sedimentary characteristics and origin of the late pleistocene ice complex on north east siberian arctic coastal lowlands and islands a review abstract the origin of late pleistocene ice rich fine grained permafrost sequences ice complex deposits in arctic and subarctic siberia has been in dispute for a long time corresponding permafrost sequences are frequently exposed along seacoasts and river banks in yedoma hills which are considered to be erosional remnants of late pleistocene accumulation plains detailed cryolithological sedimentological geochronological and stratigraphical results from 14 study sites along the laptev and east siberian seacoasts were summarized for the first time in order to compare and correlate the local datasets on a large regional scale the sediments of the ice complex are characterized by poorly sorted silt to fine sand buried cryosols toc contents of 1 2 4 8 wt and very high ground ice content 40 60 wt absolute a second large constituent of the ice complex are large syngenetic ice wedges resulting in a total ice content of the ice complex of up to 80 vol ice complex deposits were mostly formed during the middle weichselian interstadial and or during the late weichselian stadial periods a conceptual model of nival lithogenesis of ice complex deposits was developed that integrates various other formation hypotheses a combination of various local and regional paleogeographical geological and paleoclimate conditions controlled the formation of ice complex sequences during the late pleistocene in northern east siberia they are chronologically and stratigraphically but not genetically equivalent to eurasian and alaskan loess deposits

preliminary paleoenvironmental analysis of permafrost deposits at batagaika megaslump yana uplands northeast siberia a megaslump at batagaika in northern yakutia exposes a remarkable stratigraphic sequence of permafrost deposits 50 80 m thick to determine their potential for answering key questions about quaternary environmental and climatic change in northeast siberia we carried out a reconnaissance study of their cryostratigraphy and paleoecology supported by four rangefinder 14c ages the sequence includes two ice complexes separated by a unit of fine sand containing narrow syngenetic ice wedges and multiple palaeosols overall the sequence developed as permafrost grew syngenetically through an eolian sand sheet aggrading on a hillslope wood remains occur in two forest beds each associated with a reddened weathering horizon the lower bed contains high amounts of larix pollen 20 plus small amounts of picea and pinus pumila and is attributed to interglacial conditions pollen from the overlying sequence is dominated by herbaceous taxa 70 80 attributed to an open tundra landscape during interstadial climatic conditions of three hypothetical age schemes considered we tentatively attribute much of the batagaika sequence to marine isotope stage mis 3 the upper and lower forest beds may represent a mid mis 3 optimum and mis 5 respectively although we cannot discount alternative attributions to mis 5 and 7

channel change fluvial geomorphology and river engineering the case of the afon trannon mid wales the afon trannon a gravel bed river in mid wales with a catchment area of 72 km2 has recently been the subject of an engineering flood protection scheme following the enlargement and grading of the channel lateral instability has produced considerable problems of maintenance geomorphological investigations are described which attempt to pinpoint the lessons of the scheme historical studies of floodplain sediments and channel change indicate firstly an initially rather stable channel but secondly a considerable early history of channelization which may still have repercussions for system stability this early channelization has now been modified in the recent scheme contemporary field study by survey and sediment tracing using the magnetic technique indicates the present instability of the sediments in a meandering channel given a trapezoidal cross section and varied banks low flow adjustments are as important as flood adjustments in the lower straightened reach lessons for engineering schemes include the desirability of assessing erosion risk by rapid cheap field techniques and historical investigations and the consideration of more ecologically acceptable channel designs

geomorphic and vegetation changes in a meandering dryland river regulated by a large dam sauce grande river argentina abstract this paper investigates post dam geomorphic and vegetation changes in the sauce grande river a meandering dryland river impounded by a large water conservation dam as the dam impounds a river section with scarce influence of tributaries sources for fresh water and sediment downstream are limited changes were inspected based on i analysis of historical photographs imagery spanning pre 1961 and post dam 1981 2004 channel conditions for two river segments located above and below the dam and ii field survey of present channel conditions for a set of eight reference reaches along the river segments whilst the unregulated river exhibited active lateral migration with consequent adjustments of the channel shape and size the river section below the dam was characterized by i marked planform stability 93 to 97 and by ii vegetation encroachment leading to alternating yet localized contraction of the channel width up to 30 the present river displays a moribund stable channel where i redistribution of sediment along the river course no longer occurs and ii channel forms constitute a remnant of a fluvial environment created before closing the dam under conditions of higher energy in addition to providing new information on the complex geomorphic response of dryland rivers to impoundment this paper represents the very first geomorphic assessment of the regulated sauce grande and therefore provides an important platform to underpin further research assessing the geomorphic state of this highly regulated dryland river

