microbially induced cementation to control sand response to undrained shear current methods to improve the engineering properties of sands are diverse with respect to methodology treatment uniformity cost environmental impact site accessibility requirements etc all of these methods have benefits and drawbacks and there continues to be a need to explore new possibilities of soil improvement particularly as suitable land for development becomes more scarce this paper presents the results of a study in which natural microbial biological processes were used to engineer a cemented soil matrix within initially loose collapsible sand microbially induced calcite precipitation micp was achieved using the microorganism bacillus pasteurii an aerobic bacterium pervasive in natural soil deposits the microbes were introduced to the sand specimens in a liquid growth medium amended with urea and a dissolved calcium source subsequent cementation treatments were passed through the specimen to increase the cementation level of the sand particle matrix the results of both micp and

rapid localized glacio isostatic uplift at glen roy scotland many studies involving measurement of the altitudes of fossil marine and lacustrine shorelines have demonstrated glacioisostatic tilting particularly in north america fennoscandia and the british isles such studies are normally illustrated by height distance diagrams in which fossil shorelines are portrayed as straight lines in some studies the shoreline relation diagram is used to analyse and illustrate the altitudinal data1 3 before constructing such a diagram it is assumed that a simple pattern of glacioisostatic uplift has prevailed warping of shorelines as opposed to uniform tilting has been inferred in north america4 6 on the other hand harme7 envisaged block movements in fennoscandia sauramo8 also proposed dislocations but his interpretation was rejected by hyyppa9 more recently the concept of the scandinavian shield as a stable area has been dismissed10 11 here we provide evidence from scotland for shoreline dislocation by differential movement of blocks of the earth s crust

coupling patterns between para glacial and permafrost degradation responses in antarctica the recently deglaciated environments in maritime permafrost regions are usually affected by very active paraglacial processes elephant point is an ice free area of 1 16 km2 located in the sw of livingston island south shetland islands antarctica between 1956 2010 the retreat of the ice cap covering most part of this island has exposed 17 3 of the land surface in this peninsula two geomorphological units were identified in this new ice free area a moraine extending from the western to the eastern coastlines and a relatively flat proglacial surface the glacier in 1956 sat in contact with the northern slope of the moraine but its accelerated retreat in parallel to the warming trend recorded in the antarctic peninsula left these areas free of glacier ice subsequently the postglacial evolution was controlled by the relaxation phase typical of paraglacial systems the typology and intensity of geomorphological processes show a significantly different dynamics between the southern and northern slopes of the moraine this pattern is related to the different stage of paraglacial adjustment in both slopes in the southern side on coarser sediments pronival ramparts debris flows and alluvial fans are distributed with a low to moderate activity of slope processes in the northern side mass wasting processes are extremely active on fine grained unconsolidated sediments ice rich permafrost is being degraded by thermokarst processes landslides and mudflows transfer large amounts of sediments down slope the surface affected by retrogressive thaw slumps in the moraine has been quantified in 24 172 m2 which accounts for 9 6 of its surface the abundance of kettle lakes is also indicative of the degradation of the ground ice paraglacial processes are expected to continue in the moraine and proglacial area in the near future although their intensity and duration will depend on the magnitude and rate of future climate trends in the northern antarctic peninsula copyright 2015 john wiley sons ltd

the holocene deglaciation of the byers peninsula livingston island antarctica based on the dating of lake sedimentary records the process of deglaciation in the antarctic peninsula region has large implications for the geomorphological and ecological dynamics of the ice free environments however uncertainties still remain regarding the age of deglaciation in many coastal environments as is the case in the south shetland islands this study focuses on the byers peninsula the largest ice free area in this archipelago and the one with greatest biodiversity in antarctica a complete lacustrine sedimentary sequence was collected from five lakes distributed along a transect from the western coast to the rotch dome glacier front limnopolar chester escondido cerro negro and domo lakes a multiple dating approach based on 14c thermoluminescence and tephrochronology was applied to the cores in order to infer the holocene environmental history and identify the deglaciation chronology in the byers peninsula the onset of the deglaciation started during the early holocene in the western fringe of the byers peninsula according to the basal dating of limnopolar lake ca 8 3 cal ky bp glacial retreat gradually exposed the highest parts of the cerro negro nunatak in the se corner of byers where cerro negro lake is located this lake was glacier free since at least 7 5 ky during the mid holocene the retreat of the rotch dome glacier cleared the central part of the byers plateau of ice and escondido and chester lakes formed at 6 cal ky bp and 5 9 ky respectively the dating of the basal sediments of domo lake suggests that the deglaciation of the current ice free easternmost part of the byers peninsula occurred before 1 8 cal ky bp

the early holocene sea level rise the causes anatomy and consequences of the early holocene sea level rise ehslr are reviewed the rise of ca 60m took place over most of the earth as the volume of the oceans increased during deglaciation and is dated at 11 650 7000 cal bp the ehslr was largely driven by meltwater release from decaying ice masses and the break up of coastal ice streams the patterns of ice sheet decay and the evidence for meltwater pulses are reviewed and it is argued that the ehslr was a factor in the ca 8470 bp flood from lake agassiz ojibway patterns of relative sea level changes are examined and it is argued that in addition to regional variations temporal changes are indicated the impact of the ehslr on climate is reviewed and it is maintained that the event was a factor in the 8200 bp cooling event as well as in changes in ocean current patterns and their resultant effects the ehslr may also have enhanced volcanic activity but no clear evidence of a causal link with submarine sliding on continental slopes and shelves can yet be demonstrated the rise probably influenced rates and patterns of human migrations and cultural changes it is concluded that the ehslr was a major event of global significance knowledge of which is relevant to an understanding of the impacts of global climate change in the future

generalized terrain topography in radar scattering models modeling of terrain topography is crucial for vegetated areas given that even small slopes impact and alter the radar wave interactions between the ground and the overlying vegetation current missions either exclude pixels with large topographic slopes or disregard the terrain topography entirely potentially accumulating substantial modeling errors and therefore impacting the retrieval performance over such sloped pixels the underlying terrain topography needs to be considered and modeled to obtain a truly general and accurate radar scattering model in this paper a flexible and modular model is developed the vegetation is considered by a multilayered multispecies vegetation model capable of representing a wide range of vegetation cover types ranging from bare soil to dense forests the ground is incorporated with the stabilized extended boundary condition method allowing the representation of an n layered soil structure with rough interfaces terrain topography is characterized by a 2 d slope with two tilt angles alpha beta simulation results for an evergreen forest show the impact of a 2 d slope for a range of tilt angles a 10 circ tilt in the plane of incidence translates to a change of up to 15 db in hh 10 db in vv and 1 5 db in hv for the total radar backscatter terrain topography is shown to be crucial for accurate forward modeling especially over forested areas

seismicity and tectonics of the south shetland islands and bransfield strait from a regional broadband seismograph deployment 1 we investigate the tectonics of the south shetland trench and bransfield strait by performing a detailed study of local seismicity during 1997 1999 we deployed seven land seismometers and 14 ocean bottom seismometers in the south shetland island region the data we obtained indicate a high level of local seismicity mb 2 5 and we accurately located 150 earthquakes many of the earthquakes occur at locations and depths indicative of ongoing subduction in the south shetland trench a focal mechanism for the largest event in the forearc indicates shallow angle thrusting the maximum depth of seismicity is 65 km but the majority of the events are shallower than 30 km these seismic results are consistent with recent magnetic gps and multichannel seismic reflection data that suggest continued subduction at a very slow rate the south shetland trench thus represents an extreme end member of hot subduction resulting from slow convergence of young lithosphere and the absence of intermediate depth earthquakes is consistent with thermal assimilation of the slab at shallow depths we have located many earthquakes associated with volcanism and rifting in bransfield strait a swarm of events near a submarine volcano suggests current magmatic activity a normal faulting focal mechanism in the northeastern part of the strait gives evidence of extension earthquakes associated with rifting in the northeastern portion of the strait are clustered along well established rifts but the seismicity is much more diffuse to the southwest this observation is consistent with other evidence that extension has propagated from northeast to southwest

