaven and from south america the amazon paraguay and tributaries of the colorado and negro

changes in the thermal climate in northwestern europe during marine oxygen isotope stage 3 estimated from fossil insect assemblages abstract more than 30 fossil coleopteran beetle assemblages have been recorded from oxygen isotope stage 3 in northern europe comprising several hundred identified species using the mutual climatic range method for quantifying palaeotemperatures these assemblages show that the climates of the times can be divided into two distinct interstadial types one a short phase of temperate oceanic climate occurred between 43 000 and 42 000 14c yr b p when conditions were not much different from those of the present day in spite of the temperate climate trees did not colonize northwestern europe at this time two both before and after this temperate interlude there were phases of cold continental climate during which summers were too cold for trees to grow and winters were of siberian intensity it is possible that periods of even colder conditions intervened from time to time between the interstadial but because of the intensity of the cold biological systems were so inhibited that no fossil evidence for them can be found in northern europe evidence for them must be sought in the fossil records from the warmer parts of southern europe or in the physical evidence in the greenland ice cores

the global topography of mars and implications for surface evolution elevations measured by the mars orbiter laser altimeter have yielded a high accuracy global map of the topography of mars dominant features include the low northern hemisphere the tharsis province and the hellas impact basin the northern hemisphere depression is primarily a long wavelength effect that has been shaped by an internal mechanism the topography of tharsis consists of two broad rises material excavated from hellas contributes to the high elevation of the southern hemisphere and to the scarp along the hemispheric boundary the present topography has three major drainage centers with the northern lowlands being the largest the two polar cap volumes yield an upper limit of the present surface water inventory of 3 2 to 4 7 million cubic kilometers

the elbe fault system in north central europe a basement controlled zone of crustal weakness abstract the elbe fault system efs is a wnw striking zone extending from the southeastern north sea to southwestern poland along the present southern margin of the north german basin and the northern margin of the sudetes mountains although details are still under debate geological and geophysical data reveal that upper crustal deformation along the elbe fault system has taken place repeatedly since late carboniferous times with changing kinematic activity in response to variation in the stress regime in late carboniferous to early permian times the elbe fault system was part of a post variscan wrench fault system and acted as the southern boundary fault during the formation of the permian basins along the trans european suture zone sensu geol mag 134 5 1997 585 the teisseyre tornquist zone ttz most probably provided the northern counterpart in a pull apart scenario at that time further strain localisation took place during late mesozoic transtension when local shear within the elbe fault system caused subsidence and basin formation along and parallel to the fault system the most intense deformation took place along the system during late cretaceous early cenozoic time when the elbe fault system responded to regional compression with up to 4 km of uplift and formation of internal flexural highs compressional deformation continued during early cenozoic time and actually may be ongoing the upper crust of the elbe fault system which itself reacted in a more or less ductile fashion is underlain by a lower crust characterised by low p wave velocities low densities and a weak rheology structural seismic and gravimetric data as well as rheology models support the assumption that a weak stress sensitive zone in the lower crust is the reason for the high mobility of the area and repeated strain localisation along the elbe fault system

an inter ice stream glaciated margin submarine landforms and a geomorphic model based on marine geophysical data from svalbard well preserved submarine landforms from the continental shelf and fjords of northwest ernmost svalbard provide an example of ice sheet deposition in an inter ice stream setting em1002 swath bathymetric imagery covering 1280 km 2 was examined at the shelf edge a distinctive and continuous belt of hum mocky topography represents the grounding zone of a slow moving late weichselian ice sheet active ice on the outer shelf is inferred from subtle lineations orientated parallel to fl ow low amplitude transverse moraines crosscut the lineations suggesting ice retreat across the outer shelf with brief stillstands on the middle and inner shelf large moraine ridges indicate multiple stillstands during de glaciation there are arcuate moraine ridges at fjord mouths streamlined crag and tail landforms are preserved from when ac tive full glacial ice fl owed out of the fjords clusters of smaller transverse ridges indi cate slow retreat of grounded ice through the fjords holocene sedimentation is by rainout from sediment rich meltwater producing smooth basin fi ll small slides from the fjord walls are common little ice age glacier readvance produced another set of terminal moraines and smaller retreat moraines in the innermost fjords a schematic model of this inter ice stream glacial landform assem blage summarizes the geomorphic record it is compared with a model derived from sev eral svalbard cross shelf troughs occupied by fast fl owing late weichselian ice streams in general the seafl oor morphology of continen tal margins affected by ice streams is domi nated by streamlined subglacially produced landforms oriented in the former ice fl ow direction interrupted by major grounding zone wedges formed during temporary halts in ice retreat by contrast between ice streams shelf and fjord morphology records submarine landforms of various dimensions oriented mainly transverse to ice fl ow pro duced at slowly retreating grounded ice sheet margins there is little evidence for channeled subglacial water fl ow in the form of eskers and ice contact fans on the sval bard margin implying that basal water is drained or advected mainly within soft sub glacial sediments