insights into river bank erosion processes derived from analysis of negative erosion pin recordings observations from three recent uk studies recent studies of river bank erosion in three catchments in the uk have been characterized by the persistent occurrence of negative erosion pin results the cause of these negative recordings is considered with reference to field data from the afon trannon nant tanllwyth and river arrow and to a laboratory study of freeze thaw and desiccation processes it seems that there is potential for and in some cases evidence of a number of different circumstances that generate negative results but none of these alone is sufficient to explain all incidents factors considered include deposition of sediment during high flows soil fall from the upper parts of the bank on to lower erosion pins loosening of the soil surface and expansion contraction of the soil mass with fluctuations in temperature and moisture content movement of the erosion pin within the bank and human interference each has its own implications for the use of erosion pins further issues arise when including negative data in subsequent data analysis and it is demonstrated that attempts to correlate erosion rates with hydro meteorological data in order to ascertain causes of erosion will be influenced by the way in which negative data are handled it is thus suggested that any study of river bank erosion using erosion pins should state whether or not negative data were obtained and if so how they were included in data analysis failure to include this information could lead to comparison of mean erosion rates that reflect bank processes very differently the studies presented here offer a clear example of the value of anomalous field data results which do not appear to fit expected patterns can reveal as much about the processes in operation as those that do

eemian and late glacial holocene palaeoenvironmental records from permafrost sequences at the dmitry laptev strait ne siberia russia abstract terrestrial permafrost sections from the southern and northern coasts of dmitry laptev strait have preserved records of landscape transition from glacial to interglacial periods they allow geomorphologic and environmental changes to be traced from pre eemian time to the eemian and from the late glacial to the holocene the transition from one period to another induced extensive thawing of permafrost thermokarst evolving thermokarst depressions transformed formerly frozen ground into taberal unfrozen deposits with accumulating overlying lacustrine deposits lacustrine horizons rich in palaeontological remains retain evidence of changes in environmental conditions the pollen records reflect changes from grass sedge dominated vegetation during the early eemian to shrub dominated spectra during the middle eemian thermal optimum followed by late eemian grass sedge dominated tundra vegetation abundant larix pollen have been found in middle eemian deposits from the south coast of the dmitry laptev strait oyogos yar but are absent in similar deposits from the north coast bol shoy lyakhovsky island likely indicating that the northern tree line was located near the oyogos yar region during the eemian thermal optimum grass sedge dominated tundra vegetation occurred during the late glacial holocene transition which was replaced by shrub tundra during the early holocene rich fossil ostracod records from eemian and late glacial holocene lacustrine deposits could be correlated with the eemian thermal optimum and the late glacial allerod warm period for both periods the stable oxygen isotope data from the fossil ostracods suggest an approximate mean summer water temperature range between about 10 and 19 c in the palaeo lakes

present day downcutting of the raba river channel western carpathians poland and its environmental effects abstract timing and causes of the present day channel downcutting of carpathian tributaries to the vistula river are exemplified by a case study of the raba river a gravel bed stream characterized by great variability of water stage and discharge up to 3 m of river incision has occurred since the beginning of the present century associated with an increase in stream power caused by river control works and reduction in bed material load linked to changes in basin management gravel extraction from the channel and modifications in flood flows have increased rates of incision over the last thirty years lowering of ground water levels on the valley floor increase in river bank susceptibility to erosion decrease or cessation of overbank sediment accretion and impoverishment of plant and animal communities of riverside biotopes are the principal environmental effects of channel downcutting