polar gravel beach ridge systems sedimentary architecture genesis and implications for climate reconstructions south shetland islands western antarctic peninsula abstract the sedimentary architecture of polar gravel beach ridges is presented and it is shown that ridge internal geometries reflect past wave climate conditions ground penetrating radar gpr data obtained along the coasts of potter peninsula king george island show that beach ridges unconformably overlie the prograding strand plain development of individual ridges is seen to result from multiple storms in periods of increased storm wave impact on the coast strand plain progradation by contrast is the result of swash sedimentation at the beach face under persistent calm conditions the sedimentary architecture of beach ridges in sheltered parts of the coast is characterized by seaward dipping prograding beds being the result of swash deposition under stormy conditions or aggrading beds formed by wave overtopping by contrast ridges exposed to high energy waves are composed of seaward as well as landward dipping strata bundled by numerous erosional unconformities these erosional unconformities are the result of sediment starvation or partial reworking of ridge material during exceptional strong storms the number of individual ridges which are preserved from a given time interval varies along the coast depending on the morphodynamic setting sheltered coasts are characterized by numerous small ridges whereas fewer but larger ridges develop on exposed beaches the frequency of ridge building ranges from decades in the low energy settings up to 1600 years under high energy conditions beach ridges in the study area cluster at 9 5 7 5 5 5 and below 3 5 m above the present day storm beach based on radiocarbon data this is interpreted to reflect distinct periods of increased storminess and or shortened annual sea ice coverage in the area of the south shetland islands for the times around 4 3 c 3 1 1 9 ka cal bp and after 0 65 ka cal bp ages further indicate that even ridges at higher elevations can be subject to later reactivation and reworking a careful investigation of the stratigraphic architecture is therefore essential prior to sampling for dating purposes

biogeochemical processes and geotechnical applications progress opportunities and challenges consideration of soil as a living ecosystem offers the potential for innovative and sustainable solutions to geotechnical problems this is a new paradigm for many in geotechnical engineering realising the potential of this paradigm requires a multidisciplinary approach that embraces biology and geochemistry to develop techniques for beneficial ground modification this paper assesses the progress opportunities and challenges in this emerging field biomediated geochemical processes which consist of a geochemical reaction regulated by subsurface microbiology currently being explored include mineral precipitation gas generation biofilm formation and biopolymer generation for each of these processes subsurface microbial processes are employed to create an environment conducive to the desired geochemical reactions among the minerals organic matter pore fluids and gases that constitute soil geotechnical applications currently being explored include cementation of sands to enhance bearing capacity and liquefaction resistance sequestration of carbon soil erosion control groundwater flow control and remediation of soil and groundwater impacted by metals and radionuclides challenges in biomediated ground modification include upscaling processes from the laboratory to the field in situ monitoring of reactions reaction products and properties developing integrated biogeochemical and geotechnical models management of treatment by products establishing the durability and longevity reversibility of the process and education of engineers and researchers

assessment of scattering mechanism of polarimetric sar signal from mountainous forest areas this study aims to understand the effects of the topographic slope variation on the vegetation backscattering characteristics of polarimetric imaging radar most of the previous studies in modeling microwave backscattering signatures of vegetated area have been carried out over relatively flat areas in order to model vegetation scattering mechanisms of mountainous forests this paper presents an improvement of the radiative transfer model that accounts for the tilted scattering surface beneath a forest canopy an l band polarimetric synthetic aperture radar sar data set acquired by the nasa jet propulsion laboratory airborne sar system was used to test and to assess the vegetation scattering model for a sloping forest area experimental result shows the proposed model to be adequate for evaluating slope induced changes in microwave scattering mechanisms

relative sea level curves for the south shetland islands and marguerite bay antarctic peninsula this paper presents preliminary relative sea level curves for the marguerite bay region and for the south shetland islands the marguerite bay curve is constrained by both new and previously published 14c dates on penguin remains and shells and on two isolation basins dating back to 6500 14c yr bp extrapolation back to the marine limit yields a minimum deglaciation date for marguerite bay of ca 9000 14c yr bp analysis of beach clasts suggests that there was a period of increased wave activity perhaps related to a reduction in summer sea ice extent between ca 3500 and ca 2400 14c yr bp the curve for the south shetland islands is derived entirely from published 14c dates from isolation basins and on whalebone penguin bone and seal bone the curve shows an initial relative sea level fall which was interrupted by a period in the mid holocene when relative sea level rose to a highstand of between 14 5 and 16 m above mean sea level amsl before falling again

late quaternary environmental changes in marguerite bay antarctic peninsula inferred from lake sediments and raised beaches the antarctic peninsula is one of the fastest warming regions on earth but its palaeoenvironmental history south of 63 latitude is relatively poorly documented relying principally on the marine geological record and short ice cores in this paper we present evidence of late quaternary environmental change from the marguerite bay region combining data from lake sediment records on horseshoe island and pourquoi pas island and raised beaches at horseshoe island pourquoi pas island and calmette bay lake sediments were radiocarbon dated and analysed using a combination of sedimentological geochemical and microfossil methods raised beaches were surveyed and analysed for changes in clast composition size and roundness results suggest a non erosive glacial regime could have existed on horseshoe island from 35 780 38 650 33 380 or 32 910 34 630 31 370 cal yr bp onwards there is radiocarbon and macrofossil evidence for possible local deglaciation events at 28 830 29 370 28 320 cal yr bp immediately post dating antarctic isotopic maximum 4 and 21 110 21 510 20 730 interpolated cal yr bp coinciding with or immediately post dating antarctic isotopic maximum 2 the holocene deglaciation of horseshoe island commenced from 10 610 11 000 10 300 cal yr bp at the same time as the early holocene temperature maximum recorded in antarctic ice cores this was followed by the onset of marine sedimentation in the narrows pourquoi pas island before 8850 8480 9260 cal yr bp relative sea level high stands of 40 79 m above present at pourquoi pas island and 40 55 m above present at calmette bay occurred sometime after 9000 cal yr bp and suggest that a thicker ice sheet including grounded ice streams was present in this region of the antarctic peninsula than that recorded at sites further north isolation of the narrows lake basin on pourquoi pas island shows relative sea level in this region had fallen rapidly to 19 41 m by 7270 7385 7155 cal yr bp chaetoceros resting spores suggest high productivity and stratified surface waters in the narrows after 8850 9260 8480 cal yr bp and beach clasts provide evidence of a period of increased wave energy at approximately 8000 yr bp lake sediment and beach data suggest an extended period of regional warming sometime between 6200 and 2030 cal yr bp followed by the onset of neoglacial conditions from 2630 and 2030 cal yr bp in narrows lake and col lake 1 respectively diatom and 13c vs c n and macrofossil evidence suggest a potential increase in the number of birds and seals visiting the narrows lake catchment sometime after 2100 2250 2000 cal yr bp with enhanced nutrient enrichment evident after 1150 1230 1080 cal yr bp and particularly from c 460 540 380 cal yr bp a very recent increase in gomphonema species and organic carbon in the top centimetre of the narrows lake sediment core after c 410 490 320 cal yr bp and increased sedimentation rates in the col lake 1 sediment core after c 400 490 310 cal yr bp may be a response to the regional late holocene warming of the antarctic peninsula

a geological constraint on relative sea level in marine isotope stage 3 in the larsemann hills lambert glacier region east antarctica 31 366 33 228 cal yr bp abstract in this paper we present geological evidence from the larsemann hills lambert glacier amery ice shelf region east antarctica of marine sediments at an altitude of c 8 m a s l as revealed by diatom pigment and geochemical proxies in a lake sediment core the sediments yielded radiocarbon dates between c 26 650 and 28 750 14c yr bp 31 366 33 228 cal yr bp this information can be used to constrain relative sea level adjacent to the lambert glacier at the end of marine isotope stage 3 these data are compared with the age and altitude of marine isotope stage 3 marine deposits elsewhere in east antarctica and discussed with reference to late quaternary ice sheet history and eustatic sea level change