glacial geomorphology of trygghamna western svalbard integrating terrestrial and submarine archives for a better understanding of past glacial dynamics abstract detailed geomorphological mapping was carried out in the terrestrial and submarine forefields of protektor harriet and kjerulfbreen in trygghamna western svalbard based on high resolution aerial images and bathymetric data the mapping reveals that crevasse squeeze ridges csrs are only observed on land in the forefield of the surge type harriet and kjerulfbreen and recessional moraines are only formed at the sea floor in relation to the retreat of these two glaciers different factors affect the preservation potential and formation of landforms between the two environments that could explain the absence of csrs in the submarine environment and the terrestrial forefield of protektorbreen the landform assemblage in trygghamna does not comply well with existing surge type glacier landsystem models we present a conceptual landsystem model for surge type glaciers with combined terrestrial and marine margins based on the geomorphological archive from trygghamna the contrast between the landform assemblages demonstrates how differences in the thermal regime result in different glacier behavior between the warm based submarine margins and the inactive cold based terrestrial margin this study emphasizes the importance of integrating data from both archives to reconstruct past glacier behavior and understand the effect of different glacial dynamics and environments on the preservation potential of sediments and landforms

post ir irsl dating the oldest river terrace sediments in the polish outer carpathians insights into the landscape evolution abstract post infrared infrared stimulated luminescence post ir irsl or pirir was applied to determine the age of the highest elevated alluvial sediments in the polish outer carpathians these sediments are preserved on the western slope of the dunajec river valley and are located 150 155 m above the present day river channel so far they have been interpreted as accumulated during the praetiglian 2 58 2 40 ma the pirir ages however indicate that the sediments were deposited 2 ma later such results incorporate an important record of river system evolution which has been developing very dynamically since the time of the sediment accommodation the determined ages introduce average rate of river incision which can be calculated as 0 48 0 50 mm a 1 since the last 309 ka this implies that the river section has been fairly tectonically uplifting and brings attention to the rates of uplift in the rest part of the polish outer carpathians also adopting results from the former dating campaign it is clear that relics of pleistocene alluvial sediments are predominantly of cold climate origin and a scenario for this style of sediment preservation is proposed

planetary science the north south martian divide some of the differences between the northern and southern hemispheres of mars may stem from asymmetry in the planet s atmospheric circulation and the resulting distribution of water and dust

holocene glacier variations of blaisen hardangerjokulen central southern norway abstract a 1 m deep gully section 460 m beyond the maximum little ice age marginal moraines of blaisen hardangerjokulen central southern norway revealed alternations of minerogenic and organic sediments the geographical geological settings of the dated section provides a unique on off signal of holocene glacier fluctuations of blaisen lithostratigraphy sediment characteristics and radiocarbon dates from the study section indicate one period of glacier re advance between the late preboreal deglaciation of the inland ice sheet and 8660 100 yr b p a grey sand layer 56 57 cm below the surface is interpreted to be of fluvial colluvial origin and is radiocarbon dated to about 7700 yr b p at 48 cm below the surface a bluish grey sand silt layer is radiocarbon dated to 7590 12 yr b p 6560 6240 b c and interpreted to be glaciofluvial origin a minor glacier oscillation postdates 1130 70 yr b p 810 990 a d the medieval little ice age glacier advance of blaisen beyond its modern extent occurred after 1040 60 yr b p 960 1030 a d calculations of the modern and little ice age equilibrium line altitudes elas on hardangerjokulen suggest an ela depression of ca 130 m during the little ice age maximum