permafrost response to last interglacial warming field evidence from non glaciated yukon and alaska abstract we present stratigraphic observations from three sites in eastern beringia ch ijee s bluff in northern yukon and nearby exposures on the old crow river the palisades on the yukon river in alaska and placer mining exposures at thistle creek in west central yukon which provide insight into the response of permafrost to regional warming during the last interglaciation chronology is based on the presence of old crow tephra an important regional stratigraphic marker that dates to late marine isotope stage 6 supplemented by paleoecology and non finite 14c ages on wood rich organic silts old crow tephra overlies several relict ice wedges at the palisades and thistle creek indicating that permafrost at these sites did not thaw completely during the last interglaciation prominent deposits of last interglacial wood rich organic silt are present at multiple sites in eastern beringia and probably represent accumulations of reworked forest vegetation due to thaw slumping or deposition into thermokarst ponds or depressions consistent stratigraphic relations between these deposits old crow tephra and ice wedge pseudomorphs at our three study sites and at least six other sites in eastern beringia suggest that thaw of shallow permafrost was widespread during the last interglaciation limited stratigraphic evidence suggests that thaw was probably on the order of meters rather than 10s of meters the ubiquity of shallow permafrost degradation during the last interglaciation suggests that current ground warming may foreshadow widespread near surface thaw under even modest future warming scenarios however the persistence of relict pre last interglacial ice wedges highlights the potential for the regional antiquity of discontinuous permafrost and provides compelling field evidence for the long term resilience of deep permafrost during sustained periods of warmer than present climate

ice complex permafrost of mis5 age in the dmitry laptev strait coastal region east siberian arctic ice complex deposits locally known as the buchchagy ice complex are exposed at both coasts of the east siberian dmitry laptev strait and preserved below the yedoma ice complex that formed during mis3 and mis2 marine isotope stage and lateglacial holocene thermokarst deposits mis1 radioisotope disequilibria 230th u of peaty horizons date the buchchagy ice complex deposition to 126 16 13 kyr and 117 19 14 kyr until 98 5 kyr and 89 5 kyr the deposit is characterised by poorlysorted medium to coarse silts with cryogenic structures of horizontal ice bands lens like and lenslike reticulated segregation ice two peaty horizons within the buchchagy ice complex and syngenetic ice wedges 2e4 m wide up to 10 m high are striking the isotopic composition d18o dd of buchchagy ice wedge ice indicates winter conditions colder than during the mis3 interstadial and warmer than during mis2 stadial and similar atmospheric winter moisture sources as during the mis2 stadial buchchagy ice complex pollen spectra reveal tundra steppe vegetation and harsher summer conditions than during the mis3 interstadial and rather similar vegetation as during the mis2 stadial short term climatic variability during mis5 is reflected in the record even though the regional chronostratigraphic relationship of the buchchagy ice complex to the last interglacial remains unclear because numerical dating is widely lacking the present study indicates permafrost ice complex formation during mis5 sensu lato and its preservation afterwards palaeoenvironmental insights into past climate and the periglacial landscape dynamics of arctic lowlands in eastern siberia are deduced from the record

tracing sediment movement in interrill overland flow on a semi arid grassland hillslope using magnetic susceptibility experiments were undertaken to determine the feasibility of tracing sediment movement in interrill overland flow crushed magnetite was introduced as a source line 10 cm wide by 8 m long on a runoff plot 18 m wide by 29 m long located in southern arizona initial magnetic susceptibilities along this source line and along three transects located 0 25 2 95 and 5 m downslope of the source line were measured movement of the magnetite in response to three rainfall simulation experiments was monitored during the first two experiments overland flow discharge was sampled at miniature flumes located along two cross sections on the plot downslope of the source line and at a supercritical flume at the plot outlet magnetic susceptibilities along the source line and transects were measured after all three experiments results show that the magnetite moves very early in the experiments and that it reaches one of the flumes 2 m downslope of the source line in 3 min most of the tracer moves a very short distance 29 7 per cent is deposited within 25 cm of the source line and only 2 2 per cent is deposited 2 95 m away the deposition rate appears to decrease exponentially away from the source line very little magnetite is recorded in the flow through the miniature flumes in general it makes up less than 1 per cent of the total sediment load no temporal pattern in these percentages is observed magnetite appears to be an effective tracer of sediment movement in interrill overland flow though its higher density than natural soil may affect its detachment and transport