the effect of topography on radar scattering from vegetated areas the ways in which radar scattering from vegetated areas is affected by the topography of the surface underneath the vegetation are discussed it is shown using a discrete scatterer model that the dominant scattering mechanism may change drastically when the ground surface is tilted relative to the horizontal for a horizontal ground surface for example the total scattering may be dominated by scattering off the tree trunks followed by a reflection off the ground surface for a relatively small tilt in the ground surface the ground trunk interaction term may be replaced by scattering from the branches alone as the dominant scattering mechanism the effect of the topography is more pronounced for scattering by longer wavelengths and the implications on algorithms designed to infer forest woody biomass and soil and vegetation moisture using polarimetric sar data are discussed the effect of the topography on the scattering behavior from forested areas is illustrated with images acquired by the nasa jpl three frequency polarimetric sar over the black forest in germany

late holocene relative sea level rise and the neoglacial history of the greenland ice sheet in west greenland early and mid holocene relative sea level rsl fall was replaced by late holocene rsl rise during the neoglacial after 4 3 cal ka bp thousand calibrated years before present here we present the results of an isolation basin rsl study completed near to the coastal town of sisimiut in central west greenland rsl fell from 14 m above sea level at 5 7 cal ka bp to reach a lowstand of 4 0 m at 2 3 1 2 cal ka bp before rising by an equivalent amount to present differences in the timing and magnitude of the rsl lowstand between this and other sites in west and south greenland record the varied interplay of local and non greenland rsl processes notably the reloading of the earth s crust caused by a neoglacial expansion of the greenland ice sheet gis and the subsidence associated with the collapse of the laurentide ice sheet forebulge this means that the timing of the sea level lowstand cannot be used to infer directly when the gis advanced during the neoglacial the rise in late holocene rsl is contrary to recently reported bedrock uplift in the sisimiut area based on repeat gps surveys this indicates that a belt of peripheral subsidence around the current ice sheet margin was more extensive in the late holocene and that there has been a switch from subsidence to uplift at some point in the last thousand years or so

patterns of isostatic land uplift during the holocene evidence from mainland scotland preliminary results of a lengthy and detailed investigation into middle and late holocene raised shorelines in mainland scotland indicate that three shorelines are sufficiently widely distributed to permit an examination of their extent and of the patterns of uplift which they indicate the shorelines are the storegga tsunami shoreline reached at c 7100 14c years bp at the culmination of the main postglacial transgression and the blairdrummond shoreline reached after the main postglacial shoreline at c 2000 4200 14c years bp at the time of a tsunami believed to have been caused by the second storegga submarine slide the main postglacial shoreline reached at c 5800 6850 14c years bp the main postglacial shoreline previously believed to be the highest holocene raised shoreline in scotland is now believed to be overlapped around the periphery of the uplifted area by the later blairdrummond shoreline isobase models based upon quadratic trend surface analysis of available comparable height dat

ice stream initiation duration and thinning on james ross island northern antarctic peninsula predicting the future response of the antarctic ice sheet to climate change requires an understanding of the ice streams that dominate its dynamics here we use cosmogenic isotope exposure age dating 26al 10be and 36cl of erratic boulders on ice free land on james ross island north eastern antarctic peninsula to define the evolution of last glacial maximum lgm ice in the adjacent prince gustav channel these data include ice sheet extent thickness and dynamical behaviour prior to 18 ka the lgm antarctic peninsula ice sheet extended to the continental shelf edge and transported erratic boulders onto high elevation mesas on james ross island after 18 ka there was a period of rapid ice sheet surface lowering coincident with the initiation of the prince gustav ice stream this timing coincided with rapid increases in atmospheric temperature and eustatic sea level rise around the antarctic peninsula collectively these data provide evidence for a transition from a thick cold based lgm antarctic peninsula ice sheet to a thinner partially warm based ice sheet during deglaciation

assessing the link between coastal morphology wave energy and sea ice throughout the holocene from antarctic raised beaches post glacial rebound has preserved beaches across many ice free parts of the antarctic coastline these beaches typically contain gravel to boulder sized deposits and are built by high magnitude waves five new ages from the western antarctic peninsula were added to a compilation of 282 published ages from antarctic beaches a reduced compilation based solely on those ages that date beach formation is used to assess variations in beach formation throughout the holocene around antarctica we suggest the clustering of beach ages centered at 0 8 and 2 4 ka in the antarctic peninsula 1 5 3 6 and 6 0 ka in the ross sea and a broad peak from 2 7 to 6 3 ka in east antarctica indicates periods of heightened wave exposure leading to increased beach formation measurements of clast roundness from raised beaches show more rounded material is coincident with periods of heightened beach formation providing an independent means of assessing wave climate a comparison of periods of increased beach formation with available sea ice proxies suggests beach formation is synchronous with reduced sea ice conditions and thus higher wave climate as the presence or absence of sea ice determines open water conditions the factors that control sea ice directly influence antarctic coastal evolution

biota and geomorphic processes as key environmental factors controlling soil formation at elephant point maritime antarctica abstract we examined the main soil forming factors affecting the soil composition soil properties and the associated soil forming processes at elephant point a small ice free environment in the south shetland islands maritime antarctica for this purpose we collected twenty soil samples from each of ten different sites distributed along a linear transect running from the coast to the front of the rotch dome glacier the samples were obtained from surface layers 0 10 cm and at depth 40 50 cm although collection was limited in the moraine area by the permafrost table we determined ph electrical conductivity size particle distribution total organic carbon total nitrogen and total concentrations of al fe ca and p for physical and chemical characterization of the samples we also analysed the samples to determine the bioavailability of nutrients and fe al and p partitioning and finally examined them by isotopic 15n and x ray diffraction xrd analysis the results of the analyses revealed two clear geochemical environments corresponding to the two most extensive geomorphological units in this peninsula moraine and marine terraces soils from the moraine were characterized by alkaline reaction and high quantity of minerals with a low degree of crystallinity whereas soils from the marine terraces showed acid reaction high concentration of organometallic complexes and a high diversity of phosphate minerals taranakite minyulite struvite hydroxylapatite and leucophosphite which seem to be generated by phosphatization of faecal matter deposited by seabirds and seals consequently biota activity is the most relevant soil differentiating factor in the marine terraces which add organic matter and activate geochemical cycles on the other hand geomorphic processes strongly affected by physical weathering processes such as glacial abrasion by grinding process frost shattering and wind abrasion are the main soil forming factors in moraine these forces break up the parent material transform it and translocate the products formed

description and dating of a submerged beach in the northern north sea abstract an assumed submerged beach bordering the northern part of the north sea plateau towards the norwegian trench at 130 to 160 m waterdepth has previously been described based on interpretation of seismic profiling the seismic unit is parallel to the edge of the plateau for at least 50 km with an eastward dipping bedding soil borings and vibrocorer samples reveal that a stiff to hard clay is overlain by a thin lag deposit of coarse material on the plateau by an up to 40 m thick coarsening upwards sequence of sand and gravel on the upper part of the slope and by gradually finer material further eastwards in deeper water a low sea level is also indicated by the foraminiferal faunas and abundant littoral and aeolian textures on quartz sand grains nine radiocarbon datings of shell material found in sand and gravel from about 1 to 23 m below the sea bed gave ages from 10 800 to 12 500 yrs b p we thus consider the interpretation of the edge of the plateau and the top of the slope as a submerged beach built out in late weichselian time to be confirmed by the sample evidence