estimation of error in bankfull width comparisons from temporally sequenced raw and corrected aerial photographs this study investigates the propagation of error through image to image comparison of 285 river bankfull width measurements of the afon trannon mid wales bankfull width is quantified from both aerial photographs analysed as rectified images in erdas imagine orthomax and raw images in paintshop pro a method for the robust estimation of bankfull width measurement error through temporal sequences of scanned aerial photographs is presented and the improvement in accuracy achieved using rectified imagery is quantified results from this study are placed in the context of previously published rates of bankfull width change from a wide range of river scales and the bankfull change rates for robust medium term analysis using approximately 1 10 000 historical aerial photography are identified

interglacials of the last 800 000 years interglacials including the present holocene period are warm low land ice extent high sea level end members of glacial cycles based on a sea level definition we identify eleven interglacials in the last 800 000 years a result that is robust to alternative definitions data compilations suggest that despite spatial heterogeneity marine isotope stages mis 5e last interglacial and 11c 400 ka ago were globally strong warm while mis 13a 500 ka ago was cool at many locations a step change in strength of interglacials at 450 ka is apparent only in atmospheric co2 and in antarctic and deep ocean temperature the onset of an interglacial glacial termination seems to require a reducing precession parameter increasing northern hemisphere summer insolation but this condition alone is insufficient terminations involve rapid nonlinear reactions of ice volume co2 and temperature to external astronomical forcing the precise timing of events may be modulated by millennial scale climate change that can lead to a contrasting timing of maximum interglacial intensity in each hemisphere a variety of temporal trends is observed such that maxima in the main records are observed either early or late in different interglacials the end of an interglacial glacial inception is a slower process involving a global sequence of changes interglacials have been typically 10 30 ka long the combination of minimal reduction in northern summer insolation over the next few orbital cycles owing to low eccentricity and high atmospheric greenhouse gas concentrations implies that the next glacial inception is many tens of millennia in the future

the deep permafrost carbon pool of the yedoma region in siberia and alaska estimates for circumpolar permafrost organic carbon oc storage suggest that this pool contains twice the amount of current atmospheric carbon the yedoma region sequestered substantial quantities of oc and is unique because its deep oc was incorporated into permafrost during ice age conditions rapid inclusion of labile organic matter into permafrost halted decomposition and resulted in a deep long term sink we show that the deep frozen oc in the yedoma region consists of two distinct major sub reservoirs yedoma deposits late pleistocene ice and organic rich silty sediments and deposits formed in thaw lake basins generalized as thermokarst deposits we quantified the oc pool based on field data and extrapolation using geospatial datasets to 83 61 57 gt for yedoma deposits and to 128 99 96 gt for thermokarst deposits the total yedoma region 211 160 153 gt is a substantial amount of thaw vulnerable oc that must be accounted for in global models

230th u dating of frozen peat bol shoy lyakhovsky island northern siberia abstract the chronology of quaternary paleoenvironment and climate in northeastern siberia is poorly understood due to a lack of reliable numerical age determinations the best climatic archives are ice rich permafrost sequences which are widely distributed in northeastern siberia for this study 230 th u ages were determined by thermal ionization mass spectrometry tims from frozen peat in a permafrost deposit at the southern cliff of the bol shoy lyakhovsky island new siberian archipelago west of the zimov e river these yielded a pre eemian isochron corrected 230 th u age of 200 900 3400 yr this result is reliable because permafrost deposits behave as closed systems with respect to uranium and thorium our findings suggest that 230 th u dating of frozen peat in permafrost deposits is a useful tool for the reconstruction of the middle quaternary environment of northern siberia and of the whole arctic

vegetation and climate history in the laptev sea region arctic siberia during late quaternary inferred from pollen records abstract paleoenvironmental records from a number of permafrost sections and lacustrine cores from the laptev sea region dated by several methods 14 c ams tl irsl osl and 230 th u were analyzed for pollen and palynomorphs the records reveal the environmental history for the last ca 200 kyr for interglacial pollen spectra quantitative temperature values were estimated using the best modern analogue method sparse grass sedge vegetation indicating arctic desert environmental conditions existed prior to 200 kyr ago dense wet grass sedge tundra habitats dominated during an interstadial ca 200 190 kyr ago reflecting warmer and wetter summers than before sparser vegetation communities point to much more severe stadial conditions ca 190 130 kyr ago open grass and artemisia communities with shrub stands alnus fruticosa salix betula nana in more protected and moister places characterized the beginning of the last interglacial indicate climate conditions similar to present shrub tundra alnus fruticosa and betula nana dominated during the middle eemian climatic optimum when summer temperatures were 4 5 c higher than today early weichselian sparse grass sedge dominated vegetation indicates climate conditions colder and dryer than in the previous interval middle weichselian interstadial records indicate moister and warmer climate conditions for example in the interval 40 32 kyr bp salix was present within dense grass sedge dominated vegetation sedge grass artemisia communities indicate that climate became cooler and drier after 30 kyr bp and cold dry conditions characterized the late weichselian ca 26 16 kyr bp when grass dominated communities with caryophyllaceae asteraceae cichoriaceae selaginella rupestris were present from 16 to 12 kyr bp grass sedge communities with caryophyllaceae asteraceae and cichoriaceae indicate climate was significantly warmer and moister than during the previous interval the presence of salix and betula reflect temperatures about 4 c higher than present at about 12 11 kyr bp during the allerod interval but shrubs were absent in the younger dryas interval pointing to a deterioration of climate conditions alnus fruticosa betula nana poaceae and cyperaceae dominate early holocene spectra reconstructed absolute temperature values were substantially warmer than present up to 12 c shrubs gradually disappeared from coastal areas after 7 6 kyr bp when vegetation cover became similar to modern a comparison of proxy based paleoenvironmental reconstructions with the simulations performed by an earth system model of intermediate complexity climber 2 show good accordance between the regional paleodata and model simulations especially for the warmer intervals

repeated pleistocene glaciation of the east siberian continental margin during glacial periods ice sheets covered continental margins through much of arctic north america greenland and western eurasia marine structures suggest that an ice sheet up to a kilometre in depth periodically covered the east siberian continental shelf as well

palaeoclimate a fresh look at arctic ice sheets during the last glacial maximum ice sheets in eurasia terminated at the edge of the laptev sea seismic data now suggest that a separate ice sheet was repeatedly centred further east in the east siberian sea during previous glacial periods

numerical 230th u dating and a palynological review of the holsteinian hoxnian interglacial abstract earth scientists increasingly consider the holsteinian interglacial and mis 11 as synonyms despite the limited number of numerical dates and ambiguous stratigraphic and palynological correlation with the numerical marine isotope timescale hence we present new tims 230th u dates from two fen peat layers of the holsteinian reference site at bossel in northern germany and re evaluate published numerical data from two sites with hoxnian deposits in england a new method for the calculation of methodically controlled minimum 230th u ages mcma was developed the synopsis of the 230th u dates allows a correlation of both the holsteinian and hoxnian interglacials to mis 9 this correlation is supported by supplementary 230th u dates of fen peat from several pre eemian but non holsteinian sites in germany there is palynological evidence for a reliable correlation between precisely investigated and numerically dated holsteinian deposits in poland germany england sw ireland and france an apparently contradictory palynological correlation from the french central massif is discussed

paleontological records indicate the occurrence of open woodlands in a dry inland climate at the present day arctic coast in western beringia during the last interglacial abstract permafrost records accessible at outcrops along the coast of oyogos yar at the dmitry laptev strait ne siberia provide unique insights into the environmental history of western beringia during the last interglacial the remains of terrestrial and freshwater organisms including plants coleopterans chironomids cladocerans ostracods and molluscs have been preserved in the frozen deposits of a shallow paleo lake and indicate a boreal climate at the present day arctic mainland coast during the last interglacial terrestrial beetle and plant remains suggest the former existence of open forest tundra with larch larix dahurica tree alder alnus incana birch and alder shrubs duschekia fruticosa betula fruticosa betula divaricata betula nana interspersed with patches of steppe and meadows consequently the tree line was shifted to at least 270 km north of its current position aquatic organisms such as chironomids cladocerans ostracods molluscs and hydrophytes indicate the formation of a shallow lake as the result of thermokarst processes steppe plants and beetles suggest low net precipitation littoral pioneer plants and chironomids indicate intense lake level fluctuations due to high evaporation many of the organisms are thermophilous indicating a mean air temperature of the warmest month that was greater than 13 c which is above the minimum requirements for tree growth these temperatures are in contrast to the modern values of less than 4 c in the study area the terrestrial and freshwater organism remains were found at a coastal exposure that was only 3 5 m above sea level and in a position where they should have been under sea during the last interglacial when the global sea level was 6 10 m higher than the current levels the results suggest that during the last warm stage the site was inland and its modern coastal situation is the result of tectonic subsidence