the marine record of deglaciation of the south shetland islands antarctica since the last glacial maximum abstract the marine geological record of the glacial retreat history of the south shetland islands is derived from the integration of seismic data core lithofacies radiocarbon ages and geomorphological data from two study areas on the northern shelf we present one of the first published multibeam bathymetric images of the seafloor this new image combined with descriptions of new and existing short sediment cores and high resolution seismic data from the continental shelf north of king george island are used to map a grounding zone wedge that marks the minimum seaward extent of the south shetland ice cap during the last glacial maximum seismic data multibeam bathymetry and sediment cores from maxwell bay on the opposite side of king george island are used to provide further spatial constrains on the history of grounding and retreat of the ice cap along the southern margin of the south shetland islands during the last glacial maximum the south shetland ice cap extended onto the outer continental shelf some 50 km north of its present location the ice grounded on the shelf in troughs in present water depths of almost 400 m it had a minimum thickness of 570 m and was also grounded in the deepest part of fjords and straits between the islands to the south the ice cap extended seaward of the mouths of fjords and straits to the steep northern boundary of the bransfield strait sediment eroded from the fjords and straits was deposited in prominent fans that extend into the bransfield strait and show evidence for an ice shelf that covered the bransfield strait during the last glacial maximum a long drill core shaldril in maxwell bay and several jumbo piston cores yielded carbonate material used to constrain the timing and spatial extent of glacial retreat within maxwell bay the oldest glacimarine sediments in the fjord date back to 14 1 to 14 8 ka and suggest an initial deglaciation earlier than most previous studies of the south shetland islands upper maxwell bay was ice free by 9 1 ka and most of maxwell bay proper was ice free by 5 9 ka except for the smaller tributary fjords of maxwell bay these smaller tributary fjords were ice free by 1 7 ka but may have been ice free earlier but reoccupied by a neoglacial advance that ended approximately 1 7 ka

patterns of spatio temporal paraglacial response in the antarctic peninsula region and associated ecological implications abstract the antarctic peninsula ap constitutes the warmest region of antarctica although 98 of the surface is still covered by glaciers the region shows contrasting geographic and climatic properties which have conditioned past and present glacial activity this paper constitutes a review of the spatial and temporal patterns of paraglacial activity across the ap bridging the geomorphological and ecological perspectives the number and extent of ice free environments has increased since the last glacial maximum particularly during the early holocene and the 20th century following deglaciation the redefinition of coastlines and the uplift of landmasses proceeded differently in the three sectors of ap with maximum uplift in the western sector 40 m a s l the minimum on the north 20 4 m a s l and intermediate in the eastern sector 30 m there are also differences in the levels of raised beaches with the highest complexity in the northern ap 5 7 levels and the lowest in the eastern ap 3 levels the transition from glacial to periglacial conditions paraglacial stage also differed greatly between the three sectors with the absence of rock glaciers in the western sector the development almost exclusively of glacier derived rock glaciers in the eastern ap and the majority of talus derived rock glaciers in the northern ap the development of protalus lobes block streams and other periglacial features was highly dependent on the cold warm based character of individual glaciers this characteristic determines the existence or absence of permafrost following deglaciation which in turn conditions the type and intensity of geomorphic processes in newly exposed ice free areas more recently following the post 1950s regional warming there have still been important differences between the three sectors in the development of paraglacial environments permafrost degradation has occurred in newly exposed areas accelerating mass wasting and sediment redistribution and changing hydrological processes especially in the northern and western ap while sudden glacial outburst flooding has occurred in the eastern ap the most apparent major ecological response to this recent warming is greening due to vegetation expansion which is more evident where paraglacial and periglacial processes are less intense the accurate characterization of the different paraglacial responses existing in the ap enables a better understanding of future environmental responses in this climatically sensitive region where climate models forecast significant environmental change for during forthcoming decades

relative sea level history from the lambert glacier region east antarctica and its relation to deglaciation and holocene glacier readvance we present a relative sea level rsl history constrained by ams radiocarbon dated marine freshwater transitions in isolation basins from a site adjacent to the lambert glacier east antarctica the rsl data suggest an initial ice retreat between c 15 370 and 12 660 cal yr b p within this period meltwater pulse ia mwp ia between c 14 600 14 200 and 14 100 13 700 cal yr b p occurred an exceptionally large ice melting event inferred from far field sea level records the rsl curve shows a pronounced highstand of approximately 8 m between c 7570 7270 and 7250 6950 cal yr b p that is consistent with the timing of the rsl highstand in the nearby vestfold hills this is followed by a fall in rsl to the present in contrast to previous findings the isolation of the lakes in the larsemann hills postdates the isolation of lakes with similar sill heights in the vestfold hills an increase in rsl fall during the late holocene may record a decline in the rate of isostatic uplift in the larsemann hills between c 7250 6950 and 2847 2509 cal yr b p that occurred in response to a documented mid holocene glacier readvance followed by a late holocene retreat

quaternary sea level changes in western scotland abstract in recent years major advances have been made in our understanding of late quaternary sea level changes in western scotland in particular new hypotheses have been advanced to explain the ages and origins of high level rock platform fragments and high level marine shell beds certain raised shorelines in islay and jura sw argyll and wester ross have been related to former margins of the last ice sheet and are associated with drops in the lateglacial marine limit in some areas the decline in lateglacial sea level took place in association with a stationary ice margin while in others the fall in sea level occurred in conjunction with considerable ice retreat during the lateglacial interstadial relative sea level fell rapidly between ca 13 and ca 12 ka bp and thereafter more slowly until ca 11 ka bp renewed marine erosion during the cold climate of the loch lomond younger dryas stadial ca 11 10 ka bp resulted in the production of the main lateglacial shoreline which declines in altitude to the w sw and s away from the centre of glacio isostatic uplift in the w highlands the shoreline has a maximum altitude of 10 11 m o d in the oban area and passes below sea level in ne islay ardnamurchan colonsay w mull kintyre and arran during the early holocene a pronounced marine transgression took place probably culminating between 6 6 and 7 0 ka bp the culmination of the transgression is represented by the main postglacial shoreline that reaches a maximum altitude of ca 14 m in the oban area and declines gently in altitude away from the centre of glacio isostatic uplift reconstruction of the uplift isobases for this shoreline appears to indicate a slight eastward migration of the uplift centre since the younger dryas in peripheral areas of western scotland the main postglacial shoreline is not present owing to the effect of holocene submergence

timing of formation of neoglacial landforms in the south shetland islands antarctic peninsula regional and global implications abstract the timing of neoglacial advances in the antarctic peninsula ap is not yet well constrained accurate temporal reconstruction of neoglaciation in the ap is needed to better understand past glacial responses and regional and global teleconnections during the holocene here we examine all available information about neoglacial advances in the south shetland islands ssi as well as in the broader geographical context of the ap region and antarctic continent in order to shed light on the contrasting chronologies existing for neoglacial advances in these regions we focused on a case study where a detailed picture of the holocene deglaciation was already available lake sediments revealed that byers peninsula west of livingston island ssi was fully deglaciated during the holocene thermal maximum to complement this approach we identified glacially polished bedrock surfaces erratic boulders and a moraine ridge near the present front of the glacier in the se corner we applied cosmogenic ray exposure cre dating using in situ 36cl for basalt rocks and 10be for granitic rocks in i 8 samples from glacial erratic and ice rafted boulders ii 2 samples from moraine boulders iii 2 samples from polished bedrock surfaces and iv 1 sample from an erratic boulder deposited on one of these surfaces the cre dates indicate that the onset of deglaciation started around 9 9 1 2 ka with two phases of glacier expansion during the mid late holocene forming moraines at 4 1 0 5 and 1 0 0 2 ka respectively the main neoglacial advances in the ap and the ssi were mostly synchronous and coincided with cold periods as shown by other records e g glacio isostatic marine terraces marine and lake sediments in addition these periods of glacial expansion show a similar timing to those recorded in the arctic these results suggest that neoglaciation was driven by global climate forcing in both polar areas despite temporal variations at regional and local scale

mechanical limits to microbial activity in deep sediments the observed decline in microbial abundance with increasing depth has been associated to various environmental factors meanwhile the role of geometrical constraints and soil bacteria mechanical interactions remains poorly analyzed pore and pore throat sizes may restrict habitable pore space and traversable interconnected porosity and sediment cell interaction may cause puncture or tensile failure of the cell membrane in this study we compile published evidence on the presence of bacteria in deep sediments as well as pore and pore throat size data in sediments at different depths to establish possible geometrical conditions for the sediment cell complex compiled data are complemented with experimental results gathered through controlled axial compression experiments that reproduce the mechanical consolidation of deep sediment sequences then we analyze the mechanical interaction between bacteria and sediments that may cause cell death finally we combine data and model predictions to define the main regions in a particle size versus depth space that characterize the fate of bacteria active and motile trapped inside pores and dead or dormant these regions constrain hypotheses related to the role of biological activity in deep sediments research protocols and sampling methods the viability of bioremediation strategies for contaminated sites and the potential development of bioengineered sediments