an assessment of the impact of upland afforestation on lowland river reaches the afon trannon mid wales upland afforestation in the uk was the largest rural land use change last century as a consequence the bed load yields of upland catchments increased substantially circumstantial evidence suggests that when this increased load reaches the lowland catchment it is deposited triggering flow diversion and channel instability however despite the widespread adoption of this theory it remains to be properly tested this paper uses aerial photograph analysis and contemporary channel digital terrain models dtms to assess this concept on the afon trannon mid wales the upper catchment of which was afforested between 1948 and 1978 construction of a sediment budget demonstrates that upland catchment bed load yields are only equivalent to localized inputs of gravel from bank erosion and are therefore unlikely to be totally responsible for producing the high rates of channel change observed in some lowland reaches channel instability appears to be more related to the nature of the local bank input as those reaches where gravel is not present in the bank material are stable additionally flood magnitude and frequency are shown to have increased since 1988 a factor of at least equal importance to that of bed load yields from either upland catchments or local bank erosion it is concluded that in contrast to previous work afforestation in the uplands has only a minor influence on downstream reaches of the afon trannon situations where upland afforestation may have a greater impact on downstream reaches are discussed and the implications for best management practice explored

ratio of 36cl cl in ground ice of east siberia and its application for chronometry abundance of the cosmogenic nuclide chlorine 36 36cl was measured together with the chloride cl concentration in different horizons of quaternary permafrost samples collected from various types of ground ice in the northeastern part of siberia the 36cl cl in 32 samples ranged in value from 2 4 10 14 to 1 4 10 12 nonetheless after a few extreme values were excluded these 36cl cl ratios provided a local permafrost chronometry the general concordance of the modeled ages with geological expectations and other chronological methods supports the potential power of the proposed dating method however the large observed change in ratios from higher to lower values during the transition from last glacial maximum to holocene climatic conditions remains unexplained an attempt to make use of the corresponding beryllium 10 10be absolute concentrations in the same samples failed because input of 10be attached to particulate matter into permafrost is unknown further 36cl cl serial measurements of modern precipitation and fossil ground ice are needed to refine this dating method into a practical tool with a clear protocol

ice complex formation on bol shoy lyakhovsky island new siberian archipelago east siberian arctic since about 200 ka late quaternary landscapes of unglaciated beringia were largely shaped by ice wedge polygon tundra ice complex ic strata preserve such ancient polygon formations here we report on the yukagir ic from bol shoy lyakhovsky island in northeastern siberia and suggest that new radioisotope disequilibria 230th u dates of the yukagir ic peat confirm its formation during the mis 7a c interglacial the preservation of the ice rich yukagir ic proves its resilience to last interglacial and lateglacial holocene warming this study compares the yukagir ic to ic strata of mis 5 mis 3 and mis 2 ages exposed on bol shoy lyakhovsky island besides high intrasedimental ice content and syngenetic ice wedges intersecting silts sandy silts the yukagir ic is characterized by high organic matter om accumulation and low om decomposition of a distinctive drepanocladus moss peat the yukagir ic pollen data reveals grassshrub moss tundra indicating rather wet summer conditions similar to modern ones the stable isotope composition of yukagir ic wedge ice is similar to those of the mis 5 and mis 3 ics pointing to similar atmospheric moisture generation and transport patterns in winter ice complex data from glacial and interglacial periods provide insights into permafrost and climate dynamics since about 200 ka

last glacial maximum records in permafrost of the east siberian arctic palaeontological proxy data and cryolithological information from siberian arctic permafrost preserves records of late quaternary climate and environmental conditions in west beringia and their variability which results from interglacial glacial and interstadial stadial dynamics to date the last glacial maximum lgm period has been rather poorly represented in east siberian permafrost records here we present pollen sediment and ground ice stable water isotope data obtained from coastal exposures on bol shoy lyakhovsky island new siberian archipelago arctic ocean that mirror the coldest conditions during the sartan period between about 26 and 22 ka bp using pollen and sediment data for summer conditions and stable water isotope data for winter conditions the pollen record revealed a cold tundra steppe vegetation with characteristic predominance of grass pollen over sedge pollen while the stable isotope ice wedges data indicate extremely cold winter temperatures with mean values of d 18 oo f about 37 dd of about 290 combined with available regional lgm permafrost records that extend from the taymyr peninsula in the west to the yana river lowland in the east the new data set from bol shoy lyakhovsky island indicate that the regional appearance of lgm conditions depended on atmospheric circulation patterns that were influenced by the extent of the northern hemisphere glaciation

palaeobotanical evidence for warm summers in the east siberian arctic during the last cold stage plant macrofossils from the mamontovy khayata permafrost sequence 71 60 n 129 25 e on the bykovsky peninsula reflect climate and plant biodiversity in west beringia during the last cold stage 70 ams and 20 conventional 14c dates suggest sediment accumulation between about 60 000 and 7500 14c yr b p the plant remains prove that during the last cold stage arctic species minuartia arctica draba spp kobresia myosuroides coexisted with aquatic potamogeton vaginatus callitriche hermaphroditica littoral ranunculus reptans rumex maritimus meadow hordeum brevisubulatum puccinellia tenuiflora and steppe taxa alyssum obovatum silene repens koeleria cristata linum perenne the reconstructed vegetation composition is similar to modern vegetation mosaics in central and northeast yakutian relict steppe areas thus productive meadow and steppe communities played an important role in the siberian arctic vegetation during the late pleistocene and could have served as food resource for large populations of herbivores the floristic composition reflects an extremely continental arid climate with winters colder and summers distinctly warmer than at present holocene macrofossil assemblages indicate a successive paludification possibly connected with marine transgression increased oceanic influence and atmospheric humidity although some steppe taxa were still present in the early holocene they disappeared completely before 2900 14c yr b p

the principles of cryostratigraphy abstract cryostratigraphy adopts concepts from both russian geocryology and modern sedimentology structures formed by the amount and distribution of ice within sediment and rock are termed cryostructures typically layered cryostructures are indicative of syngenetic permafrost while reticulate and irregular cryostructures are indicative of epigenetic permafrost cryofacies can be defined according to patterns of sediment characterized by distinct ice lenses and layers volumetric ice content and ice crystal size cryofacies can be subdivided according to cryostructure where a number of cryofacies form a distinctive cryostratigraphic unit these are termed a cryofacies assemblage the recognition if present of i thaw unconformities ii other ice bodies such as vein ice ice wedges aggradational ice and thermokarst cave pool ice and iii ice sand and gravelly pseudomorphs is also important in determining the nature of the freezing process the conditions under which frozen sediment accumulates and the history of permafrost

ice complex formation in arctic east siberia during the mis3 interstadial abstract a continuous 15 m long sequence of ice complex permafrost yedoma exposed in a thermo cirque at the southern coast of bol shoy lyakhovsky island new siberian archipelago dmitry laptev strait was studied to reconstruct past landscape and environmental dynamics the sequence accumulated during the marine isotope stage 3 mis3 interstadial between 49 and 29 ka bp in an ice wedge polygon the frozen deposits were cryolithologically described and sampled on a vertical bluff between two ice wedges according to sedimentological and geochronological data the section is subdivided into three units which correlate with environmental conditions of the early middle and late mis3 period palynological data support this stratification the stable isotope signature of texture ice in the polygon structure reflects fractionation due to local freeze thaw processes while the signature of an approximately 5 m wide and more than 17 m high ice wedge fits very well into the regional stable water isotope record regional climate dynamics during the mis3 interstadial and local landscape conditions of the polygonal patterned ground controlled the ice complex formation the sequence presented here completes previously published mis3 permafrost records in northeast siberia late quaternary stadial interstadial climate variability in arctic west beringia is preserved at millennial resolution in the ice complex a mis3 climate optimum was revealed between 48 and 38 ka bp from the ice complex on bol shoy lyakhovsky island