retreating glacier fronts on the antarctic peninsula over the past half century the continued retreat of ice shelves on the antarctic peninsula has been widely attributed to recent atmospheric warming but there is little published work describing changes in glacier margin positions we present trends in 244 marine glacier fronts on the peninsula and associated islands over the past 61 years of these glaciers 87 have retreated and a clear boundary between mean advance and retreat has migrated progressively southward the pattern is broadly compatible with retreat driven by atmospheric warming but the rapidity of the migration suggests that this may not be the sole driver of glacier retreat in this region

low vhf band backscatter from coniferous forests on sloping terrain low frequency synthetic aperture radar sar is a promising technique for stem volume retrieval particularly for dense forests due to the good penetration of forest canopies however it is well known that the dominant scattering mechanism the trunk ground dihedral interaction decreases rapidly on sloping terrain in this paper we use low vhf band sar data collected with carabas over dense coniferous forests in sweden to examine the effect of topography using flight passes with different headings the effect of slope and aspect angle on backscatter is characterized for tall trees spl sim 30 m on the steepest slopes in the test site up to spl sim 12 spl deg differences of up to 8 db are observed between images acquired with different look directions relative to the slope a physical model is developed to investigate the different scattering mechanisms and their sensitivity to terrain slopes the model shows that the trunk ground scattering still dominates the response for large trees on moderate slopes and a semiempirical model for the effect of topography on backscatter is proposed the model shows good agreement with measurements indicating the possibility of using it to compensate for the effects of sloping terrain when retrieving stem volume in coniferous forest

holocene isostatic uplift of the south shetland islands antarctic peninsula modelled from raised beaches we present new isobases constraining the holocene isostatic uplift of the south shetland islands northern antarctic peninsula based on evidence from raised shorelines holocene shorelines were described and surveyed at fifteen sites to determine the spatial variability of relative sea level rsl change across the south shetland islands and provide new spatial rsl change corrections for the region results show that the highest shoreline is a transgressive feature correlated by geomorphological evidence on most exposed coastlines of the archipelago its surveyed height was corrected for local variability in wave energy by subtracting the measured altitude of the present day shoreline these corrected surveyed heights of the highest raised beach were modelled using quadratic polynomial trend surface analysis to constrain differing rates of regional isostatic uplift we present two isobase models of isostatic uplift since formation of the highest holocene raised beach circa 7360 7000 years ago these models suggests a maximum uplift of ca 20 m was centred on an area north of greenwich island with isobases implying an elongate zone of uplift orientated east southeast to west northwest along the spine of the island chain this corresponds well with previously published geomorphologically based estimates of palaeo ice extent and the deglaciation history of the south shetland islands and gives new context to the palaeo ice extent and glacial history of the region

rapid collapse of northern larsen ice shelf antarctica in january 1995 4200 square kilometers of the northern larsen ice shelf antarctic peninsula broke away radar images from the ers 1 satellite complemented by field observations showed that the two northernmost sections of the ice shelf fractured and disintegrated almost completely within a few days this breakup followed a period of steady retreat that coincided with a regional trend of atmospheric warming the observations imply that after an ice shelf retreats beyond a critical limit it may collapse rapidly as a result of perturbated mass balance

a new holocene relative sea level curve for the south shetland islands antarctica abstract precise relative sea level rsl data are important for inferring regional ice sheet histories as well as helping to validate numerical models of ice sheet evolution and glacial isostatic adjustment here we develop a new rsl curve for fildes peninsula south shetland islands ssis a sub antarctic archipelago peripheral to the northern antarctic peninsula ice sheet by integrating sedimentary evidence from isolation basins with geomorphological evidence from raised beaches this combined approach yields not only a holocene rsl curve but also the spatial pattern of how rsl change varied across the archipelago the curve shows a mid holocene rsl highstand on fildes peninsula at 15 5 m above mean sea level between 8000 and 7000 cal a bp subsequently rsl gradually fell as a consequence of isostatic uplift in response to regional deglaciation we propose that isostatic uplift occurred at a non steady rate with a temporary pause in ice retreat ca 7200 cal a bp leading to a short lived rsl rise of 1 m and forming a second peak to the mid holocene highstand two independent approaches were taken to constrain the long term tectonic uplift rate of the ssis at 0 22 0 48 m ka placing the tectonic contribution to the reconstructed rsl highstand between 1 4 and 2 9 m finally we make comparisons to predictions from three global sea level models

relative sea level history of marguerite bay antarctic peninsula derived from optically stimulated luminescence dated beach cobbles abstract calmette bay within marguerite bay along the western side of the antarctic peninsula contains one of the most continuous flights of raised beaches described to date in antarctica raised beaches extend to 40 8 m above sea level masl and are thought to reflect glacial isostatic adjustment due to the retreat of the antarctic peninsula ice sheet using optically stimulated luminescence osl we dated quartz extracts from cobble surfaces buried in raised beaches at calmette bay the beaches are separated into upper and lower beaches based on osl ages geomorphology and sedimentary fabric the two sets of beaches are separated by a prominent scarp one of our osl ages from the upper beaches dates to 9 3 thousand years ago ka as of 1950 consistent with previous extrapolation of sea level data and the time of ice retreat from inner marguerite bay however four of the seven ages from the upper beaches date to the timing of glaciation we interpret these ages to represent reworking of beaches deposited prior to the last glacial maximum lgm by advancing and retreating lgm ice ages from the lower beaches record relative sea level fall due to holocene glacial isostatic adjustment we suggest a holocene marine limit of 21 7 masl with an age of 5 5 7 3 ka based on osl ages from calmette bay and other sea level constraints in the area a marine limit at 21 7 masl implies half as much relative sea level change in marguerite bay during the holocene as suggested by previous sea level reconstructions no evidence for a relative sea level signature of neoglacial events such as a decrease followed by an increase in rsl fall due to ice advance and retreat associated with the little ice age is found within marguerite bay indicating either 1 no significant neoglacial advances occurred within marguerite bay 2 rheological heterogeneity allows part of the antarctic peninsula i e the south shetland islands to respond to rapid ice mass changes while other regions are incapable of responding to short lived ice advances or 3 the magnitude of neoglacial events within marguerite bay is too small to resolve through relative sea level reconstructions although the application of reconstructing sea level histories using osl dated raised beach deposits provides a better understanding of the timing and nature of relative sea level change in marguerite bay we highlight possible problems associated with using raised beaches as sea level indices due to post depositional reworking by storm waves

reaction of a polar gravel spit system to atmospheric warming and glacier retreat as reflected by morphology and internal sediment geometries south shetland islands antarctica sedimentary architecture and morphogenetic evolution of a polar bay mouth gravel spit system are revealed based on topographic mapping sedimentological data radiocarbon dating and ground penetrating radar investigations data document variable rates of spit progradation in reaction to atmospheric warming synchronous to the termination of the last glacial re advance lgr 0 45 0 25 ka bp the southern hemisphere equivalent of the little ice age cooling period results show an interruption of spit progradation that coincides with the proposed onset of accelerated isostatic rebound in reaction to glacier retreat spit growth resumed in the late 19th century after the rate of isostatic rebound decreased and continues until today the direction of modern spit progradation however is rotated northwards compared with the growth axis of the early post lgr spit this is interpreted to reflect the shift and strengthening in the regional wind field during the last century a new concept for the interplay of polar gravel spit progradation and glacio isostatic adjustment is presented allowing for the prediction of future coastal evolution in comparable polar settings

holocene sea level changes and glacio isostasy in the gulf of finland baltic sea abstract shoreline displacement in the eastern part of the gulf of finland during the past 9000 radiocarbon years was reconstructed by studying a total of 10 isolated lake and mire basins located in virolahti in southeastern finland and on the karelian isthmus and in ingermanland in russia study methods were diatom analyses sediment lithostratigraphical interpretation and radiocarbon dating in southeastern finland the marine litorina transgression maximum occurred ca 6500 6200 14 c yr bp 7400 7100 cal yr bp in areas of the slower land uplift rate on the karelian isthmus and in ingermanland the transgression maximum occurred ca 6400 6000 14 c yr bp 7300 6800 cal yr bp the highest litorina shoreline is located at ca 23 m above present sea level in southeastern finland whereas in the eastern part of the karelian isthmus near st petersburg it is located at ca 8 m above present sea level the amplitude of the litorina transgression in virolahti area is ca 4 m whereas on the karelian isthmus and in ingermanland the amplitude has varied between 5 and 7 m the regional differences between areas are solely due to different glacio isostatic land uplift rates the seven basins studied in this research were connected to the baltic sea basin during the litorina sea stage and their diatom and lithostratigraphical records indicate a single smooth litorina transgression

pseudo ice wedge casts of connecticut northeastern united states since 1965 ice wedge casts have been reported in deposits of sand and gravel in connecticut these are wedge forms up to 1 1 m wide and many meters high most are single forms not in polygonal array they are found in adjoining states as well their distribution dimensions structure and fabric and an assessment of the former physical environment preclude their origin as permafrost features they appear to be tension fractures produced by the loading of coarse clastics on fine clastics near and below the water table where sediments creep toward a stream or depression locally movement started with kettle formation during deglaciation however some wedges cut horizontal layers of iron coated sand and gravel and must be younger than those distinctly postglacial phenomena moreover modern b horizons of the overlying soil have moved down into some wedges more than 2 m indicating that fracturing is still active today complex fracture fillings in bedrock also have been attributed to a permafrost origin but this too seems unlikely

towards improved empirical isobase models of holocene land uplift for mainland scotland uk a new approach to modelling patterns of glacio isostatic land uplift during the holocene in mainland scotland uk is described the approach is based upon altitude measurements at the inner margin or locally highest point of raised estuarine surfaces dated by radiocarbon assay supported by microfossil analyses 2241 altitudes have been analysed by a technique new to studies of former sea levels gaussian trend surface analysis and isobase models for four holocene shorelines the holocene storegga slide tsunami shoreline abandoned rapidly circa 7900 sidereal years bp the main postglacial shoreline abandoned during circa 6400 7700 sidereal years bp the blairdrummond shoreline abandoned during circa 4500 5800 sidereal years bp and a speculative fourth shoreline the wigtown shoreline abandoned during circa 1520 3700 sidereal years bp are shown in a series of maps the implications of the shoreline patterns for glaicio isostasy in the area are discussed it is maintained that the statistical technique used enables broad estimates to be made of nearshore sea surface change

the quaternary deposits and landforms of scotland and the neighbouring shelves a review abstract a thick sequence of quaternary sediments up to 1000 m has been deposited in the north sea basin and perhaps five major glacial episodes the first occurring prior to ca 1 8 2 1 ma bp and the last during the late devensian can be recognised between the glacial events periods of low salinity arctic marine or glacio marine sedimentation have been dominant although episodes of ameliorated climate when north atlantic drift waters had access to the north sea have been identified a number of horizons in separate boreholes have been correlated with the last interglacial oxygen isotope stage 5e and a sequence of water mass movements around the scottish coasts can be reconstructed for the last ca 125 ka on land sequences of quaternary deposits relating to several glacial and non glacial terrestrial and marine events occur in different areas but due to poor dating correlation between these sequences cannot yet be achieved in particular north east scotland has a complex glacial history with evidence for ice sheet glaciation on at least four occasions evidence from the outer hebrides north east scotland and the north sea basin indicates that the late devensian scottish ice sheet had a rather restricted extent only reaching a short distance offshore along much of the east and west coasts at this time ice free areas existed in north east scotland on the isle of lewis and probably in caithness and orkney whilst part of the outer shelf around st kilda was dry land a marine embayment extended down the east coast of scotland between the scottish and scandinavian ice sheets and independent ice caps existed on the outer hebrides and probably on shetland deglaciation of the greater part of the country took place prior to ca 13 ka bp whilst the climate was still very cold the ice retreat appears to have been orderly with stagnant ice masses being trapped only in topographically suitable locations a number of retreat stages or minor readvances occurred during the general deglaciation the firth of clyde was one of the last areas outside the highlands to be deglaciated and this occurred in a rapid possibly catastrophic fashion shortly prior to ca 13 ka bp despite the mild climate at the start of the lateglacial interstadial it is not known if there was complete deglaciation prior to the loch lomond readvance the readvance glaciers however may have started to advance during the latter part of the interstadial when declining terrestrial temperatures coincided with a period of mild marine conditions the loch lomond readvance maximum can only be dated to some time after ca 10 9 ka bp and it is likely that final ice free conditions were not achieved until the earliest holocene

recent atmospheric warming and retreat of ice shelves on the antarctic peninsula in 1978 mercer1 discussed the probable effects of climate warming on the antarctic ice sheet predicting that one sign of a warming trend in this region would be the retreat of ice shelves on the antarctic peninsula analyses of 50 year meteorological records have since revealed atmospheric warming on the antarctic peninsula2 3 and a number of ice shelves have retreated4 8 here we present time series of observations of the areal extent of nine ice shelves on the antarctic peninsula showing that five northerly ones have retreated dramatically in the past fifty years while those further south show no clear trend comparison with airtemperature data shows that the pattern and magnitude of ice shelf retreat is consistent with the existence of an abrupt thermal limit on iceshelf viability the isotherm associated with this limit having been driven south by the atmospheric warming ice shelves therefore appear to be sensitive indicators of climate change

holocene sea level change and ice sheet history in the vestfold hills east antarctica abstract a new holocene sea level record from the vestfold hills antarctica has been obtained by dating the lacustrine marine and marine lacustrine transitions that occur in sediment cores from lakes which were formerly connected to the sea from an elevation of 7 5 m 8000 yr ago relative sea level rose to a maximum 9 m above present sea level 6200 yr ago since then sea level has fallen monotonically until the present the precision of the new record makes it suitable for constraining the recent history of the ice sheet in that region using numerical models of glacio hydro isostasy simplified regional models suggest that the ice sheet margin has retreated 30 40 km since the last glacial maximum with 600 700 m of thinning occurring at the present coastline

timing of the most recent neoglacial advance and retreat in the south shetland islands antarctic peninsula insights from raised beaches and holocene uplift rates abstract the timing of the most recent neoglacial advance in the antarctic peninsula is important for establishing global climate teleconnections and providing important post glacial rebound corrections to gravity based satellite measurements of ice loss however obtaining accurate ages from terrestrial geomorphic and sedimentary indicators of the most recent neoglacial advance in antarctica has been hampered by the lack of historical records and the difficulty of dating materials in antarctica here we use a new approach to dating flights of raised beaches in the south shetland islands of the northern antarctic peninsula to bracket the age of a neoglacial advance that occurred between 1500 and 1700 ad broadly synchronous with compilations for the timing of the little ice age in the northern hemisphere our approach is based on optically stimulated luminescence of the underside of buried cobbles to obtain the age of beaches previously shown to have been deposited immediately inside and outside the moraines of the most recent neoglacial advance in addition these beaches mark the timing of an apparent change in the rate of isostatic rebound thought to be in response to the same glacial advance within the south shetland islands we use a maxwell viscoelastic model of glacial isostatic adjustment gia to determine whether the rates of uplift calculated from the raised beaches are realistic given the limited constraints on the ice advance during this most recent neoglacial advance our rebound model suggests that the subsequent melting of an additional 16 22 increase in the volume of ice within the south shetland islands would result in a subsequent uplift rate of 12 5 mm yr that lasted until 1840 ad resulting in a cumulative uplift of 2 5 m this uplift rate and magnitude are in close agreement with observed rates and magnitudes calculated from the raised beaches since the most recent neoglacial advance along the south shetland islands and falls within the range of uplift rates from similar settings such as alaska