changing landscapes five decades of applied geomorphology abstract much geomorphological research has potential to be applied but this paper examines the extent and nature of actual applications to environmental management it reviews how this work has expanded and changed and reflects on the stimuli types of involvement and attitudes these aspects and how geomorphology can be applied effectively are exemplified by developments in coastal and river management in the uk highlighting the contributions made by geomorphology to sustainable strategies applied geomorphology has been recognised as a topic and component within geomorphology throughout the last 50 yr contributing about 10 of published research papers in the subject major increase in direct involvement with environmental policy and practice came in the 1980s and 1990s but it has been followed by enormous expansion since then including employment of professional geomorphologists in all stages and scales of projects from provision of specific solutions to design and initiation of projects through to national policy development major stimuli to this increase in application encompassed the evident failure and detrimental effects of earlier approaches using hard engineering changes in environmental awareness and attitudes of the public and increased threat of climate change and incidence of major storms and natural disasters these led to developments in approaches that work with nature implementation of demonstration projects in river restoration managed coastal retreat and now natural flood management and the explicit need for geomorphological assessment of water bodies following eu legislation these have contributed to produce the present situation where applied geomorphology is booming with high demand for geomorphologists evidence is provided that geomorphologists have contributed significantly to this change in thinking and are now very actively involved in developing and applying means of using their understanding and skills to implement more sustainable management to the benefit of the environment and society

the measurement of river bank erosion and lateral channel change a review a detailed review and chronological survey is presented of the various techniques which have been used for the measurement of river bank erosion and channel change the techniques are classified according to the time scales involved long intermediate and short and each is discussed with respect to accuracy and repeatability the methods covered include sedimentological evidence botanical evidence historical sources planimetric resurvey repeated cross profiling erosion pins and terrestrial photogrammetry prospects for future developments are also discussed

3d ground penetrating radar imaging of ice complex deposits in northern east siberia abstractice complex deposits are characteristic ice rich formations in northern east siberia and represent an important part in the arctic carbon pool recently these late quaternary deposits are the objective of numerous investigations typically relying on outcrop and borehole data many of these studies can benefit from a 3d structural model of the subsurface for upscaling their observations or for constraining estimations of inventories such as the local carbon stock we have addressed this problem of structural imaging by 3d ground penetrating radar gpr which in permafrost studies has been primarily used for 2d profiling we have used a 3d kinematic gpr surveying strategy at a field site located in the new siberian archipelago on top of an ice complex after applying a 3d gpr processing sequence we were able to trace two horizons at depths below 20 m taking available borehole and outcrop data into account we have interpreted these two features as interfaces of major lithologic units and der

prelude to the extinction revision of the achchagyi allaikha and berelyokh mass accumulations of mammoth abstract the little known achchagyi allaikha mass assemblage of mammoths and the well known berelyokh site lower indigirka river arctic siberia were studied detailed study of the achchagyi allaikha site provided ample data concerning its geology stratigraphy taphonomy and the gender age structure of the taphocoenosis the achchagyi allaikha assemblage included redeposited bones from numerous young not less than 21 and some adult female mammoths with limited quantities of bison equus and rangifer bones collagen from mammoth bones preserved at the achchagyi allaikha site n 6 was radiocarbon dated at 12 490 80 to 12 400 60 bp at the berelyokh site eight mammoth bones were radiocarbon dated at 12 720 100 to 11 900 50 bp one bison bone was dated at 12 380 150 bp and one mammoth bone dated at 36 500 1000 redeposited bone included in younger sediments the mass accumulations are synchronous and are similar in their mode of formation the assemblage of mammoths in the achchagyi allaikha and berelyokh sites resulted from simultaneous deaths of a large number of animals probably herd family groups in one or several seasons it is very probable that the deposits in both cases were not of cultural origin the formation of the burials is a direct consequence of short but strong climatic warming bolling oscillation that resulted in many unfavorable environmental conditions among these the increase of snow cover and stronger spring floods were very notable bolling warming is a model of the large scale holocene event mass death of mammoths during the bolling phase was a prelude to their final extinction

fluvial geomorphology a perspective on current status and methods fluvial geomorphology seeks to study river landform history understand formative processes and predict changes using a combination of field observation experimental studies and numerical models a resurgence in fluvial geomorphology is taking place fostered for example by its interaction with river engineering and the availability of new analytical methods instrumentation and techniques these have enabled development of new applications in river management landscape restoration hazard studies river history and geoarchaeology this paper presents a perspective on recent advances in fluvial geomorphology and introduces a selection of papers presented during the fluvial geomorphology and palaeohydrology session within the sixth international conference on geomorphology held in zaragoza spain in september 2005