biocalcification of sand through ureolysis biological processes may provide great and previously unexplored opportunities for cost effective in situ improvement of the engineering properties of soil a laboratory study was conducted to evaluate the changes in geomechanical properties of sand attributable to the formation of calcium precipitates induced through ureolysis catalyzed by sporosarcina pasteurii s pasteurii specifically direct shear and california bearing ratio cbr tests were conducted on sand specimens subjected to treatment by growing resting and dead s pasteurii cells in completely stirred tank reactors and completely mixed biofilm reactors respectively scanning electron microscopy analyses were also conducted to evaluate microbially induced precipitation the results of the study show that the bacterial cells effectively improved the geomechanical properties of the sand growing cells improved the sand properties owing to microbially induced precipitation and related pore volume changes whereas dead and resting cells ge

geological constraints on glacio isostatic adjustment models of relative sea level change during deglaciation of prince gustav channel antarctic peninsula the recent disintegration of antarctic peninsula ice shelves and the associated accelerated discharge and retreat of continental glaciers has highlighted the necessity of quantifying the current rate of antarctic ice mass loss and the regional contributions to future sea level rise observations of present day ice mass change need to be corrected for ongoing glacial isostatic adjustment a process which must be constrained by geological data however there are relatively little geological data on the geometry volume and melt history of the antarctic peninsula ice sheet apis after termination 1 and during the holocene so the glacial isostatic correction remains poorly constrained to address this we provide field constraints on the timing and rate of apis deglaciation and changes in relative sea level rsl for the north eastern antarctic peninsula based on geomorphological evidence of former marine limits and radiocarbon dated marine freshwater transitions from a series of isolation basins at different altitudes on beak island relative sea level fell from a maximum of c 15 m above present at c 8000 cal yr bp at a rate of 3 91 mm yr 1 declining to c 2 11 mm yr 1 between c 6900 2900 cal yr bp 1 63 mm yr 1 between c 2900 1800 cal yr bp and finally to 0 29 mm yr 1 during the last c 1800 years the new beak island rsl curve improves the spatial coverage of rsl data in the antarctic it is in broad agreement with some glacio isostatic adjustment models applied to this location and with work undertaken elsewhere on the antarctic peninsula these geological and rsl constraints from beak island imply significant thinning of the north eastern apis by the early holocene further they provide key data for the glacial isostatic correction required by satellite derived gravity measurements of contemporary ice mass loss which can be used to better assess the future contribution of the apis to rising sea levels

widespread acceleration of tidewater glaciers on the antarctic peninsula over the last half century the antarctic peninsula ap has been among the most rapidly warming regions on earth this has led to increased summer snowmelt loss of ice shelves and retreat of 87 of marine and tidewater glacier fronts tidewater glacier flow is sensitive to changes in basal water supply and to thinning of the terminus and faster flow leads directly to sea level rise the flow rates of most ap tidewater glaciers have never been measured however and hence their dynamic response to the recent changes is unknown we present repeated flow rate measurements from over 300 glaciers on the ap west coast through nine summers from 1992 to 2005 we show that the flow rate increased by similar to 12 on average and that this trend is greater than the seasonal variability in flow rate we attribute this widespread acceleration trend not to meltwater enhanced lubrication or increased snowfall but to a dynamic response to frontal thinning we estimate that as a result the annual sea level contribution from this region has increased by 0 047 0 011 mm between 1993 and 2003 this contribution together with previous studies that assessed increased runoff from the area and acceleration of glaciers resulting from the removal of ice shelves implies a combined ap contribution of 0 16 0 06 mm yr 1 this is comparable to the contribution from alaskan glaciers and combined with estimated mass loss from west antarctica is probably large enough to outweigh mass gains in east antarctica and to make the total antarctic sea level contribution positive

bio grouting to enhance axial pull out response of pervious concrete ground improvement piles bio grouting is an environmentallly friendly sustainable and low cost ground improvement technique which mainly utilizes microbial induced carbonate precipitation previous large scale applications of micp have encountered practical difficulties including bio clogging which resulted in a limited zone of cemented soil around injection points the research presented in this paper focuses on evaluating the feasibility of cementing a limited soil zone surrounding permeable piles using micp bio grouting to improve the mechanical response of permeable piles under axial pull out loading two instrumented pervious concrete piles test units one with and one without micp bio grouting were subjected to pull out loading at the soil structure interaction facility at lehigh university the pervious concrete pile served as an injection point during the micp bio grouting the mechanical responses of the test units and surrounding soil were analyzed along with shear wave s wave velocities moisture and caco3 c

a late devensian ice free area and possible interglacial site on the isle of lewis scotland at the time of the last glacial maximum the last scottish ice sheet has been considered by some1 2 to have extended to the continental shelf edge fig 1a whilst others3 4 have suggested that there were ice free areas in northern scotland no radiocarbon dated strati graphical evidence has been published to support either interpretation we present here data from the isle of lewis establishing that the shelly deposits from the north of that island are of late devensian age but which also show that a late devensian ice margin lay across northern lewis leaving part of the island ice free a peat possibly of interglacial status has been found in the ice free area the last scottish ice sheet therefore did not pass beyond the outer hebrides and may not even have reached the north of the island chain this evidence is also of interest to the debate on the relative expansions of the northern and southern margins of the laurentide and scandinavian ice sheets at the last glacial maximum5 6 for it suggests a restricted glacial expansion of the northern margin of the last british ice sheet at the time of its greatest southerly extent

late holocene relative sea levels near palmer station northern antarctic peninsula strongly controlled by late holocene ice mass changes abstract many studies of holocene relative sea level rsl changes across antarctica assume that their reconstructions record uplift from glacial isostatic adjustment caused by the demise of the last glacial maximum lgm ice sheets however recent analysis of gps observations suggests that mantle viscosity beneath the antarctic peninsula is weaker than previously thought which would imply that solid earth motion is not controlled by post lgm ice sheet retreat but instead by late holocene ice mass changes if this hypothesis is correct one might expect to find holocene rsl records that do not reflect a monotonic decrease in the rate of rsl fall but show variations in the rate of rsl change through the holocene we present a new record of late holocene rsl change from torgersen island near palmer station in the western antarctic peninsula that shows an increase in the rate of relative sea level fall from 3 0 1 2 mm yr to 5 1 1 8 mm yr during the late holocene independent studies of the glacial history of the region provide evidence of ice sheet changes over similar time scales that may be driving this change when our rsl records are corrected for sea surface height changes associated with glacial isostatic adjustment gia the rate of post 0 79 ka land uplift at torgersen island 5 3 1 8 mm yr is much higher than the rate of uplift recorded at a nearby gps site at palmer station prior to the larsen b breakup in 2002 ad 1998 2002 ad

early holocene retreat of the george vi ice shelf antarctic peninsula the recent collapse of several antarctic peninsula ice shelves has been linked to rapid regional atmospheric warming during the twentieth century new high resolution lake sediment records of holocene ice shelf behavior show that the george vi ice shelf was absent beginning ca 9595 calibrated cal yr b p but reformed by ca 7945 cal yr b p this retreat immediately followed a period of maximum holocene warmth that is recorded in some ice cores and occurred at the same time as an influx of warmer ocean water onto the antarctic peninsula shelf the absence of the ice shelf suggests that early holocene ocean atmosphere variability in the antarctic peninsula was greater than that measured in recent decades

geomorphological processes and frozen ground conditions in elephant point livingston island south shetland islands antarctica abstract elephant point is an ice free area in the sw corner of livingston island maritime antarctica the retreat of rotch dome glacier during the holocene has exposed a land area of 1 16 km2 up to 17 3 of this surface has become ice free between 1956 and 2010 a detailed geomorphological mapping of this ice free environment was conducted in late january 2014 a wide range of active periglacial landforms show that periglacial processes are widespread from the glacier to the coast four different geomorphological areas are identified proglacial environment moraine complex bedrock plateaus and marine terraces in situ measurements of the thawed soil depth show evidence of the widespread frozen ground conditions in the area field observations of permafrost exposures suggest that these frost conditions may be related to a soil permafrost regime almost down to sea level the activity of penguin colonies and elephant seals has created minor geomorphological features in the raised marine terraces here several archaeological sites related to early human colonization of antarctica were also found in natural shelters

factors affecting improvement in engineering properties of residual soil through microbial induced calcite precipitation abstractstudies of soil improvement by microbial induced calcite precipitation micp have focused primarily on fine sand this paper explores the viability of the micp technique for improving the engineering properties of a typical tropical residual soil a species of bacillus b megaterium was used to trigger calcite precipitation four variables were considered in this study the concentration of b megaterium the concentration of the cementation reagent the treatment duration and the flow pressure of the cementation reagent the results show that the improvement in the engineering properties of the micp treated residual soils is comparable to those of treated fine sands the preferable treatment conditions for the soil studied are b megaterium concentration of 1 108 cfu ml cementation reagent concentration of 0 5 m flow pressure of 1 1 bar of the cementation reagent and treatment duration of 48 h using this combination of parameters the obtained shear strength increase and hydraulic conduct

a generalized radar backscattering model based on wave theory for multilayer multispecies vegetation a generalized radar scattering model based on wave theory is described the model predicts polarimetric radar backscattering coefficients for structurally complex vegetation comprised of multiple species and layers compared to conventional two layer crown trunk models modeling of actual forests has been improved substantially allowing better understanding of microwave interaction with vegetation the model generalizes an existing single species discrete scatterer model and by including scattering and propagation effects through judiciously defined vegetation layers enables its application to an arbitrary number of species types the scatterers within each layer are modeled as finite cylinders or disks having arbitrary size density and orientation as in the predecessor model the distorted born approximation is used to represent the propagation through each layer while scattering from each is modeled as a linear superposition of scattering from its respective random collection of scatterers interactions of waves within and between each layer and direct scattering from the ground are accounted for validation of the model is presented based on its application to 23 wooded savanna sites located in queensland australia and comparison with advanced land observing satellite alos phased arrayed l band synthetic aperture radar palsar and national aeronautics and space administration nasa jet propulsion laboratory jpl airborne synthetic aperture radar airsar data results indicate good agreement between simulated and actual backscattering coefficients particularly at hh and vv polarizations more discrepancies are found at hv polarizations and can be explained by uncertainties in the knowledge of input parameters such as inaccuracies in the surface model surface roughness parameterization and soil moisture

late devensian and holocene relative sea level changes in northwestern scotland new data to test existing models abstract pollen diatom lithostratigraphic and radiocarbon data from five sites in northwestern scotland provide new data from an area previously devoid of reliable and precise information on late devensian and holocene sea level changes the sites cover a range of palaeoenvironments indicative of diversity in coastal evolution since deglaciation for each site and palaeoenvironment the reference water tide level indicative range age and tendency of sea level movement of all sea level index points are quantified to enable correlation of the diverse coastal environments the data record patterns of relative sea level change and tendencies of sea level movement from 12 ka bp to 1 ka bp this is the longest and most comprehensive published record of relative sea level change from the area the information is used to test the accuracy of existing models of relative sea level change the results are only broadly consistent with a quantitative rebound model and there is significant disagreement with empirical models during the late devensian and the early holocene

new relative sea level curves for the southern scott coast antarctica evidence for holocene deglaciation of the western ross sea here we present new relative sea level rsl curves developed from holocene aged raised beaches along the southern scott coast of the western ross sea antarctica fifty four dates of marine shells seal skin and elephant seal remains incorporated within raised beaches during storms afford a chronology for these curves all of the curves show the same pattern and timing of rsl change within a small range of error the best dated curve suggests that final unloading of grounded ross sea ice from the southern scott coast and mcmurdo sound region occurred shortly before 6500 14c yr bp this age is consistent with glacial geological evidence that places deglaciation between 5730 and 8340 14c yr bp our data strongly suggest that grounding line retreat of the ross sea ice sheet southward through the mcmurdo sound region occurred in mid and late holocene time if this is correct then rising sea level could not have driven ice recession to the present day grounding line on the siple coast because global deglacial sea level rise was essentially accomplished by mid holocene time copyright 1999 john wiley sons ltd

reconstruction of ice sheet changes in the antarctic peninsula since the last glacial maximum this paper compiles and reviews marine and terrestrial data constraining the dimensions and configuration of the antarctic peninsula ice sheet apis from the last glacial maximum lgm through deglaciation to the present day these data are used to reconstruct grounding line retreat in 5 ka time steps from 25 ka bp to present glacial landforms and subglacial tills on the eastern and western antarctic peninsula ap shelf indicate that the apis was grounded to the outer shelf shelf edge at the lgm and contained a series of fast flowing ice streams that drained along cross shelf bathymetric troughs the ice sheet was grounded at the shelf edge until 20 cal ka bp chronological control on retreat is provided by radiocarbon dates on glacimarine sediments from the shelf troughs and on lacustrine and terrestrial organic remains as well as cosmogenic nuclide dates on erratics and ice moulded bedrock retreat in the east was underway by about 18 cal ka bp the earliest dates on recession in the west are from bransfield basin where recession was underway by 17 5 cal ka bp ice streams were active during deglaciation at least until the ice sheet had pulled back to the mid shelf the timing of initial retreat decreased progressively southwards along the western ap shelf the large ice stream in marguerite trough may have remained grounded at the shelf edge until about 14 cal ka bp although terrestrial cosmogenic nuclide ages indicate that thinning had commenced by 18 ka bp between 15 and 10 cal ka bp the apis underwent significant recession along the western ap margin although retreat between individual troughs was asynchronous ice in marguerite trough may have still been grounded on the mid shelf at 10 cal ka bp in the larsen a region the transition from grounded to floating ice was established by 10 7 10 6 cal ka bp the apis had retreated towards its present configuration in the western ap by the mid holocene but on the eastern peninsula may have approached its present configuration several thousand years earlier by the start of the holocene mid to late holocene retreat was diachronous with stillstands re advances and changes in ice shelf configuration being recorded in most places subglacial topography exerted a major control on grounding line retreat with grounding zone wedges and thus by inference slow downs or stillstands in the retreat of the grounding line occurring in some cases on reverse bed slopes

mechanisms of holocene palaeoenvironmental change in the antarctic peninsula region the antarctic peninsula is one of the three fastest warming regions on earth here we review holocene proxy records of marine and terrestrial palaeoclimate in the region and discuss possible forcing mechanisms underlying past change with a specific focus on past warm periods our aim is to critically evaluate the mechanisms by which palaeoclimate changes might have occurred in order to provide a longer term context for assessing the drivers of recent warming two warm events are well recorded in the holocene palaeoclimate record namely the early holocene warm period and the mid holocene hypsithermal mhh whereas there are fewer proxy data for the mediaeval warm period mwp and the recent rapid regional rrr warming we show that the early holocene warm period and mhh might be explained by relatively abrupt shifts in position of the southern westerlies superimposed on slower solar insolation changes a key finding of our synthesis is that the marine and terrestrial records in the ap appear to show markedly different behaviour during the mhh this might be partly explained by contrasts in the seasonal insolation forcing between these records circumpolar deep water cdw has been implicated in several of the prominent changes through the holocene but there are still differences in interpretation of the proxy record that make its influence difficult to assess further work is required to investigate contrasts between marine and terrestrial proxy records east west contrasts in palaeoclimate the history of cdw to retrieve a long onshore high resolution record of the holocene and determine the role of sea ice in driving or modulating palaeoclimate change along with further efforts to study the proxy record of the rrr and the mwp

holocene land and sea level changes in great britain analysis of more than 1200 radiocarbon dated samples that constrain relative sea levels in great britain over the past 16 000 yr provides estimates of current land level changes negative of relative sea level change maximum relative land uplift occurs in central and western scotland ca 1 6 mm yr 1 and maximum subsidence is in southwest england ca 1 2 mm yr 1 sediment consolidation arising from autocompaction as the sediment accumulates and from land drainage increases the subsidence in areas with thick sequences of holocene sediments with an average effect equivalent to at least an extra ca 0 2 mm yr 1 land subsidence but more in parts of southeast england 0 5 1 1 mm yr 1 modelled changes in tidal range during the mid to late holocene in eastern england suggest that the calculated rate of land subsidence is overestimated unless such changes are quantified the effect is most significant for large coastal lowlands the fenland and humber ca 0 5 and 0 6 mm yr 1 that were tidal embayments during the mid to late holocene